Revert change (sorry!)

Fix lexer range calculation for tokens

.gitignore

@@ -1,3 +1,5 @@
 .conche/
 .build/
 Packages/
+Package.pins
+*.xcodeproj

.swift-version

@@ -1 +0,0 @@
-3.0.1

.travis.yml

@@ -1,11 +1,19 @@
-os:
-- osx
-- linux
+matrix:
+  include:
+    - os: osx
+      osx_image: xcode9.4
+      env: SWIFT_VERSION=4.1
+    - os: osx
+      osx_image: xcode10
+      env: SWIFT_VERSION=4.2
+    - os: linux
+      env: SWIFT_VERSION=4.1
+    - os: linux
+      env: SWIFT_VERSION=4.2
 language: generic
 sudo: required
 dist: trusty
-osx_image: xcode8
 install:
-- eval "$(curl -sL https://gist.githubusercontent.com/kylef/5c0475ff02b7c7671d2a/raw/9f442512a46d7a2af7b850d65a7e9bd31edfb09b/swiftenv-install.sh)"
+  - eval "$(curl -sL https://swiftenv.fuller.li/install.sh)"
 script:
 - swift test

CHANGELOG.md

@@ -1,5 +1,220 @@
 # Stencil Changelog
 
+## 0.13.1
+
+### Bug Fixes
+
+- Fixed a bug in Stencil 0.13 where tags without spaces were incorrectly parsed.  
+  [David Jennes](https://github.com/djbe)
+  [#252](https://github.com/stencilproject/Stencil/pull/252)
+
+
+## 0.13.0
+
+### Breaking
+
+- Now requires Swift 4.1 or newer.  
+  [Yonas Kolb](https://github.com/yonaskolb)
+  [#228](https://github.com/stencilproject/Stencil/pull/228)
+- You can now use parentheses in boolean expressions to change operator precedence.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#165](https://github.com/stencilproject/Stencil/pull/165)
+- Added method to add boolean filters with their negative counterparts.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#160](https://github.com/stencilproject/Stencil/pull/160)
+
+### Enhancements
+
+- Now you can conditionally render variables with `{{ variable if condition }}`, which is a shorthand for `{% if condition %}{{ variable }}{% endif %}`. You can also use `else` like `{{ variable1 if condition else variable2 }}`, which is a shorthand for `{% if condition %}{{ variable1 }}{% else %}{{ variable2 }}{% endif %}`  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#243](https://github.com/stencilproject/Stencil/pull/243)
+- Now you can access string characters by index or get string length the same was as if it was an array, i.e. `{{ 'string'.first }}`, `{{ 'string'.last }}`, `{{ 'string'.1 }}`, `{{ 'string'.count }}`.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#245](https://github.com/stencilproject/Stencil/pull/245)
+
+### Bug Fixes
+
+- Fixed the performance issues introduced in Stencil 0.12 with the error log improvements.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#230](https://github.com/stencilproject/Stencil/pull/230)
+- Now accessing undefined keys in NSObject does not cause runtime crash and instead renders empty string.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#234](https://github.com/stencilproject/Stencil/pull/234)
+- `for` tag: When iterating over a dictionary the keys will now always be sorted (in an ascending order) to ensure consistent output generation.  
+  [David Jennes](https://github.com/djbe)
+  [#240](https://github.com/stencilproject/Stencil/pull/240)
+
+### Internal Changes
+
+- Updated the codebase to use Swift 4 features.  
+  [David Jennes](https://github.com/djbe)
+  [#239](https://github.com/stencilproject/Stencil/pull/239)
+- Update to Spectre 0.9.0.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#247](https://github.com/stencilproject/Stencil/pull/247)
+- Optimise Scanner performance.  
+  [Eric Thorpe](https://github.com/trametheka)
+  [Sébastien Duperron](https://github.com/Liquidsoul)
+  [David Jennes](https://github.com/djbe)
+  [#226](https://github.com/stencilproject/Stencil/pull/226)
+
+
+## 0.12.1
+
+### Internal Changes
+
+- Updated the PathKit dependency to 0.9.0 in CocoaPods, to be in line with SPM.  
+  [David Jennes](https://github.com/djbe)
+  [#227](https://github.com/stencilproject/Stencil/pull/227)
+
+
+## 0.12.0
+
+### Enhancements
+
+- Added an optional second parameter to the `include` tag for passing a sub context to the included file.  
+  [Yonas Kolb](https://github.com/yonaskolb)
+  [#214](https://github.com/stencilproject/Stencil/pull/214)
+- Variables now support the subscript notation. For example, if you have a variable `key = "name"`, and an
+  object `item = ["name": "John"]`, then `{{ item[key] }}` will evaluate to "John".  
+  [David Jennes](https://github.com/djbe)
+  [#215](https://github.com/stencilproject/Stencil/pull/215)
+- Adds support for using spaces in filter expression.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#178](https://github.com/stencilproject/Stencil/pull/178)
+- Improvements in error reporting.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#167](https://github.com/stencilproject/Stencil/pull/167)
+
+### Bug Fixes
+
+- Fixed using quote as a filter parameter.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#210](https://github.com/stencilproject/Stencil/pull/210)
+
+
+## 0.11.0 (2018-04-04)
+
+### Enhancements
+
+- Added support for resolving superclass properties for not-NSObject subclasses.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#152](https://github.com/stencilproject/Stencil/pull/152)
+- The `{% for %}` tag can now iterate over tuples, structures and classes via
+  their stored properties.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#172](https://github.com/stencilproject/Stencil/pull/173)
+- Added `split` filter.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#187](https://github.com/stencilproject/Stencil/pull/187)
+- Allow default string filters to be applied to arrays.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#190](https://github.com/stencilproject/Stencil/pull/190)
+- Similar filters are suggested when unknown filter is used.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#186](https://github.com/stencilproject/Stencil/pull/186)
+- Added `indent` filter.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#188](https://github.com/stencilproject/Stencil/pull/188)
+- Allow using new lines inside tags.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#202](https://github.com/stencilproject/Stencil/pull/202)
+- Added support for iterating arrays of tuples.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#177](https://github.com/stencilproject/Stencil/pull/177)
+- Added support for ranges in if-in expression.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#193](https://github.com/stencilproject/Stencil/pull/193)
+- Added property `forloop.length` to get number of items in the loop.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#171](https://github.com/stencilproject/Stencil/pull/171)
+- Now you can construct ranges for loops using `a...b` syntax, i.e. `for i in 1...array.count`.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#192](https://github.com/stencilproject/Stencil/pull/192)
+
+### Bug Fixes
+
+- Fixed rendering `{{ block.super }}` with several levels of inheritance.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#154](https://github.com/stencilproject/Stencil/pull/154)
+- Fixed checking dictionary values for nil in `default` filter.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#162](https://github.com/stencilproject/Stencil/pull/162)
+- Fixed comparing string variables with string literals, in Swift 4 string literals became `Substring` and thus couldn't be directly compared to strings.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#168](https://github.com/stencilproject/Stencil/pull/168)
+- Integer literals now resolve into Int values, not Float.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#181](https://github.com/stencilproject/Stencil/pull/181)
+- Fixed accessing properties of optional properties via reflection.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#204](https://github.com/stencilproject/Stencil/pull/204)
+- No longer render optional values in arrays as `Optional(..)`.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#205](https://github.com/stencilproject/Stencil/pull/205)
+- Fixed subscription tuples by value index, i.e. `{{ tuple.0 }}`.  
+  [Ilya Puchka](https://github.com/ilyapuchka)
+  [#172](https://github.com/stencilproject/Stencil/pull/172)
+
+
+## 0.10.1
+
+### Enhancements
+
+- Add support for Xcode 9.1.
+
+## 0.10.0
+
+### Enhancements
+
+- Adds `counter0` to for loop context allowing you to get the current index of
+  the for loop 0 indexed.
+- Introduces a new `DictionaryLoader` for loading templates from a Swift
+  Dictionary.
+- Added `in` expression in if tag for strings and arrays of hashable types
+- You can now access the amount of items in a dictionary using the `count`
+  property.
+
+### Bug Fixes
+
+- Fixes a potential crash when using the `{% for %}` template tag with the
+  incorrect amount of arguments.
+- Fixes a potential crash when using incomplete tokens in a template for
+  example, `{%%}` or `{{}}`.
+- Fixes evaluating nil properties as true
+
+
+## 0.9.0
+
+### Enhancements
+
+- `for` block now can contain `where` expression to filter array items. For example `{% for item in items where item > 1 %}` is now supported.
+- `if` blocks may now contain else if (`elif`) conditions.
+
+  ```html+django
+  {% if one or two and not three %}
+    one or two but not three
+  {% elif four %}
+    four
+  {% else %}
+    not one, two, or four
+  {% endif %}
+  ```
+
+- `for` block now allows you to iterate over array of tuples or dictionaries.
+
+  ```html+django
+  {% for key,value in thing %}
+    <li>{{ key }}: {{ value }}</li>
+  {% endfor %}
+  ```
+
+### Bug Fixes
+
+- You can now use literal filter arguments which contain quotes.
+  [#98](https://github.com/kylef/Stencil/pull/98)
+
+
 ## 0.8.0
 
 ### Breaking
@@ -140,10 +355,10 @@
 ### Bug Fixes
 
 - Variables (`{{ variable.5 }}`) that reference an array index at an unknown
-  index will now resolve to `nil` instead of causing a crash.
+  index will now resolve to `nil` instead of causing a crash.  
   [#72](https://github.com/kylef/Stencil/issues/72)
 
-- Templates can now extend templates that extend other templates.
+- Templates can now extend templates that extend other templates.  
   [#60](https://github.com/kylef/Stencil/issues/60)
 
 - If comparisons will now treat 0 and below numbers as negative.

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2014, Kyle Fuller
+Copyright (c) 2018, Kyle Fuller
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
@@ -21,4 +21,3 @@ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-

Package.resolved

@@ -0,0 +1,25 @@
+{
+  "object": {
+    "pins": [
+      {
+        "package": "PathKit",
+        "repositoryURL": "https://github.com/kylef/PathKit.git",
+        "state": {
+          "branch": null,
+          "revision": "e2f5be30e4c8f531c9c1e8765aa7b71c0a45d7a0",
+          "version": "0.9.2"
+        }
+      },
+      {
+        "package": "Spectre",
+        "repositoryURL": "https://github.com/kylef/Spectre.git",
+        "state": {
+          "branch": null,
+          "revision": "f14ff47f45642aa5703900980b014c2e9394b6e5",
+          "version": "0.9.0"
+        }
+      }
+    ]
+  },
+  "version": 1
+}

Package.swift

@@ -1,11 +1,22 @@
+// swift-tools-version:4.1
 import PackageDescription
 
 let package = Package(
   name: "Stencil",
+  products: [
+    .library(name: "Stencil", targets: ["Stencil"])
+  ],
   dependencies: [
-    .Package(url: "https://github.com/kylef/PathKit.git", majorVersion: 0, minor: 8),
-
-    // https://github.com/apple/swift-package-manager/pull/597
-    .Package(url: "https://github.com/kylef/Spectre.git", majorVersion: 0, minor: 7),
+    .package(url: "https://github.com/kylef/PathKit.git", from: "0.9.0"),
+    .package(url: "https://github.com/kylef/Spectre.git", from: "0.9.0")
+  ],
+  targets: [
+    .target(name: "Stencil", dependencies: [
+      "PathKit"
+    ], path: "Sources"),
+    .testTarget(name: "StencilTests", dependencies: [
+      "Stencil",
+      "Spectre"
+    ])
   ]
 )

Package@swift-4.2.swift

@@ -0,0 +1,23 @@
+// swift-tools-version:4.2
+import PackageDescription
+
+let package = Package(
+  name: "Stencil",
+  products: [
+    .library(name: "Stencil", targets: ["Stencil"])
+  ],
+  dependencies: [
+    .package(url: "https://github.com/kylef/PathKit.git", from: "0.9.0"),
+    .package(url: "https://github.com/kylef/Spectre.git", from: "0.9.0")
+  ],
+  targets: [
+    .target(name: "Stencil", dependencies: [
+      "PathKit"
+    ], path: "Sources"),
+    .testTarget(name: "StencilTests", dependencies: [
+      "Stencil",
+      "Spectre"
+    ])
+  ],
+  swiftLanguageVersions: [.v4, .v4_2]
+)

README.md

@@ -1,6 +1,6 @@
 # Stencil
 
-[![Build Status](https://travis-ci.org/kylef/Stencil.svg?branch=master)](https://travis-ci.org/kylef/Stencil)
+[![Build Status](https://travis-ci.org/stencilproject/Stencil.svg?branch=master)](https://travis-ci.org/stencilproject/Stencil)
 
 Stencil is a simple and powerful template language for Swift. It provides a
 syntax similar to Django and Mustache. If you're familiar with these, you will
@@ -33,8 +33,8 @@ let context = [
   ]
 ]
 
-let environment = Environment(loader: FileSystemLoader(paths: ["templates/"])
-let rendered = try environment.renderTemplate(name: context)
+let environment = Environment(loader: FileSystemLoader(paths: ["templates/"]))
+let rendered = try environment.renderTemplate(name: "article_list.html", context: context)
 
 print(rendered)
 ```
@@ -63,6 +63,13 @@ Resources to help you integrate Stencil into a Swift project:
 - [API Reference](http://stencil.fuller.li/en/latest/api.html)
 - [Custom Template Tags and Filters](http://stencil.fuller.li/en/latest/custom-template-tags-and-filters.html)
 
+## Projects that use Stencil
+
+[Sourcery](https://github.com/krzysztofzablocki/Sourcery),
+[SwiftGen](https://github.com/SwiftGen/SwiftGen),
+[Kitura](https://github.com/IBM-Swift/Kitura),
+[Weaver](https://github.com/scribd/Weaver)
+
 ## License
 
 Stencil is licensed under the BSD license. See [LICENSE](LICENSE) for more

Sources/Context.swift

@@ -3,7 +3,7 @@ public class Context {
   var dictionaries: [[String: Any?]]
 
   public let environment: Environment
-
+  
   init(dictionary: [String: Any]? = nil, environment: Environment? = nil) {
     if let dictionary = dictionary {
       dictionaries = [dictionary]
@@ -42,7 +42,7 @@ public class Context {
   }
 
   /// Pop the last level off of the Context
-  fileprivate func pop() -> [String: Any]? {
+  fileprivate func pop() -> [String: Any?]? {
     return dictionaries.popLast()
   }
 

Sources/Environment.swift

@@ -1,10 +1,13 @@
 public struct Environment {
   public let templateClass: Template.Type
-  public let extensions: [Extension]
+  public var extensions: [Extension]
 
   public var loader: Loader?
 
-  public init(loader: Loader? = nil, extensions: [Extension]? = nil, templateClass: Template.Type = Template.self) {
+  public init(loader: Loader? = nil,
+              extensions: [Extension]? = nil,
+              templateClass: Template.Type = Template.self) {
+
     self.templateClass = templateClass
     self.loader = loader
     self.extensions = (extensions ?? []) + [DefaultExtension()]
@@ -28,11 +31,18 @@ public struct Environment {
 
   public func renderTemplate(name: String, context: [String: Any]? = nil) throws -> String {
     let template = try loadTemplate(name: name)
-    return try template.render(context)
+    return try render(template: template, context: context)
   }
 
   public func renderTemplate(string: String, context: [String: Any]? = nil) throws -> String {
     let template = templateClass.init(templateString: string, environment: self)
+    return try render(template: template, context: context)
+  }
+
+  func render(template: Template, context: [String: Any]?) throws -> String {
+    // update template environment as it can be created from string literal with default environment
+    template.environment = self
     return try template.render(context)
   }
+
 }

Sources/Errors.swift

@@ -17,3 +17,67 @@ public class TemplateDoesNotExist: Error, CustomStringConvertible {
     return "Template named `\(templates)` does not exist. No loaders found"
   }
 }
+
+public struct TemplateSyntaxError : Error, Equatable, CustomStringConvertible {
+  public let reason: String
+  public var description: String { return reason }
+  public internal(set) var token: Token?
+  public internal(set) var stackTrace: [Token]
+  public var templateName: String? { return token?.sourceMap.filename }
+  var allTokens: [Token] {
+    return stackTrace + (token.map({ [$0] }) ?? [])
+  }
+
+  public init(reason: String, token: Token? = nil, stackTrace: [Token] = []) {
+    self.reason = reason
+    self.stackTrace = stackTrace
+    self.token = token
+  }
+
+  public init(_ description: String) {
+    self.init(reason: description)
+  }
+}
+
+extension Error {
+  func withToken(_ token: Token?) -> Error {
+    if var error = self as? TemplateSyntaxError {
+      error.token = error.token ?? token
+      return error
+    } else {
+      return TemplateSyntaxError(reason: "\(self)", token: token)
+    }
+  }
+}
+
+public protocol ErrorReporter: class {
+  func renderError(_ error: Error) -> String
+}
+
+open class SimpleErrorReporter: ErrorReporter {
+
+  open func renderError(_ error: Error) -> String {
+    guard let templateError = error as? TemplateSyntaxError else { return error.localizedDescription }
+
+    func describe(token: Token) -> String {
+      let templateName = token.sourceMap.filename ?? ""
+      let location = token.sourceMap.location
+      let highlight = """
+        \(String(Array(repeating: " ", count: location.lineOffset)))\
+        ^\(String(Array(repeating: "~", count: max(token.contents.count - 1, 0))))
+        """
+
+      return """
+        \(templateName)\(location.lineNumber):\(location.lineOffset): error: \(templateError.reason)
+        \(location.content)
+        \(highlight)
+        """
+    }
+
+    var descriptions = templateError.stackTrace.reduce([]) { $0 + [describe(token: $1)] }
+    let description = templateError.token.map(describe(token:)) ?? templateError.reason
+    descriptions.append(description)
+    return descriptions.joined(separator: "\n")
+  }
+
+}

Sources/Expression.swift

@@ -85,6 +85,41 @@ final class NotExpression: Expression, PrefixOperator, CustomStringConvertible {
   }
 }
 
+final class InExpression: Expression, InfixOperator, CustomStringConvertible {
+  let lhs: Expression
+  let rhs: Expression
+
+  init(lhs: Expression, rhs: Expression) {
+    self.lhs = lhs
+    self.rhs = rhs
+  }
+
+  var description: String {
+    return "(\(lhs) in \(rhs))"
+  }
+
+  func evaluate(context: Context) throws -> Bool {
+    if let lhs = lhs as? VariableExpression, let rhs = rhs as? VariableExpression {
+      let lhsValue = try lhs.variable.resolve(context)
+      let rhsValue = try rhs.variable.resolve(context)
+
+      if let lhs = lhsValue as? AnyHashable, let rhs = rhsValue as? [AnyHashable] {
+        return rhs.contains(lhs)
+      } else if let lhs = lhsValue as? Int, let rhs = rhsValue as? CountableClosedRange<Int> {
+        return rhs.contains(lhs)
+      } else if let lhs = lhsValue as? Int, let rhs = rhsValue as? CountableRange<Int> {
+        return rhs.contains(lhs)
+      } else if let lhs = lhsValue as? String, let rhs = rhsValue as? String {
+        return rhs.contains(lhs)
+      } else if lhsValue == nil && rhsValue == nil {
+        return true
+      }
+    }
+
+    return false
+  }
+
+}
 
 final class OrExpression: Expression, InfixOperator, CustomStringConvertible {
   let lhs: Expression

Sources/Extension.swift

@@ -15,9 +15,18 @@ open class Extension {
   /// Registers a simple template tag with a name and a handler
   public func registerSimpleTag(_ name: String, handler: @escaping (Context) throws -> String) {
     registerTag(name, parser: { parser, token in
-      return SimpleNode(handler: handler)
+      return SimpleNode(token: token, handler: handler)
     })
   }
+  
+  /// Registers boolean filter with it's negative counterpart
+  public func registerFilter(name: String, negativeFilterName: String, filter: @escaping (Any?) throws -> Bool?) {
+    filters[name] = .simple(filter)
+    filters[negativeFilterName] = .simple {
+      guard let result = try filter($0) else { return nil }
+      return !result
+    }
+  }
 
   /// Registers a template filter with the given name
   public func registerFilter(_ name: String, filter: @escaping (Any?) throws -> Any?) {
@@ -42,9 +51,9 @@ class DefaultExtension: Extension {
     registerTag("for", parser: ForNode.parse)
     registerTag("if", parser: IfNode.parse)
     registerTag("ifnot", parser: IfNode.parse_ifnot)
-#if !os(Linux)
-    registerTag("now", parser: NowNode.parse)
-#endif
+    #if !os(Linux)
+      registerTag("now", parser: NowNode.parse)
+    #endif
     registerTag("include", parser: IncludeNode.parse)
     registerTag("extends", parser: ExtendsNode.parse)
     registerTag("block", parser: BlockNode.parse)
@@ -57,6 +66,8 @@ class DefaultExtension: Extension {
     registerFilter("uppercase", filter: uppercase)
     registerFilter("lowercase", filter: lowercase)
     registerFilter("join", filter: joinFilter)
+    registerFilter("split", filter: splitFilter)
+    registerFilter("indent", filter: indentFilter)
   }
 }
 

Sources/FilterTag.swift

@@ -1,6 +1,7 @@
 class FilterNode : NodeType {
   let resolvable: Resolvable
   let nodes: [NodeType]
+  let token: Token?
 
   class func parse(_ parser: TokenParser, token: Token) throws -> NodeType {
     let bits = token.components()
@@ -15,20 +16,21 @@ class FilterNode : NodeType {
       throw TemplateSyntaxError("`endfilter` was not found.")
     }
 
-    let resolvable = try parser.compileFilter("filter_value|\(bits[1])")
-    return FilterNode(nodes: blocks, resolvable: resolvable)
+    let resolvable = try parser.compileFilter("filter_value|\(bits[1])", containedIn: token)
+    return FilterNode(nodes: blocks, resolvable: resolvable, token: token)
   }
 
-  init(nodes: [NodeType], resolvable: Resolvable) {
+  init(nodes: [NodeType], resolvable: Resolvable, token: Token) {
     self.nodes = nodes
     self.resolvable = resolvable
+    self.token = token
   }
 
   func render(_ context: Context) throws -> String {
     let value = try renderNodes(nodes, context)
 
     return try context.push(dictionary: ["filter_value": value]) {
-      return try VariableNode(variable: resolvable).render(context)
+      return try VariableNode(variable: resolvable, token: token).render(context)
     }
   }
 }

Sources/Filters.swift

@@ -1,17 +1,30 @@
 func capitalise(_ value: Any?) -> Any? {
-  return stringify(value).capitalized
+  if let array = value as? [Any?] {
+    return array.map { stringify($0).capitalized }
+  } else {
+    return stringify(value).capitalized
+  }
 }
 
 func uppercase(_ value: Any?) -> Any? {
-  return stringify(value).uppercased()
+  if let array = value as? [Any?] {
+    return array.map { stringify($0).uppercased() }
+  } else {
+    return stringify(value).uppercased()
+  }
 }
 
 func lowercase(_ value: Any?) -> Any? {
-  return stringify(value).lowercased()
+  if let array = value as? [Any?] {
+    return array.map { stringify($0).lowercased() }
+  } else {
+    return stringify(value).lowercased()
+  }
 }
 
 func defaultFilter(value: Any?, arguments: [Any?]) -> Any? {
-  if let value = value {
+  // value can be optional wrapping nil, so this way we check for underlying value
+  if let value = value, String(describing: value) != "nil" {
     return value
   }
 
@@ -39,3 +52,66 @@ func joinFilter(value: Any?, arguments: [Any?]) throws -> Any? {
 
   return value
 }
+
+func splitFilter(value: Any?, arguments: [Any?]) throws -> Any? {
+  guard arguments.count < 2 else {
+    throw TemplateSyntaxError("'split' filter takes a single argument")
+  }
+
+  let separator = stringify(arguments.first ?? " ")
+  if let value = value as? String {
+    return value.components(separatedBy: separator)
+  }
+
+  return value
+}
+
+func indentFilter(value: Any?, arguments: [Any?]) throws -> Any? {
+  guard arguments.count <= 3 else {
+    throw TemplateSyntaxError("'indent' filter can take at most 3 arguments")
+  }
+
+  var indentWidth = 4
+  if arguments.count > 0 {
+    guard let value = arguments[0] as? Int else {
+      throw TemplateSyntaxError("""
+        'indent' filter width argument must be an Integer (\(String(describing: arguments[0])))
+        """)
+    }
+    indentWidth = value
+  }
+
+  var indentationChar = " "
+  if arguments.count > 1 {
+    guard let value = arguments[1] as? String else {
+      throw TemplateSyntaxError("""
+        'indent' filter indentation argument must be a String (\(String(describing: arguments[1]))
+        """)
+    }
+    indentationChar = value
+  }
+
+  var indentFirst = false
+  if arguments.count > 2 {
+    guard let value = arguments[2] as? Bool else {
+      throw TemplateSyntaxError("'indent' filter indentFirst argument must be a Bool")
+    }
+    indentFirst = value
+  }
+
+  let indentation = [String](repeating: indentationChar, count: indentWidth).joined(separator: "")
+  return indent(stringify(value), indentation: indentation, indentFirst: indentFirst)
+}
+
+
+func indent(_ content: String, indentation: String, indentFirst: Bool) -> String {
+  guard !indentation.isEmpty else { return content }
+
+  var lines = content.components(separatedBy: .newlines)
+  let firstLine = (indentFirst ? indentation : "") + lines.removeFirst()
+  let result = lines.reduce([firstLine]) { (result, line) in
+    return result + [(line.isEmpty ? "" : "\(indentation)\(line)")]
+  }
+  return result.joined(separator: "\n")
+}
+

Sources/ForTag.swift

@@ -1,20 +1,38 @@
+import Foundation
+
 class ForNode : NodeType {
   let resolvable: Resolvable
-  let loopVariable:String
+  let loopVariables: [String]
   let nodes:[NodeType]
   let emptyNodes: [NodeType]
+  let `where`: Expression?
+  let token: Token?
 
   class func parse(_ parser:TokenParser, token:Token) throws -> NodeType {
     let components = token.components()
 
-    guard components.count == 4 && components[2] == "in" else {
-      throw TemplateSyntaxError("'for' statements should use the following 'for x in y' `\(token.contents)`.")
+    func hasToken(_ token: String, at index: Int) -> Bool {
+      return components.count > (index + 1) && components[index] == token
     }
 
-    let loopVariable = components[1]
-    let variable = components[3]
+    func endsOrHasToken(_ token: String, at index: Int) -> Bool {
+      return components.count == index || hasToken(token, at: index)
+    }
 
-    var emptyNodes = [NodeType]()
+    guard hasToken("in", at: 2) && endsOrHasToken("where", at: 4) else {
+      throw TemplateSyntaxError("'for' statements should use the syntax: `for <x> in <y> [where <condition>]`.")
+    }
+
+    let loopVariables = components[1]
+      .split(separator: ",")
+      .map(String.init)
+      .map { $0.trim(character: " ") }
+
+    let resolvable = try parser.compileResolvable(components[3], containedIn: token)
+
+    let `where` = hasToken("where", at: 4)
+      ? try parseExpression(components: Array(components.suffix(from: 5)), tokenParser: parser, token: token)
+      : nil
 
     let forNodes = try parser.parse(until(["endfor", "empty"]))
 
@@ -22,38 +40,112 @@ class ForNode : NodeType {
       throw TemplateSyntaxError("`endfor` was not found.")
     }
 
+    var emptyNodes = [NodeType]()
     if token.contents == "empty" {
       emptyNodes = try parser.parse(until(["endfor"]))
       _ = parser.nextToken()
     }
 
-    let filter = try parser.compileFilter(variable)
-    return ForNode(resolvable: filter, loopVariable: loopVariable, nodes: forNodes, emptyNodes:emptyNodes)
+    return ForNode(resolvable: resolvable, loopVariables: loopVariables, nodes: forNodes, emptyNodes: emptyNodes, where: `where`, token: token)
   }
 
-  init(resolvable: Resolvable, loopVariable:String, nodes:[NodeType], emptyNodes:[NodeType]) {
+  init(resolvable: Resolvable, loopVariables: [String], nodes: [NodeType], emptyNodes: [NodeType], where: Expression? = nil, token: Token? = nil) {
     self.resolvable = resolvable
-    self.loopVariable = loopVariable
+    self.loopVariables = loopVariables
     self.nodes = nodes
     self.emptyNodes = emptyNodes
+    self.where = `where`
+    self.token = token
+  }
+
+  func push<Result>(value: Any, context: Context, closure: () throws -> (Result)) throws -> Result {
+    if loopVariables.isEmpty {
+      return try context.push() {
+        return try closure()
+      }
+    }
+
+    let valueMirror = Mirror(reflecting: value)
+    if case .tuple? = valueMirror.displayStyle {
+      if loopVariables.count > Int(valueMirror.children.count) {
+        throw TemplateSyntaxError("Tuple '\(value)' has less values than loop variables")
+      }
+      var variablesContext = [String: Any]()
+      valueMirror.children.prefix(loopVariables.count).enumerated().forEach({ (offset, element) in
+        if loopVariables[offset] != "_" {
+          variablesContext[loopVariables[offset]] = element.value
+        }
+      })
+
+      return try context.push(dictionary: variablesContext) {
+        return try closure()
+      }
+    }
+
+    return try context.push(dictionary: [loopVariables.first!: value]) {
+      return try closure()
+    }
   }
 
   func render(_ context: Context) throws -> String {
-    let values = try resolvable.resolve(context)
+    let resolved = try resolvable.resolve(context)
 
-    if let values = values as? [Any] , values.count > 0 {
+    var values: [Any]
+
+    if let dictionary = resolved as? [String: Any], !dictionary.isEmpty {
+      values = dictionary.sorted { $0.key < $1.key }
+    } else if let array = resolved as? [Any] {
+      values = array
+    } else if let range = resolved as? CountableClosedRange<Int> {
+      values = Array(range)
+    } else if let range = resolved as? CountableRange<Int> {
+      values = Array(range)
+    } else if let resolved = resolved {
+      let mirror = Mirror(reflecting: resolved)
+      switch mirror.displayStyle {
+      case .struct?, .tuple?:
+        values = Array(mirror.children)
+      case .class?:
+        var children = Array(mirror.children)
+        var currentMirror: Mirror? = mirror
+        while let superclassMirror = currentMirror?.superclassMirror {
+          children.append(contentsOf: superclassMirror.children)
+          currentMirror = superclassMirror
+        }
+        values = Array(children)
+      default:
+        values = []
+      }
+    } else {
+      values = []
+    }
+
+    if let `where` = self.where {
+      values = try values.filter({ item -> Bool in
+        return try push(value: item, context: context) {
+          try `where`.evaluate(context: context)
+        }
+      })
+    }
+
+    if !values.isEmpty {
       let count = values.count
+
       return try values.enumerated().map { index, item in
         let forContext: [String: Any] = [
           "first": index == 0,
           "last": index == (count - 1),
           "counter": index + 1,
+          "counter0": index,
+          "length": count
         ]
 
-        return try context.push(dictionary: [loopVariable: item, "forloop": forContext]) {
-          try renderNodes(nodes, context)
+        return try context.push(dictionary: ["forloop": forContext]) {
+          return try push(value: item, context: context) {
+            try renderNodes(nodes, context)
+          }
         }
-      }.joined(separator: "")
+        }.joined(separator: "")
     }
 
     return try context.push {

Sources/IfTag.swift

@@ -14,6 +14,7 @@ enum Operator {
 
 
 let operators: [Operator] = [
+  .infix("in", 5, InExpression.self),
   .infix("or", 6, OrExpression.self),
   .infix("and", 7, AndExpression.self),
   .prefix("not", 8, NotExpression.self),
@@ -37,10 +38,11 @@ func findOperator(name: String) -> Operator? {
 }
 
 
-enum IfToken {
-  case infix(name: String, bindingPower: Int, op: InfixOperator.Type)
-  case prefix(name: String, bindingPower: Int, op: PrefixOperator.Type)
+indirect enum IfToken {
+  case infix(name: String, bindingPower: Int, operatorType: InfixOperator.Type)
+  case prefix(name: String, bindingPower: Int, operatorType: PrefixOperator.Type)
   case variable(Resolvable)
+  case subExpression(Expression)
   case end
 
   var bindingPower: Int {
@@ -51,8 +53,10 @@ enum IfToken {
       return bindingPower
     case .variable(_):
       return 0
+    case .subExpression(_):
+      return 0
     case .end:
-        return 0
+      return 0
     }
   }
 
@@ -65,6 +69,8 @@ enum IfToken {
       return op.init(expression: expression)
     case .variable(let variable):
       return VariableExpression(variable: variable)
+    case .subExpression(let expression):
+      return expression
     case .end:
       throw TemplateSyntaxError("'if' expression error: end")
     }
@@ -79,6 +85,8 @@ enum IfToken {
       throw TemplateSyntaxError("'if' expression error: prefix operator '\(name)' was called with a left hand side")
     case .variable(let variable):
       throw TemplateSyntaxError("'if' expression error: variable '\(variable)' was called with a left hand side")
+    case .subExpression(_):
+      throw TemplateSyntaxError("'if' expression error: sub expression was called with a left hand side")
     case .end:
       throw TemplateSyntaxError("'if' expression error: end")
     }
@@ -99,21 +107,71 @@ final class IfExpressionParser {
   let tokens: [IfToken]
   var position: Int = 0
 
-  init(components: [String], tokenParser: TokenParser) throws {
-    self.tokens = try components.map { component in
-      if let op = findOperator(name: component) {
-        switch op {
-        case .infix(let name, let bindingPower, let cls):
-          return .infix(name: name, bindingPower: bindingPower, op: cls)
-        case .prefix(let name, let bindingPower, let cls):
-          return .prefix(name: name, bindingPower: bindingPower, op: cls)
-        }
-      }
+  private init(tokens: [IfToken]) {
+    self.tokens = tokens
+  }
+  
+  static func parser(components: [String], tokenParser: TokenParser, token: Token) throws -> IfExpressionParser {
+    return try IfExpressionParser(components: ArraySlice(components), tokenParser: tokenParser, token: token)
+  }
 
-      return .variable(try tokenParser.compileFilter(component))
+  private init(components: ArraySlice<String>, tokenParser: TokenParser, token: Token) throws {
+    var parsedComponents = Set<Int>()
+    var bracketsBalance = 0
+    self.tokens = try zip(components.indices, components).compactMap { (index, component) in
+      guard !parsedComponents.contains(index) else { return nil }
+
+      if component == "(" {
+        bracketsBalance += 1
+        let (expression, parsedCount) = try IfExpressionParser.subExpression(
+          from: components.suffix(from: index + 1),
+          tokenParser: tokenParser,
+          token: token
+        )
+        parsedComponents.formUnion(Set(index...(index + parsedCount)))
+        return .subExpression(expression)
+      } else if component == ")" {
+        bracketsBalance -= 1
+        if bracketsBalance < 0 {
+          throw TemplateSyntaxError("'if' expression error: missing opening bracket")
+        }
+        parsedComponents.insert(index)
+        return nil
+      } else {
+        parsedComponents.insert(index)
+        if let op = findOperator(name: component) {
+          switch op {
+          case .infix(let name, let bindingPower, let operatorType):
+            return .infix(name: name, bindingPower: bindingPower, operatorType: operatorType)
+          case .prefix(let name, let bindingPower, let operatorType):
+            return .prefix(name: name, bindingPower: bindingPower, operatorType: operatorType)
+          }
+        }
+        return .variable(try tokenParser.compileResolvable(component, containedIn: token))
+      }
     }
   }
 
+  private static func subExpression(from components: ArraySlice<String>, tokenParser: TokenParser, token: Token) throws -> (Expression, Int) {
+    var bracketsBalance = 1
+    let subComponents = components
+      .prefix(while: {
+        if $0 == "(" {
+            bracketsBalance += 1
+        } else if $0 == ")" {
+            bracketsBalance -= 1
+        }
+        return bracketsBalance != 0
+      })
+    if bracketsBalance > 0 {
+      throw TemplateSyntaxError("'if' expression error: missing closing bracket")
+    }
+
+    let expressionParser = try IfExpressionParser(components: subComponents, tokenParser: tokenParser, token: token)
+    let expression = try expressionParser.parse()
+    return (expression, subComponents.count)
+  }
+  
   var currentToken: IfToken {
     if tokens.count > position {
       return tokens[position]
@@ -153,48 +211,77 @@ final class IfExpressionParser {
   }
 }
 
-
-func parseExpression(components: [String], tokenParser: TokenParser) throws -> Expression {
-  let parser = try IfExpressionParser(components: components, tokenParser: tokenParser)
+func parseExpression(components: [String], tokenParser: TokenParser, token: Token) throws -> Expression {
+  let parser = try IfExpressionParser.parser(components: components, tokenParser: tokenParser, token: token)
   return try parser.parse()
 }
 
+/// Represents an if condition and the associated nodes when the condition
+/// evaluates
+final class IfCondition {
+  let expression: Expression?
+  let nodes: [NodeType]
+
+  init(expression: Expression?, nodes: [NodeType]) {
+    self.expression = expression
+    self.nodes = nodes
+  }
+
+  func render(_ context: Context) throws -> String {
+    return try context.push {
+      return try renderNodes(nodes, context)
+    }
+  }
+}
+
 
 class IfNode : NodeType {
-  let expression: Expression
-  let trueNodes: [NodeType]
-  let falseNodes: [NodeType]
+  let conditions: [IfCondition]
+  let token: Token?
 
   class func parse(_ parser: TokenParser, token: Token) throws -> NodeType {
     var components = token.components()
     components.removeFirst()
-    var trueNodes = [NodeType]()
-    var falseNodes = [NodeType]()
 
-    trueNodes = try parser.parse(until(["endif", "else"]))
+    let expression = try parseExpression(components: components, tokenParser: parser, token: token)
+    let nodes = try parser.parse(until(["endif", "elif", "else"]))
+    var conditions: [IfCondition] = [
+      IfCondition(expression: expression, nodes: nodes)
+    ]
 
-    guard let token = parser.nextToken() else {
+    var nextToken = parser.nextToken()
+    while let current = nextToken, current.contents.hasPrefix("elif") {
+      var components = current.components()
+      components.removeFirst()
+      let expression = try parseExpression(components: components, tokenParser: parser, token: current)
+
+      let nodes = try parser.parse(until(["endif", "elif", "else"]))
+      nextToken = parser.nextToken()
+      conditions.append(IfCondition(expression: expression, nodes: nodes))
+    }
+
+    if let current = nextToken, current.contents == "else" {
+      conditions.append(IfCondition(expression: nil, nodes: try parser.parse(until(["endif"]))))
+      nextToken = parser.nextToken()
+    }
+
+    guard let current = nextToken, current.contents == "endif" else {
       throw TemplateSyntaxError("`endif` was not found.")
     }
 
-    if token.contents == "else" {
-      falseNodes = try parser.parse(until(["endif"]))
-      _ = parser.nextToken()
-    }
-
-    let expression = try parseExpression(components: components, tokenParser: parser)
-    return IfNode(expression: expression, trueNodes: trueNodes, falseNodes: falseNodes)
+    return IfNode(conditions: conditions, token: token)
   }
 
   class func parse_ifnot(_ parser: TokenParser, token: Token) throws -> NodeType {
     var components = token.components()
     guard components.count == 2 else {
-      throw TemplateSyntaxError("'ifnot' statements should use the following 'ifnot condition' `\(token.contents)`.")
+      throw TemplateSyntaxError("'ifnot' statements should use the following syntax 'ifnot condition'.")
     }
     components.removeFirst()
     var trueNodes = [NodeType]()
     var falseNodes = [NodeType]()
 
+    let expression = try parseExpression(components: components, tokenParser: parser, token: token)
     falseNodes = try parser.parse(until(["endif", "else"]))
 
     guard let token = parser.nextToken() else {
@@ -206,25 +293,30 @@ class IfNode : NodeType {
       _ = parser.nextToken()
     }
 
-    let expression = try parseExpression(components: components, tokenParser: parser)
-    return IfNode(expression: expression, trueNodes: trueNodes, falseNodes: falseNodes)
+    return IfNode(conditions: [
+      IfCondition(expression: expression, nodes: trueNodes),
+      IfCondition(expression: nil, nodes: falseNodes),
+      ], token: token)
   }
 
-  init(expression: Expression, trueNodes: [NodeType], falseNodes: [NodeType]) {
-    self.expression = expression
-    self.trueNodes = trueNodes
-    self.falseNodes = falseNodes
+  init(conditions: [IfCondition], token: Token? = nil) {
+    self.conditions = conditions
+    self.token = token
   }
 
   func render(_ context: Context) throws -> String {
-    let truthy = try expression.evaluate(context: context)
+    for condition in conditions {
+      if let expression = condition.expression {
+        let truthy = try expression.evaluate(context: context)
 
-    return try context.push {
-      if truthy {
-        return try renderNodes(trueNodes, context)
+        if truthy {
+          return try condition.render(context)
+        }
       } else {
-        return try renderNodes(falseNodes, context)
+        return try condition.render(context)
       }
     }
+
+    return ""
   }
 }

Sources/Include.swift

@@ -3,19 +3,27 @@ import PathKit
 
 class IncludeNode : NodeType {
   let templateName: Variable
+  let includeContext: String?
+  let token: Token?
 
   class func parse(_ parser: TokenParser, token: Token) throws -> NodeType {
     let bits = token.components()
 
-    guard bits.count == 2 else {
-      throw TemplateSyntaxError("'include' tag takes one argument, the template file to be included")
+    guard bits.count == 2 || bits.count == 3 else {
+      throw TemplateSyntaxError("""
+        'include' tag requires one argument, the template file to be included. \
+        A second optional argument can be used to specify the context that will \
+        be passed to the included file
+        """)
     }
 
-    return IncludeNode(templateName: Variable(bits[1]))
+    return IncludeNode(templateName: Variable(bits[1]), includeContext: bits.count == 3 ? bits[2] : nil, token: token)
   }
 
-  init(templateName: Variable) {
+  init(templateName: Variable, includeContext: String? = nil, token: Token) {
     self.templateName = templateName
+    self.includeContext = includeContext
+    self.token = token
   }
 
   func render(_ context: Context) throws -> String {
@@ -25,8 +33,17 @@ class IncludeNode : NodeType {
 
     let template = try context.environment.loadTemplate(name: templateName)
 
-    return try context.push {
-      return try template.render(context)
+    do {
+      let subContext = includeContext.flatMap { context[$0] as? [String: Any] }
+      return try context.push(dictionary: subContext) {
+        return try template.render(context)
+      }
+    } catch {
+      if let error = error as? TemplateSyntaxError {
+        throw TemplateSyntaxError(reason: error.reason, stackTrace: error.allTokens)
+      } else {
+        throw error
+      }
     }
   }
 }

Sources/Inheritence.swift

@@ -1,14 +1,35 @@
 class BlockContext {
   class var contextKey: String { return "block_context" }
 
-  var blocks: [String: BlockNode]
+  // contains mapping of block names to their nodes and templates where they are defined
+  var blocks: [String: [BlockNode]]
 
   init(blocks: [String: BlockNode]) {
-    self.blocks = blocks
+    self.blocks = [:]
+    blocks.forEach { self.blocks[$0.key] = [$0.value] }
+  }
+
+  func push(_ block: BlockNode, forKey blockName: String) {
+    if var blocks = blocks[blockName] {
+      blocks.append(block)
+      self.blocks[blockName] = blocks
+    } else {
+      self.blocks[blockName] = [block]
+    }
   }
 
   func pop(_ blockName: String) -> BlockNode? {
-    return blocks.removeValue(forKey: blockName)
+    if var blocks = blocks[blockName] {
+      let block = blocks.removeFirst()
+      if blocks.isEmpty {
+        self.blocks.removeValue(forKey: blockName)
+      } else {
+        self.blocks[blockName] = blocks
+      }
+      return block
+    } else {
+      return nil
+    }
   }
 }
 
@@ -29,6 +50,7 @@ extension Collection {
 class ExtendsNode : NodeType {
   let templateName: Variable
   let blocks: [String:BlockNode]
+  let token: Token?
 
   class func parse(_ parser: TokenParser, token: Token) throws -> NodeType {
     let bits = token.components()
@@ -42,7 +64,7 @@ class ExtendsNode : NodeType {
       throw TemplateSyntaxError("'extends' cannot appear more than once in the same template")
     }
 
-    let blockNodes = parsedNodes.flatMap { $0 as? BlockNode }
+    let blockNodes = parsedNodes.compactMap { $0 as? BlockNode }
 
     let nodes = blockNodes.reduce([String: BlockNode]()) { (accumulator, node) -> [String: BlockNode] in
       var dict = accumulator
@@ -50,12 +72,13 @@ class ExtendsNode : NodeType {
       return dict
     }
 
-    return ExtendsNode(templateName: Variable(bits[1]), blocks: nodes)
+    return ExtendsNode(templateName: Variable(bits[1]), blocks: nodes, token: token)
   }
 
-  init(templateName: Variable, blocks: [String: BlockNode]) {
+  init(templateName: Variable, blocks: [String: BlockNode], token: Token) {
     self.templateName = templateName
     self.blocks = blocks
+    self.token = token
   }
 
   func render(_ context: Context) throws -> String {
@@ -63,23 +86,33 @@ class ExtendsNode : NodeType {
       throw TemplateSyntaxError("'\(self.templateName)' could not be resolved as a string")
     }
 
-    let template = try context.environment.loadTemplate(name: templateName)
+    let baseTemplate = try context.environment.loadTemplate(name: templateName)
 
     let blockContext: BlockContext
-    if let context = context[BlockContext.contextKey] as? BlockContext {
-      blockContext = context
-
-      for (key, value) in blocks {
-        if !blockContext.blocks.keys.contains(key) {
-          blockContext.blocks[key] = value
-        }
+    if let currentBlockContext = context[BlockContext.contextKey] as? BlockContext {
+      blockContext = currentBlockContext
+      for (name, block) in blocks {
+        blockContext.push(block, forKey: name)
       }
     } else {
       blockContext = BlockContext(blocks: blocks)
     }
 
-    return try context.push(dictionary: [BlockContext.contextKey: blockContext]) {
-      return try template.render(context)
+    do {
+      // pushes base template and renders it's content
+      // block_context contains all blocks from child templates
+      return try context.push(dictionary: [BlockContext.contextKey: blockContext]) {
+        return try baseTemplate.render(context)
+      }
+    } catch {
+      // if error template is already set (see catch in BlockNode)
+      // and it happend in the same template as current template
+      // there is no need to wrap it in another error
+      if let error = error as? TemplateSyntaxError, error.templateName != token?.sourceMap.filename {
+        throw TemplateSyntaxError(reason: error.reason, stackTrace: error.allTokens)
+      } else {
+        throw error
+      }
     }
   }
 }
@@ -88,6 +121,7 @@ class ExtendsNode : NodeType {
 class BlockNode : NodeType {
   let name: String
   let nodes: [NodeType]
+  let token: Token?
 
   class func parse(_ parser: TokenParser, token: Token) throws -> NodeType {
     let bits = token.components()
@@ -99,21 +133,57 @@ class BlockNode : NodeType {
     let blockName = bits[1]
     let nodes = try parser.parse(until(["endblock"]))
     _ = parser.nextToken()
-    return BlockNode(name:blockName, nodes:nodes)
+    return BlockNode(name:blockName, nodes:nodes, token: token)
   }
 
-  init(name: String, nodes: [NodeType]) {
+  init(name: String, nodes: [NodeType], token: Token) {
     self.name = name
     self.nodes = nodes
+    self.token = token
   }
 
   func render(_ context: Context) throws -> String {
-    if let blockContext = context[BlockContext.contextKey] as? BlockContext, let node = blockContext.pop(name) {
-      return try context.push(dictionary: ["block": ["super": self]]) {
-        return try node.render(context)
+    if let blockContext = context[BlockContext.contextKey] as? BlockContext, let child = blockContext.pop(name) {
+      let childContext = try self.childContext(child, blockContext: blockContext, context: context)
+      // render extension node
+      do {
+        return try context.push(dictionary: childContext) {
+          return try child.render(context)
+        }
+      } catch {
+        throw error.withToken(child.token)
       }
     }
 
     return try renderNodes(nodes, context)
   }
+
+  // child node is a block node from child template that extends this node (has the same name)
+  func childContext(_ child: BlockNode, blockContext: BlockContext, context: Context) throws -> [String: Any] {
+    var childContext: [String: Any] = [BlockContext.contextKey: blockContext]
+
+    if let blockSuperNode = child.nodes.first(where: {
+      if case .variable(let variable, _)? = $0.token, variable == "block.super" { return true }
+      else { return false}
+    }) {
+      do {
+        // render base node so that its content can be used as part of child node that extends it
+        childContext["block"] = ["super": try self.render(context)]
+      } catch {
+        if let error = error as? TemplateSyntaxError {
+          throw TemplateSyntaxError(
+            reason: error.reason,
+            token: blockSuperNode.token,
+            stackTrace: error.allTokens)
+        } else {
+          throw TemplateSyntaxError(
+            reason: "\(error)",
+            token: blockSuperNode.token,
+            stackTrace: [])
+        }
+      }
+    }
+    return childContext
+  }
+
 }

Sources/KeyPath.swift

@@ -0,0 +1,112 @@
+import Foundation
+
+/// A structure used to represent a template variable, and to resolve it in a given context.
+final class KeyPath {
+  private var components = [String]()
+  private var current = ""
+  private var partialComponents = [String]()
+  private var subscriptLevel = 0
+
+  let variable: String
+  let context: Context
+
+  // Split the keypath string and resolve references if possible
+  init(_ variable: String, in context: Context) {
+    self.variable = variable
+    self.context = context
+  }
+
+  func parse() throws -> [String] {
+    defer {
+      components = []
+      current = ""
+      partialComponents = []
+      subscriptLevel = 0
+    }
+
+    for c in variable {
+      switch c {
+      case "." where subscriptLevel == 0:
+        try foundSeparator()
+      case "[":
+        try openBracket()
+      case "]":
+        try closeBracket()
+      default:
+        try addCharacter(c)
+      }
+    }
+    try finish()
+
+    return components
+  }
+
+  private func foundSeparator() throws {
+    if !current.isEmpty {
+      partialComponents.append(current)
+    }
+
+    guard !partialComponents.isEmpty else {
+      throw TemplateSyntaxError("Unexpected '.' in variable '\(variable)'")
+    }
+
+    components += partialComponents
+    current = ""
+    partialComponents = []
+  }
+
+  // when opening the first bracket, we must have a partial component
+  private func openBracket() throws {
+    guard !partialComponents.isEmpty || !current.isEmpty else {
+      throw TemplateSyntaxError("Unexpected '[' in variable '\(variable)'")
+    }
+
+    if subscriptLevel > 0 {
+      current.append("[")
+    } else if !current.isEmpty {
+      partialComponents.append(current)
+      current = ""
+    }
+
+    subscriptLevel += 1
+  }
+
+  // for a closing bracket at root level, try to resolve the reference
+  private func closeBracket() throws {
+    guard subscriptLevel > 0 else {
+      throw TemplateSyntaxError("Unbalanced ']' in variable '\(variable)'")
+    }
+
+    if subscriptLevel > 1 {
+      current.append("]")
+    } else if !current.isEmpty,
+      let value = try Variable(current).resolve(context) {
+      partialComponents.append("\(value)")
+      current = ""
+    } else {
+      throw TemplateSyntaxError("Unable to resolve subscript '\(current)' in variable '\(variable)'")
+    }
+
+    subscriptLevel -= 1
+  }
+
+  private func addCharacter(_ c: Character) throws {
+    guard partialComponents.isEmpty || subscriptLevel > 0 else {
+      throw TemplateSyntaxError("Unexpected character '\(c)' in variable '\(variable)'")
+    }
+
+    current.append(c)
+  }
+
+  private func finish() throws {
+    // check if we have a last piece
+    if !current.isEmpty {
+      partialComponents.append(current)
+    }
+    components += partialComponents
+
+    guard subscriptLevel == 0 else {
+      throw TemplateSyntaxError("Unbalanced subscript brackets in variable '\(variable)'")
+    }
+  }
+}

Sources/Lexer.swift

@@ -1,122 +1,198 @@
+import Foundation
+
+typealias Line = (content: String, number: UInt, range: Range<String.Index>)
+
 struct Lexer {
+  let templateName: String?
   let templateString: String
+  let lines: [Line]
 
-  init(templateString: String) {
+  /// The potential token start characters. In a template these appear after a
+  /// `{` character, for example `{{`, `{%`, `{#`, ...
+  private static let tokenChars: [Unicode.Scalar] = ["{", "%", "#"]
+
+  /// The token end characters, corresponding to their token start characters.
+  /// For example, a variable token starts with `{{` and ends with `}}`
+  private static let tokenCharMap: [Unicode.Scalar: Unicode.Scalar] = [
+    "{": "}",
+    "%": "%",
+    "#": "#"
+  ]
+
+  init(templateName: String? = nil, templateString: String) {
+    self.templateName = templateName
     self.templateString = templateString
+
+    self.lines = templateString.components(separatedBy: .newlines).enumerated().compactMap {
+      guard !$0.element.isEmpty else { return nil }
+      return (content: $0.element, number: UInt($0.offset + 1), templateString.range(of: $0.element)!)
+    }
   }
 
-  func createToken(string:String) -> Token {
+  /// Create a token that will be passed on to the parser, with the given
+  /// content and a range. The content will be tested to see if it's a
+  /// `variable`, a `block` or a `comment`, otherwise it'll default to a simple
+  /// `text` token.
+  ///
+  /// - Parameters:
+  ///   - string: The content string of the token
+  ///   - range: The range within the template content, used for smart
+  ///            error reporting
+  func createToken(string: String, at range: Range<String.Index>) -> Token {
     func strip() -> String {
-      let start = string.index(string.startIndex, offsetBy: 2)
-      let end = string.index(string.endIndex, offsetBy: -2)
-      return string[start..<end].trim(character: " ")
+      guard string.count > 4 else { return "" }
+      let trimmed = String(string.dropFirst(2).dropLast(2))
+        .components(separatedBy: "\n")
+        .filter({ !$0.isEmpty })
+        .map({ $0.trim(character: " ") })
+        .joined(separator: " ")
+      return trimmed
     }
 
-    if string.hasPrefix("{{") {
-      return .variable(value: strip())
-    } else if string.hasPrefix("{%") {
-      return .block(value: strip())
-    } else if string.hasPrefix("{#") {
-      return .comment(value: strip())
+    if string.hasPrefix("{{") || string.hasPrefix("{%") || string.hasPrefix("{#") {
+      let value = strip()
+      let range = templateString.range(of: value, range: range) ?? range
+      let location = rangeLocation(range)
+      let sourceMap = SourceMap(filename: templateName, location: location)
+
+      if string.hasPrefix("{{") {
+        return .variable(value: value, at: sourceMap)
+      } else if string.hasPrefix("{%") {
+        return .block(value: value, at: sourceMap)
+      } else if string.hasPrefix("{#") {
+        return .comment(value: value, at: sourceMap)
+      }
     }
 
-    return .text(value: string)
+    let location = rangeLocation(range)
+    let sourceMap = SourceMap(filename: templateName, location: location)
+    return .text(value: string, at: sourceMap)
   }
 
-  /// Returns an array of tokens from a given template string.
+  /// Transforms the template into a list of tokens, that will eventually be
+  /// passed on to the parser.
+  ///
+  /// - Returns: The list of tokens (see `createToken(string: at:)`).
   func tokenize() -> [Token] {
     var tokens: [Token] = []
 
     let scanner = Scanner(templateString)
-
-    let map = [
-      "{{": "}}",
-      "{%": "%}",
-      "{#": "#}",
-    ]
-
     while !scanner.isEmpty {
-      if let text = scanner.scan(until: ["{{", "{%", "{#"]) {
-        if !text.1.isEmpty {
-          tokens.append(createToken(string: text.1))
+      if let (char, text) = scanner.scanForTokenStart(Lexer.tokenChars) {
+        if !text.isEmpty {
+          tokens.append(createToken(string: text, at: scanner.range))
         }
 
-        let end = map[text.0]!
-        let result = scanner.scan(until: end, returnUntil: true)
-        tokens.append(createToken(string: result))
+        guard let end = Lexer.tokenCharMap[char] else { continue }
+        let result = scanner.scanForTokenEnd(end)
+        tokens.append(createToken(string: result, at: scanner.range))
       } else {
-        tokens.append(createToken(string: scanner.content))
+        tokens.append(createToken(string: scanner.content, at: scanner.range))
         scanner.content = ""
       }
     }
 
     return tokens
   }
+
+  /// Finds the line matching the given range (for a token)
+  ///
+  /// - Parameter range: The range to search for.
+  /// - Returns: The content for that line, the line number and offset within
+  ///            the line.
+  func rangeLocation(_ range: Range<String.Index>) -> ContentLocation {
+    guard let line = self.lines.first(where: { $0.range.contains(range.lowerBound) }) else {
+      return ("", 0, 0)
+    }
+    let offset = templateString.distance(from: line.range.lowerBound, to: range.lowerBound)
+    return (line.content, line.number, offset)
+  }
+
 }
 
-
 class Scanner {
+  let originalContent: String
   var content: String
+  var range: Range<String.Index>
+
+  /// The start delimiter for a token.
+  private static let tokenStartDelimiter: Unicode.Scalar = "{"
+  /// And the corresponding end delimiter for a token.
+  private static let tokenEndDelimiter: Unicode.Scalar = "}"
 
   init(_ content: String) {
+    self.originalContent = content
     self.content = content
+    range = content.startIndex..<content.startIndex
   }
 
   var isEmpty: Bool {
     return content.isEmpty
   }
 
-  func scan(until: String, returnUntil: Bool = false) -> String {
-    if until.isEmpty {
-      return ""
-    }
-
-    var index = content.startIndex
-    while index != content.endIndex {
-      let substring = content.substring(from: index)
-
-      if substring.hasPrefix(until) {
-        let result = content.substring(to: index)
-        content = substring
-
-        if returnUntil {
-          content = content.substring(from: until.endIndex)
-          return result + until
-        }
+  /// Scans for the end of a token, with a specific ending character. If we're
+  /// searching for the end of a block token `%}`, this method receives a `%`.
+  /// The scanner will search for that `%` followed by a `}`.
+  ///
+  /// Note: if the end of a token is found, the `content` and `range`
+  /// properties are updated to reflect this. `content` will be set to what
+  /// remains of the template after the token. `range` will be set to the range
+  /// of the token within the template.
+  ///
+  /// - Parameter tokenChar: The token end character to search for.
+  /// - Returns: The content of a token, or "" if no token end was found.
+  func scanForTokenEnd(_ tokenChar: Unicode.Scalar) -> String {
+    var foundChar = false
 
+    for (index, char) in content.unicodeScalars.enumerated() {
+      if foundChar && char == Scanner.tokenEndDelimiter {
+        let result = String(content.prefix(index + 1))
+        content = String(content.dropFirst(index + 1))
+        range = range.upperBound..<originalContent.index(range.upperBound, offsetBy: index + 1)
         return result
+      } else {
+        foundChar = (char == tokenChar)
       }
-
-      index = content.index(after: index)
     }
 
+    content = ""
     return ""
   }
 
-  func scan(until: [String]) -> (String, String)? {
-    if until.isEmpty {
-      return nil
-    }
+  /// Scans for the start of a token, with a list of potential starting
+  /// characters. To scan for the start of variables (`{{`), blocks (`{%`) and
+  /// comments (`{#`), this method receives the characters `{`, `%` and `#`.
+  /// The scanner will search for a `{`, followed by one of the search
+  /// characters. It will give the found character, and the content that came
+  /// before the token.
+  ///
+  /// Note: if the start of a token is found, the `content` and `range`
+  /// properties are updated to reflect this. `content` will be set to what
+  /// remains of the template starting with the token. `range` will be set to
+  /// the start of the token within the template.
+  ///
+  /// - Parameter tokenChars: List of token start characters to search for.
+  /// - Returns: The found token start character, together with the content
+  ///            before the token, or nil of no token start was found.
+  func scanForTokenStart(_ tokenChars: [Unicode.Scalar]) -> (Unicode.Scalar, String)? {
+    var foundBrace = false
 
-    var index = content.startIndex
-    while index != content.endIndex {
-      let substring = content.substring(from: index)
-      for string in until {
-        if substring.hasPrefix(string) {
-          let result = content.substring(to: index)
-          content = substring
-          return (string, result)
-        }
+    range = range.upperBound..<range.upperBound
+    for (index, char) in content.unicodeScalars.enumerated() {
+      if foundBrace && tokenChars.contains(char) {
+        let result = String(content.prefix(index - 1))
+        content = String(content.dropFirst(index - 1))
+        range = range.upperBound..<originalContent.index(range.upperBound, offsetBy: index - 1)
+        return (char, result)
+      } else {
+        foundBrace = (char == Scanner.tokenStartDelimiter)
       }
-
-      index = content.index(after: index)
     }
 
     return nil
   }
 }
 
-
 extension String {
   func findFirstNot(character: Character) -> String.Index? {
     var index = startIndex
@@ -147,6 +223,8 @@ extension String {
   func trim(character: Character) -> String {
     let first = findFirstNot(character: character) ?? startIndex
     let last = findLastNot(character: character) ?? endIndex
-    return self[first..<last]
+    return String(self[first..<last])
   }
 }
+
+public typealias ContentLocation = (content: String, lineNumber: UInt, lineOffset: Int)

Sources/Loader.swift

@@ -52,7 +52,7 @@ public class FileSystemLoader: Loader, CustomStringConvertible {
       }
 
       let content: String = try templatePath.read()
-      return try environment.templateClass.init(templateString: content, environment: environment, name: name)
+      return environment.templateClass.init(templateString: content, environment: environment, name: name)
     }
 
     throw TemplateDoesNotExist(templateNames: [name], loader: self)
@@ -65,7 +65,7 @@ public class FileSystemLoader: Loader, CustomStringConvertible {
 
         if templatePath.exists {
           let content: String = try templatePath.read()
-          return try environment.templateClass.init(templateString: content, environment: environment, name: templateName)
+          return environment.templateClass.init(templateString: content, environment: environment, name: templateName)
         }
       }
     }
@@ -75,6 +75,33 @@ public class FileSystemLoader: Loader, CustomStringConvertible {
 }
 
 
+public class DictionaryLoader: Loader {
+  public let templates: [String: String]
+
+  public init(templates: [String: String]) {
+    self.templates = templates
+  }
+
+  public func loadTemplate(name: String, environment: Environment) throws -> Template {
+    if let content = templates[name] {
+      return environment.templateClass.init(templateString: content, environment: environment, name: name)
+    }
+
+    throw TemplateDoesNotExist(templateNames: [name], loader: self)
+  }
+
+  public func loadTemplate(names: [String], environment: Environment) throws -> Template {
+    for name in names {
+      if let content = templates[name] {
+        return environment.templateClass.init(templateString: content, environment: environment, name: name)
+      }
+    }
+
+    throw TemplateDoesNotExist(templateNames: names, loader: self)
+  }
+}
+
+
 extension Path {
   func safeJoin(path: Path) throws -> Path {
     let newPath = self + path

Sources/Node.swift

@@ -1,35 +1,31 @@
 import Foundation
 
-
-public struct TemplateSyntaxError : Error, Equatable, CustomStringConvertible {
-  public let description:String
-
-  public init(_ description:String) {
-    self.description = description
-  }
-}
-
-
-public func ==(lhs:TemplateSyntaxError, rhs:TemplateSyntaxError) -> Bool {
-  return lhs.description == rhs.description
-}
-
-
 public protocol NodeType {
   /// Render the node in the given context
   func render(_ context:Context) throws -> String
+
+  /// Reference to this node's token
+  var token: Token? { get }
 }
 
 
 /// Render the collection of nodes in the given context
 public func renderNodes(_ nodes:[NodeType], _ context:Context) throws -> String {
-  return try nodes.map { try $0.render(context) }.joined(separator: "")
+  return try nodes.map {
+    do {
+      return try $0.render(context)
+    } catch {
+      throw error.withToken($0.token)
+    }
+    }.joined(separator: "")
 }
 
 public class SimpleNode : NodeType {
   public let handler:(Context) throws -> String
+  public let token: Token?
 
-  public init(handler: @escaping (Context) throws -> String) {
+  public init(token: Token, handler: @escaping (Context) throws -> String) {
+    self.token = token
     self.handler = handler
   }
 
@@ -41,9 +37,11 @@ public class SimpleNode : NodeType {
 
 public class TextNode : NodeType {
   public let text:String
+  public let token: Token?
 
   public init(text:String) {
     self.text = text
+    self.token = nil
   }
 
   public func render(_ context:Context) throws -> String {
@@ -59,16 +57,65 @@ public protocol Resolvable {
 
 public class VariableNode : NodeType {
   public let variable: Resolvable
+  public var token: Token?
+  let condition: Expression?
+  let elseExpression: Resolvable?
 
-  public init(variable: Resolvable) {
-    self.variable = variable
+  class func parse(_ parser:TokenParser, token:Token) throws -> NodeType {
+    var components = token.components()
+
+    func hasToken(_ token: String, at index: Int) -> Bool {
+      return components.count > (index + 1) && components[index] == token
+    }
+
+    let condition: Expression?
+    let elseExpression: Resolvable?
+
+    if hasToken("if", at: 1) {
+      let components = components.suffix(from: 2)
+      if let elseIndex = components.index(of: "else") {
+        condition = try parseExpression(components: Array(components.prefix(upTo: elseIndex)), tokenParser: parser, token: token)
+        let elseToken = components.suffix(from: elseIndex.advanced(by: 1)).joined(separator: " ")
+        elseExpression = try parser.compileResolvable(elseToken, containedIn: token)
+      } else {
+        condition = try parseExpression(components: Array(components), tokenParser: parser, token: token)
+        elseExpression = nil
+      }
+    } else {
+      condition = nil
+      elseExpression = nil
+    }
+
+    let filter = try parser.compileResolvable(components[0], containedIn: token)
+    return VariableNode(variable: filter, token: token, condition: condition, elseExpression: elseExpression)
   }
 
-  public init(variable: String) {
+  public init(variable: Resolvable, token: Token? = nil) {
+    self.variable = variable
+    self.token = token
+    self.condition = nil
+    self.elseExpression = nil
+  }
+
+  init(variable: Resolvable, token: Token? = nil, condition: Expression?, elseExpression: Resolvable?) {
+    self.variable = variable
+    self.token = token
+    self.condition = condition
+    self.elseExpression = elseExpression
+  }
+
+  public init(variable: String, token: Token? = nil) {
     self.variable = Variable(variable)
+    self.token = token
+    self.condition = nil
+    self.elseExpression = nil
   }
 
   public func render(_ context: Context) throws -> String {
+    if let condition = self.condition, try condition.evaluate(context: context) == false {
+      return try elseExpression?.resolve(context).map(stringify) ?? ""
+    }
+
     let result = try variable.resolve(context)
     return stringify(result)
   }
@@ -78,6 +125,8 @@ public class VariableNode : NodeType {
 func stringify(_ result: Any?) -> String {
   if let result = result as? String {
     return result
+  } else if let array = result as? [Any?] {
+    return unwrap(array).description
   } else if let result = result as? CustomStringConvertible {
     return result.description
   } else if let result = result as? NSObject {
@@ -86,3 +135,16 @@ func stringify(_ result: Any?) -> String {
 
   return ""
 }
+
+func unwrap(_ array: [Any?]) -> [Any] {
+  return array.map { (item: Any?) -> Any in
+    if let item = item {
+      if let items = item as? [Any?] {
+        return unwrap(items)
+      } else {
+        return item
+      }
+    }
+    else { return item as Any }
+  }
+}

Sources/NowTag.swift

@@ -4,23 +4,25 @@ import Foundation
 
 class NowNode : NodeType {
   let format:Variable
+  let token: Token?
 
   class func parse(_ parser:TokenParser, token:Token) throws -> NodeType {
     var format:Variable?
 
     let components = token.components()
     guard components.count <= 2 else {
-      throw TemplateSyntaxError("'now' tags may only have one argument: the format string `\(token.contents)`.")
+      throw TemplateSyntaxError("'now' tags may only have one argument: the format string.")
     }
     if components.count == 2 {
       format = Variable(components[1])
     }
 
-    return NowNode(format:format)
+    return NowNode(format:format, token: token)
   }
 
-  init(format:Variable?) {
+  init(format:Variable?, token: Token? = nil) {
     self.format = format ?? Variable("\"yyyy-MM-dd 'at' HH:mm\"")
+    self.token = token
   }
 
   func render(_ context: Context) throws -> String {

Sources/Parser.swift

@@ -37,10 +37,10 @@ public class TokenParser {
       let token = nextToken()!
 
       switch token {
-      case .text(let text):
+      case .text(let text, _):
         nodes.append(TextNode(text: text))
       case .variable:
-        nodes.append(VariableNode(variable: try compileFilter(token.contents)))
+        try nodes.append(VariableNode.parse(self, token: token))
       case .block:
         if let parse_until = parse_until , parse_until(self, token) {
           prependToken(token)
@@ -48,8 +48,13 @@ public class TokenParser {
         }
 
         if let tag = token.components().first {
-          let parser = try findTag(name: tag)
-          nodes.append(try parser(self, token))
+          do {
+            let parser = try findTag(name: tag)
+            let node = try parser(self, token)
+            nodes.append(node)
+          } catch {
+            throw error.withToken(token)
+          }
         }
       case .comment:
         continue
@@ -88,11 +93,106 @@ public class TokenParser {
       }
     }
 
-    throw TemplateSyntaxError("Unknown filter '\(name)'")
+    let suggestedFilters = self.suggestedFilters(for: name)
+    if suggestedFilters.isEmpty {
+      throw TemplateSyntaxError("Unknown filter '\(name)'.")
+    } else {
+      throw TemplateSyntaxError("""
+        Unknown filter '\(name)'. \
+        Found similar filters: \(suggestedFilters.map({ "'\($0)'" }).joined(separator: ", ")).
+        """)
+    }
   }
 
+  private func suggestedFilters(for name: String) -> [String] {
+    let allFilters = environment.extensions.flatMap({ $0.filters.keys })
+
+    let filtersWithDistance = allFilters
+                .map({ (filterName: $0, distance: $0.levenshteinDistance(name)) })
+                // do not suggest filters which names are shorter than the distance
+                .filter({ $0.filterName.count > $0.distance })
+    guard let minDistance = filtersWithDistance.min(by: { $0.distance < $1.distance })?.distance else {
+      return []
+    }
+    // suggest all filters with the same distance
+    return filtersWithDistance.filter({ $0.distance == minDistance }).map({ $0.filterName })
+  }
+
+  public func compileFilter(_ filterToken: String, containedIn containingToken: Token) throws -> Resolvable {
+    do {
+      return try FilterExpression(token: filterToken, parser: self)
+    } catch {
+      guard var syntaxError = error as? TemplateSyntaxError, syntaxError.token == nil else {
+        throw error
+      }
+      // find offset of filter in the containing token so that only filter is highligted, not the whole token
+      if let filterTokenRange = containingToken.contents.range(of: filterToken) {
+        var location = containingToken.sourceMap.location
+        location.lineOffset += containingToken.contents.distance(from: containingToken.contents.startIndex, to: filterTokenRange.lowerBound)
+        syntaxError.token = .variable(value: filterToken, at: SourceMap(filename: containingToken.sourceMap.filename, location: location))
+      } else {
+        syntaxError.token = containingToken
+      }
+      throw syntaxError
+    }
+  }
+
+  @available(*, deprecated, message: "Use compileFilter(_:containedIn:)")
   public func compileFilter(_ token: String) throws -> Resolvable {
     return try FilterExpression(token: token, parser: self)
   }
 
+  @available(*, deprecated, message: "Use compileResolvable(_:containedIn:)")
+  public func compileResolvable(_ token: String) throws -> Resolvable {
+    return try RangeVariable(token, parser: self)
+      ?? compileFilter(token)
+  }
+
+  public func compileResolvable(_ token: String, containedIn containingToken: Token) throws -> Resolvable {
+    return try RangeVariable(token, parser: self, containedIn: containingToken)
+        ?? compileFilter(token, containedIn: containingToken)
+  }
+
+}
+
+// https://en.wikipedia.org/wiki/Levenshtein_distance#Iterative_with_two_matrix_rows
+extension String {
+
+  subscript(_ i: Int) -> Character {
+    return self[self.index(self.startIndex, offsetBy: i)]
+  }
+
+  func levenshteinDistance(_ target: String) -> Int {
+    // create two work vectors of integer distances
+    var last, current: [Int]
+
+    // initialize v0 (the previous row of distances)
+    // this row is A[0][i]: edit distance for an empty s
+    // the distance is just the number of characters to delete from t
+    last = [Int](0...target.count)
+    current = [Int](repeating: 0, count: target.count + 1)
+
+    for i in 0..<self.count {
+      // calculate v1 (current row distances) from the previous row v0
+
+      // first element of v1 is A[i+1][0]
+      //   edit distance is delete (i+1) chars from s to match empty t
+      current[0] = i + 1
+
+      // use formula to fill in the rest of the row
+      for j in 0..<target.count {
+        current[j+1] = Swift.min(
+          last[j+1] + 1,
+          current[j] + 1,
+          last[j] + (self[i] == target[j] ? 0 : 1)
+        )
+      }
+
+      // copy v1 (current row) to v0 (previous row) for next iteration
+      last = current
+    }
+
+    return current[target.count]
+  }
+
 }

Sources/Template.swift

@@ -7,7 +7,8 @@ let NSFileNoSuchFileError = 4
 
 /// A class representing a template
 open class Template: ExpressibleByStringLiteral {
-  let environment: Environment
+  let templateString: String
+  internal(set) var environment: Environment
   let tokens: [Token]
 
   /// The name of the loaded Template if the Template was loaded from a Loader
@@ -17,8 +18,9 @@ open class Template: ExpressibleByStringLiteral {
   public required init(templateString: String, environment: Environment? = nil, name: String? = nil) {
     self.environment = environment ?? Environment()
     self.name = name
+    self.templateString = templateString
 
-    let lexer = Lexer(templateString: templateString)
+    let lexer = Lexer(templateName: name, templateString: templateString)
     tokens = lexer.tokenize()
   }
 

Sources/Tokenizer.swift

@@ -7,15 +7,34 @@ extension String {
     var word = ""
     var components: [String] = []
     var separate: Character = separator
+    var singleQuoteCount = 0
+    var doubleQuoteCount = 0
+
+    let specialCharacters = ",|:"
+    func appendWord(_ word: String) {
+      if components.count > 0 {
+        if let precedingChar = components.last?.last, specialCharacters.contains(precedingChar) {
+          components[components.count-1] += word
+        } else if specialCharacters.contains(word) {
+          components[components.count-1] += word
+        } else {
+          components.append(word)
+        }
+      } else {
+        components.append(word)
+      }
+    }
+
+    for character in self {
+      if character == "'" { singleQuoteCount += 1 }
+      else if character == "\"" { doubleQuoteCount += 1 }
 
-    for character in self.characters {
       if character == separate {
+
         if separate != separator {
           word.append(separate)
-        }
-
-        if !word.isEmpty {
-          components.append(word)
+        } else if (singleQuoteCount % 2 == 0 || doubleQuoteCount % 2 == 0) && !word.isEmpty {
+          appendWord(word)
           word = ""
         }
 
@@ -29,67 +48,70 @@ extension String {
     }
 
     if !word.isEmpty {
-      components.append(word)
+      appendWord(word)
     }
 
     return components
   }
 }
 
+public struct SourceMap: Equatable {
+  public let filename: String?
+  public let location: ContentLocation
+
+  init(filename: String? = nil, location: ContentLocation = ("", 0, 0)) {
+    self.filename = filename
+    self.location = location
+  }
+
+  static let unknown = SourceMap()
+
+  public static func ==(lhs: SourceMap, rhs: SourceMap) -> Bool {
+    return lhs.filename == rhs.filename && lhs.location == rhs.location
+  }
+}
 
 public enum Token : Equatable {
   /// A token representing a piece of text.
-  case text(value: String)
+  case text(value: String, at: SourceMap)
 
   /// A token representing a variable.
-  case variable(value: String)
+  case variable(value: String, at: SourceMap)
 
   /// A token representing a comment.
-  case comment(value: String)
+  case comment(value: String, at: SourceMap)
 
   /// A token representing a template block.
-  case block(value: String)
+  case block(value: String, at: SourceMap)
 
   /// Returns the underlying value as an array seperated by spaces
   public func components() -> [String] {
     switch self {
-    case .block(let value):
-      return value.smartSplit()
-    case .variable(let value):
-      return value.smartSplit()
-    case .text(let value):
-      return value.smartSplit()
-    case .comment(let value):
+    case .block(let value, _),
+         .variable(let value, _),
+         .text(let value, _),
+         .comment(let value, _):
       return value.smartSplit()
     }
   }
 
   public var contents: String {
     switch self {
-    case .block(let value):
-      return value
-    case .variable(let value):
-      return value
-    case .text(let value):
-      return value
-    case .comment(let value):
+    case .block(let value, _),
+         .variable(let value, _),
+         .text(let value, _),
+         .comment(let value, _):
       return value
     }
   }
-}
 
-
-public func == (lhs: Token, rhs: Token) -> Bool {
-  switch (lhs, rhs) {
-  case (.text(let lhsValue), .text(let rhsValue)):
-    return lhsValue == rhsValue
-  case (.variable(let lhsValue), .variable(let rhsValue)):
-    return lhsValue == rhsValue
-  case (.block(let lhsValue), .block(let rhsValue)):
-    return lhsValue == rhsValue
-  case (.comment(let lhsValue), .comment(let rhsValue)):
-    return lhsValue == rhsValue
-  default:
-    return false
+  public var sourceMap: SourceMap {
+    switch self {
+    case .block(_, let sourceMap),
+         .variable(_, let sourceMap),
+         .text(_, let sourceMap),
+         .comment(_, let sourceMap):
+      return sourceMap
+    }
   }
 }

Sources/Variable.swift

@@ -9,10 +9,8 @@ class FilterExpression : Resolvable {
   let variable: Variable
 
   init(token: String, parser: TokenParser) throws {
-    let bits = token.characters.split(separator: "|").map({ String($0).trim(character: " ") })
+    let bits = token.split(separator: "|").map({ String($0).trim(character: " ") })
     if bits.isEmpty {
-      filters = []
-      variable = Variable("")
       throw TemplateSyntaxError("Variable tags must include at least 1 argument")
     }
 
@@ -50,8 +48,10 @@ public struct Variable : Equatable, Resolvable {
     self.variable = variable
   }
 
-  fileprivate func lookup() -> [String] {
-    return variable.characters.split(separator: ".").map(String.init)
+  // Split the lookup string and resolve references if possible
+  fileprivate func lookup(_ context: Context) throws -> [String] {
+    let keyPath = KeyPath(variable, in: context)
+    return try keyPath.parse()
   }
 
   /// Resolve the variable in the given context
@@ -60,45 +60,46 @@ public struct Variable : Equatable, Resolvable {
 
     if (variable.hasPrefix("'") && variable.hasSuffix("'")) || (variable.hasPrefix("\"") && variable.hasSuffix("\"")) {
       // String literal
-      return variable[variable.characters.index(after: variable.startIndex) ..< variable.characters.index(before: variable.endIndex)]
+      return String(variable[variable.index(after: variable.startIndex) ..< variable.index(before: variable.endIndex)])
     }
 
+    // Number literal
+    if let int = Int(variable) {
+      return int
+    }
     if let number = Number(variable) {
-      // Number literal
       return number
     }
+    // Boolean literal
+    if let bool = Bool(variable) {
+      return bool
+    }
 
-    for bit in lookup() {
+    for bit in try lookup(context) {
       current = normalize(current)
 
       if let context = current as? Context {
         current = context[bit]
       } else if let dictionary = current as? [String: Any] {
-        current = dictionary[bit]
-      } else if let array = current as? [Any] {
-        if let index = Int(bit) {
-          if index >= 0 && index < array.count {
-            current = array[index]
-          } else {
-            current = nil
-          }
-        } else if bit == "first" {
-          current = array.first
-        } else if bit == "last" {
-          current = array.last
-        } else if bit == "count" {
-          current = array.count
+        if bit == "count" {
+          current = dictionary.count
+        } else {
+          current = dictionary[bit]
         }
+      } else if let array = current as? [Any] {
+        current = resolveCollection(array, bit: bit)
+      } else if let string = current as? String {
+        current = resolveCollection(string, bit: bit)
       } else if let object = current as? NSObject {  // NSKeyValueCoding
-#if os(Linux)
-        return nil
-#else
-        current = object.value(forKey: bit)
-#endif
+        #if os(Linux)
+          return nil
+        #else
+          if object.responds(to: Selector(bit)) {
+            current = object.value(forKey: bit)
+          }
+        #endif
       } else if let value = current {
-        let mirror = Mirror(reflecting: value)
-        current = mirror.descendant(bit)
-
+        current = Mirror(reflecting: value).getValue(for: bit)
         if current == nil {
           return nil
         }
@@ -117,8 +118,69 @@ public struct Variable : Equatable, Resolvable {
   }
 }
 
-public func ==(lhs: Variable, rhs: Variable) -> Bool {
-  return lhs.variable == rhs.variable
+private func resolveCollection<T: Collection>(_ collection: T, bit: String) -> Any? {
+  if let index = Int(bit) {
+    if index >= 0 && index < collection.count {
+      return collection[collection.index(collection.startIndex, offsetBy: index)]
+    } else {
+      return nil
+    }
+  } else if bit == "first" {
+    return collection.first
+  } else if bit == "last" {
+    return collection[collection.index(collection.endIndex, offsetBy: -1)]
+  } else if bit == "count" {
+    return collection.count
+  } else {
+    return nil
+  }
+}
+
+/// A structure used to represet range of two integer values expressed as `from...to`.
+/// Values should be numbers (they will be converted to integers).
+/// Rendering this variable produces array from range `from...to`.
+/// If `from` is more than `to` array will contain values of reversed range.
+public struct RangeVariable: Resolvable {
+  public let from: Resolvable
+  public let to: Resolvable
+
+  @available(*, deprecated, message: "Use init?(_:parser:containedIn:)")
+  public init?(_ token: String, parser: TokenParser) throws {
+    let components = token.components(separatedBy: "...")
+    guard components.count == 2 else {
+      return nil
+    }
+
+    self.from = try parser.compileFilter(components[0])
+    self.to = try parser.compileFilter(components[1])
+  }
+
+  public init?(_ token: String, parser: TokenParser, containedIn containingToken: Token) throws {
+    let components = token.components(separatedBy: "...")
+    guard components.count == 2 else {
+      return nil
+    }
+
+    self.from = try parser.compileFilter(components[0], containedIn: containingToken)
+    self.to = try parser.compileFilter(components[1], containedIn: containingToken)
+  }
+
+  public func resolve(_ context: Context) throws -> Any? {
+    let fromResolved = try from.resolve(context)
+    let toResolved = try to.resolve(context)
+
+    guard let from = fromResolved.flatMap(toNumber(value:)).flatMap(Int.init) else {
+      throw TemplateSyntaxError("'from' value is not an Integer (\(fromResolved ?? "nil"))")
+    }
+
+    guard let to = toResolved.flatMap(toNumber(value:)).flatMap(Int.init) else {
+      throw TemplateSyntaxError("'to' value is not an Integer (\(toResolved ?? "nil") )")
+    }
+
+    let range = min(from, to)...max(from, to)
+    return from > to ? Array(range.reversed()) : Array(range)
+  }
+
 }
 
 
@@ -164,10 +226,47 @@ extension Dictionary : Normalizable {
 
 func parseFilterComponents(token: String) -> (String, [Variable]) {
   var components = token.smartSplit(separator: ":")
-  let name = components.removeFirst()
+  let name = components.removeFirst().trim(character: " ")
   let variables = components
     .joined(separator: ":")
     .smartSplit(separator: ",")
-    .map { Variable($0) }
+    .map { Variable($0.trim(character: " ")) }
   return (name, variables)
 }
+
+extension Mirror {
+  func getValue(for key: String) -> Any? {
+    let result = descendant(key) ?? Int(key).flatMap({ descendant($0) })
+    if result == nil {
+      // go through inheritance chain to reach superclass properties
+      return superclassMirror?.getValue(for: key)
+    } else if let result = result {
+      guard String(describing: result) != "nil" else {
+        // mirror returns non-nil value even for nil-containing properties
+        // so we have to check if its value is actually nil or not
+        return nil
+      }
+      if let result = (result as? AnyOptional)?.wrapped {
+        return result
+      } else {
+        return result
+      }
+    }
+    return result
+  }
+}
+
+protocol AnyOptional {
+  var wrapped: Any? { get }
+}
+
+extension Optional: AnyOptional {
+  var wrapped: Any? {
+    switch self {
+    case let .some(value): return value
+    case .none: return nil
+    }
+  }
+}
+
+

Stencil.podspec.json

@@ -1,6 +1,6 @@
 {
   "name": "Stencil",
-  "version": "0.8.0",
+  "version": "0.13.1",
   "summary": "Stencil is a simple and powerful template language for Swift.",
   "homepage": "https://stencil.fuller.li",
   "license": {
@@ -12,8 +12,8 @@
   },
   "social_media_url": "https://twitter.com/kylefuller",
   "source": {
-    "git": "https://github.com/kylef/Stencil.git",
-    "tag": "0.8.0"
+    "git": "https://github.com/stencilproject/Stencil.git",
+    "tag": "0.13.1"
   },
   "source_files": [
     "Sources/*.swift"
@@ -23,8 +23,12 @@
     "osx": "10.9",
     "tvos": "9.0"
   },
+  "cocoapods_version": ">= 1.4.0",
+  "swift_version": "4.2",
   "requires_arc": true,
   "dependencies": {
-    "PathKit": [ "~> 0.8.0" ]
+    "PathKit": [
+      "~> 0.9.0"
+    ]
   }
 }

Tests/LinuxMain.swift

@@ -1,3 +1,8 @@
+import XCTest
+
 import StencilTests
 
-stencilTests()
+var tests = [XCTestCaseEntry]()
+tests += StencilTests.__allTests()
+
+XCTMain(tests)

Tests/StencilTests/ContextSpec.swift

@@ -1,80 +1,84 @@
+import XCTest
 import Spectre
 @testable import Stencil
 
 
-func testContext() {
-  describe("Context") {
-    var context: Context!
+class ContextTests: XCTestCase {
+  
+  func testContext() {
+    describe("Context") {
+      var context: Context!
 
-    $0.before {
-      context = Context(dictionary: ["name": "Kyle"])
-    }
+      $0.before {
+        context = Context(dictionary: ["name": "Kyle"])
+      }
 
-    $0.it("allows you to get a value via subscripting") {
-      try expect(context["name"] as? String) == "Kyle"
-    }
-
-    $0.it("allows you to set a value via subscripting") {
-      context["name"] = "Katie"
-
-      try expect(context["name"] as? String) == "Katie"
-    }
-
-    $0.it("allows you to remove a value via subscripting") {
-      context["name"] = nil
-
-      try expect(context["name"]).to.beNil()
-    }
-
-    $0.it("allows you to retrieve a value from a parent") {
-      try context.push {
+      $0.it("allows you to get a value via subscripting") {
         try expect(context["name"] as? String) == "Kyle"
       }
-    }
 
-    $0.it("allows you to override a parent's value") {
-      try context.push {
+      $0.it("allows you to set a value via subscripting") {
         context["name"] = "Katie"
+
         try expect(context["name"] as? String) == "Katie"
       }
-    }
 
-    $0.it("allows you to pop to restore previous state") {
-      context.push {
-        context["name"] = "Katie"
-      }
-
-      try expect(context["name"] as? String) == "Kyle"
-    }
-
-    $0.it("allows you to remove a parent's value in a level") {
-      try context.push {
+      $0.it("allows you to remove a value via subscripting") {
         context["name"] = nil
+
         try expect(context["name"]).to.beNil()
       }
 
-      try expect(context["name"] as? String) == "Kyle"
-    }
-
-    $0.it("allows you to push a dictionary and run a closure then restoring previous state") {
-      var didRun = false
-
-      try context.push(dictionary: ["name": "Katie"]) {
-        didRun = true
-        try expect(context["name"] as? String) == "Katie"
+      $0.it("allows you to retrieve a value from a parent") {
+        try context.push {
+          try expect(context["name"] as? String) == "Kyle"
+        }
       }
 
-      try expect(didRun).to.beTrue()
-      try expect(context["name"] as? String) == "Kyle"
-    }
+      $0.it("allows you to override a parent's value") {
+        try context.push {
+          context["name"] = "Katie"
+          try expect(context["name"] as? String) == "Katie"
+        }
+      }
 
-    $0.it("allows you to flatten the context contents") {
-      try context.push(dictionary: ["test": "abc"]) {
-        let flattened = context.flatten()
+      $0.it("allows you to pop to restore previous state") {
+        context.push {
+          context["name"] = "Katie"
+        }
 
-        try expect(flattened.count) == 2
-        try expect(flattened["name"] as? String) == "Kyle"
-        try expect(flattened["test"] as? String) == "abc"
+        try expect(context["name"] as? String) == "Kyle"
+      }
+
+      $0.it("allows you to remove a parent's value in a level") {
+        try context.push {
+          context["name"] = nil
+          try expect(context["name"]).to.beNil()
+        }
+
+        try expect(context["name"] as? String) == "Kyle"
+      }
+
+      $0.it("allows you to push a dictionary and run a closure then restoring previous state") {
+        var didRun = false
+
+        try context.push(dictionary: ["name": "Katie"]) {
+          didRun = true
+          try expect(context["name"] as? String) == "Katie"
+        }
+
+        try expect(didRun).to.beTrue()
+        try expect(context["name"] as? String) == "Kyle"
+      }
+
+      $0.it("allows you to flatten the context contents") {
+        try context.push(dictionary: ["test": "abc"]) {
+          let flattened = context.flatten()
+
+          try expect(flattened.count) == 2
+          try expect(flattened["name"] as? String) == "Kyle"
+          try expect(flattened["test"] as? String) == "abc"
+        }
       }
     }
   }

Tests/StencilTests/EnvironmentSpec.swift

@@ -1,40 +1,360 @@
+import XCTest
 import Spectre
-import Stencil
+import PathKit
+@testable import Stencil
 
+class EnvironmentTests: XCTestCase {
+  func testEnvironment() {
+    describe("Environment") {
+      var environment: Environment!
+      var template: Template!
 
-func testEnvironment() {
-  describe("Environment") {
-    let environment = Environment(loader: ExampleLoader())
+      $0.before {
+        environment =  Environment(loader: ExampleLoader())
+        template = nil
+      }
 
-    $0.it("can load a template from a name") {
-      let template = try environment.loadTemplate(name: "example.html")
-      try expect(template.name) == "example.html"
-    }
+      $0.it("can load a template from a name") {
+        let template = try environment.loadTemplate(name: "example.html")
+        try expect(template.name) == "example.html"
+      }
 
-    $0.it("can load a template from a names") {
-      let template = try environment.loadTemplate(names: ["first.html", "example.html"])
-      try expect(template.name) == "example.html"
-    }
+      $0.it("can load a template from a names") {
+        let template = try environment.loadTemplate(names: ["first.html", "example.html"])
+        try expect(template.name) == "example.html"
+      }
 
-    $0.it("can render a template from a string") {
-      let result = try environment.renderTemplate(string: "Hello World")
-      try expect(result) == "Hello World"
-    }
+      $0.it("can render a template from a string") {
+        let result = try environment.renderTemplate(string: "Hello World")
+        try expect(result) == "Hello World"
+      }
 
-    $0.it("can render a template from a file") {
-      let result = try environment.renderTemplate(name: "example.html")
-      try expect(result) == "Hello World!"
-    }
+      $0.it("can render a template from a file") {
+        let result = try environment.renderTemplate(name: "example.html")
+        try expect(result) == "Hello World!"
+      }
 
-    $0.it("allows you to provide a custom template class") {
-      let environment = Environment(loader: ExampleLoader(), templateClass: CustomTemplate.self)
-      let result = try environment.renderTemplate(string: "Hello World")
+      $0.it("allows you to provide a custom template class") {
+        let environment = Environment(loader: ExampleLoader(), templateClass: CustomTemplate.self)
+        let result = try environment.renderTemplate(string: "Hello World")
+
+        try expect(result) == "here"
+      }
+
+      func expectedSyntaxError(token: String, template: Template, description: String) -> TemplateSyntaxError {
+        guard let range = template.templateString.range(of: token) else {
+          fatalError("Can't find '\(token)' in '\(template)'")
+        }
+        let lexer = Lexer(templateString: template.templateString)
+        let location = lexer.rangeLocation(range)
+        let sourceMap = SourceMap(filename: template.name, location: location)
+        let token = Token.block(value: token, at: sourceMap)
+        return TemplateSyntaxError(reason: description, token: token, stackTrace: [])
+      }
+
+      func expectError(reason: String, token: String,
+                       file: String = #file, line: Int = #line, function: String = #function) throws {
+        let expectedError = expectedSyntaxError(token: token, template: template, description: reason)
+
+        let error = try expect(environment.render(template: template, context: ["names": ["Bob", "Alice"], "name": "Bob"]),
+                               file: file, line: line, function: function).toThrow() as TemplateSyntaxError
+        let reporter = SimpleErrorReporter()
+        try expect(reporter.renderError(error), file: file, line: line, function: function) == reporter.renderError(expectedError)
+      }
+
+      $0.context("given syntax error") {
+
+        $0.it("reports syntax error on invalid for tag syntax") {
+          template = "Hello {% for name in %}{{ name }}, {% endfor %}!"
+          try expectError(reason: "'for' statements should use the syntax: `for <x> in <y> [where <condition>]`.", token: "for name in")
+        }
+
+        $0.it("reports syntax error on missing endfor") {
+          template = "{% for name in names %}{{ name }}"
+          try expectError(reason: "`endfor` was not found.", token: "for name in names")
+        }
+
+        $0.it("reports syntax error on unknown tag") {
+          template = "{% for name in names %}{{ name }}{% end %}"
+          try expectError(reason: "Unknown template tag 'end'", token: "end")
+        }
+
+      }
+
+      $0.context("given unknown filter") {
+
+        $0.it("reports syntax error in for tag") {
+          template = "{% for name in names|unknown %}{{ name }}{% endfor %}"
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.", token: "names|unknown")
+        }
+
+        $0.it("reports syntax error in for-where tag") {
+          template = "{% for name in names where name|unknown %}{{ name }}{% endfor %}"
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.", token: "name|unknown")
+        }
+
+        $0.it("reports syntax error in if tag") {
+          template = "{% if name|unknown %}{{ name }}{% endif %}"
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.", token: "name|unknown")
+        }
+
+        $0.it("reports syntax error in elif tag") {
+          template = "{% if name %}{{ name }}{% elif name|unknown %}{% endif %}"
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.", token: "name|unknown")
+        }
+
+        $0.it("reports syntax error in ifnot tag") {
+          template = "{% ifnot name|unknown %}{{ name }}{% endif %}"
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.", token: "name|unknown")
+        }
+
+        $0.it("reports syntax error in filter tag") {
+          template = "{% filter unknown %}Text{% endfilter %}"
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.", token: "filter unknown")
+        }
+
+        $0.it("reports syntax error in variable tag") {
+          template = "{{ name|unknown }}"
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.", token: "name|unknown")
+        }
+
+      }
+
+      $0.context("given rendering error") {
+
+        $0.it("reports rendering error in variable filter") {
+          let filterExtension = Extension()
+          filterExtension.registerFilter("throw") { (value: Any?) in
+            throw TemplateSyntaxError("filter error")
+          }
+          environment.extensions += [filterExtension]
+
+          template = Template(templateString: "{{ name|throw }}", environment: environment)
+          try expectError(reason: "filter error", token: "name|throw")
+        }
+
+        $0.it("reports rendering error in filter tag") {
+          let filterExtension = Extension()
+          filterExtension.registerFilter("throw") { (value: Any?) in
+            throw TemplateSyntaxError("filter error")
+          }
+          environment.extensions += [filterExtension]
+
+          template = Template(templateString: "{% filter throw %}Test{% endfilter %}", environment: environment)
+          try expectError(reason: "filter error", token: "filter throw")
+        }
+
+        $0.it("reports rendering error in simple tag") {
+          let tagExtension = Extension()
+          tagExtension.registerSimpleTag("simpletag") { context in
+            throw TemplateSyntaxError("simpletag error")
+          }
+          environment.extensions += [tagExtension]
+
+          template = Template(templateString: "{% simpletag %}", environment: environment)
+          try expectError(reason: "simpletag error", token: "simpletag")
+        }
+
+        $0.it("reporsts passing argument to simple filter") {
+          template = "{{ name|uppercase:5 }}"
+          try expectError(reason: "cannot invoke filter with an argument", token: "name|uppercase:5")
+        }
+
+        $0.it("reports rendering error in custom tag") {
+          let tagExtension = Extension()
+          tagExtension.registerTag("customtag") { parser, token in
+            return ErrorNode(token: token)
+          }
+          environment.extensions += [tagExtension]
+
+          template = Template(templateString: "{% customtag %}", environment: environment)
+          try expectError(reason: "Custom Error", token: "customtag")
+        }
+
+        $0.it("reports rendering error in for body") {
+          let tagExtension = Extension()
+          tagExtension.registerTag("customtag") { parser, token in
+            return ErrorNode(token: token)
+          }
+          environment.extensions += [tagExtension]
+
+          template = Template(templateString: "{% for name in names %}{% customtag %}{% endfor %}", environment: environment)
+          try expectError(reason: "Custom Error", token: "customtag")
+        }
+
+        $0.it("reports rendering error in block") {
+          let tagExtension = Extension()
+          tagExtension.registerTag("customtag") { parser, token in
+            return ErrorNode(token: token)
+          }
+          environment.extensions += [tagExtension]
+
+          template = Template(templateString: "{% block some %}{% customtag %}{% endblock %}", environment: environment)
+          try expectError(reason: "Custom Error", token: "customtag")
+        }
+      }
+
+      $0.context("given included template") {
+        let path = Path(#file) + ".." + "fixtures"
+        let loader = FileSystemLoader(paths: [path])
+        var environment = Environment(loader: loader)
+        var template: Template!
+        var includedTemplate: Template!
+
+        $0.before {
+          environment = Environment(loader: loader)
+          template = nil
+          includedTemplate = nil
+        }
+
+        func expectError(reason: String, token: String, includedToken: String,
+                         file: String = #file, line: Int = #line, function: String = #function) throws {
+          var expectedError = expectedSyntaxError(token: token, template: template, description: reason)
+          expectedError.stackTrace = [expectedSyntaxError(token: includedToken, template: includedTemplate, description: reason).token!]
+
+          let error = try expect(environment.render(template: template, context: ["target": "World"]),
+                                 file: file, line: line, function: function).toThrow() as TemplateSyntaxError
+          let reporter = SimpleErrorReporter()
+          try expect(reporter.renderError(error), file: file, line: line, function: function) == reporter.renderError(expectedError)
+        }
+
+        $0.it("reports syntax error in included template") {
+          template = Template(templateString: """
+          {% include "invalid-include.html" %}
+          """, environment: environment)
+          includedTemplate = try environment.loadTemplate(name: "invalid-include.html")
+
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
+                          token: """
+                          include "invalid-include.html"
+                          """,
+                          includedToken: "target|unknown")
+        }
+
+        $0.it("reports runtime error in included template") {
+          let filterExtension = Extension()
+          filterExtension.registerFilter("unknown", filter: {  (_: Any?) in
+            throw TemplateSyntaxError("filter error")
+          })
+          environment.extensions += [filterExtension]
+
+          template = Template(templateString: """
+          {% include "invalid-include.html" %}
+          """, environment: environment)
+          includedTemplate = try environment.loadTemplate(name: "invalid-include.html")
+
+          try expectError(reason: "filter error",
+                          token: "include \"invalid-include.html\"",
+                          includedToken: "target|unknown")
+        }
+
+      }
+
+      $0.context("given base and child templates") {
+        let path = Path(#file) + ".." + "fixtures"
+        let loader = FileSystemLoader(paths: [path])
+        var environment: Environment!
+        var childTemplate: Template!
+        var baseTemplate: Template!
+
+        $0.before {
+          environment = Environment(loader: loader)
+          childTemplate = nil
+          baseTemplate = nil
+        }
+
+        func expectError(reason: String, childToken: String, baseToken: String?,
+                         file: String = #file, line: Int = #line, function: String = #function) throws {
+          var expectedError = expectedSyntaxError(token: childToken, template: childTemplate, description: reason)
+          if let baseToken = baseToken {
+            expectedError.stackTrace = [expectedSyntaxError(token: baseToken, template: baseTemplate, description: reason).token!]
+          }
+          let error = try expect(environment.render(template: childTemplate, context: ["target": "World"]),
+                                 file: file, line: line, function: function).toThrow() as TemplateSyntaxError
+          let reporter = SimpleErrorReporter()
+          try expect(reporter.renderError(error), file: file, line: line, function: function) == reporter.renderError(expectedError)
+        }
+
+        $0.it("reports syntax error in base template") {
+          childTemplate = try environment.loadTemplate(name: "invalid-child-super.html")
+          baseTemplate = try environment.loadTemplate(name: "invalid-base.html")
+
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
+                          childToken: "extends \"invalid-base.html\"",
+                          baseToken: "target|unknown")
+        }
+
+        $0.it("reports runtime error in base template") {
+          let filterExtension = Extension()
+          filterExtension.registerFilter("unknown", filter: {  (_: Any?) in
+            throw TemplateSyntaxError("filter error")
+          })
+          environment.extensions += [filterExtension]
+
+          childTemplate = try environment.loadTemplate(name: "invalid-child-super.html")
+          baseTemplate = try environment.loadTemplate(name: "invalid-base.html")
+
+          try expectError(reason: "filter error",
+                          childToken: "block.super",
+                          baseToken: "target|unknown")
+        }
+
+        $0.it("reports syntax error in child template") {
+          childTemplate = Template(templateString: """
+          {% extends "base.html" %}
+          {% block body %}Child {{ target|unknown }}{% endblock %}
+          """, environment: environment, name: nil)
+
+          try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
+                          childToken: "target|unknown",
+                          baseToken: nil)
+        }
+
+        $0.it("reports runtime error in child template") {
+          let filterExtension = Extension()
+          filterExtension.registerFilter("unknown", filter: {  (_: Any?) in
+            throw TemplateSyntaxError("filter error")
+          })
+          environment.extensions += [filterExtension]
+
+          childTemplate = Template(templateString: """
+          {% extends "base.html" %}
+          {% block body %}Child {{ target|unknown }}{% endblock %}
+          """, environment: environment, name: nil)
+
+          try expectError(reason: "filter error",
+                          childToken: "target|unknown",
+                          baseToken: nil)
+        }
+
+      }
 
-      try expect(result) == "here"
     }
   }
 }
 
+extension Expectation {
+  @discardableResult
+  func toThrow<T: Error>() throws -> T {
+    var thrownError: Error? = nil
+
+    do {
+      _ = try expression()
+    } catch {
+      thrownError = error
+    }
+
+    if let thrownError = thrownError {
+      if let thrownError = thrownError as? T {
+        return thrownError
+      } else {
+        throw failure("\(thrownError) is not \(T.self)")
+      }
+    } else {
+      throw failure("expression did not throw an error")
+    }
+  }
+}
 
 fileprivate class ExampleLoader: Loader {
   func loadTemplate(name: String, environment: Environment) throws -> Template {

Tests/StencilTests/ExpressionSpec.swift

@@ -1,283 +1,345 @@
+import XCTest
 import Spectre
 @testable import Stencil
 
+class ExpressionsTests: XCTestCase {
+  func testExpressions() {
+    describe("Expression") {
+      let parser = TokenParser(tokens: [], environment: Environment())
 
-func testExpressions() {
-  describe("Expression") {
-    let parser = TokenParser(tokens: [], environment: Environment())
-
-    $0.describe("VariableExpression") {
-      let expression = VariableExpression(variable: Variable("value"))
-
-      $0.it("evaluates to true when value is not nil") {
-        let context = Context(dictionary: ["value": "known"])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
+      func parseExpression(components: [String]) throws -> Expression {
+        let parser = try IfExpressionParser.parser(components: components, tokenParser: parser, token: .text(value: "", at: .unknown))
+        return try parser.parse()
       }
 
-      $0.it("evaluates to false when value is unset") {
-        let context = Context()
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
+      $0.describe("VariableExpression") {
+        let expression = VariableExpression(variable: Variable("value"))
 
-      $0.it("evaluates to true when array variable is not empty") {
-        let items: [[String: Any]] = [["key":"key1","value":42],["key":"key2","value":1337]]
-        let context = Context(dictionary: ["value": [items]])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when array value is empty") {
-        let emptyItems = [[String: Any]]()
-        let context = Context(dictionary: ["value": emptyItems])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to false when dictionary value is empty") {
-        let emptyItems = [String:Any]()
-        let context = Context(dictionary: ["value": emptyItems])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to false when Array<Any> value is empty") {
-        let context = Context(dictionary: ["value": ([] as [Any])])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to true when integer value is above 0") {
-        let context = Context(dictionary: ["value": 1])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to true with string") {
-        let context = Context(dictionary: ["value": "test"])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when empty string") {
-        let context = Context(dictionary: ["value": ""])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to false when integer value is below 0 or below") {
-        let context = Context(dictionary: ["value": 0])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-
-        let negativeContext = Context(dictionary: ["value": 0])
-        try expect(try expression.evaluate(context: negativeContext)).to.beFalse()
-      }
-
-      $0.it("evaluates to true when float value is above 0") {
-        let context = Context(dictionary: ["value": Float(0.5)])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when float is 0 or below") {
-        let context = Context(dictionary: ["value": Float(0)])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to true when double value is above 0") {
-        let context = Context(dictionary: ["value": Double(0.5)])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when double is 0 or below") {
-        let context = Context(dictionary: ["value": Double(0)])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to false when uint is 0") {
-        let context = Context(dictionary: ["value": UInt(0)])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-    }
-
-    $0.describe("NotExpression") {
-      $0.it("returns truthy for positive expressions") {
-        let expression = NotExpression(expression: StaticExpression(value: true))
-        try expect(expression.evaluate(context: Context())).to.beFalse()
-      }
-
-      $0.it("returns falsy for negative expressions") {
-        let expression = NotExpression(expression: StaticExpression(value: false))
-        try expect(expression.evaluate(context: Context())).to.beTrue()
-      }
-    }
-
-    $0.describe("expression parsing") {
-      $0.it("can parse a variable expression") {
-        let expression = try parseExpression(components: ["value"], tokenParser: parser)
-        try expect(expression.evaluate(context: Context())).to.beFalse()
-        try expect(expression.evaluate(context: Context(dictionary: ["value": true]))).to.beTrue()
-      }
-
-      $0.it("can parse a not expression") {
-        let expression = try parseExpression(components: ["not", "value"], tokenParser: parser)
-        try expect(expression.evaluate(context: Context())).to.beTrue()
-        try expect(expression.evaluate(context: Context(dictionary: ["value": true]))).to.beFalse()
-      }
-
-      $0.describe("and expression") {
-        let expression = try! parseExpression(components: ["lhs", "and", "rhs"], tokenParser: parser)
-
-        $0.it("evaluates to false with lhs false") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beFalse()
+        $0.it("evaluates to true when value is not nil") {
+          let context = Context(dictionary: ["value": "known"])
+          try expect(try expression.evaluate(context: context)).to.beTrue()
         }
 
-        $0.it("evaluates to false with rhs false") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beFalse()
+        $0.it("evaluates to false when value is unset") {
+          let context = Context()
+          try expect(try expression.evaluate(context: context)).to.beFalse()
         }
 
-        $0.it("evaluates to false with lhs and rhs false") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": false]))).to.beFalse()
+        $0.it("evaluates to true when array variable is not empty") {
+          let items: [[String: Any]] = [["key":"key1","value":42],["key":"key2","value":1337]]
+          let context = Context(dictionary: ["value": [items]])
+          try expect(try expression.evaluate(context: context)).to.beTrue()
         }
 
-        $0.it("evaluates to true with lhs and rhs true") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
+        $0.it("evaluates to false when array value is empty") {
+          let emptyItems = [[String: Any]]()
+          let context = Context(dictionary: ["value": emptyItems])
+          try expect(try expression.evaluate(context: context)).to.beFalse()
+        }
+
+        $0.it("evaluates to false when dictionary value is empty") {
+          let emptyItems = [String:Any]()
+          let context = Context(dictionary: ["value": emptyItems])
+          try expect(try expression.evaluate(context: context)).to.beFalse()
+        }
+
+        $0.it("evaluates to false when Array<Any> value is empty") {
+          let context = Context(dictionary: ["value": ([] as [Any])])
+          try expect(try expression.evaluate(context: context)).to.beFalse()
+        }
+
+        $0.it("evaluates to true when integer value is above 0") {
+          let context = Context(dictionary: ["value": 1])
+          try expect(try expression.evaluate(context: context)).to.beTrue()
+        }
+
+        $0.it("evaluates to true with string") {
+          let context = Context(dictionary: ["value": "test"])
+          try expect(try expression.evaluate(context: context)).to.beTrue()
+        }
+
+        $0.it("evaluates to false when empty string") {
+          let context = Context(dictionary: ["value": ""])
+          try expect(try expression.evaluate(context: context)).to.beFalse()
+        }
+
+        $0.it("evaluates to false when integer value is below 0 or below") {
+          let context = Context(dictionary: ["value": 0])
+          try expect(try expression.evaluate(context: context)).to.beFalse()
+
+          let negativeContext = Context(dictionary: ["value": 0])
+          try expect(try expression.evaluate(context: negativeContext)).to.beFalse()
+        }
+
+        $0.it("evaluates to true when float value is above 0") {
+          let context = Context(dictionary: ["value": Float(0.5)])
+          try expect(try expression.evaluate(context: context)).to.beTrue()
+        }
+
+        $0.it("evaluates to false when float is 0 or below") {
+          let context = Context(dictionary: ["value": Float(0)])
+          try expect(try expression.evaluate(context: context)).to.beFalse()
+        }
+
+        $0.it("evaluates to true when double value is above 0") {
+          let context = Context(dictionary: ["value": Double(0.5)])
+          try expect(try expression.evaluate(context: context)).to.beTrue()
+        }
+
+        $0.it("evaluates to false when double is 0 or below") {
+          let context = Context(dictionary: ["value": Double(0)])
+          try expect(try expression.evaluate(context: context)).to.beFalse()
+        }
+
+        $0.it("evaluates to false when uint is 0") {
+          let context = Context(dictionary: ["value": UInt(0)])
+          try expect(try expression.evaluate(context: context)).to.beFalse()
         }
       }
 
-      $0.describe("or expression") {
-        let expression = try! parseExpression(components: ["lhs", "or", "rhs"], tokenParser: parser)
-
-        $0.it("evaluates to true with lhs true") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with rhs true") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with lhs and rhs true") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with lhs and rhs false") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": false]))).to.beFalse()
-        }
-      }
-
-      $0.describe("equality expression") {
-        let expression = try! parseExpression(components: ["lhs", "==", "rhs"], tokenParser: parser)
-
-        $0.it("evaluates to true with equal lhs/rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "a"]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with non equal lhs/rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "b"]))).to.beFalse()
-        }
-
-        $0.it("evaluates to true with nils") {
-          try expect(expression.evaluate(context: Context(dictionary: [:]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with numbers") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 1, "rhs": 1.0]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with non equal numbers") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 1, "rhs": 1.1]))).to.beFalse()
-        }
-
-        $0.it("evaluates to true with booleans") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with falsy booleans") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beFalse()
-        }
-
-        $0.it("evaluates to false with different types") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": 1]))).to.beFalse()
-        }
-      }
-
-      $0.describe("inequality expression") {
-        let expression = try! parseExpression(components: ["lhs", "!=", "rhs"], tokenParser: parser)
-
-        $0.it("evaluates to true with inequal lhs/rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "b"]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with equal lhs/rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": "b", "rhs": "b"]))).to.beFalse()
-        }
-      }
-
-      $0.describe("more than expression") {
-        let expression = try! parseExpression(components: ["lhs", ">", "rhs"], tokenParser: parser)
-
-        $0.it("evaluates to true with lhs > rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 4]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with lhs == rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5.0]))).to.beFalse()
-        }
-      }
-
-      $0.describe("more than equal expression") {
-        let expression = try! parseExpression(components: ["lhs", ">=", "rhs"], tokenParser: parser)
-
-        $0.it("evaluates to true with lhs == rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with lhs < rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5.1]))).to.beFalse()
-        }
-      }
-
-      $0.describe("less than expression") {
-        let expression = try! parseExpression(components: ["lhs", "<", "rhs"], tokenParser: parser)
-
-        $0.it("evaluates to true with lhs < rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 4, "rhs": 4.5]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with lhs == rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5.0]))).to.beFalse()
-        }
-      }
-
-      $0.describe("less than equal expression") {
-        let expression = try! parseExpression(components: ["lhs", "<=", "rhs"], tokenParser: parser)
-
-        $0.it("evaluates to true with lhs == rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with lhs > rhs") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.1, "rhs": 5.0]))).to.beFalse()
-        }
-      }
-
-      $0.describe("multiple expression") {
-        let expression = try! parseExpression(components: ["one", "or", "two", "and", "not", "three"], tokenParser: parser)
-
-        $0.it("evaluates to true with one") {
-          try expect(expression.evaluate(context: Context(dictionary: ["one": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with one and three") {
-          try expect(expression.evaluate(context: Context(dictionary: ["one": true, "three": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with two") {
-          try expect(expression.evaluate(context: Context(dictionary: ["two": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with two and three") {
-          try expect(expression.evaluate(context: Context(dictionary: ["two": true, "three": true]))).to.beFalse()
-        }
-
-        $0.it("evaluates to false with two and three") {
-          try expect(expression.evaluate(context: Context(dictionary: ["two": true, "three": true]))).to.beFalse()
-        }
-
-        $0.it("evaluates to false with nothing") {
+      $0.describe("NotExpression") {
+        $0.it("returns truthy for positive expressions") {
+          let expression = NotExpression(expression: StaticExpression(value: true))
           try expect(expression.evaluate(context: Context())).to.beFalse()
         }
+
+        $0.it("returns falsy for negative expressions") {
+          let expression = NotExpression(expression: StaticExpression(value: false))
+          try expect(expression.evaluate(context: Context())).to.beTrue()
+        }
+      }
+
+      $0.describe("expression parsing") {
+        $0.it("can parse a variable expression") {
+          let expression = try parseExpression(components: ["value"])
+          try expect(expression.evaluate(context: Context())).to.beFalse()
+          try expect(expression.evaluate(context: Context(dictionary: ["value": true]))).to.beTrue()
+        }
+
+        $0.it("can parse a not expression") {
+          let expression = try parseExpression(components: ["not", "value"])
+          try expect(expression.evaluate(context: Context())).to.beTrue()
+          try expect(expression.evaluate(context: Context(dictionary: ["value": true]))).to.beFalse()
+        }
+
+        $0.describe("and expression") {
+          let expression = try! parseExpression(components: ["lhs", "and", "rhs"])
+
+          $0.it("evaluates to false with lhs false") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beFalse()
+          }
+
+          $0.it("evaluates to false with rhs false") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beFalse()
+          }
+
+          $0.it("evaluates to false with lhs and rhs false") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": false]))).to.beFalse()
+          }
+
+          $0.it("evaluates to true with lhs and rhs true") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
+          }
+        }
+
+        $0.describe("or expression") {
+          let expression = try! parseExpression(components: ["lhs", "or", "rhs"])
+
+          $0.it("evaluates to true with lhs true") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beTrue()
+          }
+
+          $0.it("evaluates to true with rhs true") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beTrue()
+          }
+
+          $0.it("evaluates to true with lhs and rhs true") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with lhs and rhs false") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": false]))).to.beFalse()
+          }
+        }
+
+        $0.describe("equality expression") {
+          let expression = try! parseExpression(components: ["lhs", "==", "rhs"])
+
+          $0.it("evaluates to true with equal lhs/rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "a"]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with non equal lhs/rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "b"]))).to.beFalse()
+          }
+
+          $0.it("evaluates to true with nils") {
+            try expect(expression.evaluate(context: Context(dictionary: [:]))).to.beTrue()
+          }
+
+          $0.it("evaluates to true with numbers") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 1, "rhs": 1.0]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with non equal numbers") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 1, "rhs": 1.1]))).to.beFalse()
+          }
+
+          $0.it("evaluates to true with booleans") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with falsy booleans") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beFalse()
+          }
+
+          $0.it("evaluates to false with different types") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": 1]))).to.beFalse()
+          }
+        }
+
+        $0.describe("inequality expression") {
+          let expression = try! parseExpression(components: ["lhs", "!=", "rhs"])
+
+          $0.it("evaluates to true with inequal lhs/rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "b"]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with equal lhs/rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": "b", "rhs": "b"]))).to.beFalse()
+          }
+        }
+
+        $0.describe("more than expression") {
+          let expression = try! parseExpression(components: ["lhs", ">", "rhs"])
+
+          $0.it("evaluates to true with lhs > rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 4]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with lhs == rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5.0]))).to.beFalse()
+          }
+        }
+
+        $0.describe("more than equal expression") {
+          let expression = try! parseExpression(components: ["lhs", ">=", "rhs"])
+
+          $0.it("evaluates to true with lhs == rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with lhs < rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5.1]))).to.beFalse()
+          }
+        }
+
+        $0.describe("less than expression") {
+          let expression = try! parseExpression(components: ["lhs", "<", "rhs"])
+
+          $0.it("evaluates to true with lhs < rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 4, "rhs": 4.5]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with lhs == rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5.0]))).to.beFalse()
+          }
+        }
+
+        $0.describe("less than equal expression") {
+          let expression = try! parseExpression(components: ["lhs", "<=", "rhs"])
+
+          $0.it("evaluates to true with lhs == rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with lhs > rhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.1, "rhs": 5.0]))).to.beFalse()
+          }
+        }
+
+        $0.describe("multiple expression") {
+          let expression = try! parseExpression(components: ["one", "or", "two", "and", "not", "three"])
+
+          $0.it("evaluates to true with one") {
+            try expect(expression.evaluate(context: Context(dictionary: ["one": true]))).to.beTrue()
+          }
+
+          $0.it("evaluates to true with one and three") {
+            try expect(expression.evaluate(context: Context(dictionary: ["one": true, "three": true]))).to.beTrue()
+          }
+
+          $0.it("evaluates to true with two") {
+            try expect(expression.evaluate(context: Context(dictionary: ["two": true]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false with two and three") {
+            try expect(expression.evaluate(context: Context(dictionary: ["two": true, "three": true]))).to.beFalse()
+          }
+
+          $0.it("evaluates to false with two and three") {
+            try expect(expression.evaluate(context: Context(dictionary: ["two": true, "three": true]))).to.beFalse()
+          }
+
+          $0.it("evaluates to false with nothing") {
+            try expect(expression.evaluate(context: Context())).to.beFalse()
+          }
+        }
+
+        $0.describe("in expression") {
+          let expression = try! parseExpression(components: ["lhs", "in", "rhs"])
+
+          $0.it("evaluates to true when rhs contains lhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 1, "rhs": [1, 2, 3]]))).to.beTrue()
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": ["a", "b", "c"]]))).to.beTrue()
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "abc"]))).to.beTrue()
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 1, "rhs": 1...3]))).to.beTrue()
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 1, "rhs": 1..<3]))).to.beTrue()
+          }
+
+          $0.it("evaluates to false when rhs does not contain lhs") {
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 1, "rhs": [2, 3, 4]]))).to.beFalse()
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": ["b", "c", "d"]]))).to.beFalse()
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "bcd"]))).to.beFalse()
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 4, "rhs": 1...3]))).to.beFalse()
+            try expect(expression.evaluate(context: Context(dictionary: ["lhs": 3, "rhs": 1..<3]))).to.beFalse()
+          }
+        }
+
+        $0.describe("sub expression") {
+          $0.it("evaluates correctly") {
+            let context = Context(dictionary: ["one": false, "two": false, "three": true, "four": true])
+
+            let expression = try! parseExpression(components: ["one", "and", "two", "or", "three", "and", "four"])
+            let expressionWithBrackets = try! parseExpression(components: ["one", "and", "(", "(", "two", ")", "or", "(", "three", "and", "four", ")", ")"])
+
+            try expect(expression.evaluate(context: context)).to.beTrue()
+            try expect(expressionWithBrackets.evaluate(context: context)).to.beFalse()
+
+            let notExpression = try! parseExpression(components: ["not", "one", "or", "three"])
+            let notExpressionWithBrackets = try! parseExpression(components: ["not", "(", "one", "or", "three", ")"])
+
+            try expect(notExpression.evaluate(context: context)).to.beTrue()
+            try expect(notExpressionWithBrackets.evaluate(context: context)).to.beFalse()
+          }
+
+          $0.it("fails when brackets are not balanced") {
+            try expect(parseExpression(components: ["(", "lhs", "and", "rhs"]))
+              .toThrow(TemplateSyntaxError("'if' expression error: missing closing bracket"))
+            try expect(parseExpression(components: [")", "lhs", "and", "rhs"]))
+              .toThrow(TemplateSyntaxError("'if' expression error: missing opening bracket"))
+            try expect(parseExpression(components: ["lhs", "and", "rhs", ")"]))
+              .toThrow(TemplateSyntaxError("'if' expression error: missing opening bracket"))
+            try expect(parseExpression(components: ["(", "lhs", "and", "rhs", ")", "("]))
+              .toThrow(TemplateSyntaxError("'if' expression error: missing closing bracket"))
+            try expect(parseExpression(components: ["(", "lhs", "and", "rhs", ")", ")"]))
+              .toThrow(TemplateSyntaxError("'if' expression error: missing opening bracket"))
+            try expect(parseExpression(components: ["(", "lhs", "and", ")"]))
+              .toThrow(TemplateSyntaxError("'if' expression error: end"))
+            try expect(parseExpression(components: ["(", "and", "rhs", ")"]))
+              .toThrow(TemplateSyntaxError("'if' expression error: infix operator 'and' doesn't have a left hand side"))
+          }
+        }
       }
     }
   }

Tests/StencilTests/FilterSpec.swift

@@ -1,150 +1,390 @@
+import XCTest
 import Spectre
 @testable import Stencil
 
+class FilterTests: XCTestCase {
+  func testFilter() {
+    describe("template filters") {
+      let context: [String: Any] = ["name": "Kyle"]
 
-func testFilter() {
-  describe("template filters") {
-    let context: [String: Any] = ["name": "Kyle"]
+      $0.it("allows you to register a custom filter") {
+        let template = Template(templateString: "{{ name|repeat }}")
 
-    $0.it("allows you to register a custom filter") {
-      let template = Template(templateString: "{{ name|repeat }}")
+        let repeatExtension = Extension()
+        repeatExtension.registerFilter("repeat") { (value: Any?) in
+          if let value = value as? String {
+            return "\(value) \(value)"
+          }
 
-      let repeatExtension = Extension()
-      repeatExtension.registerFilter("repeat") { (value: Any?) in
-        if let value = value as? String {
-          return "\(value) \(value)"
+          return nil
         }
 
-        return nil
+        let result = try template.render(Context(dictionary: context, environment: Environment(extensions: [repeatExtension])))
+        try expect(result) == "Kyle Kyle"
+      }
+        
+      $0.it("allows you to register boolean filters") {
+        let repeatExtension = Extension()
+        repeatExtension.registerFilter(name: "isPositive", negativeFilterName: "isNotPositive") { (value: Any?) in
+          if let value = value as? Int {
+            return value > 0
+          }
+          return nil
+        }
+        
+        let result = try Template(templateString: "{{ value|isPositive }}")
+          .render(Context(dictionary: ["value": 1], environment: Environment(extensions: [repeatExtension])))
+        try expect(result) == "true"
+        
+        let negativeResult = try Template(templateString: "{{ value|isNotPositive }}")
+          .render(Context(dictionary: ["value": -1], environment: Environment(extensions: [repeatExtension])))
+        try expect(negativeResult) == "true"
       }
 
-      let result = try template.render(Context(dictionary: context, environment: Environment(extensions: [repeatExtension])))
-      try expect(result) == "Kyle Kyle"
-    }
+      $0.it("allows you to register a custom filter which accepts single argument") {
+        let template = Template(templateString: """
+          {{ name|repeat:'value1, "value2"' }}
+          """)
 
-    $0.it("allows you to register a custom filter which accepts arguments") {
-      let template = Template(templateString: "{{ name|repeat:'value' }}")
+        let repeatExtension = Extension()
+        repeatExtension.registerFilter("repeat") { value, arguments in
+          if !arguments.isEmpty {
+            return "\(value!) \(value!) with args \(arguments.first!!)"
+          }
 
-      let repeatExtension = Extension()
-      repeatExtension.registerFilter("repeat") { value, arguments in
-        if !arguments.isEmpty {
-          return "\(value!) \(value!) with args \(arguments.first!!)"
+          return nil
         }
 
-        return nil
+        let result = try template.render(Context(dictionary: context, environment: Environment(extensions: [repeatExtension])))
+        try expect(result) == """
+          Kyle Kyle with args value1, "value2"
+          """
       }
 
-      let result = try template.render(Context(dictionary: context, environment: Environment(extensions: [repeatExtension])))
-      try expect(result) == "Kyle Kyle with args value"
-    }
+      $0.it("allows you to register a custom filter which accepts several arguments") {
+          let template = Template(templateString: """
+            {{ name|repeat:'value"1"',"value'2'",'(key, value)' }}
+            """)
 
-    $0.it("allows you to register a custom which throws") {
-      let template = Template(templateString: "{{ name|repeat }}")
-      let repeatExtension = Extension()
-      repeatExtension.registerFilter("repeat") { (value: Any?) in
-        throw TemplateSyntaxError("No Repeat")
+          let repeatExtension = Extension()
+          repeatExtension.registerFilter("repeat") { value, arguments in
+              if !arguments.isEmpty {
+                  return "\(value!) \(value!) with args 0: \(arguments[0]!), 1: \(arguments[1]!), 2: \(arguments[2]!)"
+              }
+
+              return nil
+          }
+
+          let result = try template.render(Context(dictionary: context, environment: Environment(extensions: [repeatExtension])))
+          try expect(result) == """
+            Kyle Kyle with args 0: value"1", 1: value'2', 2: (key, value)
+            """
       }
 
-      let context = Context(dictionary: context, environment: Environment(extensions: [repeatExtension]))
-      try expect(try template.render(context)).toThrow(TemplateSyntaxError("No Repeat"))
-    }
+      $0.it("allows you to register a custom which throws") {
+        let template = Template(templateString: "{{ name|repeat }}")
+        let repeatExtension = Extension()
+        repeatExtension.registerFilter("repeat") { (value: Any?) in
+          throw TemplateSyntaxError("No Repeat")
+        }
 
-    $0.it("allows you to override a default filter") {
-      let template = Template(templateString: "{{ name|join }}")
-
-      let repeatExtension = Extension()
-      repeatExtension.registerFilter("join") { (value: Any?) in
-        return "joined"
+        let context = Context(dictionary: context, environment: Environment(extensions: [repeatExtension]))
+        try expect(try template.render(context)).toThrow(TemplateSyntaxError(reason: "No Repeat", token: template.tokens.first))
       }
 
-      let result = try template.render(Context(dictionary: context, environment: Environment(extensions: [repeatExtension])))
-      try expect(result) == "joined"
+      $0.it("allows you to override a default filter") {
+        let template = Template(templateString: "{{ name|join }}")
+
+        let repeatExtension = Extension()
+        repeatExtension.registerFilter("join") { (value: Any?) in
+          return "joined"
+        }
+
+        let result = try template.render(Context(dictionary: context, environment: Environment(extensions: [repeatExtension])))
+        try expect(result) == "joined"
+      }
+
+      $0.it("allows whitespace in expression") {
+        let template = Template(templateString: """
+            {{ value | join : ", " }}
+            """)
+        let result = try template.render(Context(dictionary: ["value": ["One", "Two"]]))
+        try expect(result) == "One, Two"
+      }
+
+      $0.it("throws when you pass arguments to simple filter") {
+        let template = Template(templateString: "{{ name|uppercase:5 }}")
+        try expect(try template.render(Context(dictionary: ["name": "kyle"]))).toThrow()
+      }
     }
 
-    $0.it("allows whitespace in expression") {
-      let template = Template(templateString: "{{ name | uppercase }}")
-      let result = try template.render(Context(dictionary: ["name": "kyle"]))
-      try expect(result) == "KYLE"
+    describe("string filters") {
+      $0.context("given string") {
+        $0.it("transforms a string to be capitalized") {
+          let template = Template(templateString: "{{ name|capitalize }}")
+          let result = try template.render(Context(dictionary: ["name": "kyle"]))
+          try expect(result) == "Kyle"
+        }
+
+        $0.it("transforms a string to be uppercase") {
+          let template = Template(templateString: "{{ name|uppercase }}")
+          let result = try template.render(Context(dictionary: ["name": "kyle"]))
+          try expect(result) == "KYLE"
+        }
+
+        $0.it("transforms a string to be lowercase") {
+          let template = Template(templateString: "{{ name|lowercase }}")
+          let result = try template.render(Context(dictionary: ["name": "Kyle"]))
+          try expect(result) == "kyle"
+        }
+      }
+
+      $0.context("given array of strings") {
+        $0.it("transforms a string to be capitalized") {
+          let template = Template(templateString: "{{ names|capitalize }}")
+          let result = try template.render(Context(dictionary: ["names": ["kyle", "kyle"]]))
+          try expect(result) == """
+            ["Kyle", "Kyle"]
+            """
+        }
+
+        $0.it("transforms a string to be uppercase") {
+          let template = Template(templateString: "{{ names|uppercase }}")
+          let result = try template.render(Context(dictionary: ["names": ["kyle", "kyle"]]))
+          try expect(result) == """
+            ["KYLE", "KYLE"]
+            """
+        }
+
+        $0.it("transforms a string to be lowercase") {
+          let template = Template(templateString: "{{ names|lowercase }}")
+          let result = try template.render(Context(dictionary: ["names": ["Kyle", "Kyle"]]))
+          try expect(result) == """
+            ["kyle", "kyle"]
+            """
+        }
+      }
     }
 
-    $0.it("throws when you pass arguments to simple filter") {
-      let template = Template(templateString: "{{ name|uppercase:5 }}")
-      try expect(try template.render(Context(dictionary: ["name": "kyle"]))).toThrow()
-    }
-  }
+    describe("default filter") {
+      let template = Template(templateString: """
+        Hello {{ name|default:"World" }}
+        """)
 
+      $0.it("shows the variable value") {
+        let result = try template.render(Context(dictionary: ["name": "Kyle"]))
+        try expect(result) == "Hello Kyle"
+      }
 
-  describe("capitalize filter") {
-    let template = Template(templateString: "{{ name|capitalize }}")
+      $0.it("shows the default value") {
+        let result = try template.render(Context(dictionary: [:]))
+        try expect(result) == "Hello World"
+      }
 
-    $0.it("capitalizes a string") {
-      let result = try template.render(Context(dictionary: ["name": "kyle"]))
-      try expect(result) == "Kyle"
-    }
-  }
+      $0.it("supports multiple defaults") {
+        let template = Template(templateString: """
+          Hello {{ name|default:a,b,c,"World" }}
+          """)
+        let result = try template.render(Context(dictionary: [:]))
+        try expect(result) == "Hello World"
+      }
 
+      $0.it("can use int as default") {
+        let template = Template(templateString: "{{ value|default:1 }}")
+        let result = try template.render(Context(dictionary: [:]))
+        try expect(result) == "1"
+      }
 
-  describe("uppercase filter") {
-    let template = Template(templateString: "{{ name|uppercase }}")
+      $0.it("can use float as default") {
+        let template = Template(templateString: "{{ value|default:1.5 }}")
+        let result = try template.render(Context(dictionary: [:]))
+        try expect(result) == "1.5"
+      }
 
-    $0.it("transforms a string to be uppercase") {
-      let result = try template.render(Context(dictionary: ["name": "kyle"]))
-      try expect(result) == "KYLE"
-    }
-  }
-
-  describe("lowercase filter") {
-    let template = Template(templateString: "{{ name|lowercase }}")
-
-    $0.it("transforms a string to be lowercase") {
-      let result = try template.render(Context(dictionary: ["name": "Kyle"]))
-      try expect(result) == "kyle"
-    }
-  }
-
-  describe("default filter") {
-    let template = Template(templateString: "Hello {{ name|default:\"World\" }}")
-
-    $0.it("shows the variable value") {
-      let result = try template.render(Context(dictionary: ["name": "Kyle"]))
-      try expect(result) == "Hello Kyle"
+      $0.it("checks for underlying nil value correctly") {
+        let template = Template(templateString: """
+          Hello {{ user.name|default:"anonymous" }}
+          """)
+        let nilName: String? = nil
+        let user: [String: Any?] = ["name": nilName]
+        let result = try template.render(Context(dictionary: ["user": user]))
+        try expect(result) == "Hello anonymous"
+      }
     }
 
-    $0.it("shows the default value") {
-      let result = try template.render(Context(dictionary: [:]))
-      try expect(result) == "Hello World"
+    describe("join filter") {
+      let template = Template(templateString: """
+        {{ value|join:", " }}
+        """)
+
+      $0.it("joins a collection of strings") {
+        let result = try template.render(Context(dictionary: ["value": ["One", "Two"]]))
+        try expect(result) == "One, Two"
+      }
+
+      $0.it("joins a mixed-type collection") {
+        let result = try template.render(Context(dictionary: ["value": ["One", 2, true, 10.5, "Five"]]))
+        try expect(result) == "One, 2, true, 10.5, Five"
+      }
+
+      $0.it("can join by non string") {
+        let template = Template(templateString: """
+          {{ value|join:separator }}
+          """)
+        let result = try template.render(Context(dictionary: ["value": ["One", "Two"], "separator": true]))
+        try expect(result) == "OnetrueTwo"
+      }
+
+      $0.it("can join without arguments") {
+        let template = Template(templateString: """
+          {{ value|join }}
+          """)
+        let result = try template.render(Context(dictionary: ["value": ["One", "Two"]]))
+        try expect(result) == "OneTwo"
+      }
     }
 
-    $0.it("supports multiple defaults") {
-      let template = Template(templateString: "Hello {{ name|default:a,b,c,\"World\" }}")
-      let result = try template.render(Context(dictionary: [:]))
-      try expect(result) == "Hello World"
-    }
-  }
+    describe("split filter") {
+      let template = Template(templateString: """
+        {{ value|split:", " }}
+        """)
 
-  describe("join filter") {
-    let template = Template(templateString: "{{ value|join:\", \" }}")
+      $0.it("split a string into array") {
+        let result = try template.render(Context(dictionary: ["value": "One, Two"]))
+        try expect(result) == """
+          ["One", "Two"]
+          """
+      }
 
-    $0.it("joins a collection of strings") {
-      let result = try template.render(Context(dictionary: ["value": ["One", "Two"]]))
-      try expect(result) == "One, Two"
+      $0.it("can split without arguments") {
+        let template = Template(templateString: """
+          {{ value|split }}
+          """)
+        let result = try template.render(Context(dictionary: ["value": "One, Two"]))
+        try expect(result) == """
+          ["One,", "Two"]
+          """
+      }
     }
 
-    $0.it("joins a mixed-type collection") {
-      let result = try template.render(Context(dictionary: ["value": ["One", 2, true, 10.5, "Five"]]))
-      try expect(result) == "One, 2, true, 10.5, Five"
+
+    describe("filter suggestion") {
+      var template: Template!
+      var filterExtension: Extension!
+
+      func expectedSyntaxError(token: String, template: Template, description: String) -> TemplateSyntaxError {
+        guard let range = template.templateString.range(of: token) else {
+          fatalError("Can't find '\(token)' in '\(template)'")
+        }
+        let lexer = Lexer(templateString: template.templateString)
+        let location = lexer.rangeLocation(range)
+        let sourceMap = SourceMap(filename: template.name, location: location)
+        let token = Token.block(value: token, at: sourceMap)
+        return TemplateSyntaxError(reason: description, token: token, stackTrace: [])
+      }
+
+      func expectError(reason: String, token: String,
+                       file: String = #file, line: Int = #line, function: String = #function) throws {
+        let expectedError = expectedSyntaxError(token: token, template: template, description: reason)
+        let environment = Environment(extensions: [filterExtension])
+
+        let error = try expect(environment.render(template: template, context: [:]),
+                               file: file, line: line, function: function).toThrow() as TemplateSyntaxError
+        let reporter = SimpleErrorReporter()
+        try expect(reporter.renderError(error), file: file, line: line, function: function) == reporter.renderError(expectedError)
+      }
+
+      $0.it("made for unknown filter") {
+        template = Template(templateString: "{{ value|unknownFilter }}")
+
+        filterExtension = Extension()
+        filterExtension.registerFilter("knownFilter") { value, _ in value }
+
+        try expectError(reason: "Unknown filter 'unknownFilter'. Found similar filters: 'knownFilter'.", token: "value|unknownFilter")
+      }
+
+      $0.it("made for multiple similar filters") {
+        template = Template(templateString: "{{ value|lowerFirst }}")
+
+        filterExtension = Extension()
+        filterExtension.registerFilter("lowerFirstWord") { value, _ in value }
+        filterExtension.registerFilter("lowerFirstLetter") { value, _ in value }
+
+        try expectError(reason: "Unknown filter 'lowerFirst'. Found similar filters: 'lowerFirstWord', 'lowercase'.", token: "value|lowerFirst")
+      }
+
+      $0.it("not made when can't find similar filter") {
+        template = Template(templateString: "{{ value|unknownFilter }}")
+        try expectError(reason: "Unknown filter 'unknownFilter'. Found similar filters: 'lowerFirstWord'.", token: "value|unknownFilter")
+      }
+
     }
 
-    $0.it("can join by non string") {
-      let template = Template(templateString: "{{ value|join:separator }}")
-      let result = try template.render(Context(dictionary: ["value": ["One", "Two"], "separator": true]))
-      try expect(result) == "OnetrueTwo"
-    }
 
-    $0.it("can join without arguments") {
-      let template = Template(templateString: "{{ value|join }}")
-      let result = try template.render(Context(dictionary: ["value": ["One", "Two"]]))
-      try expect(result) == "OneTwo"
+    describe("indent filter") {
+      $0.it("indents content") {
+        let template = Template(templateString: """
+          {{ value|indent:2 }}
+          """)
+        let result = try template.render(Context(dictionary: ["value": """
+          One
+          Two
+          """]))
+        try expect(result) == """
+          One
+            Two
+          """
+      }
+
+      $0.it("can indent with arbitrary character") {
+        let template = Template(templateString: """
+          {{ value|indent:2,"\t" }}
+          """)
+        let result = try template.render(Context(dictionary: ["value": """
+          One
+          Two
+          """]))
+        try expect(result) == """
+          One
+          \t\tTwo
+          """
+      }
+
+      $0.it("can indent first line") {
+        let template = Template(templateString: """
+          {{ value|indent:2," ",true }}
+          """)
+        let result = try template.render(Context(dictionary: ["value": """
+          One
+          Two
+          """]))
+        try expect(result) == """
+            One
+            Two
+          """
+      }
+
+      $0.it("does not indent empty lines") {
+        let template = Template(templateString: """
+          {{ value|indent }}
+          """)
+        let result = try template.render(Context(dictionary: ["value": """
+          One
+
+
+          Two
+
+
+          """]))
+        try expect(result) == """
+          One
+
+
+              Two
+
+
+          """
+      }
     }
   }
 }

Tests/StencilTests/FilterTagSpec.swift

@@ -1,25 +1,51 @@
+import XCTest
 import Spectre
 import Stencil
 
+class FilterTagTests: XCTestCase {
+  func testFilterTag() {
+    describe("Filter Tag") {
+      $0.it("allows you to use a filter") {
+        let template = Template(templateString: "{% filter uppercase %}Test{% endfilter %}")
+        let result = try template.render()
+        try expect(result) == "TEST"
+      }
 
-func testFilterTag() {
-  describe("Filter Tag") {
-    $0.it("allows you to use a filter") {
-      let template = Template(templateString: "{% filter uppercase %}Test{% endfilter %}")
-      let result = try template.render()
-      try expect(result) == "TEST"
+      $0.it("allows you to chain filters") {
+        let template = Template(templateString: "{% filter lowercase|capitalize %}TEST{% endfilter %}")
+        let result = try template.render()
+        try expect(result) == "Test"
+      }
+
+      $0.it("errors without a filter") {
+        let template = Template(templateString: "Some {% filter %}Test{% endfilter %}")
+        try expect(try template.render()).toThrow()
+      }
+
+      $0.it("can render filters with arguments") {
+        let ext = Extension()
+        ext.registerFilter("split", filter: {
+          return ($0 as! String).components(separatedBy: $1[0] as! String)
+        })
+        let env = Environment(extensions: [ext])
+        let result = try env.renderTemplate(string: """
+        {% filter split:","|join:";"  %}{{ items|join:"," }}{% endfilter %}
+        """, context: ["items": [1, 2]])
+        try expect(result) == "1;2"
+      }
+
+      $0.it("can render filters with quote as an argument") {
+        let ext = Extension()
+        ext.registerFilter("replace", filter: {
+          print($1[0] as! String)
+          return ($0 as! String).replacingOccurrences(of: $1[0] as! String, with: $1[1] as! String)
+        })
+        let env = Environment(extensions: [ext])
+        let result = try env.renderTemplate(string: """
+          {% filter replace:'"',"" %}{{ items|join:"," }}{% endfilter %}
+          """, context: ["items": ["\"1\"", "\"2\""]])
+        try expect(result) == "1,2"
+      }
     }
-
-    $0.it("allows you to chain filters") {
-      let template = Template(templateString: "{% filter lowercase|capitalize %}TEST{% endfilter %}")
-      let result = try template.render()
-      try expect(result) == "Test"
-    }
-
-    $0.it("errors without a filter") {
-      let template = Template(templateString: "{% filter %}Test{% endfilter %}")
-      try expect(try template.render()).toThrow()
-    }
-
   }
 }

Tests/StencilTests/ForNodeSpec.swift

@@ -1,94 +1,355 @@
+import XCTest
 import Spectre
 @testable import Stencil
 import Foundation
 
-
-func testForNode() {
-  describe("ForNode") {
-    let context = Context(dictionary: [
-      "items": [1, 2, 3],
-      "emptyItems": [Int](),
-    ])
-
-    $0.it("renders the given nodes for each item") {
-      let nodes: [NodeType] = [VariableNode(variable: "item")]
-      let node = ForNode(resolvable: Variable("items"), loopVariable: "item", nodes: nodes, emptyNodes: [])
-      try expect(try node.render(context)) == "123"
-    }
-
-    $0.it("renders the given empty nodes when no items found item") {
-      let nodes: [NodeType] = [VariableNode(variable: "item")]
-      let emptyNodes: [NodeType] = [TextNode(text: "empty")]
-      let node = ForNode(resolvable: Variable("emptyItems"), loopVariable: "item", nodes: nodes, emptyNodes: emptyNodes)
-      try expect(try node.render(context)) == "empty"
-    }
-
-    $0.it("renders a context variable of type Array<Any>") {
-      let any_context = Context(dictionary: [
-        "items": ([1, 2, 3] as [Any])
-      ])
-
-      let nodes: [NodeType] = [VariableNode(variable: "item")]
-      let node = ForNode(resolvable: Variable("items"), loopVariable: "item", nodes: nodes, emptyNodes: [])
-      try expect(try node.render(any_context)) == "123"
-    }
-
-#if os(OSX)
-    $0.it("renders a context variable of type NSArray") {
-      let nsarray_context = Context(dictionary: [
-        "items": NSArray(array: [1, 2, 3])
-      ])
-
-      let nodes: [NodeType] = [VariableNode(variable: "item")]
-      let node = ForNode(resolvable: Variable("items"), loopVariable: "item", nodes: nodes, emptyNodes: [])
-      try expect(try node.render(nsarray_context)) == "123"
-    }
-#endif
-
-    $0.it("renders the given nodes while providing if the item is first in the context") {
-      let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.first")]
-      let node = ForNode(resolvable: Variable("items"), loopVariable: "item", nodes: nodes, emptyNodes: [])
-      try expect(try node.render(context)) == "1true2false3false"
-    }
-
-    $0.it("renders the given nodes while providing if the item is last in the context") {
-      let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.last")]
-      let node = ForNode(resolvable: Variable("items"), loopVariable: "item", nodes: nodes, emptyNodes: [])
-      try expect(try node.render(context)) == "1false2false3true"
-    }
-
-    $0.it("renders the given nodes while providing item counter") {
-      let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.counter")]
-      let node = ForNode(resolvable: Variable("items"), loopVariable: "item", nodes: nodes, emptyNodes: [])
-      try expect(try node.render(context)) == "112233"
-    }
-
-    $0.it("can render a filter") {
-      let templateString = "{% for article in ars|default:articles %}" +
-        "- {{ article.title }} by {{ article.author }}.\n" +
-        "{% endfor %}\n"
-
+class ForNodeTests: XCTestCase {
+  func testForNode() {
+    describe("ForNode") {
       let context = Context(dictionary: [
-        "articles": [
-          Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
-          Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
-        ]
-      ])
+        "items": [1, 2, 3],
+        "emptyItems": [Int](),
+        "dict": [
+          "one": "I",
+          "two": "II",
+        ],
+        "tuples": [(1, 2, 3), (4, 5, 6)]
+        ])
 
-      let template = Template(templateString: templateString)
-      let result = try template.render(context)
+      $0.it("renders the given nodes for each item") {
+        let nodes: [NodeType] = [VariableNode(variable: "item")]
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+        try expect(try node.render(context)) == "123"
+      }
 
-      let fixture = "" +
-        "- Migrating from OCUnit to XCTest by Kyle Fuller.\n" +
-        "- Memory Management with ARC by Kyle Fuller.\n" +
-        "\n"
+      $0.it("renders the given empty nodes when no items found item") {
+        let nodes: [NodeType] = [VariableNode(variable: "item")]
+        let emptyNodes: [NodeType] = [TextNode(text: "empty")]
+        let node = ForNode(resolvable: Variable("emptyItems"), loopVariables: ["item"], nodes: nodes, emptyNodes: emptyNodes)
+        try expect(try node.render(context)) == "empty"
+      }
+
+      $0.it("renders a context variable of type Array<Any>") {
+        let any_context = Context(dictionary: [
+          "items": ([1, 2, 3] as [Any])
+          ])
+
+        let nodes: [NodeType] = [VariableNode(variable: "item")]
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+        try expect(try node.render(any_context)) == "123"
+      }
+
+      $0.it("renders a context variable of type CountableClosedRange<Int>") {
+        let context = Context(dictionary: ["range": 1...3])
+        let nodes: [NodeType] = [VariableNode(variable: "item")]
+        let node = ForNode(resolvable: Variable("range"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+
+        try expect(try node.render(context)) == "123"
+      }
+
+      $0.it("renders a context variable of type CountableRange<Int>") {
+        let context = Context(dictionary: ["range": 1..<4])
+        let nodes: [NodeType] = [VariableNode(variable: "item")]
+        let node = ForNode(resolvable: Variable("range"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+
+        try expect(try node.render(context)) == "123"
+      }
+
+      #if os(OSX)
+      $0.it("renders a context variable of type NSArray") {
+        let nsarray_context = Context(dictionary: [
+          "items": NSArray(array: [1, 2, 3])
+          ])
+
+        let nodes: [NodeType] = [VariableNode(variable: "item")]
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+        try expect(try node.render(nsarray_context)) == "123"
+      }
+      #endif
+
+      $0.it("renders the given nodes while providing if the item is first in the context") {
+        let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.first")]
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+        try expect(try node.render(context)) == "1true2false3false"
+      }
+
+      $0.it("renders the given nodes while providing if the item is last in the context") {
+        let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.last")]
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+        try expect(try node.render(context)) == "1false2false3true"
+      }
+
+      $0.it("renders the given nodes while providing item counter") {
+        let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.counter")]
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+        try expect(try node.render(context)) == "112233"
+      }
+
+      $0.it("renders the given nodes while providing item counter") {
+        let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.counter0")]
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+        try expect(try node.render(context)) == "102132"
+      }
+
+      $0.it("renders the given nodes while providing loop length") {
+        let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.length")]
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
+        try expect(try node.render(context)) == "132333"
+      }
+
+      $0.it("renders the given nodes while filtering items using where expression") {
+        let nodes: [NodeType] = [VariableNode(variable: "item"), VariableNode(variable: "forloop.counter")]
+        let `where` = try parseExpression(components: ["item", ">", "1"], tokenParser: TokenParser(tokens: [], environment: Environment()), token: .text(value: "", at: .unknown))
+        let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [], where: `where`)
+        try expect(try node.render(context)) == "2132"
+      }
+
+      $0.it("renders the given empty nodes when all items filtered out with where expression") {
+        let nodes: [NodeType] = [VariableNode(variable: "item")]
+        let emptyNodes: [NodeType] = [TextNode(text: "empty")]
+        let `where` = try parseExpression(components: ["item", "==", "0"], tokenParser: TokenParser(tokens: [], environment: Environment()), token: .text(value: "", at: .unknown))
+        let node = ForNode(resolvable: Variable("emptyItems"), loopVariables: ["item"], nodes: nodes, emptyNodes: emptyNodes, where: `where`)
+        try expect(try node.render(context)) == "empty"
+      }
+
+      $0.it("can render a filter with spaces") {
+        let templateString = """
+        {% for article in ars | default: a, b , articles %}\
+        - {{ article.title }} by {{ article.author }}.
+        {% endfor %}
+        """
+
+        let context = Context(dictionary: [
+          "articles": [
+            Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
+            Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
+          ]
+          ])
+
+        let template = Template(templateString: templateString)
+        let result = try template.render(context)
+
+        try expect(result) == """
+        - Migrating from OCUnit to XCTest by Kyle Fuller.
+        - Memory Management with ARC by Kyle Fuller.
+
+        """
+      }
+
+      $0.context("given array of tuples") {
+        $0.it("can iterate over all tuple values") {
+          let templateString = """
+          {% for first,second,third in tuples %}\
+          {{ first }}, {{ second }}, {{ third }}
+          {% endfor %}
+          """
+
+          let template = Template(templateString: templateString)
+          let result = try template.render(context)
+
+          try expect(result) == """
+          1, 2, 3
+          4, 5, 6
+
+          """
+        }
+
+        $0.it("can iterate with less number of variables") {
+          let templateString = """
+          {% for first,second in tuples %}\
+          {{ first }}, {{ second }}
+          {% endfor %}
+          """
+
+          let template = Template(templateString: templateString)
+          let result = try template.render(context)
+
+          try expect(result) == """
+          1, 2
+          4, 5
+
+          """
+        }
+
+        $0.it("can use _ to skip variables") {
+          let templateString = """
+          {% for first,_,third in tuples %}\
+          {{ first }}, {{ third }}
+          {% endfor %}
+          """
+
+          let template = Template(templateString: templateString)
+          let result = try template.render(context)
+
+          try expect(result) == """
+          1, 3
+          4, 6
+
+          """
+        }
+
+        $0.it("throws when number of variables is more than number of tuple values") {
+          let templateString = """
+          {% for key,value,smth in dict %}
+          {% endfor %}
+          """
+
+          let template = Template(templateString: templateString)
+          try expect(template.render(context)).toThrow()
+        }
+
+      }
+
+      $0.it("can iterate over dictionary") {
+        let templateString = """
+        {% for key, value in dict %}\
+        {{ key }}: {{ value }},\
+        {% endfor %}
+        """
+
+        let template = Template(templateString: templateString)
+        let result = try template.render(context)
+
+        try expect(result) == """
+        one: I,two: II,
+        """
+      }
+
+      $0.it("renders supports iterating over dictionary") {
+        let nodes: [NodeType] = [
+          VariableNode(variable: "key"),
+          TextNode(text: ","),
+          ]
+        let emptyNodes: [NodeType] = [TextNode(text: "empty")]
+        let node = ForNode(resolvable: Variable("dict"), loopVariables: ["key"], nodes: nodes, emptyNodes: emptyNodes, where: nil)
+        let result = try node.render(context)
+
+        try expect(result) == """
+        one,two,
+        """
+      }
+
+      $0.it("renders supports iterating over dictionary") {
+        let nodes: [NodeType] = [
+          VariableNode(variable: "key"),
+          TextNode(text: "="),
+          VariableNode(variable: "value"),
+          TextNode(text: ","),
+          ]
+        let emptyNodes: [NodeType] = [TextNode(text: "empty")]
+        let node = ForNode(resolvable: Variable("dict"), loopVariables: ["key", "value"], nodes: nodes, emptyNodes: emptyNodes, where: nil)
+        let result = try node.render(context)
+
+        try expect(result) == """
+        one=I,two=II,
+        """
+      }
+
+      $0.it("handles invalid input") {
+        let token = Token.block(value: "for i", at: .unknown)
+        let parser = TokenParser(tokens: [token], environment: Environment())
+        let error = TemplateSyntaxError(reason: "'for' statements should use the syntax: `for <x> in <y> [where <condition>]`.", token: token)
+        try expect(try parser.parse()).toThrow(error)
+      }
+
+      $0.it("can iterate over struct properties") {
+        struct MyStruct {
+          let string: String
+          let number: Int
+        }
+
+        let context = Context(dictionary: [
+          "struct": MyStruct(string: "abc", number: 123)
+          ])
+
+        let nodes: [NodeType] = [
+          VariableNode(variable: "property"),
+          TextNode(text: "="),
+          VariableNode(variable: "value"),
+          TextNode(text: "\n"),
+          ]
+        let node = ForNode(resolvable: Variable("struct"), loopVariables: ["property", "value"], nodes: nodes, emptyNodes: [])
+        let result = try node.render(context)
+
+        try expect(result) == """
+        string=abc
+        number=123
+
+        """
+      }
+
+      $0.it("can iterate tuple items") {
+        let context = Context(dictionary: [
+          "tuple": (one: 1, two: "dva"),
+          ])
+
+        let nodes: [NodeType] = [
+          VariableNode(variable: "label"),
+          TextNode(text: "="),
+          VariableNode(variable: "value"),
+          TextNode(text: "\n"),
+          ]
+
+        let node = ForNode(resolvable: Variable("tuple"), loopVariables: ["label", "value"], nodes: nodes, emptyNodes: [])
+        let result = try node.render(context)
+
+        try expect(result) == """
+        one=1
+        two=dva
+
+        """
+      }
+
+      $0.it("can iterate over class properties") {
+        class MyClass {
+          var baseString: String
+          var baseInt: Int
+          init(_ string: String, _ int: Int) {
+            baseString = string
+            baseInt = int
+          }
+        }
+
+        class MySubclass: MyClass {
+          var childString: String
+          init(_ childString: String, _ string: String, _ int: Int) {
+            self.childString = childString
+            super.init(string, int)
+          }
+        }
+
+        let context = Context(dictionary: [
+          "class": MySubclass("child", "base", 1)
+          ])
+
+        let nodes: [NodeType] = [
+          VariableNode(variable: "label"),
+          TextNode(text: "="),
+          VariableNode(variable: "value"),
+          TextNode(text: "\n"),
+          ]
+
+        let node = ForNode(resolvable: Variable("class"), loopVariables: ["label", "value"], nodes: nodes, emptyNodes: [])
+        let result = try node.render(context)
+
+        try expect(result) == """
+        childString=child
+        baseString=base
+        baseInt=1
+
+        """
+      }
+
+      $0.it("can iterate in range of variables") {
+        let template: Template = "{% for i in 1...j %}{{ i }}{% endfor %}"
+        try expect(try template.render(Context(dictionary: ["j": 3]))) == "123"
+      }
 
-      try expect(result) == fixture
     }
+
   }
 }
 
-
 fileprivate struct Article {
   let title: String
   let author: String

Tests/StencilTests/IfNodeSpec.swift

@@ -1,114 +1,247 @@
+import XCTest
 import Spectre
 @testable import Stencil
 
+class IfNodeTests: XCTestCase {
+  func testIfNode() {
+    describe("IfNode") {
+      $0.describe("parsing") {
+        $0.it("can parse an if block") {
+          let tokens: [Token] = [
+            .block(value: "if value", at: .unknown),
+            .text(value: "true", at: .unknown),
+            .block(value: "endif", at: .unknown)
+          ]
 
-func testIfNode() {
-  describe("IfNode") {
-    $0.describe("parsing") {
-      $0.it("can parse an if block") {
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let nodes = try parser.parse()
+          let node = nodes.first as? IfNode
+
+          let conditions = node?.conditions
+          try expect(conditions?.count) == 1
+          try expect(conditions?[0].nodes.count) == 1
+          let trueNode = conditions?[0].nodes.first as? TextNode
+          try expect(trueNode?.text) == "true"
+        }
+
+        $0.it("can parse an if with else block") {
+          let tokens: [Token] = [
+            .block(value: "if value", at: .unknown),
+            .text(value: "true", at: .unknown),
+            .block(value: "else", at: .unknown),
+            .text(value: "false", at: .unknown),
+            .block(value: "endif", at: .unknown)
+          ]
+
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let nodes = try parser.parse()
+          let node = nodes.first as? IfNode
+
+          let conditions = node?.conditions
+          try expect(conditions?.count) == 2
+
+          try expect(conditions?[0].nodes.count) == 1
+          let trueNode = conditions?[0].nodes.first as? TextNode
+          try expect(trueNode?.text) == "true"
+
+          try expect(conditions?[1].nodes.count) == 1
+          let falseNode = conditions?[1].nodes.first as? TextNode
+          try expect(falseNode?.text) == "false"
+        }
+
+        $0.it("can parse an if with elif block") {
+          let tokens: [Token] = [
+            .block(value: "if value", at: .unknown),
+            .text(value: "true", at: .unknown),
+            .block(value: "elif something", at: .unknown),
+            .text(value: "some", at: .unknown),
+            .block(value: "else", at: .unknown),
+            .text(value: "false", at: .unknown),
+            .block(value: "endif", at: .unknown)
+          ]
+
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let nodes = try parser.parse()
+          let node = nodes.first as? IfNode
+
+          let conditions = node?.conditions
+          try expect(conditions?.count) == 3
+
+          try expect(conditions?[0].nodes.count) == 1
+          let trueNode = conditions?[0].nodes.first as? TextNode
+          try expect(trueNode?.text) == "true"
+
+          try expect(conditions?[1].nodes.count) == 1
+          let elifNode = conditions?[1].nodes.first as? TextNode
+          try expect(elifNode?.text) == "some"
+
+          try expect(conditions?[2].nodes.count) == 1
+          let falseNode = conditions?[2].nodes.first as? TextNode
+          try expect(falseNode?.text) == "false"
+        }
+
+        $0.it("can parse an if with elif block without else") {
+          let tokens: [Token] = [
+            .block(value: "if value", at: .unknown),
+            .text(value: "true", at: .unknown),
+            .block(value: "elif something", at: .unknown),
+            .text(value: "some", at: .unknown),
+            .block(value: "endif", at: .unknown)
+          ]
+
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let nodes = try parser.parse()
+          let node = nodes.first as? IfNode
+
+          let conditions = node?.conditions
+          try expect(conditions?.count) == 2
+
+          try expect(conditions?[0].nodes.count) == 1
+          let trueNode = conditions?[0].nodes.first as? TextNode
+          try expect(trueNode?.text) == "true"
+
+          try expect(conditions?[1].nodes.count) == 1
+          let elifNode = conditions?[1].nodes.first as? TextNode
+          try expect(elifNode?.text) == "some"
+        }
+
+        $0.it("can parse an if with multiple elif block") {
+          let tokens: [Token] = [
+            .block(value: "if value", at: .unknown),
+            .text(value: "true", at: .unknown),
+            .block(value: "elif something1", at: .unknown),
+            .text(value: "some1", at: .unknown),
+            .block(value: "elif something2", at: .unknown),
+            .text(value: "some2", at: .unknown),
+            .block(value: "else", at: .unknown),
+            .text(value: "false", at: .unknown),
+            .block(value: "endif", at: .unknown)
+          ]
+
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let nodes = try parser.parse()
+          let node = nodes.first as? IfNode
+
+          let conditions = node?.conditions
+          try expect(conditions?.count) == 4
+
+          try expect(conditions?[0].nodes.count) == 1
+          let trueNode = conditions?[0].nodes.first as? TextNode
+          try expect(trueNode?.text) == "true"
+
+          try expect(conditions?[1].nodes.count) == 1
+          let elifNode = conditions?[1].nodes.first as? TextNode
+          try expect(elifNode?.text) == "some1"
+
+          try expect(conditions?[2].nodes.count) == 1
+          let elif2Node = conditions?[2].nodes.first as? TextNode
+          try expect(elif2Node?.text) == "some2"
+
+          try expect(conditions?[3].nodes.count) == 1
+          let falseNode = conditions?[3].nodes.first as? TextNode
+          try expect(falseNode?.text) == "false"
+        }
+
+
+        $0.it("can parse an if with complex expression") {
+          let tokens: [Token] = [
+            .block(value: "if value == \"test\" and not name", at: .unknown),
+            .text(value: "true", at: .unknown),
+            .block(value: "endif", at: .unknown)
+          ]
+
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let nodes = try parser.parse()
+          try expect(nodes.first is IfNode).beTrue()
+        }
+
+        $0.it("can parse an ifnot block") {
+          let tokens: [Token] = [
+            .block(value: "ifnot value", at: .unknown),
+            .text(value: "false", at: .unknown),
+            .block(value: "else", at: .unknown),
+            .text(value: "true", at: .unknown),
+            .block(value: "endif", at: .unknown)
+          ]
+
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let nodes = try parser.parse()
+          let node = nodes.first as? IfNode
+          let conditions = node?.conditions
+          try expect(conditions?.count) == 2
+
+          try expect(conditions?[0].nodes.count) == 1
+          let trueNode = conditions?[0].nodes.first as? TextNode
+          try expect(trueNode?.text) == "true"
+
+          try expect(conditions?[1].nodes.count) == 1
+          let falseNode = conditions?[1].nodes.first as? TextNode
+          try expect(falseNode?.text) == "false"
+        }
+
+        $0.it("throws an error when parsing an if block without an endif") {
+          let tokens: [Token] = [.block(value: "if value", at: .unknown)]
+
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let error = TemplateSyntaxError(reason: "`endif` was not found.", token: tokens.first)
+          try expect(try parser.parse()).toThrow(error)
+        }
+
+        $0.it("throws an error when parsing an ifnot without an endif") {
+          let tokens: [Token] = [.block(value: "ifnot value", at: .unknown)]
+
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let error = TemplateSyntaxError(reason: "`endif` was not found.", token: tokens.first)
+          try expect(try parser.parse()).toThrow(error)
+        }
+      }
+
+      $0.describe("rendering") {
+        $0.it("renders a true expression") {
+          let node = IfNode(conditions: [
+            IfCondition(expression: StaticExpression(value: true), nodes: [TextNode(text: "1")]),
+            IfCondition(expression: StaticExpression(value: true), nodes: [TextNode(text: "2")]),
+            IfCondition(expression: nil, nodes: [TextNode(text: "3")]),
+            ])
+
+          try expect(try node.render(Context())) == "1"
+        }
+
+        $0.it("renders the first true expression") {
+          let node = IfNode(conditions: [
+            IfCondition(expression: StaticExpression(value: false), nodes: [TextNode(text: "1")]),
+            IfCondition(expression: StaticExpression(value: true), nodes: [TextNode(text: "2")]),
+            IfCondition(expression: nil, nodes: [TextNode(text: "3")]),
+            ])
+
+          try expect(try node.render(Context())) == "2"
+        }
+
+        $0.it("renders the empty expression when other conditions are falsy") {
+          let node = IfNode(conditions: [
+            IfCondition(expression: StaticExpression(value: false), nodes: [TextNode(text: "1")]),
+            IfCondition(expression: StaticExpression(value: false), nodes: [TextNode(text: "2")]),
+            IfCondition(expression: nil, nodes: [TextNode(text: "3")]),
+            ])
+
+          try expect(try node.render(Context())) == "3"
+        }
+
+        $0.it("renders empty when no truthy conditions") {
+          let node = IfNode(conditions: [
+            IfCondition(expression: StaticExpression(value: false), nodes: [TextNode(text: "1")]),
+            IfCondition(expression: StaticExpression(value: false), nodes: [TextNode(text: "2")]),
+            ])
+
+          try expect(try node.render(Context())) == ""
+        }
+      }
+
+      $0.it("supports variable filters in the if expression") {
         let tokens: [Token] = [
-          .block(value: "if value"),
-          .text(value: "true"),
-          .block(value: "else"),
-          .text(value: "false"),
-          .block(value: "endif")
-        ]
-
-        let parser = TokenParser(tokens: tokens, environment: Environment())
-        let nodes = try parser.parse()
-        let node = nodes.first as? IfNode
-        let trueNode = node?.trueNodes.first as? TextNode
-        let falseNode = node?.falseNodes.first as? TextNode
-
-        try expect(nodes.count) == 1
-        try expect(node?.trueNodes.count) == 1
-        try expect(trueNode?.text) == "true"
-        try expect(node?.falseNodes.count) == 1
-        try expect(falseNode?.text) == "false"
-      }
-
-      $0.it("can parse an if with complex expression") {
-        let tokens: [Token] = [
-          .block(value: "if value == \"test\" and not name"),
-          .text(value: "true"),
-          .block(value: "else"),
-          .text(value: "false"),
-          .block(value: "endif")
-        ]
-
-        let parser = TokenParser(tokens: tokens, environment: Environment())
-        let nodes = try parser.parse()
-        let node = nodes.first as? IfNode
-        let trueNode = node?.trueNodes.first as? TextNode
-        let falseNode = node?.falseNodes.first as? TextNode
-
-        try expect(nodes.count) == 1
-        try expect(node?.trueNodes.count) == 1
-        try expect(trueNode?.text) == "true"
-        try expect(node?.falseNodes.count) == 1
-        try expect(falseNode?.text) == "false"
-      }
-
-      $0.it("can parse an ifnot block") {
-        let tokens: [Token] = [
-          .block(value: "ifnot value"),
-          .text(value: "false"),
-          .block(value: "else"),
-          .text(value: "true"),
-          .block(value: "endif")
-        ]
-
-        let parser = TokenParser(tokens: tokens, environment: Environment())
-        let nodes = try parser.parse()
-        let node = nodes.first as? IfNode
-        let trueNode = node?.trueNodes.first as? TextNode
-        let falseNode = node?.falseNodes.first as? TextNode
-
-        try expect(nodes.count) == 1
-        try expect(node?.trueNodes.count) == 1
-        try expect(trueNode?.text) == "true"
-        try expect(node?.falseNodes.count) == 1
-        try expect(falseNode?.text) == "false"
-      }
-
-      $0.it("throws an error when parsing an if block without an endif") {
-        let tokens: [Token] = [
-          .block(value: "if value"),
-        ]
-
-        let parser = TokenParser(tokens: tokens, environment: Environment())
-        let error = TemplateSyntaxError("`endif` was not found.")
-        try expect(try parser.parse()).toThrow(error)
-      }
-
-      $0.it("throws an error when parsing an ifnot without an endif") {
-        let tokens: [Token] = [
-            .block(value: "ifnot value"),
-        ]
-
-        let parser = TokenParser(tokens: tokens, environment: Environment())
-        let error = TemplateSyntaxError("`endif` was not found.")
-        try expect(try parser.parse()).toThrow(error)
-      }
-    }
-
-    $0.describe("rendering") {
-      $0.it("renders the truth when expression evaluates to true") {
-        let node = IfNode(expression: StaticExpression(value: true), trueNodes: [TextNode(text: "true")], falseNodes: [TextNode(text: "false")])
-        try expect(try node.render(Context())) == "true"
-      }
-
-      $0.it("renders the false when expression evaluates to false") {
-        let node = IfNode(expression: StaticExpression(value: false), trueNodes: [TextNode(text: "true")], falseNodes: [TextNode(text: "false")])
-        try expect(try node.render(Context())) == "false"
-      }
-    }
-
-    $0.it("supports variable filters in the if expression") {
-        let tokens: [Token] = [
-          .block(value: "if value|uppercase == \"TEST\""),
-          .text(value: "true"),
-          .block(value: "endif")
+          .block(value: "if value|uppercase == \"TEST\"", at: .unknown),
+          .text(value: "true", at: .unknown),
+          .block(value: "endif", at: .unknown)
         ]
 
         let parser = TokenParser(tokens: tokens, environment: Environment())
@@ -116,6 +249,41 @@ func testIfNode() {
 
         let result = try renderNodes(nodes, Context(dictionary: ["value": "test"]))
         try expect(result) == "true"
+      }
+
+      $0.it("evaluates nil properties as false") {
+        let tokens: [Token] = [
+          .block(value: "if instance.value", at: .unknown),
+          .text(value: "true", at: .unknown),
+          .block(value: "endif", at: .unknown)
+        ]
+
+        let parser = TokenParser(tokens: tokens, environment: Environment())
+        let nodes = try parser.parse()
+
+        struct SomeType {
+          let value: String? = nil
+        }
+        let result = try renderNodes(nodes, Context(dictionary: ["instance": SomeType()]))
+        try expect(result) == ""
+      }
+
+      $0.it("supports closed range variables") {
+        let tokens: [Token] = [
+          .block(value: "if value in 1...3", at: .unknown),
+          .text(value: "true", at: .unknown),
+          .block(value: "else", at: .unknown),
+          .text(value: "false", at: .unknown),
+          .block(value: "endif", at: .unknown)
+        ]
+
+        let parser = TokenParser(tokens: tokens, environment: Environment())
+        let nodes = try parser.parse()
+
+        try expect(renderNodes(nodes, Context(dictionary: ["value": 3]))) == "true"
+        try expect(renderNodes(nodes, Context(dictionary: ["value": 4]))) == "false"
+      }
+
     }
   }
 }

Tests/StencilTests/IncludeSpec.swift

@@ -1,60 +1,71 @@
+import XCTest
 import Spectre
 @testable import Stencil
 import PathKit
 
+class IncludeTests: XCTestCase {
+  func testInclude() {
+    describe("Include") {
+      let path = Path(#file) + ".." + "fixtures"
+      let loader = FileSystemLoader(paths: [path])
+      let environment = Environment(loader: loader)
 
-func testInclude() {
-  describe("Include") {
-    let path = Path(#file) + ".." + "fixtures"
-    let loader = FileSystemLoader(paths: [path])
-    let environment = Environment(loader: loader)
+      $0.describe("parsing") {
+        $0.it("throws an error when no template is given") {
+          let tokens: [Token] = [ .block(value: "include", at: .unknown) ]
+          let parser = TokenParser(tokens: tokens, environment: Environment())
 
-    $0.describe("parsing") {
-      $0.it("throws an error when no template is given") {
-        let tokens: [Token] = [ .block(value: "include") ]
-        let parser = TokenParser(tokens: tokens, environment: Environment())
+          let error = TemplateSyntaxError(reason: "'include' tag requires one argument, the template file to be included. A second optional argument can be used to specify the context that will be passed to the included file", token: tokens.first)
+          try expect(try parser.parse()).toThrow(error)
+        }
 
-        let error = TemplateSyntaxError("'include' tag takes one argument, the template file to be included")
-        try expect(try parser.parse()).toThrow(error)
-      }
+        $0.it("can parse a valid include block") {
+          let tokens: [Token] = [ .block(value: "include \"test.html\"", at: .unknown) ]
+          let parser = TokenParser(tokens: tokens, environment: Environment())
 
-      $0.it("can parse a valid include block") {
-        let tokens: [Token] = [ .block(value: "include \"test.html\"") ]
-        let parser = TokenParser(tokens: tokens, environment: Environment())
-
-        let nodes = try parser.parse()
-        let node = nodes.first as? IncludeNode
-        try expect(nodes.count) == 1
-        try expect(node?.templateName) == Variable("\"test.html\"")
-      }
-    }
-
-    $0.describe("rendering") {
-      $0.it("throws an error when rendering without a loader") {
-        let node = IncludeNode(templateName: Variable("\"test.html\""))
-
-        do {
-          _ = try node.render(Context())
-        } catch {
-          try expect("\(error)") == "Template named `test.html` does not exist. No loaders found"
+          let nodes = try parser.parse()
+          let node = nodes.first as? IncludeNode
+          try expect(nodes.count) == 1
+          try expect(node?.templateName) == Variable("\"test.html\"")
         }
       }
 
-      $0.it("throws an error when it cannot find the included template") {
-        let node = IncludeNode(templateName: Variable("\"unknown.html\""))
+      $0.describe("rendering") {
+        $0.it("throws an error when rendering without a loader") {
+          let node = IncludeNode(templateName: Variable("\"test.html\""), token: .block(value: "", at: .unknown))
 
-        do {
-          _ = try node.render(Context(environment: environment))
-        } catch {
-          try expect("\(error)".hasPrefix("Template named `unknown.html` does not exist in loader")).to.beTrue()
+          do {
+            _ = try node.render(Context())
+          } catch {
+            try expect("\(error)") == "Template named `test.html` does not exist. No loaders found"
+          }
         }
-      }
 
-      $0.it("successfully renders a found included template") {
-        let node = IncludeNode(templateName: Variable("\"test.html\""))
-        let context = Context(dictionary: ["target": "World"], environment: environment)
-        let value = try node.render(context)
-        try expect(value) == "Hello World!"
+        $0.it("throws an error when it cannot find the included template") {
+          let node = IncludeNode(templateName: Variable("\"unknown.html\""), token: .block(value: "", at: .unknown))
+
+          do {
+            _ = try node.render(Context(environment: environment))
+          } catch {
+            try expect("\(error)".hasPrefix("Template named `unknown.html` does not exist in loader")).to.beTrue()
+          }
+        }
+
+        $0.it("successfully renders a found included template") {
+          let node = IncludeNode(templateName: Variable("\"test.html\""), token: .block(value: "", at: .unknown))
+          let context = Context(dictionary: ["target": "World"], environment: environment)
+          let value = try node.render(context)
+          try expect(value) == "Hello World!"
+        }
+
+        $0.it("successfully passes context") {
+          let template = Template(templateString: """
+          {% include "test.html" child %}
+          """)
+          let context = Context(dictionary: ["child": ["target": "World"]], environment: environment)
+          let value = try template.render(context)
+          try expect(value) == "Hello World!"
+        }
       }
     }
   }

Tests/StencilTests/InheritenceSpec.swift

@@ -1,27 +1,38 @@
+import XCTest
 import Spectre
 import Stencil
 import PathKit
 
+class InheritenceTests: XCTestCase {
+  func testInheritence() {
+    describe("Inheritence") {
+      let path = Path(#file) + ".." + "fixtures"
+      let loader = FileSystemLoader(paths: [path])
+      let environment = Environment(loader: loader)
 
-func testInheritence() {
-  describe("Inheritence") {
-    let path = Path(#file) + ".." + "fixtures"
-    let loader = FileSystemLoader(paths: [path])
-    let environment = Environment(loader: loader)
+      $0.it("can inherit from another template") {
+        let template = try environment.loadTemplate(name: "child.html")
+        try expect(try template.render()) == """
+        Super_Header Child_Header
+        Child_Body
+        """
+      }
 
-    $0.it("can inherit from another template") {
-      let template = try environment.loadTemplate(name: "child.html")
-      try expect(try template.render()) == "Header\nChild"
-    }
+      $0.it("can inherit from another template inheriting from another template") {
+        let template = try environment.loadTemplate(name: "child-child.html")
+        try expect(try template.render()) == """
+        Super_Header Child_Header Child_Child_Header
+        Child_Body
+        """
+      }
 
-    $0.it("can inherit from another template inheriting from another template") {
-      let template = try environment.loadTemplate(name: "child-child.html")
-      try expect(try template.render()) == "Child Child Header\nChild"
-    }
-
-    $0.it("can inherit from a template that calls a super block") {
-      let template = try environment.loadTemplate(name: "child-super.html")
-      try expect(try template.render()) == "Header\nChild Body"
+      $0.it("can inherit from a template that calls a super block") {
+        let template = try environment.loadTemplate(name: "child-super.html")
+        try expect(try template.render()) == """
+        Header
+        Child_Body
+        """
+      }
     }
   }
 }

Tests/StencilTests/LexerSpec.swift

@@ -1,50 +1,137 @@
+import PathKit
 import Spectre
 @testable import Stencil
+import XCTest
 
+class LexerTests: XCTestCase {
+  func testLexer() {
+    describe("Lexer") {
+      func makeSourceMap(_ token: String, for lexer: Lexer, options: String.CompareOptions = []) -> SourceMap {
+        guard let range = lexer.templateString.range(of: token, options: options) else { fatalError("Token not found") }
+        return SourceMap(location: lexer.rangeLocation(range))
+      }
 
-func testLexer() {
-  describe("Lexer") {
-    $0.it("can tokenize text") {
-      let lexer = Lexer(templateString: "Hello World")
-      let tokens = lexer.tokenize()
+      $0.it("can tokenize text") {
+        let lexer = Lexer(templateString: "Hello World")
+        let tokens = lexer.tokenize()
 
-      try expect(tokens.count) == 1
-      try expect(tokens.first) == .text(value: "Hello World")
+        try expect(tokens.count) == 1
+        try expect(tokens.first) == .text(value: "Hello World", at: makeSourceMap("Hello World", for: lexer))
+      }
+
+      $0.it("can tokenize a comment") {
+        let lexer = Lexer(templateString: "{# Comment #}")
+        let tokens = lexer.tokenize()
+
+        try expect(tokens.count) == 1
+        try expect(tokens.first) == .comment(value: "Comment", at: makeSourceMap("Comment", for: lexer))
+      }
+
+      $0.it("can tokenize a variable") {
+        let lexer = Lexer(templateString: "{{ Variable }}")
+        let tokens = lexer.tokenize()
+
+        try expect(tokens.count) == 1
+        try expect(tokens.first) == .variable(value: "Variable", at: makeSourceMap("Variable", for: lexer))
+      }
+
+      $0.it("can tokenize a token without spaces") {
+        let lexer = Lexer(templateString: "{{Variable}}")
+        let tokens = lexer.tokenize()
+
+        try expect(tokens.count) == 1
+        try expect(tokens.first) == .variable(value: "Variable", at: makeSourceMap("Variable", for: lexer))
+      }
+
+      $0.it("can tokenize unclosed tag by ignoring it") {
+        let templateString = "{{ thing"
+        let lexer = Lexer(templateString: templateString)
+        let tokens = lexer.tokenize()
+
+        try expect(tokens.count) == 1
+        try expect(tokens.first) == .text(value: "", at: makeSourceMap("{{ thing", for: lexer))
+      }
+
+      $0.it("can tokenize a mixture of content") {
+        let templateString = "My name is {{ myname }}."
+        let lexer = Lexer(templateString: templateString)
+        let tokens = lexer.tokenize()
+
+        try expect(tokens.count) == 3
+        try expect(tokens[0]) == Token.text(value: "My name is ", at: makeSourceMap("My name is ", for: lexer))
+        try expect(tokens[1]) == Token.variable(value: "myname", at: makeSourceMap("myname", for: lexer))
+        try expect(tokens[2]) == Token.text(value: ".", at: makeSourceMap(".", for: lexer))
+      }
+
+      $0.it("can tokenize two variables without being greedy") {
+        let templateString = "{{ thing }}{{ name }}"
+        let lexer = Lexer(templateString: templateString)
+        let tokens = lexer.tokenize()
+
+        try expect(tokens.count) == 2
+        try expect(tokens[0]) == Token.variable(value: "thing", at: makeSourceMap("thing", for: lexer))
+        try expect(tokens[1]) == Token.variable(value: "name", at: makeSourceMap("name", for: lexer))
+      }
+
+      $0.it("can tokenize an unclosed block") {
+        let lexer = Lexer(templateString: "{%}")
+        _ = lexer.tokenize()
+      }
+
+      $0.it("can tokenize incorrect syntax without crashing") {
+        let lexer = Lexer(templateString: "func some() {{% if %}")
+        _ = lexer.tokenize()
+      }
+
+      $0.it("can tokenize an empty variable") {
+        let lexer = Lexer(templateString: "{{}}")
+        _ = lexer.tokenize()
+      }
+
+      $0.it("can tokenize with new lines") {
+        let templateString = """
+          My name is {%
+              if name
+               and
+              name
+          %}{{
+          name
+          }}{%
+          endif %}.
+          """
+        let lexer = Lexer(templateString: templateString)
+        let tokens = lexer.tokenize()
+
+        try expect(tokens.count) == 5
+        try expect(tokens[0]) == Token.text(value: "My name is ", at: makeSourceMap("My name is", for: lexer))
+        try expect(tokens[1]) == Token.block(value: "if name and name", at: makeSourceMap("{%", for: lexer))
+        try expect(tokens[2]) == Token.variable(value: "name", at: makeSourceMap("name", for: lexer, options: .backwards))
+        try expect(tokens[3]) == Token.block(value: "endif", at: makeSourceMap("endif", for: lexer))
+        try expect(tokens[4]) == Token.text(value: ".", at: makeSourceMap(".", for: lexer))
+      }
+
+      $0.it("can tokenize escape sequences") {
+        let templateString = "class Some {{ '{' }}{% if true %}{{ stuff }}{% endif %}"
+        let lexer = Lexer(templateString: templateString)
+        let tokens = lexer.tokenize()
+
+        try expect(tokens.count) == 5
+        try expect(tokens[0]) == Token.text(value: "class Some ", at: makeSourceMap("class Some ", for: lexer))
+        try expect(tokens[1]) == Token.variable(value: "'{'", at: makeSourceMap("'{'", for: lexer))
+        try expect(tokens[2]) == Token.block(value: "if true", at: makeSourceMap("if true", for: lexer))
+        try expect(tokens[3]) == Token.variable(value: "stuff", at: makeSourceMap("stuff", for: lexer))
+        try expect(tokens[4]) == Token.block(value: "endif", at: makeSourceMap("endif", for: lexer))
+      }
     }
+  }
 
-    $0.it("can tokenize a comment") {
-      let lexer = Lexer(templateString: "{# Comment #}")
-      let tokens = lexer.tokenize()
+  func testPerformance() throws {
+    let path = Path(#file) + ".."  + "fixtures" + "huge.html"
+    let content: String = try path.read()
 
-      try expect(tokens.count) == (1)
-      try expect(tokens.first) == .comment(value: "Comment")
-    }
-
-    $0.it("can tokenize a variable") {
-      let lexer = Lexer(templateString: "{{ Variable }}")
-      let tokens = lexer.tokenize()
-
-      try expect(tokens.count) == 1
-      try expect(tokens.first) == .variable(value: "Variable")
-    }
-
-    $0.it("can tokenize a mixture of content") {
-      let lexer = Lexer(templateString: "My name is {{ name }}.")
-      let tokens = lexer.tokenize()
-
-      try expect(tokens.count) == 3
-      try expect(tokens[0]) == Token.text(value: "My name is ")
-      try expect(tokens[1]) == Token.variable(value: "name")
-      try expect(tokens[2]) == Token.text(value: ".")
-    }
-
-    $0.it("can tokenize two variables without being greedy") {
-      let lexer = Lexer(templateString: "{{ thing }}{{ name }}")
-      let tokens = lexer.tokenize()
-
-      try expect(tokens.count) == 2
-      try expect(tokens[0]) == Token.variable(value: "thing")
-      try expect(tokens[1]) == Token.variable(value: "name")
+    measure {
+      let lexer = Lexer(templateString: content)
+      _ = lexer.tokenize()
     }
   }
 }

Tests/StencilTests/LoaderSpec.swift

@@ -1,32 +1,57 @@
+import XCTest
 import Spectre
 import Stencil
 import PathKit
 
+class TemplateLoaderTests: XCTestCase {
+  func testTemplateLoader() {
+    describe("FileSystemLoader") {
+      let path = Path(#file) + ".."  + "fixtures"
+      let loader = FileSystemLoader(paths: [path])
+      let environment = Environment(loader: loader)
 
-func testTemplateLoader() {
-  describe("FileSystemLoader") {
-    let path = Path(#file) + ".."  + "fixtures"
-    let loader = FileSystemLoader(paths: [path])
-    let environment = Environment(loader: loader)
+      $0.it("errors when a template cannot be found") {
+        try expect(try environment.loadTemplate(name: "unknown.html")).toThrow()
+      }
 
-    $0.it("errors when a template cannot be found") {
-      try expect(try environment.loadTemplate(name: "unknown.html")).toThrow()
+      $0.it("errors when an array of templates cannot be found") {
+        try expect(try environment.loadTemplate(names: ["unknown.html", "unknown2.html"])).toThrow()
+      }
+
+      $0.it("can load a template from a file") {
+        _ = try environment.loadTemplate(name: "test.html")
+      }
+
+      $0.it("errors when loading absolute file outside of the selected path") {
+        try expect(try environment.loadTemplate(name: "/etc/hosts")).toThrow()
+      }
+
+      $0.it("errors when loading relative file outside of the selected path") {
+        try expect(try environment.loadTemplate(name: "../LoaderSpec.swift")).toThrow()
+      }
     }
 
-    $0.it("errors when an array of templates cannot be found") {
-      try expect(try environment.loadTemplate(names: ["unknown.html", "unknown2.html"])).toThrow()
-    }
+    describe("DictionaryLoader") {
+      let loader = DictionaryLoader(templates: [
+        "index.html": "Hello World"
+        ])
+      let environment = Environment(loader: loader)
 
-    $0.it("can load a template from a file") {
-      _ = try environment.loadTemplate(name: "test.html")
-    }
+      $0.it("errors when a template cannot be found") {
+        try expect(try environment.loadTemplate(name: "unknown.html")).toThrow()
+      }
 
-    $0.it("errors when loading absolute file outside of the selected path") {
-      try expect(try environment.loadTemplate(name: "/etc/hosts")).toThrow()
-    }
+      $0.it("errors when an array of templates cannot be found") {
+        try expect(try environment.loadTemplate(names: ["unknown.html", "unknown2.html"])).toThrow()
+      }
 
-    $0.it("errors when loading relative file outside of the selected path") {
-      try expect(try environment.loadTemplate(name: "../LoaderSpec.swift")).toThrow()
+      $0.it("can load a template from a known templates") {
+        _ = try environment.loadTemplate(name: "index.html")
+      }
+
+      $0.it("can load a known template from a collection of templates") {
+        _ = try environment.loadTemplate(names: ["unknown.html", "index.html"])
+      }
     }
   }
 }

Tests/StencilTests/NodeSpec.swift

@@ -1,59 +1,65 @@
+import XCTest
 import Spectre
 @testable import Stencil
 
-
 class ErrorNode : NodeType {
+  let token: Token?
+  init(token: Token? = nil) {
+    self.token = token
+  }
+
   func render(_ context: Context) throws -> String {
     throw TemplateSyntaxError("Custom Error")
   }
 }
 
+class NodeTests: XCTestCase {
+  func testNode() {
+    describe("Node") {
+      let context = Context(dictionary: [
+        "name": "Kyle",
+        "age": 27,
+        "items": [1, 2, 3],
+        ])
 
-func testNode() {
-  describe("Node") {
-    let context = Context(dictionary: [
-      "name": "Kyle",
-      "age": 27,
-      "items": [1, 2, 3],
-    ])
-
-    $0.describe("TextNode") {
-      $0.it("renders the given text") {
-        let node = TextNode(text: "Hello World")
-        try expect(try node.render(context)) == "Hello World"
-      }
-    }
-
-    $0.describe("VariableNode") {
-      $0.it("resolves and renders the variable") {
-        let node = VariableNode(variable: Variable("name"))
-        try expect(try node.render(context)) == "Kyle"
+      $0.describe("TextNode") {
+        $0.it("renders the given text") {
+          let node = TextNode(text: "Hello World")
+          try expect(try node.render(context)) == "Hello World"
+        }
       }
 
-      $0.it("resolves and renders a non string variable") {
-        let node = VariableNode(variable: Variable("age"))
-        try expect(try node.render(context)) == "27"
-      }
-    }
+      $0.describe("VariableNode") {
+        $0.it("resolves and renders the variable") {
+          let node = VariableNode(variable: Variable("name"))
+          try expect(try node.render(context)) == "Kyle"
+        }
 
-    $0.describe("rendering nodes") {
-      $0.it("renders the nodes") {
-        let nodes: [NodeType] = [
-          TextNode(text:"Hello "),
-          VariableNode(variable: "name"),
-        ]
-
-        try expect(try renderNodes(nodes, context)) == "Hello Kyle"
+        $0.it("resolves and renders a non string variable") {
+          let node = VariableNode(variable: Variable("age"))
+          try expect(try node.render(context)) == "27"
+        }
       }
 
-      $0.it("correctly throws a nodes failure") {
-        let nodes: [NodeType] = [
-          TextNode(text:"Hello "),
-          VariableNode(variable: "name"),
-          ErrorNode(),
-        ]
+      $0.describe("rendering nodes") {
+        $0.it("renders the nodes") {
+          let nodes: [NodeType] = [
+            TextNode(text:"Hello "),
+            VariableNode(variable: "name"),
+            ]
 
-        try expect(try renderNodes(nodes, context)).toThrow(TemplateSyntaxError("Custom Error"))
+          try expect(try renderNodes(nodes, context)) == "Hello Kyle"
+        }
+
+        $0.it("correctly throws a nodes failure") {
+          let nodes: [NodeType] = [
+            TextNode(text:"Hello "),
+            VariableNode(variable: "name"),
+            ErrorNode(),
+            ]
+
+          try expect(try renderNodes(nodes, context)).toThrow(TemplateSyntaxError("Custom Error"))
+        }
       }
     }
   }

Tests/StencilTests/NowNodeSpec.swift

@@ -1,43 +1,46 @@
+import XCTest
 import Foundation
 import Spectre
 @testable import Stencil
 
 
-func testNowNode() {
-#if !os(Linux)
-  describe("NowNode") {
-    $0.describe("parsing") {
-      $0.it("parses default format without any now arguments") {
-        let tokens: [Token] = [ .block(value: "now") ]
-        let parser = TokenParser(tokens: tokens, environment: Environment())
+class NowNodeTests: XCTestCase {
+  func testNowNode() {
+    #if !os(Linux)
+    describe("NowNode") {
+      $0.describe("parsing") {
+        $0.it("parses default format without any now arguments") {
+          let tokens: [Token] = [ .block(value: "now", at: .unknown) ]
+          let parser = TokenParser(tokens: tokens, environment: Environment())
 
-        let nodes = try parser.parse()
-        let node = nodes.first as? NowNode
-        try expect(nodes.count) == 1
-        try expect(node?.format.variable) == "\"yyyy-MM-dd 'at' HH:mm\""
+          let nodes = try parser.parse()
+          let node = nodes.first as? NowNode
+          try expect(nodes.count) == 1
+          try expect(node?.format.variable) == "\"yyyy-MM-dd 'at' HH:mm\""
+        }
+
+        $0.it("parses now with a format") {
+          let tokens: [Token] = [ .block(value: "now \"HH:mm\"", at: .unknown) ]
+          let parser = TokenParser(tokens: tokens, environment: Environment())
+          let nodes = try parser.parse()
+          let node = nodes.first as? NowNode
+          try expect(nodes.count) == 1
+          try expect(node?.format.variable) == "\"HH:mm\""
+        }
       }
 
-      $0.it("parses now with a format") {
-        let tokens: [Token] = [ .block(value: "now \"HH:mm\"") ]
-        let parser = TokenParser(tokens: tokens, environment: Environment())
-        let nodes = try parser.parse()
-        let node = nodes.first as? NowNode
-        try expect(nodes.count) == 1
-        try expect(node?.format.variable) == "\"HH:mm\""
-      }
-    }
-
-    $0.describe("rendering") {
-      $0.it("renders the date") {
-        let node = NowNode(format: Variable("\"yyyy-MM-dd\""))
-
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd"
-        let date = formatter.string(from: NSDate() as Date)
-
-        try expect(try node.render(Context())) == date
+      $0.describe("rendering") {
+        $0.it("renders the date") {
+          let node = NowNode(format: Variable("\"yyyy-MM-dd\""))
+
+          let formatter = DateFormatter()
+          formatter.dateFormat = "yyyy-MM-dd"
+          let date = formatter.string(from: NSDate() as Date)
+
+          try expect(try node.render(Context())) == date
+        }
       }
     }
+    #endif
   }
-#endif
 }

Tests/StencilTests/ParserSpec.swift

@@ -1,62 +1,63 @@
+import XCTest
 import Spectre
 @testable import Stencil
 
+class TokenParserTests: XCTestCase {
+  func testTokenParser() {
+    describe("TokenParser") {
+      $0.it("can parse a text token") {
+        let parser = TokenParser(tokens: [
+          .text(value: "Hello World", at: .unknown)
+          ], environment: Environment())
 
-func testTokenParser() {
-  describe("TokenParser") {
-    $0.it("can parse a text token") {
-      let parser = TokenParser(tokens: [
-        .text(value: "Hello World")
-      ], environment: Environment())
+        let nodes = try parser.parse()
+        let node = nodes.first as? TextNode
 
-      let nodes = try parser.parse()
-      let node = nodes.first as? TextNode
-
-      try expect(nodes.count) == 1
-      try expect(node?.text) == "Hello World"
-    }
-
-    $0.it("can parse a variable token") {
-      let parser = TokenParser(tokens: [
-        .variable(value: "'name'")
-      ], environment: Environment())
-
-      let nodes = try parser.parse()
-      let node = nodes.first as? VariableNode
-      try expect(nodes.count) == 1
-      let result = try node?.render(Context())
-      try expect(result) == "name"
-    }
-
-    $0.it("can parse a comment token") {
-      let parser = TokenParser(tokens: [
-        .comment(value: "Secret stuff!")
-      ], environment: Environment())
-
-      let nodes = try parser.parse()
-      try expect(nodes.count) == 0
-    }
-
-    $0.it("can parse a tag token") {
-      let simpleExtension = Extension()
-      simpleExtension.registerSimpleTag("known") { _ in
-        return ""
+        try expect(nodes.count) == 1
+        try expect(node?.text) == "Hello World"
       }
 
-      let parser = TokenParser(tokens: [
-        .block(value: "known"),
-      ], environment: Environment(extensions: [simpleExtension]))
+      $0.it("can parse a variable token") {
+        let parser = TokenParser(tokens: [
+          .variable(value: "'name'", at: .unknown)
+          ], environment: Environment())
 
-      let nodes = try parser.parse()
-      try expect(nodes.count) == 1
-    }
+        let nodes = try parser.parse()
+        let node = nodes.first as? VariableNode
+        try expect(nodes.count) == 1
+        let result = try node?.render(Context())
+        try expect(result) == "name"
+      }
 
-    $0.it("errors when parsing an unknown tag") {
-      let parser = TokenParser(tokens: [
-        .block(value: "unknown"),
-      ], environment: Environment())
+      $0.it("can parse a comment token") {
+        let parser = TokenParser(tokens: [
+          .comment(value: "Secret stuff!", at: .unknown)
+          ], environment: Environment())
 
-      try expect(try parser.parse()).toThrow(TemplateSyntaxError("Unknown template tag 'unknown'"))
+        let nodes = try parser.parse()
+        try expect(nodes.count) == 0
+      }
+
+      $0.it("can parse a tag token") {
+        let simpleExtension = Extension()
+        simpleExtension.registerSimpleTag("known") { _ in
+          return ""
+        }
+
+        let parser = TokenParser(tokens: [
+          .block(value: "known", at: .unknown),
+          ], environment: Environment(extensions: [simpleExtension]))
+
+        let nodes = try parser.parse()
+        try expect(nodes.count) == 1
+      }
+
+      $0.it("errors when parsing an unknown tag") {
+        let tokens: [Token] = [.block(value: "unknown", at: .unknown)]
+        let parser = TokenParser(tokens: tokens, environment: Environment())
+
+        try expect(try parser.parse()).toThrow(TemplateSyntaxError(reason: "Unknown template tag 'unknown'", token: tokens.first))
+      }
     }
   }
 }

Tests/StencilTests/StencilSpec.swift

@@ -1,69 +1,72 @@
+import XCTest
 import Spectre
 import Stencil
 
-
-fileprivate class CustomNode : NodeType {
+fileprivate struct CustomNode : NodeType {
+  let token: Token?
   func render(_ context:Context) throws -> String {
     return "Hello World"
   }
 }
 
-
 fileprivate struct Article {
   let title: String
   let author: String
 }
 
+class StencilTests: XCTestCase {
+  func testStencil() {
+    describe("Stencil") {
+      let exampleExtension = Extension()
 
-func testStencil() {
-  describe("Stencil") {
-    let exampleExtension = Extension()
+      exampleExtension.registerSimpleTag("simpletag") { context in
+        return "Hello World"
+      }
 
-    exampleExtension.registerSimpleTag("simpletag") { context in
-      return "Hello World"
-    }
+      exampleExtension.registerTag("customtag") { parser, token in
+        return CustomNode(token: token)
+      }
 
-    exampleExtension.registerTag("customtag") { parser, token in
-      return CustomNode()
-    }
+      let environment = Environment(extensions: [exampleExtension])
 
-    let environment = Environment(extensions: [exampleExtension])
+      $0.it("can render the README example") {
 
-    $0.it("can render the README example") {
+        let templateString = """
+          There are {{ articles.count }} articles.
 
-      let templateString = "There are {{ articles.count }} articles.\n" +
-        "\n" +
-        "{% for article in articles %}" +
-        "    - {{ article.title }} by {{ article.author }}.\n" +
-        "{% endfor %}\n"
+          {% for article in articles %}\
+              - {{ article.title }} by {{ article.author }}.
+          {% endfor %}
+          """
 
-      let context = [
-        "articles": [
-          Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
-          Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
+        let context = [
+          "articles": [
+            Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
+            Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
+          ]
         ]
-      ]
 
-      let template = Template(templateString: templateString)
-      let result = try template.render(context)
+        let template = Template(templateString: templateString)
+        let result = try template.render(context)
 
-      let fixture = "There are 2 articles.\n" +
-        "\n" +
-        "    - Migrating from OCUnit to XCTest by Kyle Fuller.\n" +
-        "    - Memory Management with ARC by Kyle Fuller.\n" +
-        "\n"
+        try expect(result) == """
+          There are 2 articles.
 
-      try expect(result) == fixture
-    }
+              - Migrating from OCUnit to XCTest by Kyle Fuller.
+              - Memory Management with ARC by Kyle Fuller.
 
-    $0.it("can render a custom template tag") {
-      let result = try environment.renderTemplate(string: "{% customtag %}")
-      try expect(result) == "Hello World"
-    }
+          """
+      }
 
-    $0.it("can render a simple custom tag") {
-      let result = try environment.renderTemplate(string: "{% simpletag %}")
-      try expect(result) == "Hello World"
+      $0.it("can render a custom template tag") {
+        let result = try environment.renderTemplate(string: "{% customtag %}")
+        try expect(result) == "Hello World"
+      }
+
+      $0.it("can render a simple custom tag") {
+        let result = try environment.renderTemplate(string: "{% simpletag %}")
+        try expect(result) == "Hello World"
+      }
     }
   }
 }

Tests/StencilTests/TemplateSpec.swift

@@ -1,19 +1,22 @@
+import XCTest
 import Spectre
-import Stencil
+@testable import Stencil
 
-
-func testTemplate() {
-  describe("Template") {
-    $0.it("can render a template from a string") {
-      let template = Template(templateString: "Hello World")
-      let result = try template.render([ "name": "Kyle" ])
-      try expect(result) == "Hello World"
-    }
-
-    $0.it("can render a template from a string literal") {
+class TemplateTests: XCTestCase {
+  func testTemplate() {
+    describe("Template") {
+      $0.it("can render a template from a string") {
+        let template = Template(templateString: "Hello World")
+        let result = try template.render([ "name": "Kyle" ])
+        try expect(result) == "Hello World"
+      }
+      
+      $0.it("can render a template from a string literal") {
         let template: Template = "Hello World"
         let result = try template.render([ "name": "Kyle" ])
         try expect(result) == "Hello World"
+      }
+
     }
   }
 }

Tests/StencilTests/TokenSpec.swift

@@ -1,34 +1,36 @@
+import XCTest
 import Spectre
-import Stencil
+@testable import Stencil
 
+class TokenTests: XCTestCase {
+  func testToken() {
+    describe("Token") {
+      $0.it("can split the contents into components") {
+        let token = Token.text(value: "hello world", at: .unknown)
+        let components = token.components()
 
-func testToken() {
-  describe("Token") {
-    $0.it("can split the contents into components") {
-      let token = Token.text(value: "hello world")
-      let components = token.components()
+        try expect(components.count) == 2
+        try expect(components[0]) == "hello"
+        try expect(components[1]) == "world"
+      }
 
-      try expect(components.count) == 2
-      try expect(components[0]) == "hello"
-      try expect(components[1]) == "world"
-    }
+      $0.it("can split the contents into components with single quoted strings") {
+        let token = Token.text(value: "hello 'kyle fuller'", at: .unknown)
+        let components = token.components()
 
-    $0.it("can split the contents into components with single quoted strings") {
-      let token = Token.text(value: "hello 'kyle fuller'")
-      let components = token.components()
+        try expect(components.count) == 2
+        try expect(components[0]) == "hello"
+        try expect(components[1]) == "'kyle fuller'"
+      }
 
-      try expect(components.count) == 2
-      try expect(components[0]) == "hello"
-      try expect(components[1]) == "'kyle fuller'"
-    }
+      $0.it("can split the contents into components with double quoted strings") {
+        let token = Token.text(value: "hello \"kyle fuller\"", at: .unknown)
+        let components = token.components()
 
-    $0.it("can split the contents into components with double quoted strings") {
-      let token = Token.text(value: "hello \"kyle fuller\"")
-      let components = token.components()
-
-      try expect(components.count) == 2
-      try expect(components[0]) == "hello"
-      try expect(components[1]) == "\"kyle fuller\""
+        try expect(components.count) == 2
+        try expect(components[0]) == "hello"
+        try expect(components[1]) == "\"kyle fuller\""
+      }
     }
   }
 }

Tests/StencilTests/VariableSpec.swift

@@ -1,11 +1,15 @@
+import XCTest
 import Foundation
 import Spectre
 @testable import Stencil
 
 
 #if os(OSX)
-@objc class Object : NSObject {
-  let title = "Hello World"
+@objc class Superclass: NSObject {
+  @objc let name = "Foo"
+}
+@objc class Object : Superclass {
+  @objc let title = "Hello World"
 }
 #endif
 
@@ -17,102 +21,392 @@ fileprivate struct Article {
   let author: Person
 }
 
+fileprivate class WebSite {
+  let url: String = "blog.com"
+}
 
-func testVariable() {
-  describe("Variable") {
-    let context = Context(dictionary: [
-      "name": "Kyle",
-      "contacts": ["Katie", "Carlton"],
-      "profiles": [
-        "github": "kylef",
-      ],
-      "article": Article(author: Person(name: "Kyle"))
-    ])
+fileprivate class Blog: WebSite {
+  let articles: [Article] = [Article(author: Person(name: "Kyle"))]
+  let featuring: Article? = Article(author: Person(name: "Jhon"))
+}
 
-#if os(OSX)
-    context["object"] = Object()
-#endif
+class VariableTests: XCTestCase {
+  func testVariable() {
+    describe("Variable") {
+      let context = Context(dictionary: [
+        "name": "Kyle",
+        "contacts": ["Katie", "Carlton"],
+        "profiles": [
+          "github": "kylef",
+        ],
+        "counter": [
+          "count": "kylef",
+          ],
+        "article": Article(author: Person(name: "Kyle")),
+        "tuple": (one: 1, two: 2)
+      ])
 
-    $0.it("can resolve a string literal with double quotes") {
-      let variable = Variable("\"name\"")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "name"
+  #if os(OSX)
+      context["object"] = Object()
+  #endif
+      context["blog"] = Blog()
+
+      $0.it("can resolve a string literal with double quotes") {
+        let variable = Variable("\"name\"")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "name"
+      }
+
+      $0.it("can resolve a string literal with single quotes") {
+        let variable = Variable("'name'")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "name"
+      }
+
+      $0.it("can resolve an integer literal") {
+        let variable = Variable("5")
+        let result = try variable.resolve(context) as? Int
+        try expect(result) == 5
+      }
+
+      $0.it("can resolve an float literal") {
+        let variable = Variable("3.14")
+        let result = try variable.resolve(context) as? Number
+        try expect(result) == 3.14
+      }
+
+      $0.it("can resolve boolean literal") {
+        try expect(Variable("true").resolve(context) as? Bool) == true
+        try expect(Variable("false").resolve(context) as? Bool) == false
+        try expect(Variable("0").resolve(context) as? Int) == 0
+        try expect(Variable("1").resolve(context) as? Int) == 1
+      }
+
+      $0.it("can resolve a string variable") {
+        let variable = Variable("name")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "Kyle"
+      }
+
+      $0.context("given string") {
+        $0.it("can resolve an item via it's index") {
+          let variable = Variable("name.0")
+          let result = try variable.resolve(context) as? Character
+          try expect(result) == "K"
+
+          let variable1 = Variable("name.1")
+          let result1 = try variable1.resolve(context) as? Character
+          try expect(result1) == "y"
+        }
+
+        $0.it("can resolve an item via unknown index") {
+          let variable = Variable("name.5")
+          let result = try variable.resolve(context) as? Character
+          try expect(result).to.beNil()
+
+          let variable1 = Variable("name.-5")
+          let result1 = try variable1.resolve(context) as? Character
+          try expect(result1).to.beNil()
+        }
+
+        $0.it("can resolve the first item") {
+          let variable = Variable("name.first")
+          let result = try variable.resolve(context) as? Character
+          try expect(result) == "K"
+        }
+
+        $0.it("can resolve the last item") {
+          let variable = Variable("name.last")
+          let result = try variable.resolve(context) as? Character
+          try expect(result) == "e"
+        }
+
+        $0.it("can get the characters count") {
+          let variable = Variable("name.count")
+          let result = try variable.resolve(context) as? Int
+          try expect(result) == 4
+        }
+      }
+
+      $0.context("given dictionary") {
+        $0.it("can resolve an item") {
+          let variable = Variable("profiles.github")
+          let result = try variable.resolve(context) as? String
+          try expect(result) == "kylef"
+        }
+
+        $0.it("can get the count") {
+          let variable = Variable("profiles.count")
+          let result = try variable.resolve(context) as? Int
+          try expect(result) == 1
+        }
+      }
+
+      $0.context("given array") {
+        $0.it("can resolve an item via it's index") {
+          let variable = Variable("contacts.0")
+          let result = try variable.resolve(context) as? String
+          try expect(result) == "Katie"
+
+          let variable1 = Variable("contacts.1")
+          let result1 = try variable1.resolve(context) as? String
+          try expect(result1) == "Carlton"
+        }
+
+        $0.it("can resolve an item via unknown index") {
+          let variable = Variable("contacts.5")
+          let result = try variable.resolve(context) as? String
+          try expect(result).to.beNil()
+
+          let variable1 = Variable("contacts.-5")
+          let result1 = try variable1.resolve(context) as? String
+          try expect(result1).to.beNil()
+        }
+
+        $0.it("can resolve the first item") {
+          let variable = Variable("contacts.first")
+          let result = try variable.resolve(context) as? String
+          try expect(result) == "Katie"
+        }
+
+        $0.it("can resolve the last item") {
+          let variable = Variable("contacts.last")
+          let result = try variable.resolve(context) as? String
+          try expect(result) == "Carlton"
+        }
+
+        $0.it("can get the count") {
+          let variable = Variable("contacts.count")
+          let result = try variable.resolve(context) as? Int
+          try expect(result) == 2
+        }
+      }
+
+      $0.it("can resolve a property with reflection") {
+        let variable = Variable("article.author.name")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "Kyle"
+      }
+
+  #if os(OSX)
+      $0.it("can resolve a value via KVO") {
+        let variable = Variable("object.title")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "Hello World"
+      }
+
+      $0.it("can resolve a superclass value via KVO") {
+        let variable = Variable("object.name")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "Foo"
+      }
+
+      $0.it("does not crash on KVO") {
+        let variable = Variable("object.fullname")
+        let result = try variable.resolve(context) as? String
+        try expect(result).to.beNil()
+      }
+  #endif
+
+      $0.it("can resolve a value via reflection") {
+        let variable = Variable("blog.articles.0.author.name")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "Kyle"
+      }
+
+      $0.it("can resolve a superclass value via reflection") {
+        let variable = Variable("blog.url")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "blog.com"
+      }
+
+      $0.it("can resolve optional variable property using reflection") {
+        let variable = Variable("blog.featuring.author.name")
+        let result = try variable.resolve(context) as? String
+        try expect(result) == "Jhon"
+      }
+
+      $0.it("does not render Optional") {
+        var array: [Any?] = [1, nil]
+        array.append(array)
+        let context = Context(dictionary: ["values": array])
+
+        try expect(VariableNode(variable: "values").render(context)) == "[1, nil, [1, nil]]"
+        try expect(VariableNode(variable: "values.1").render(context)) == ""
+      }
+
+      $0.it("can subscript tuple by index") {
+        let variable = Variable("tuple.0")
+        let result = try variable.resolve(context) as? Int
+        try expect(result) == 1
+      }
+
+      $0.it("can subscript tuple by label") {
+        let variable = Variable("tuple.two")
+        let result = try variable.resolve(context) as? Int
+        try expect(result) == 2
+      }
+
+      $0.describe("Subscripting") {
+        $0.it("can resolve a property subscript via reflection") {
+          try context.push(dictionary: ["property": "name"]) {
+            let variable = Variable("article.author[property]")
+            let result = try variable.resolve(context) as? String
+            try expect(result) == "Kyle"
+          }
+        }
+
+        $0.it("can subscript an array with a valid index") {
+          try context.push(dictionary: ["property": 0]) {
+            let variable = Variable("contacts[property]")
+            let result = try variable.resolve(context) as? String
+            try expect(result) == "Katie"
+          }
+        }
+
+        $0.it("can subscript an array with an unknown index") {
+          try context.push(dictionary: ["property": 5]) {
+            let variable = Variable("contacts[property]")
+            let result = try variable.resolve(context) as? String
+            try expect(result).to.beNil()
+          }
+        }
+
+  #if os(OSX)
+        $0.it("can resolve a subscript via KVO") {
+          try context.push(dictionary: ["property": "name"]) {
+            let variable = Variable("object[property]")
+            let result = try variable.resolve(context) as? String
+            try expect(result) == "Foo"
+          }
+        }
+  #endif
+
+        $0.it("can resolve an optional subscript via reflection") {
+          try context.push(dictionary: ["property": "featuring"]) {
+            let variable = Variable("blog[property].author.name")
+            let result = try variable.resolve(context) as? String
+            try expect(result) == "Jhon"
+          }
+        }
+
+        $0.it("can resolve multiple subscripts") {
+          try context.push(dictionary: [
+            "prop1": "articles",
+            "prop2": 0,
+            "prop3": "name"
+          ]) {
+            let variable = Variable("blog[prop1][prop2].author[prop3]")
+            let result = try variable.resolve(context) as? String
+            try expect(result) == "Kyle"
+          }
+        }
+
+        $0.it("can resolve nested subscripts") {
+          try context.push(dictionary: [
+            "prop1": "prop2",
+            "ref": ["prop2": "name"]
+          ]) {
+            let variable = Variable("article.author[ref[prop1]]")
+            let result = try variable.resolve(context) as? String
+            try expect(result) == "Kyle"
+          }
+        }
+
+        $0.it("throws for invalid keypath syntax") {
+          try context.push(dictionary: ["prop": "name"]) {
+            let samples = [
+              ".",
+              "..",
+              ".test",
+              "test..test",
+              "[prop]",
+              "article.author[prop",
+              "article.author[[prop]",
+              "article.author[prop]]",
+              "article.author[]",
+              "article.author[[]]",
+              "article.author[prop][]",
+              "article.author[prop]comments",
+              "article.author[.]"
+            ]
+
+            for lookup in samples {
+              let variable = Variable(lookup)
+              try expect(variable.resolve(context)).toThrow()
+            }
+          }
+        }
+      }
     }
 
-    $0.it("can resolve a string literal with single quotes") {
-      let variable = Variable("'name'")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "name"
+    describe("RangeVariable") {
+
+      let context: Context = {
+        let ext = Extension()
+        ext.registerFilter("incr", filter: { (arg: Any?) in toNumber(value: arg!)! + 1 })
+        let environment = Environment(extensions: [ext])
+        return Context(dictionary: [:], environment: environment)
+      }()
+
+      func makeVariable(_ token: String) throws -> RangeVariable? {
+        let token = Token.variable(value: token, at: .unknown)
+        let parser = TokenParser(tokens: [token], environment: context.environment)
+        return try RangeVariable(token.contents, parser: parser, containedIn: token)
+      }
+
+      $0.it("can resolve closed range as array") {
+        let result = try makeVariable("1...3")?.resolve(context) as? [Int]
+        try expect(result) == [1, 2, 3]
+      }
+
+      $0.it("can resolve decreasing closed range as reversed array") {
+        let result = try makeVariable("3...1")?.resolve(context) as? [Int]
+        try expect(result) == [3, 2, 1]
+      }
+
+      $0.it("can use filter on range variables") {
+        let result = try makeVariable("1|incr...3|incr")?.resolve(context) as? [Int]
+        try expect(result) == [2, 3, 4]
+      }
+
+      $0.it("throws when left value is not int") {
+        let template: Template = "{% for i in k...j %}{{ i }}{% endfor %}"
+        try expect(try template.render(Context(dictionary: ["j": 3, "k": "1"]))).toThrow()
+      }
+
+      $0.it("throws when right value is not int") {
+        let variable = try makeVariable("k...j")
+        try expect(try variable?.resolve(Context(dictionary: ["j": "3", "k": 1]))).toThrow()
+      }
+
+      $0.it("throws is left range value is missing") {
+        try expect(makeVariable("...1")).toThrow()
+      }
+
+      $0.it("throws is right range value is missing") {
+        try expect(makeVariable("1...")).toThrow()
+      }
+
     }
 
-    $0.it("can resolve an integer literal") {
-      let variable = Variable("5")
-      let result = try variable.resolve(context) as? Number
-      try expect(result) == 5
+    describe("inline if expression") {
+
+      $0.it("can conditionally render variable") {
+        let template: Template = "{{ variable if variable|uppercase == \"A\" }}"
+        try expect(template.render(Context(dictionary: ["variable": "a"]))) == "a"
+        try expect(template.render(Context(dictionary: ["variable": "b"]))) == ""
+      }
+
+      $0.it("can render with else expression") {
+        let template: Template = "{{ variable if variable|uppercase == \"A\" else fallback|uppercase }}"
+        try expect(template.render(Context(dictionary: ["variable": "b", "fallback": "c"]))) == "C"
+      }
+
+      $0.it("throws when used invalid condition") {
+        let template: Template = "{{ variable if variable \"A\" }}"
+        try expect(template.render(Context(dictionary: ["variable": "a"]))).toThrow()
+      }
     }
-
-    $0.it("can resolve an float literal") {
-      let variable = Variable("3.14")
-      let result = try variable.resolve(context) as? Number
-      try expect(result) == 3.14
-    }
-
-    $0.it("can resolve a string variable") {
-      let variable = Variable("name")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "Kyle"
-    }
-
-    $0.it("can resolve an item from a dictionary") {
-      let variable = Variable("profiles.github")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "kylef"
-    }
-
-    $0.it("can resolve an item from an array via it's index") {
-      let variable = Variable("contacts.0")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "Katie"
-
-        let variable1 = Variable("contacts.1")
-        let result1 = try variable1.resolve(context) as? String
-        try expect(result1) == "Carlton"
-    }
-
-    $0.it("can resolve an item from an array via unknown index") {
-      let variable = Variable("contacts.5")
-      let result = try variable.resolve(context) as? String
-      try expect(result).to.beNil()
-
-      let variable1 = Variable("contacts.-5")
-      let result1 = try variable1.resolve(context) as? String
-      try expect(result1).to.beNil()
-    }
-
-    $0.it("can resolve the first item from an array") {
-      let variable = Variable("contacts.first")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "Katie"
-    }
-
-    $0.it("can resolve the last item from an array") {
-      let variable = Variable("contacts.last")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "Carlton"
-    }
-
-    $0.it("can resolve a property with reflection") {
-      let variable = Variable("article.author.name")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "Kyle"
-    }
-
-#if os(OSX)
-    $0.it("can resolve a value via KVO") {
-      let variable = Variable("object.title")
-      let result = try variable.resolve(context) as? String
-      try expect(result) == "Hello World"
-    }
-#endif
   }
 }

Tests/StencilTests/XCTest.swift

@@ -1,30 +0,0 @@
-import XCTest
-
-
-public func stencilTests() {
-  testContext()
-  testFilter()
-  testLexer()
-  testToken()
-  testTokenParser()
-  testTemplateLoader()
-  testTemplate()
-  testVariable()
-  testNode()
-  testForNode()
-  testExpressions()
-  testIfNode()
-  testNowNode()
-  testInclude()
-  testInheritence()
-  testFilterTag()
-  testEnvironment()
-  testStencil()
-}
-
-
-class StencilTests: XCTestCase {
-  func testRunStencilTests() {
-    stencilTests()
-  }
-}

Tests/StencilTests/XCTestManifests.swift

@@ -0,0 +1,135 @@
+import XCTest
+
+extension ContextTests {
+    static let __allTests = [
+        ("testContext", testContext),
+    ]
+}
+
+extension EnvironmentTests {
+    static let __allTests = [
+        ("testEnvironment", testEnvironment),
+    ]
+}
+
+extension ExpressionsTests {
+    static let __allTests = [
+        ("testExpressions", testExpressions),
+    ]
+}
+
+extension FilterTagTests {
+    static let __allTests = [
+        ("testFilterTag", testFilterTag),
+    ]
+}
+
+extension FilterTests {
+    static let __allTests = [
+        ("testFilter", testFilter),
+    ]
+}
+
+extension ForNodeTests {
+    static let __allTests = [
+        ("testForNode", testForNode),
+    ]
+}
+
+extension IfNodeTests {
+    static let __allTests = [
+        ("testIfNode", testIfNode),
+    ]
+}
+
+extension IncludeTests {
+    static let __allTests = [
+        ("testInclude", testInclude),
+    ]
+}
+
+extension InheritenceTests {
+    static let __allTests = [
+        ("testInheritence", testInheritence),
+    ]
+}
+
+extension LexerTests {
+    static let __allTests = [
+        ("testLexer", testLexer),
+        ("testPerformance", testPerformance),
+    ]
+}
+
+extension NodeTests {
+    static let __allTests = [
+        ("testNode", testNode),
+    ]
+}
+
+extension NowNodeTests {
+    static let __allTests = [
+        ("testNowNode", testNowNode),
+    ]
+}
+
+extension StencilTests {
+    static let __allTests = [
+        ("testStencil", testStencil),
+    ]
+}
+
+extension TemplateLoaderTests {
+    static let __allTests = [
+        ("testTemplateLoader", testTemplateLoader),
+    ]
+}
+
+extension TemplateTests {
+    static let __allTests = [
+        ("testTemplate", testTemplate),
+    ]
+}
+
+extension TokenParserTests {
+    static let __allTests = [
+        ("testTokenParser", testTokenParser),
+    ]
+}
+
+extension TokenTests {
+    static let __allTests = [
+        ("testToken", testToken),
+    ]
+}
+
+extension VariableTests {
+    static let __allTests = [
+        ("testVariable", testVariable),
+    ]
+}
+
+#if !os(macOS)
+public func __allTests() -> [XCTestCaseEntry] {
+    return [
+        testCase(ContextTests.__allTests),
+        testCase(EnvironmentTests.__allTests),
+        testCase(ExpressionsTests.__allTests),
+        testCase(FilterTagTests.__allTests),
+        testCase(FilterTests.__allTests),
+        testCase(ForNodeTests.__allTests),
+        testCase(IfNodeTests.__allTests),
+        testCase(IncludeTests.__allTests),
+        testCase(InheritenceTests.__allTests),
+        testCase(LexerTests.__allTests),
+        testCase(NodeTests.__allTests),
+        testCase(NowNodeTests.__allTests),
+        testCase(StencilTests.__allTests),
+        testCase(TemplateLoaderTests.__allTests),
+        testCase(TemplateTests.__allTests),
+        testCase(TokenParserTests.__allTests),
+        testCase(TokenTests.__allTests),
+        testCase(VariableTests.__allTests),
+    ]
+}
+#endif

Tests/StencilTests/fixtures/child-child.html

@@ -1,2 +1,2 @@
 {% extends "child.html" %}
-{% block header %}Child Child Header{% endblock %}
+{% block header %}{{ block.super }} Child_Child_Header{% endblock %}

Tests/StencilTests/fixtures/child-super.html

@@ -1,3 +1,3 @@
 {% extends "base.html" %}
-{% block body %}Child {{ block.super }}{% endblock %}
+{% block body %}Child_{{ block.super }}{% endblock %}
 

Tests/StencilTests/fixtures/child.html

@@ -1,2 +1,3 @@
 {% extends "base.html" %}
-{% block body %}Child{% endblock %}
+{% block header %}Super_{{ block.super }} Child_Header{% endblock %}
+{% block body %}Child_Body{% endblock %}

Tests/StencilTests/fixtures/invalid-base.html

@@ -0,0 +1,2 @@
+{% block header %}Header{% endblock %}
+{% block body %}Body {{ target|unknown }} {% endblock %}

Tests/StencilTests/fixtures/invalid-child-super.html

@@ -0,0 +1,3 @@
+{% extends "invalid-base.html" %}
+{% block body %}Child {{ block.super }}{% endblock %}
+

Tests/StencilTests/fixtures/invalid-include.html

@@ -0,0 +1 @@
+Hello {{ target|unknown }}!

docs/_templates/sidebar_intro.html

@@ -2,7 +2,7 @@
 
 <p>
   <iframe
-      src="https://ghbtns.com/github-btn.html?user=kylef&repo=Stencil&type=watch&count=true&size=large"
+      src="https://ghbtns.com/github-btn.html?user=stencilproject&repo=Stencil&type=watch&count=true&size=large"
       allowtransparency="true" frameborder="0" scrolling="0" width="200px" height="35px">
   </iframe>
 </p>

docs/api.rst

@@ -73,6 +73,16 @@ on the file system.
     FileSystemLoader(bundle: [Bundle.main])
 
 
+DictionaryLoader
+~~~~~~~~~~~~~~~~
+
+Loads templates from a dictionary.
+
+.. code-block:: swift
+
+    DictionaryLoader(templates: ["index.html": "Hello World"])
+
+
 Custom Loaders
 ~~~~~~~~~~~~~~
 

docs/builtins.rst

@@ -19,6 +19,39 @@ A for loop allows you to iterate over an array found by variable lookup.
       {% endfor %}
     </ul>
 
+The ``for`` tag can iterate over dictionaries.
+
+.. code-block:: html+django
+
+    <ul>
+      {% for key, value in dict %}
+        <li>{{ key }}: {{ value }}</li>
+      {% endfor %}
+    </ul>
+    
+It can also iterate over ranges, tuple elements, structs' and classes' stored properties (using ``Mirror``).
+
+You can iterate over range literals created using ``N...M`` syntax, both in ascending and descending order:
+
+.. code-block:: html+django
+
+    <ul>
+      {% for i in 1...array.count %}
+        <li>{{ i }}</li>
+      {% endfor %}
+    </ul>
+
+The ``for`` tag can contain optional ``where`` expression to filter out
+elements on which this expression evaluates to false.
+
+.. code-block:: html+django
+
+    <ul>
+      {% for user in users where user.name != "Kyle" %}
+        <li>{{ user }}</li>
+      {% endfor %}
+    </ul>
+
 The ``for`` tag can take an optional ``{% empty %}`` block that will be
 displayed if the given list is empty or could not be found.
 
@@ -36,7 +69,26 @@ The for block sets a few variables available within the loop:
 
 - ``first`` - True if this is the first time through the loop
 - ``last`` - True if this is the last time through the loop
-- ``counter`` - The current iteration of the loop
+- ``counter`` - The current iteration of the loop (1 indexed)
+- ``counter0`` - The current iteration of the loop (0 indexed)
+- ``length`` - The total length of the loop
+
+For example:
+
+.. code-block:: html+django
+
+    {% for user in users %}
+      {% if forloop.first %}
+        This is the first user.
+      {% endif %}
+    {% endfor %}
+
+.. code-block:: html+django
+
+    {% for user in users %}
+      This is user number {{ forloop.counter }} user.
+    {% endfor %}
+
 
 ``if``
 ~~~~~~
@@ -52,10 +104,12 @@ true the contents of the block are processed. Being true is defined as:
 
 .. code-block:: html+django
 
-    {% if variable %}
-      The variable was found in the current context.
+    {% if admin %}
+      The user is an administrator.
+    {% elif user %}
+      A user is logged in.
     {% else %}
-      The variable was not found.
+      No user was found.
     {% endif %}
 
 Operators
@@ -83,7 +137,7 @@ or to negate a variable.
     {% endif %}
 
 You may use ``and``, ``or`` and ``not`` multiple times together. ``not`` has
-higest prescidence followed by ``and``. For example:
+higest precedence followed by ``and``. For example:
 
 .. code-block:: html+django
 
@@ -95,6 +149,19 @@ Will be treated as:
 
     one or (two and three)
 
+You can use parentheses to change operator precedence. For example:
+
+.. code-block:: html+django
+
+    {% if (one or two) and three %}
+
+Will be treated as:
+
+.. code-block:: text
+
+    (one or two) and three
+
+
 ``==`` operator
 """""""""""""""
 
@@ -206,6 +273,12 @@ You can include another template using the `include` tag.
 
     {% include "comment.html" %}
 
+By default the included file gets passed the current context. You can pass a sub context by using an optional 2nd parameter as a lookup in the current context.
+
+.. code-block:: html+django
+
+    {% include "comment.html" comment %}
+
 The `include` tag requires you to provide a loader which will be used to lookup
 the template.
 
@@ -240,7 +313,7 @@ Built-in Filters
 ~~~~~~~~~~~~~~
 
 The capitalize filter allows you to capitalize a string.
-For example, `stencil` to `Stencil`.
+For example, `stencil` to `Stencil`. Can be applied to array of strings to change each string.
 
 .. code-block:: html+django
 
@@ -250,7 +323,7 @@ For example, `stencil` to `Stencil`.
 ~~~~~~~~~~~~~
 
 The uppercase filter allows you to transform a string to uppercase.
-For example, `Stencil` to `STENCIL`.
+For example, `Stencil` to `STENCIL`. Can be applied to array of strings to change each string.
 
 .. code-block:: html+django
 
@@ -260,7 +333,7 @@ For example, `Stencil` to `STENCIL`.
 ~~~~~~~~~~~~~
 
 The uppercase filter allows you to transform a string to lowercase.
-For example, `Stencil` to `stencil`.
+For example, `Stencil` to `stencil`. Can be applied to array of strings to change each string.
 
 .. code-block:: html+django
 
@@ -285,4 +358,31 @@ Join an array of items.
 
     {{ value|join:", " }}
 
-.. note:: The value MUST be an array.
+.. note:: The value MUST be an array. Default argument value is empty string.
+
+``split``
+~~~~~~~~~
+
+Split string into substrings by separator.
+
+.. code-block:: html+django
+
+    {{ value|split:", " }}
+
+.. note:: The value MUST be a String. Default argument value is a single-space string.
+
+``indent``
+~~~~~~~~~
+
+Indents lines of rendered value or block.
+
+.. code-block:: html+django
+
+    {{ value|indent:2," ",true }}
+
+Filter accepts several arguments:
+
+* indentation width: number of indentation characters to indent lines with. Default is ``4``.
+* indentation character: character to be used for indentation. Default is a space.
+* indent first line: whether first line of output should be indented or not. Default is ``false``.
+

docs/conf.py

@@ -58,9 +58,9 @@ author = 'Kyle Fuller'
 # built documents.
 #
 # The short X.Y version.
-version = '0.7.0'
+version = '0.13.1'
 # The full version, including alpha/beta/rc tags.
-release = '0.7.0'
+release = '0.13.1'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.

docs/custom-template-tags-and-filters.rst

@@ -42,12 +42,23 @@ Registering custom filters with arguments:
       }
 
       if let value = value as? Int {
-        return value * 2
+        return value * amount
       }
 
       return value
     }
 
+Registering custom boolean filters:
+
+.. code-block:: swift
+
+    ext.registerFilter("ordinary", negativeFilterName: "odd") { (value: Any?) in
+        if let value = value as? Int {
+            return myInt % 2 == 0
+        }
+        return nil
+    }
+
 Custom Tags
 -----------
 

docs/getting-started.rst

@@ -17,7 +17,7 @@ the ``renderTemplate`` convinience method.
     let environment = Environment()
 
     let context = ["name": "kyle"]
-    try template.renderTemplate(string: "Hello {{ name }}", context: context)
+    try environment.renderTemplate(string: "Hello {{ name }}", context: context)
 
 Template Loaders
 ----------------
@@ -34,4 +34,4 @@ For example, to render a template called ``index.html`` inside the
     let environment = Environment(loader: fsLoader)
 
     let context = ["name": "kyle"]
-    try template.renderTemplate(name: "index.html", context: context)
+    try environment.renderTemplate(name: "index.html", context: context)

docs/installation.rst

@@ -1,7 +1,7 @@
 Installation
 ============
 
-Swift Package Mangaer
+Swift Package Manager
 ---------------------
 
 If you're using the Swift Package Manager, you can add ``Stencil`` to your
@@ -14,7 +14,7 @@ dependencies inside ``Package.swift``.
     let package = Package(
       name: "MyApplication",
       dependencies: [
-        .Package(url: "https://github.com/kylef/Stencil.git", majorVersion: 0, minor: 8),
+        .Package(url: "https://github.com/stencilproject/Stencil.git", majorVersion: 0, minor: 13),
       ]
     )
 
@@ -26,7 +26,7 @@ If you're using CocoaPods, you can add Stencil to your ``Podfile`` and then run
 
 .. code-block:: ruby
 
-    pod 'Stencil', '~> 0.8.0'
+    pod 'Stencil', '~> 0.13.1'
 
 Carthage
 --------
@@ -37,7 +37,7 @@ Carthage
 
     .. code-block:: text
 
-        github "kylef/Stencil" ~> 0.8.0
+        github "stencilproject/Stencil" ~> 0.13.1
 
 2) Checkout your dependencies, generate the Stencil Xcode project, and then use Carthage to build Stencil:
 

docs/templates.rst

@@ -20,9 +20,9 @@ following lookup:
 
 - Context lookup
 - Dictionary lookup
-- Array lookup (first, last, count, index)
+- Array and string lookup (first, last, count, by index)
 - Key value coding lookup
-- Type introspection
+- Type introspection (via ``Mirror``)
 
 For example, if `people` was an array:
 
@@ -31,6 +31,24 @@ For example, if `people` was an array:
     There are {{ people.count }} people. {{ people.first }} is the first
     person, followed by {{ people.1 }}.
 
+You can also use the subscript operator for indirect evaluation. The expression
+between brackets will be evaluated first, before the actual lookup will happen.
+
+For example, if you have the following context:
+
+.. code-block:: swift
+
+    [
+      "item": [
+        "name": "John"
+      ],
+      "key": "name"
+    ]
+
+.. code-block:: html+django
+
+    The result of {{ item[key] }} will be the same as {{ item.name }}. It will first evaluate the result of {{ key }}, and only then evaluate the lookup expression.
+
 Filters
 ~~~~~~~