Forgot version bump

Updated the PathKit dependency to 0.9.0 in CocoaPods

.gitignore

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

.swift-version

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

.travis.yml

@@ -1,11 +1,22 @@
-os:
-- osx
-- linux
+matrix:
+  include:
+    - os: osx
+      osx_image: xcode8.3
+      env: SWIFT_VERSION=3.1.1
+    - os: osx
+      osx_image: xcode9
+      env: SWIFT_VERSION=4.0
+    - os: osx
+      osx_image: xcode9.1
+      env: SWIFT_VERSION=4.0
+    - os: linux
+      env: SWIFT_VERSION=3.1.1
+    - os: linux
+      env: SWIFT_VERSION=4.0
 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

ARCHITECTURE.md

@@ -1,175 +0,0 @@
-Stencil Architecture
-====================
-
-This document outlines the architecture of Stencil and how it works internally.
-
-Stencil uses a three-step process for rendering templates. The first step is tokenising the template into an array of Token’s. Afterwards, the array of token’s are transformed into a collection of Node’s. Once we have a collection of Node’s (objects conforming to the `Node` protocol), we then call `render(context)` on each Node instructing it to render itself inside the given context.
-
-## Token
-
-Token is an enum which has four members. These represent a piece of text, a variable, a comment or a template block. They are parsed using the `TokenParser` which takes the template as a string as input and returns an array of Token’s.
-
-### Values
-
-#### Text
-
-A text token represents a string which will be rendered in the template. For example, a text token with the string `Hello World` will be rendered as such in the output.
-
-#### Variable
-
-A variable token represents a variable inside a context. It will be evaluated and rendered in the output. It is created from the template using `{{ string }}`.
-
-#### Comment
-
-The comment token represents a comment inside the source. It is created using `{# This is a comment #}`.
-
-#### Block
-
-A block represents a template tag. It is created using `{% this is a template block %}` inside a template. The template tag in this case would be called `this`. See “Block Token” below for more information.
-
-### Parsing
-
-A template is parsed using the TokenParser into an array of Token’s. For example:
-
-```html+django
-Hello {{ name }}
-```
-
-Would be parsed into two tokens. A token representing the string, `Hello ` and a token representing the variable called `name`. So, in Swift it would be represented as follows:
-
-```swift
-let tokens = [
-  Token.Text("Hello "),
-  Token.Variable("name"),
-]
-```
-
-## Node
-
-Node is a protocol with a single method, to render it inside a context. When rendering a node, it is converted into the output string, or an error if there is a failure. Token’s are converted to Node’s using the `TokenParser` class.
-
-For some Token’s, there is a direct mapping from a Token to a Node. However block node’s do not have a 1:1 mapping.
-
-### Token Parsing
-
-#### Text Token
-
-A text token is converted directly to a `TextNode` which simply returns the text when rendered.
-
-#### Variable Token
-
-Variable Token’s are transformed directly to a `VariableNode`, which will evaluate a variable in the given template when rendered.
-
-#### Comment Token
-
-A comment token is simply omitted, a comment token will be dropped when it is converted to a Node.
-
-#### Block Token
-
-Block token’s are slightly different from the other tokens, there is no direct mapping. A block token is made up of a string representing the token. For example `now` or `for article in articles`. The `TokenParser` will pull out the first word inside the string representation and use that to look-up a parser for the block. So, in this example, the template tag names will be `now` or `for`.
-
-The template tag’s are registered with a block of code which deals with the parsing for the given tag. This allows the parser to parse a set of tokens ahead of the block tone. This is useful for control flow, such as the `for` template tag will want to parse any following tokens up until the `endblock` block token.
-
-For example:
-
-```html+django
-{% for article in articles %}
-  An Article
-{% endfor %}
-```
-
-Or as a set of tokens:
-
-```swift
-let tokens = [
-  Token.Block("for article in articles"),
-  Token.Text("  An Article")
-  Token.Block("endfor")
-]
-```
-
-Will result in a single Node (a `ForNode`) which contains the sub-node containing the text. The `ForNode` class has a property called `forNodes` which contains the text node representing the text token (`  An Article`).
-
-When the `ForNode` is rendered in a context, it will look up the variable `articles` and if it’s an array it will loop over it. Inserting the variable `article` into the context while rendered the `forNodes` for each article.
-
-### Custom Nodes
-
-There are two ways to register custom template tags. A simple way which allows you to map 1:1 a block token to a Node. You can also register a more advanced template tag which has it’s own block of code for handling parsing if you want to parse up until another token such as if you are trying to provide flow-control.
-
-The tags are registered with a `Namespace` passed when rendering your `Template`.
-
-#### Simple Tags
-
-A simple tag is registered with a string for the tag name and a block of code which is evaluated when the block is rendered in a given context.
-
-Here’s an example. Registering a template tag called `custom` which just renders `Hello World` in the rendered template:
-
-```swift
-namespace.registerSimpleTag("custom") { context in
-  return "Hello World"
-}
-```
-
-You would use it as such in a template:
-
-```html+django
-{% custom %}
-```
-
-#### Advanced Tags
-
-If you need more control or functionality than the simple tag’s above, you can use the node based API where you can provide a block of code to deal with parsing. There are a few examples of this in use over at `Node.swift` inside Stencil. There is an implementation of `if` and `for` template tags.
-
-You would register a template tag using the `registerTag` API inside a `Namespace` which accepts a name for the tag and a block of code to handle parsing. The block of code is invoked with the parser and the current token as an argument. This allows you to use the API on `TokenParser` to parse node’s further in the token array.
-
-As an example, we’re going to create a template tag called `debug` which will optionally render nodes from `debug` up until `enddebug`. When rendering the `DebugNode`, it will only render the nodes inside if a variable called `debug` is set to `true` inside the template Context.
-
-```html+django
-{% debug %}
-  Debugging is enabled!
-{% enddebug %}
-```
-
-This will be represented by a `DebugNode` which will have a property containing all of the Node’s inside the `debug`/`enddebug` block. In the above example, this will just be a TextNode containing `  Debugging is enabled!`.
-
-When the `DebugNode` is rendered, it will determine if debug is enabled by introspecting the context and if it is enabled. We will render the nodes, otherwise just return an empty string to hide the debug output.
-
-So, our `DebugNode` would look like as following:
-
-```swift
-class DebugNode : Node {
-  let nodes:[Node]
-
-  init(nodes:[Node]) {
-    self.nodes = nodes
-  }
-
-  func render(context: Context) throws -> String {
-    // Is there a debug variable inside the context?
-    if let debug = context["debug"] as? Bool {
-      // Is debug set to true?
-      if debug {
-        // Let's render the given nodes in the context since debug is enabled.
-        return renderNodes(nodes, context)
-      }
-    }
-
-    // Debug is turned off, so let's not render anything
-    return ""
-  }
-}
-```
-
-We will need to write a parser to parse up until the `enddebug` template block and create a `DebugNode` with the nodes in-between. If there was another error form another Node inside, then we will return that error.
-
-```swift
-namespace.registerTag("debug") { parser, token in
-  // Use the parser to parse every token up until the `enddebug` block.
-  let nodes = try until(["enddebug"]))
-  return DebugNode(nodes)
-}
-```
-
-## Context
-
-A Context is a structure containing any templates you would like to use in a template. It’s somewhat like a dictionary, however you can push and pop to scope variables. So that means that when iterating over a for loop, you can push a new scope into the context to store any variables local to the scope.

CHANGELOG.md

@@ -1,10 +1,241 @@
 # Stencil Changelog
 
-## 0.7.2
+## 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
 
-- `Template` is now an `open` class.
+- 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
+
+- It is no longer possible to create `Context` objects. Instead, you can pass a
+  dictionary directly to a `Template`s `render` method.
+
+  ```diff
+  - try template.render(Context(dictionary: ["name": "Kyle"]))
+  + try template.render(["name": "Kyle"])
+  ```
+
+- Template loader are no longer passed into a `Context`, instead you will need
+  to pass the `Loader` to an `Environment` and create a template from the
+  `Environment`.
+
+  ```diff
+  let loader = FileSystemLoader(paths: ["templates/"])
+
+  - let template = loader.loadTemplate(name: "index.html")
+  - try template.render(Context(dictionary: ["loader": loader]))
+  + let environment = Environment(loader: loader)
+  + try environment.renderTemplate(name: "index.html")
+  ```
+
+- `Loader`s will now throw a `TemplateDoesNotExist` error when a template
+  is not found.
+
+- `Namespace` has been removed and replaced by extensions. You can create an
+  extension including any custom template tags and filters. A collection of
+  extensions can be passed to an `Environment`.
+
+### Enhancements
+
+- `Environment` is a new way to load templates. You can configure an
+  environment with custom template filters, tags and loaders and then create a
+  template from an environment.
+
+  Environment also provides a convenience method to render a template directly.
+
+- `FileSystemLoader` will now ensure that template paths are within the base
+  path. Any template names that try to escape the base path will raise a
+  `SuspiciousFileOperation` error.
+
+- New `{% filter %}` tag allowing you to perform a filter across the contents
+  of a block.
+
+  ```html+django
+  {% filter lowercase %}
+    This Text Will Be Lowercased.
+  {% endfilter %}
+  ```
+
+- You can now use `{{ block.super }}` to render a super block from another `{%
+  block %}`.
+
+- `Environment` allows you to provide a custom `Template` subclass, allowing
+  new template to use a specific subclass.
+
+- If expressions may now contain filters on variables. For example
+  `{% if name|uppercase == "TEST" %}` is now supported.
+
+### Deprecations
+
+- `Template` initialisers have been deprecated in favour of using a template
+  loader such as `FileSystemLoader` inside an `Environment`.
+
+- The use of whitespace inside variable filter expression is now deprecated.
+
+  ```diff
+  - {{ name | uppercase }}
+  + {{ name|uppercase }}
+  ```
+
+### Bug Fixes
+
+- Restores compatibility with ARM based platforms such as iOS. Stencil 0.7
+  introduced compilation errors due to using the `Float80` type which is not
+  available.
+
 
 ## 0.7.1
 
@@ -65,10 +296,10 @@
 ### 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.

Package.swift

@@ -1,11 +1,10 @@
+// swift-tools-version:3.1
 import PackageDescription
 
 let package = Package(
   name: "Stencil",
   dependencies: [
-    .Package(url: "https://github.com/kylef/PathKit.git", majorVersion: 0, minor: 7),
-
-    // https://github.com/apple/swift-package-manager/pull/597
-    .Package(url: "https://github.com/kylef/Spectre", majorVersion: 0, minor: 7),
+    .Package(url: "https://github.com/kylef/PathKit.git", majorVersion: 0, minor: 9),
+    .Package(url: "https://github.com/kylef/Spectre.git", majorVersion: 0, minor: 8),
   ]
 )

Package@swift-3.swift

@@ -0,0 +1,10 @@
+// swift-tools-version:3.1
+import PackageDescription
+
+let package = Package(
+  name: "Stencil",
+  dependencies: [
+    .Package(url: "https://github.com/kylef/PathKit.git", majorVersion: 0, minor: 8),
+    .Package(url: "https://github.com/kylef/Spectre.git", majorVersion: 0, minor: 7),
+  ]
+)

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
@@ -19,35 +19,24 @@ There are {{ articles.count }} articles.
 ```
 
 ```swift
+import Stencil
+
 struct Article {
   let title: String
   let author: String
 }
 
-let context = Context(dictionary: [
+let context = [
   "articles": [
     Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
     Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
   ]
-])
+]
 
-do {
-  let template = try Template(named: "template.html")
-  let rendered = try template.render(context)
-  print(rendered)
-} catch {
-  print("Failed to render template \(error)")
-}
-```
+let environment = Environment(loader: FileSystemLoader(paths: ["templates/"]))
+let rendered = try environment.renderTemplate(name: "article_list.html", context: context)
 
-## Installation
-
-Installation with Swift Package Manager is recommended.
-
-### CocoaPods
-
-```ruby
-pod 'Stencil'
+print(rendered)
 ```
 
 ## Philosophy
@@ -62,10 +51,25 @@ Stencil follows the same philosophy of Django:
 
 ## The User Guide
 
-- [Templates](http://stencil.fuller.li/en/latest/templates.html)
+Resources for Stencil template authors to write Stencil templates:
+
+- [Language overview](http://stencil.fuller.li/en/latest/templates.html)
 - [Built-in template tags and filters](http://stencil.fuller.li/en/latest/builtins.html)
+
+Resources to help you integrate Stencil into a Swift project:
+
+- [Installation](http://stencil.fuller.li/en/latest/installation.html)
+- [Getting Started](http://stencil.fuller.li/en/latest/getting-started.html)
+- [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

@@ -1,17 +1,17 @@
 /// A container for template variables.
 public class Context {
   var dictionaries: [[String: Any?]]
-  let namespace: Namespace
 
-  /// Initialise a Context with an optional dictionary and optional namespace
-  public init(dictionary: [String: Any]? = nil, namespace: Namespace = Namespace()) {
+  public let environment: Environment
+  
+  init(dictionary: [String: Any]? = nil, environment: Environment? = nil) {
     if let dictionary = dictionary {
       dictionaries = [dictionary]
     } else {
       dictionaries = []
     }
 
-    self.namespace = namespace
+    self.environment = environment ?? Environment()
   }
 
   public subscript(key: String) -> Any? {
@@ -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

@@ -0,0 +1,48 @@
+public struct Environment {
+  public let templateClass: Template.Type
+  public var extensions: [Extension]
+
+  public var loader: Loader?
+
+  public init(loader: Loader? = nil,
+              extensions: [Extension]? = nil,
+              templateClass: Template.Type = Template.self) {
+
+    self.templateClass = templateClass
+    self.loader = loader
+    self.extensions = (extensions ?? []) + [DefaultExtension()]
+  }
+
+  public func loadTemplate(name: String) throws -> Template {
+    if let loader = loader {
+      return try loader.loadTemplate(name: name, environment: self)
+    } else {
+      throw TemplateDoesNotExist(templateNames: [name], loader: nil)
+    }
+  }
+
+  public func loadTemplate(names: [String]) throws -> Template {
+    if let loader = loader {
+      return try loader.loadTemplate(names: names, environment: self)
+    } else {
+      throw TemplateDoesNotExist(templateNames: names, loader: nil)
+    }
+  }
+
+  public func renderTemplate(name: String, context: [String: Any]? = nil) throws -> String {
+    let template = try loadTemplate(name: name)
+    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

@@ -0,0 +1,83 @@
+public class TemplateDoesNotExist: Error, CustomStringConvertible {
+  let templateNames: [String]
+  let loader: Loader?
+
+  public init(templateNames: [String], loader: Loader? = nil) {
+    self.templateNames = templateNames
+    self.loader = loader
+  }
+
+  public var description: String {
+    let templates = templateNames.joined(separator: ", ")
+
+    if let loader = loader {
+      return "Template named `\(templates)` does not exist in loader \(loader)"
+    }
+
+    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)
+  }
+
+  public static func ==(lhs:TemplateSyntaxError, rhs:TemplateSyntaxError) -> Bool {
+    return lhs.description == rhs.description && lhs.token == rhs.token && lhs.stackTrace == rhs.stackTrace
+  }
+
+}
+
+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 line = token.sourceMap.line
+      let highlight = "\(String(Array(repeating: " ", count: line.offset)))^\(String(Array(repeating: "~", count: max(token.contents.characters.count - 1, 0))))"
+
+      return "\(templateName)\(line.number):\(line.offset): error: \(templateError.reason)\n"
+        + "\(line.content)\n"
+        + "\(highlight)\n"
+    }
+
+    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

@@ -31,18 +31,18 @@ final class StaticExpression: Expression, CustomStringConvertible {
 
 
 final class VariableExpression: Expression, CustomStringConvertible {
-  let variable: Variable
+  let variable: Resolvable
 
-  init(variable: Variable) {
+  init(variable: Resolvable) {
     self.variable = variable
   }
 
   var description: String {
-    return "(variable: \(variable.variable))"
+    return "(variable: \(variable))"
   }
 
   /// Resolves a variable in the given context as boolean
-  func resolve(context: Context, variable: Variable) throws -> Bool {
+  func resolve(context: Context, variable: Resolvable) throws -> Bool {
     let result = try variable.resolve(context)
     var truthy = false
 
@@ -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
@@ -202,7 +237,7 @@ class NumericExpression: Expression, InfixOperator, CustomStringConvertible {
     return ""
   }
 
-  func compare(lhs: Float80, rhs: Float80) -> Bool {
+  func compare(lhs: Number, rhs: Number) -> Bool {
     return false
   }
 }
@@ -213,7 +248,7 @@ class MoreThanExpression: NumericExpression {
     return ">"
   }
 
-  override func compare(lhs: Float80, rhs: Float80) -> Bool {
+  override func compare(lhs: Number, rhs: Number) -> Bool {
     return lhs > rhs
   }
 }
@@ -224,7 +259,7 @@ class MoreThanEqualExpression: NumericExpression {
     return ">="
   }
 
-  override func compare(lhs: Float80, rhs: Float80) -> Bool {
+  override func compare(lhs: Number, rhs: Number) -> Bool {
     return lhs >= rhs
   }
 }
@@ -235,7 +270,7 @@ class LessThanExpression: NumericExpression {
     return "<"
   }
 
-  override func compare(lhs: Float80, rhs: Float80) -> Bool {
+  override func compare(lhs: Number, rhs: Number) -> Bool {
     return lhs < rhs
   }
 }
@@ -246,7 +281,7 @@ class LessThanEqualExpression: NumericExpression {
     return "<="
   }
 
-  override func compare(lhs: Float80, rhs: Float80) -> Bool {
+  override func compare(lhs: Number, rhs: Number) -> Bool {
     return lhs <= rhs
   }
 }
@@ -263,37 +298,37 @@ class InequalityExpression: EqualityExpression {
 }
 
 
-func toNumber(value: Any) -> Float80? {
+func toNumber(value: Any) -> Number? {
     if let value = value as? Float {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? Double {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? UInt {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? Int {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? Int8 {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? Int16 {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? Int32 {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? Int64 {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? UInt8 {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? UInt16 {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? UInt32 {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? UInt64 {
-        return Float80(value)
-    } else if let value = value as? Float80 {
+        return Number(value)
+    } else if let value = value as? Number {
         return value
     } else if let value = value as? Float64 {
-        return Float80(value)
+        return Number(value)
     } else if let value = value as? Float32 {
-        return Float80(value)
+        return Number(value)
     }
 
     return nil

Sources/Extension.swift

@@ -1,3 +1,68 @@
+open class Extension {
+  typealias TagParser = (TokenParser, Token) throws -> NodeType
+  var tags = [String: TagParser]()
+
+  var filters = [String: Filter]()
+
+  public init() {
+  }
+
+  /// Registers a new template tag
+  public func registerTag(_ name: String, parser: @escaping (TokenParser, Token) throws -> NodeType) {
+    tags[name] = parser
+  }
+
+  /// 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(token: token, handler: handler)
+    })
+  }
+
+  /// Registers a template filter with the given name
+  public func registerFilter(_ name: String, filter: @escaping (Any?) throws -> Any?) {
+    filters[name] = .simple(filter)
+  }
+
+  /// Registers a template filter with the given name
+  public func registerFilter(_ name: String, filter: @escaping (Any?, [Any?]) throws -> Any?) {
+    filters[name] = .arguments(filter)
+  }
+}
+
+
+class DefaultExtension: Extension {
+  override init() {
+    super.init()
+    registerDefaultTags()
+    registerDefaultFilters()
+  }
+
+  fileprivate func registerDefaultTags() {
+    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
+    registerTag("include", parser: IncludeNode.parse)
+    registerTag("extends", parser: ExtendsNode.parse)
+    registerTag("block", parser: BlockNode.parse)
+    registerTag("filter", parser: FilterNode.parse)
+  }
+
+  fileprivate func registerDefaultFilters() {
+    registerFilter("default", filter: defaultFilter)
+    registerFilter("capitalize", filter: capitalise)
+    registerFilter("uppercase", filter: uppercase)
+    registerFilter("lowercase", filter: lowercase)
+    registerFilter("join", filter: joinFilter)
+    registerFilter("split", filter: splitFilter)
+    registerFilter("indent", filter: indentFilter)
+  }
+}
+
+
 protocol FilterType {
   func invoke(value: Any?, arguments: [Any?]) throws -> Any?
 }
@@ -19,58 +84,3 @@ enum Filter: FilterType {
     }
   }
 }
-
-
-public class Namespace {
-  public typealias TagParser = (TokenParser, Token) throws -> NodeType
-
-  var tags = [String: TagParser]()
-  var filters = [String: Filter]()
-
-  public init() {
-    registerDefaultTags()
-    registerDefaultFilters()
-  }
-
-  fileprivate func registerDefaultTags() {
-    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
-    registerTag("include", parser: IncludeNode.parse)
-    registerTag("extends", parser: ExtendsNode.parse)
-    registerTag("block", parser: BlockNode.parse)
-  }
-
-  fileprivate func registerDefaultFilters() {
-    registerFilter("default", filter: defaultFilter)
-    registerFilter("capitalize", filter: capitalise)
-    registerFilter("uppercase", filter: uppercase)
-    registerFilter("lowercase", filter: lowercase)
-    registerFilter("join", filter: joinFilter)
-  }
-
-  /// Registers a new template tag
-  public func registerTag(_ name: String, parser: @escaping TagParser) {
-    tags[name] = parser
-  }
-
-  /// 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)
-    })
-  }
-
-  /// Registers a template filter with the given name
-  public func registerFilter(_ name: String, filter: @escaping (Any?) throws -> Any?) {
-    filters[name] = .simple(filter)
-  }
-
-  /// Registers a template filter with the given name
-  public func registerFilter(_ name: String, filter: @escaping (Any?, [Any?]) throws -> Any?) {
-    filters[name] = .arguments(filter)
-  }
-}

Sources/FilterTag.swift

@@ -0,0 +1,37 @@
+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()
+
+    guard bits.count == 2 else {
+      throw TemplateSyntaxError("'filter' tag takes one argument, the filter expression")
+    }
+
+    let blocks = try parser.parse(until(["endfilter"]))
+
+    guard parser.nextToken() != nil else {
+      throw TemplateSyntaxError("`endfilter` was not found.")
+    }
+
+    let resolvable = try parser.compileFilter("filter_value|\(bits[1])", containedIn: token)
+    return FilterNode(nodes: blocks, resolvable: resolvable, token: token)
+  }
+
+  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, token: token).render(context)
+    }
+  }
+}
+

Sources/Filters.swift

@@ -1,39 +1,30 @@
-func toString(_ value: Any?) -> String? {
-  if let value = value as? String {
-    return value
-  } else if let value = value as? CustomStringConvertible {
-    return value.description
-  }
-
-  return nil
-}
-
 func capitalise(_ value: Any?) -> Any? {
-  if let value = toString(value) {
-    return value.capitalized
+  if let array = value as? [Any?] {
+    return array.map { stringify($0).capitalized }
+  } else {
+    return stringify(value).capitalized
   }
-
-  return value
 }
 
 func uppercase(_ value: Any?) -> Any? {
-  if let value = toString(value) {
-    return value.uppercased()
+  if let array = value as? [Any?] {
+    return array.map { stringify($0).uppercased() }
+  } else {
+    return stringify(value).uppercased()
   }
-
-  return value
 }
 
 func lowercase(_ value: Any?) -> Any? {
-  if let value = toString(value) {
-    return value.lowercased()
+  if let array = value as? [Any?] {
+    return array.map { stringify($0).lowercased() }
+  } else {
+    return stringify(value).lowercased()
   }
-
-  return value
 }
 
 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
   }
 
@@ -47,17 +38,76 @@ func defaultFilter(value: Any?, arguments: [Any?]) -> Any? {
 }
 
 func joinFilter(value: Any?, arguments: [Any?]) throws -> Any? {
-  guard arguments.count == 1 else {
+  guard arguments.count < 2 else {
     throw TemplateSyntaxError("'join' filter takes a single argument")
   }
 
-  guard let separator = arguments.first as? String else {
-    throw TemplateSyntaxError("'join' filter takes a separator as string")
+  let separator = stringify(arguments.first ?? "")
+
+  if let value = value as? [Any] {
+    return value
+      .map(stringify)
+      .joined(separator: separator)
   }
 
-  if let value = value as? [String] {
-    return value.joined(separator: separator)
-  }
-
-  return nil
+  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].characters
+      .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.map { ($0.key, $0.value) }
+    } 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),
@@ -40,7 +41,7 @@ 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)
-  case variable(Variable)
+  case variable(Resolvable)
   case end
 
   var bindingPower: Int {
@@ -52,7 +53,7 @@ enum IfToken {
     case .variable(_):
       return 0
     case .end:
-        return 0
+      return 0
     }
   }
 
@@ -99,8 +100,8 @@ final class IfExpressionParser {
   let tokens: [IfToken]
   var position: Int = 0
 
-  init(components: [String]) {
-    self.tokens = components.map { component in
+  init(components: [String], tokenParser: TokenParser, token: Token) throws {
+    self.tokens = try components.map { component in
       if let op = findOperator(name: component) {
         switch op {
         case .infix(let name, let bindingPower, let cls):
@@ -110,7 +111,7 @@ final class IfExpressionParser {
         }
       }
 
-      return .variable(Variable(component))
+      return .variable(try tokenParser.compileResolvable(component, containedIn: token))
     }
   }
 
@@ -154,47 +155,78 @@ final class IfExpressionParser {
 }
 
 
-func parseExpression(components: [String]) throws -> Expression {
-  let parser = IfExpressionParser(components: components)
+func parseExpression(components: [String], tokenParser: TokenParser, token: Token) throws -> Expression {
+  let parser = try IfExpressionParser(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)
-    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 +238,30 @@ class IfNode : NodeType {
       _ = parser.nextToken()
     }
 
-    let expression = try parseExpression(components: components)
-    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

@@ -3,35 +3,44 @@ 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 {
-    guard let loader = context["loader"] as? Loader else {
-      throw TemplateSyntaxError("Template loader not in context")
-    }
-
     guard let templateName = try self.templateName.resolve(context) as? String else {
       throw TemplateSyntaxError("'\(self.templateName)' could not be resolved as a string")
     }
 
-    guard let template = try loader.loadTemplate(name: templateName) else {
-      throw TemplateSyntaxError("'\(templateName)' template not found")
-    }
+    let template = try context.environment.loadTemplate(name: templateName)
 
-    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()
@@ -50,42 +72,47 @@ 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 {
-    guard let loader = context["loader"] as? Loader else {
-      throw TemplateSyntaxError("Template loader not in context")
-    }
-
     guard let templateName = try self.templateName.resolve(context) as? String else {
       throw TemplateSyntaxError("'\(self.templateName)' could not be resolved as a string")
     }
 
-    guard let template = try loader.loadTemplate(name: templateName) else {
-      throw TemplateSyntaxError("'\(templateName)' template not found")
-    }
+    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
+      }
     }
   }
 }
@@ -94,6 +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()
@@ -105,19 +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 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.characters {
+      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

@@ -1,26 +1,45 @@
+import Foundation
+
 struct Lexer {
+  let templateName: String?
   let templateString: String
 
-  init(templateString: String) {
+  init(templateName: String? = nil, templateString: String) {
+    self.templateName = templateName
     self.templateString = templateString
   }
 
-  func createToken(string:String) -> Token {
+  func createToken(string: String, at range: Range<String.Index>) -> Token {
     func strip() -> String {
+      guard string.characters.count > 4 else { return "" }
       let start = string.index(string.startIndex, offsetBy: 2)
       let end = string.index(string.endIndex, offsetBy: -2)
-      return string[start..<end].trim(character: " ")
+      let trimmed = String(string[start..<end])
+        .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 line = templateString.rangeLine(range)
+      let sourceMap = SourceMap(filename: templateName, line: line)
+
+      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 line = templateString.rangeLine(range)
+    let sourceMap = SourceMap(filename: templateName, line: line)
+    return .text(value: string, at: sourceMap)
   }
 
   /// Returns an array of tokens from a given template string.
@@ -33,33 +52,37 @@ struct Lexer {
       "{{": "}}",
       "{%": "%}",
       "{#": "#}",
-    ]
+      ]
 
     while !scanner.isEmpty {
       if let text = scanner.scan(until: ["{{", "{%", "{#"]) {
         if !text.1.isEmpty {
-          tokens.append(createToken(string: text.1))
+          tokens.append(createToken(string: text.1, at: scanner.range))
         }
 
         let end = map[text.0]!
         let result = scanner.scan(until: end, returnUntil: true)
-        tokens.append(createToken(string: result))
+        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
   }
+
 }
 
-
 class Scanner {
+  let originalContent: String
   var content: String
+  var range: Range<String.Index>
 
   init(_ content: String) {
+    self.originalContent = content
     self.content = content
+    range = content.startIndex..<content.startIndex
   }
 
   var isEmpty: Bool {
@@ -67,29 +90,34 @@ class Scanner {
   }
 
   func scan(until: String, returnUntil: Bool = false) -> String {
+    var index = content.startIndex
+
     if until.isEmpty {
       return ""
     }
 
-    var index = content.startIndex
+    range = range.upperBound..<range.upperBound
     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)
+          range = range.lowerBound..<originalContent.index(range.upperBound, offsetBy: until.characters.count)
+          content = substring.substring(from: until.endIndex)
           return result + until
         }
 
+        content = substring
         return result
       }
 
       index = content.index(after: index)
+      range = range.lowerBound..<originalContent.index(after: range.upperBound)
     }
 
+    content = ""
     return ""
   }
 
@@ -99,6 +127,7 @@ class Scanner {
     }
 
     var index = content.startIndex
+    range = range.upperBound..<range.upperBound
     while index != content.endIndex {
       let substring = content.substring(from: index)
       for string in until {
@@ -110,6 +139,7 @@ class Scanner {
       }
 
       index = content.index(after: index)
+      range = range.lowerBound..<originalContent.index(after: range.upperBound)
     }
 
     return nil
@@ -147,6 +177,25 @@ 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 func rangeLine(_ range: Range<String.Index>) -> RangeLine {
+    var lineNumber: UInt = 0
+    var offset: Int = 0
+    var lineContent = ""
+
+    for line in components(separatedBy: CharacterSet.newlines) {
+      lineNumber += 1
+      lineContent = line
+      if let rangeOfLine = self.range(of: line), rangeOfLine.contains(range.lowerBound) {
+        offset = distance(from: rangeOfLine.lowerBound, to: range.lowerBound)
+        break
+      }
+    }
+
+    return (lineContent, lineNumber, offset)
   }
 }
+
+public typealias RangeLine = (content: String, number: UInt, offset: Int)

Sources/Loader.swift

@@ -0,0 +1,130 @@
+import Foundation
+import PathKit
+
+
+public protocol Loader {
+  func loadTemplate(name: String, environment: Environment) throws -> Template
+  func loadTemplate(names: [String], environment: Environment) throws -> Template
+}
+
+
+extension Loader {
+  public func loadTemplate(names: [String], environment: Environment) throws -> Template {
+    for name in names {
+      do {
+        return try loadTemplate(name: name, environment: environment)
+      } catch is TemplateDoesNotExist {
+        continue
+      } catch {
+        throw error
+      }
+    }
+
+    throw TemplateDoesNotExist(templateNames: names, loader: self)
+  }
+}
+
+
+// A class for loading a template from disk
+public class FileSystemLoader: Loader, CustomStringConvertible {
+  public let paths: [Path]
+
+  public init(paths: [Path]) {
+    self.paths = paths
+  }
+
+  public init(bundle: [Bundle]) {
+    self.paths = bundle.map {
+      return Path($0.bundlePath)
+    }
+  }
+
+  public var description: String {
+    return "FileSystemLoader(\(paths))"
+  }
+
+  public func loadTemplate(name: String, environment: Environment) throws -> Template {
+    for path in paths {
+      let templatePath = try path.safeJoin(path: Path(name))
+
+      if !templatePath.exists {
+        continue
+      }
+
+      let content: String = try templatePath.read()
+      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 path in paths {
+      for templateName in names {
+        let templatePath = try path.safeJoin(path: Path(templateName))
+
+        if templatePath.exists {
+          let content: String = try templatePath.read()
+          return environment.templateClass.init(templateString: content, environment: environment, name: templateName)
+        }
+      }
+    }
+
+    throw TemplateDoesNotExist(templateNames: names, loader: self)
+  }
+}
+
+
+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
+
+    if !newPath.absolute().description.hasPrefix(absolute().description) {
+      throw SuspiciousFileOperation(basePath: self, path: newPath)
+    }
+
+    return newPath
+  }
+}
+
+
+class SuspiciousFileOperation: Error {
+  let basePath: Path
+  let path: Path
+
+  init(basePath: Path, path: Path) {
+    self.basePath = basePath
+    self.path = path
+  }
+
+  var description: String {
+    return "Path `\(path)` is located outside of base path `\(basePath)`"
+  }
+}

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 {
@@ -59,26 +57,48 @@ public protocol Resolvable {
 
 public class VariableNode : NodeType {
   public let variable: Resolvable
+  public var token: Token?
 
-  public init(variable: Resolvable) {
+  public init(variable: Resolvable, token: Token? = nil) {
     self.variable = variable
+    self.token = token
   }
 
-  public init(variable: String) {
+  public init(variable: String, token: Token? = nil) {
     self.variable = Variable(variable)
+    self.token = token
   }
 
   public func render(_ context: Context) throws -> String {
     let result = try variable.resolve(context)
-
-    if let result = result as? String {
-      return result
-    } else if let result = result as? CustomStringConvertible {
-      return result.description
-    } else if let result = result as? NSObject {
-      return result.description
-    }
-
-    return ""
+    return stringify(result)
+  }
+}
+
+
+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 {
+    return result.description
+  }
+
+  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

@@ -18,11 +18,11 @@ public class TokenParser {
   public typealias TagParser = (TokenParser, Token) throws -> NodeType
 
   fileprivate var tokens: [Token]
-  fileprivate let namespace: Namespace
+  fileprivate let environment: Environment
 
-  public init(tokens: [Token], namespace: Namespace) {
+  public init(tokens: [Token], environment: Environment) {
     self.tokens = tokens
-    self.namespace = namespace
+    self.environment = environment
   }
 
   /// Parse the given tokens into nodes
@@ -37,23 +37,24 @@ 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)))
+        let filter = try compileResolvable(token.contents, containedIn: token)
+        nodes.append(VariableNode(variable: filter, token: token))
       case .block:
-        let tag = token.components().first
-
         if let parse_until = parse_until , parse_until(self, token) {
           prependToken(token)
           return nodes
         }
 
-        if let tag = tag {
-          if let parser = namespace.tags[tag] {
-            nodes.append(try parser(self, token))
-          } else {
-            throw TemplateSyntaxError("Unknown template tag '\(tag)'")
+        if let tag = token.components().first {
+          do {
+            let parser = try findTag(name: tag)
+            let node = try parser(self, token)
+            nodes.append(node)
+          } catch {
+            throw error.withToken(token)
           }
         }
       case .comment:
@@ -76,15 +77,120 @@ public class TokenParser {
     tokens.insert(token, at: 0)
   }
 
-  func findFilter(_ name: String) throws -> FilterType {
-    if let filter = namespace.filters[name] {
-      return filter
+  func findTag(name: String) throws -> Extension.TagParser {
+    for ext in environment.extensions {
+      if let filter = ext.tags[name] {
+        return filter
+      }
     }
 
-    throw TemplateSyntaxError("Invalid filter '\(name)'")
+    throw TemplateSyntaxError("Unknown template tag '\(name)'")
   }
 
+  func findFilter(_ name: String) throws -> FilterType {
+    for ext in environment.extensions {
+      if let filter = ext.filters[name] {
+        return filter
+      }
+    }
+
+    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.characters.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 rangeLine = containingToken.sourceMap.line
+        rangeLine.offset += containingToken.contents.distance(from: containingToken.contents.startIndex, to: filterTokenRange.lowerBound)
+        syntaxError.token = .variable(value: filterToken, at: SourceMap(filename: containingToken.sourceMap.filename, line: rangeLine))
+      } 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.characters.count)
+    current = [Int](repeating: 0, count: target.characters.count + 1)
+
+    for i in 0..<self.characters.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.characters.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.characters.count]
+  }
+
 }

Sources/Template.swift

@@ -7,15 +7,25 @@ let NSFileNoSuchFileError = 4
 
 /// A class representing a template
 open class Template: ExpressibleByStringLiteral {
+  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
+  public let name: String?
+
   /// Create a template with a template string
-  public init(templateString: String) {
-    let lexer = Lexer(templateString: templateString)
+  public required init(templateString: String, environment: Environment? = nil, name: String? = nil) {
+    self.environment = environment ?? Environment()
+    self.name = name
+    self.templateString = templateString
+
+    let lexer = Lexer(templateName: name, templateString: templateString)
     tokens = lexer.tokenize()
   }
 
   /// Create a template with the given name inside the given bundle
+  @available(*, deprecated, message: "Use Environment/FileSystemLoader instead")
   public convenience init(named:String, inBundle bundle:Bundle? = nil) throws {
     let useBundle = bundle ??  Bundle.main
     guard let url = useBundle.url(forResource: named, withExtension: nil) else {
@@ -26,16 +36,20 @@ open class Template: ExpressibleByStringLiteral {
   }
 
   /// Create a template with a file found at the given URL
+  @available(*, deprecated, message: "Use Environment/FileSystemLoader instead")
   public convenience init(URL:Foundation.URL) throws {
     try self.init(path: Path(URL.path))
   }
 
   /// Create a template with a file found at the given path
-  public convenience init(path: Path) throws {
-    self.init(templateString: try path.read())
+  @available(*, deprecated, message: "Use Environment/FileSystemLoader instead")
+  public convenience init(path: Path, environment: Environment? = nil, name: String? = nil) throws {
+    self.init(templateString: try path.read(), environment: environment, name: name)
   }
 
-  // Create a template with a template string literal
+  // MARK: ExpressibleByStringLiteral
+
+  // Create a templaVte with a template string literal
   public convenience required init(stringLiteral value: String) {
     self.init(templateString: value)
   }
@@ -50,11 +64,16 @@ open class Template: ExpressibleByStringLiteral {
     self.init(stringLiteral: value)
   }
 
-  /// Render the given template
-  open func render(_ context: Context? = nil) throws -> String {
-    let context = context ?? Context()
-    let parser = TokenParser(tokens: tokens, namespace: context.namespace)
+  /// Render the given template with a context
+  func render(_ context: Context) throws -> String {
+    let context = context
+    let parser = TokenParser(tokens: tokens, environment: context.environment)
     let nodes = try parser.parse()
     return try renderNodes(nodes, context)
   }
+
+  /// Render the given template
+  open func render(_ dictionary: [String: Any]? = nil) throws -> String {
+    return try render(Context(dictionary: dictionary, environment: environment))
+  }
 }

Sources/TemplateLoader.swift

@@ -1,65 +0,0 @@
-import Foundation
-import PathKit
-
-
-public protocol Loader {
-  func loadTemplate(name: String) throws -> Template?
-  func loadTemplate(names: [String]) throws -> Template?
-}
-
-
-extension Loader {
-  func loadTemplate(names: [String]) throws -> Template? {
-    for name in names {
-      let template = try loadTemplate(name: name)
-
-      if template != nil {
-        return template
-      }
-    }
-
-    return nil
-  }
-}
-
-
-// A class for loading a template from disk
-public class FileSystemLoader: Loader {
-  public let paths: [Path]
-
-  public init(paths: [Path]) {
-    self.paths = paths
-  }
-
-  public init(bundle: [Bundle]) {
-    self.paths = bundle.map {
-      return Path($0.bundlePath)
-    }
-  }
-
-  public func loadTemplate(name: String) throws -> Template? {
-    for path in paths {
-      let templatePath = path + Path(name)
-
-      if templatePath.exists {
-        return try Template(path: templatePath)
-      }
-    }
-
-    return nil
-  }
-
-  public func loadTemplate(names: [String]) throws -> Template? {
-    for path in paths {
-      for templateName in names {
-        let templatePath = path + Path(templateName)
-
-        if templatePath.exists {
-          return try Template(path: templatePath)
-        }
-      }
-    }
-
-    return nil
-  }
-}

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?.characters.last, specialCharacters.characters.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.characters {
+      if character == "'" { singleQuoteCount += 1 }
+      else if character == "\"" { doubleQuoteCount += 1 }
+
       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 = ""
         }
 
@@ -29,66 +48,86 @@ extension String {
     }
 
     if !word.isEmpty {
-      components.append(word)
+      appendWord(word)
     }
 
     return components
   }
 }
 
+public struct SourceMap: Equatable {
+  public let filename: String?
+  public let line: RangeLine
+
+  init(filename: String? = nil, line: RangeLine = ("", 0, 0)) {
+    self.filename = filename
+    self.line = line
+  }
+
+  static let unknown = SourceMap()
+
+  public static func ==(lhs: SourceMap, rhs: SourceMap) -> Bool {
+    return lhs.filename == rhs.filename && lhs.line == rhs.line
+  }
+}
 
 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 var sourceMap: SourceMap {
+    switch self {
+    case .block(_, let sourceMap),
+         .variable(_, let sourceMap),
+         .text(_, let sourceMap),
+         .comment(_, let sourceMap):
+      return sourceMap
+    }
+  }
+
 }
 
 
 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
+  case let (.text(lhsValue, lhsAt), .text(rhsValue, rhsAt)):
+    return lhsValue == rhsValue && lhsAt == rhsAt
+  case let (.variable(lhsValue, lhsAt), .variable(rhsValue, rhsAt)):
+    return lhsValue == rhsValue && lhsAt == rhsAt
+  case let (.block(lhsValue, lhsAt), .block(rhsValue, rhsAt)):
+    return lhsValue == rhsValue && lhsAt == rhsAt
+  case let (.comment(lhsValue, lhsAt), .comment(rhsValue, rhsAt)):
+    return lhsValue == rhsValue && lhsAt == rhsAt
   default:
     return false
   }

Sources/Variable.swift

@@ -1,6 +1,9 @@
 import Foundation
 
 
+typealias Number = Float
+
+
 class FilterExpression : Resolvable {
   let filters: [(FilterType, [Variable])]
   let variable: Variable
@@ -8,8 +11,6 @@ class FilterExpression : Resolvable {
   init(token: String, parser: TokenParser) throws {
     let bits = token.characters.split(separator: "|").map({ String($0).trim(character: " ") })
     if bits.isEmpty {
-      filters = []
-      variable = Variable("")
       throw TemplateSyntaxError("Variable tags must include at least 1 argument")
     }
 
@@ -47,8 +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
@@ -57,16 +60,32 @@ 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.characters.index(after: variable.startIndex) ..< variable.characters.index(before: variable.endIndex)])
     }
 
-    for bit in lookup() {
+    // Number literal
+    if let int = Int(variable) {
+      return int
+    }
+    if let number = Number(variable) {
+      return number
+    }
+    // Boolean literal
+    if let bool = Bool(variable) {
+      return bool
+    }
+
+    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]
+        if bit == "count" {
+          current = dictionary.count
+        } else {
+          current = dictionary[bit]
+        }
       } else if let array = current as? [Any] {
         if let index = Int(bit) {
           if index >= 0 && index < array.count {
@@ -82,15 +101,13 @@ public struct Variable : Equatable, Resolvable {
           current = array.count
         }
       } 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
+          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
         }
@@ -99,6 +116,12 @@ public struct Variable : Equatable, Resolvable {
       }
     }
 
+    if let resolvable = current as? Resolvable {
+      current = try resolvable.resolve(context)
+    } else if let node = current as? NodeType {
+      current = try node.render(context)
+    }
+
     return normalize(current)
   }
 }
@@ -107,6 +130,53 @@ public func ==(lhs: Variable, rhs: Variable) -> Bool {
   return lhs.variable == rhs.variable
 }
 
+/// 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)
+  }
+
+}
+
 
 func normalize(_ current: Any?) -> Any? {
   if let current = current as? Normalizable {
@@ -150,10 +220,47 @@ 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": "0.7.2",
+  "version": "0.12.1",
   "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": "0.7.2"
+    "git": "https://github.com/stencilproject/Stencil.git",
+    "tag": "0.12.1"
   },
   "source_files": [
     "Sources/*.swift"
@@ -25,6 +25,8 @@
   },
   "requires_arc": true,
   "dependencies": {
-    "PathKit": [ "~> 0.7.0" ]
+    "PathKit": [
+      "~> 0.9.0"
+    ]
   }
 }

Tests/StencilTests/ContextSpec.swift

@@ -1,5 +1,5 @@
 import Spectre
-import Stencil
+@testable import Stencil
 
 
 func testContext() {

Tests/StencilTests/EnvironmentSpec.swift

@@ -0,0 +1,361 @@
+import Spectre
+import PathKit
+@testable import Stencil
+
+
+func testEnvironment() {
+  describe("Environment") {
+    var environment: Environment!
+    var template: Template!
+    
+    $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 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 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")
+
+      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 rangeLine = template.templateString.rangeLine(range)
+      let sourceMap = SourceMap(filename: template.name, line: rangeLine)
+      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\" %}\n" +
+          "{% 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\" %}\n" +
+          "{% block body %}Child {{ target|unknown }}{% endblock %}", environment: environment, name: nil)
+
+        try expectError(reason: "filter error",
+                        childToken: "target|unknown",
+                        baseToken: nil)
+      }
+      
+    }
+    
+  }
+}
+
+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 {
+    if name == "example.html" {
+      return Template(templateString: "Hello World!", environment: environment, name: name)
+    }
+
+    throw TemplateDoesNotExist(templateNames: [name], loader: self)
+  }
+}
+
+
+class CustomTemplate: Template {
+  override func render(_ dictionary: [String: Any]? = nil) throws -> String {
+    return "here"
+  }
+}

Tests/StencilTests/ExpressionSpec.swift

@@ -4,6 +4,8 @@ import Spectre
 
 func testExpressions() {
   describe("Expression") {
+    let parser = TokenParser(tokens: [], environment: Environment())
+
     $0.describe("VariableExpression") {
       let expression = VariableExpression(variable: Variable("value"))
 
@@ -103,19 +105,19 @@ func testExpressions() {
 
     $0.describe("expression parsing") {
       $0.it("can parse a variable expression") {
-        let expression = try parseExpression(components: ["value"])
+        let expression = try parseExpression(components: ["value"], tokenParser: parser, token: .text(value: "", at: .unknown))
         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"])
+        let expression = try parseExpression(components: ["not", "value"], tokenParser: parser, token: .text(value: "", at: .unknown))
         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"])
+        let expression = try! parseExpression(components: ["lhs", "and", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to false with lhs false") {
           try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beFalse()
@@ -135,7 +137,7 @@ func testExpressions() {
       }
 
       $0.describe("or expression") {
-        let expression = try! parseExpression(components: ["lhs", "or", "rhs"])
+        let expression = try! parseExpression(components: ["lhs", "or", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to true with lhs true") {
           try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beTrue()
@@ -155,7 +157,7 @@ func testExpressions() {
       }
 
       $0.describe("equality expression") {
-        let expression = try! parseExpression(components: ["lhs", "==", "rhs"])
+        let expression = try! parseExpression(components: ["lhs", "==", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to true with equal lhs/rhs") {
           try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "a"]))).to.beTrue()
@@ -191,7 +193,7 @@ func testExpressions() {
       }
 
       $0.describe("inequality expression") {
-        let expression = try! parseExpression(components: ["lhs", "!=", "rhs"])
+        let expression = try! parseExpression(components: ["lhs", "!=", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to true with inequal lhs/rhs") {
           try expect(expression.evaluate(context: Context(dictionary: ["lhs": "a", "rhs": "b"]))).to.beTrue()
@@ -203,7 +205,7 @@ func testExpressions() {
       }
 
       $0.describe("more than expression") {
-        let expression = try! parseExpression(components: ["lhs", ">", "rhs"])
+        let expression = try! parseExpression(components: ["lhs", ">", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to true with lhs > rhs") {
           try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 4]))).to.beTrue()
@@ -215,7 +217,7 @@ func testExpressions() {
       }
 
       $0.describe("more than equal expression") {
-        let expression = try! parseExpression(components: ["lhs", ">=", "rhs"])
+        let expression = try! parseExpression(components: ["lhs", ">=", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to true with lhs == rhs") {
           try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5]))).to.beTrue()
@@ -227,7 +229,7 @@ func testExpressions() {
       }
 
       $0.describe("less than expression") {
-        let expression = try! parseExpression(components: ["lhs", "<", "rhs"])
+        let expression = try! parseExpression(components: ["lhs", "<", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to true with lhs < rhs") {
           try expect(expression.evaluate(context: Context(dictionary: ["lhs": 4, "rhs": 4.5]))).to.beTrue()
@@ -239,7 +241,7 @@ func testExpressions() {
       }
 
       $0.describe("less than equal expression") {
-        let expression = try! parseExpression(components: ["lhs", "<=", "rhs"])
+        let expression = try! parseExpression(components: ["lhs", "<=", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to true with lhs == rhs") {
           try expect(expression.evaluate(context: Context(dictionary: ["lhs": 5.0, "rhs": 5]))).to.beTrue()
@@ -251,7 +253,7 @@ func testExpressions() {
       }
 
       $0.describe("multiple expression") {
-        let expression = try! parseExpression(components: ["one", "or", "two", "and", "not", "three"])
+        let expression = try! parseExpression(components: ["one", "or", "two", "and", "not", "three"], tokenParser: parser, token: .text(value: "", at: .unknown))
 
         $0.it("evaluates to true with one") {
           try expect(expression.evaluate(context: Context(dictionary: ["one": true]))).to.beTrue()
@@ -277,6 +279,26 @@ func testExpressions() {
           try expect(expression.evaluate(context: Context())).to.beFalse()
         }
       }
+      
+      $0.describe("in expression") {
+        let expression = try! parseExpression(components: ["lhs", "in", "rhs"], tokenParser: parser, token: .text(value: "", at: .unknown))
+        
+        $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()
+        }
+      }
     }
   }
 }

Tests/StencilTests/FilterSpec.swift

@@ -1,5 +1,5 @@
 import Spectre
-import Stencil
+@testable import Stencil
 
 
 func testFilter() {
@@ -9,8 +9,8 @@ func testFilter() {
     $0.it("allows you to register a custom filter") {
       let template = Template(templateString: "{{ name|repeat }}")
 
-      let namespace = Namespace()
-      namespace.registerFilter("repeat") { (value: Any?) in
+      let repeatExtension = Extension()
+      repeatExtension.registerFilter("repeat") { (value: Any?) in
         if let value = value as? String {
           return "\(value) \(value)"
         }
@@ -18,15 +18,15 @@ func testFilter() {
         return nil
       }
 
-      let result = try template.render(Context(dictionary: context, namespace: namespace))
+      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 arguments") {
-      let template = Template(templateString: "{{ name|repeat:'value' }}")
+    $0.it("allows you to register a custom filter which accepts single argument") {
+      let template = Template(templateString: "{{ name|repeat:'value1, \"value2\"' }}")
 
-      let namespace = Namespace()
-      namespace.registerFilter("repeat") { value, arguments in
+      let repeatExtension = Extension()
+      repeatExtension.registerFilter("repeat") { value, arguments in
         if !arguments.isEmpty {
           return "\(value!) \(value!) with args \(arguments.first!!)"
         }
@@ -34,24 +34,53 @@ func testFilter() {
         return nil
       }
 
-      let result = try template.render(Context(dictionary: context, namespace: namespace))
-      try expect(result) == "Kyle Kyle with args value"
+      let result = try template.render(Context(dictionary: context, environment: Environment(extensions: [repeatExtension])))
+      try expect(result) == "Kyle Kyle with args value1, \"value2\""
+    }
+
+    $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)' }}")
+
+        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)"
     }
 
     $0.it("allows you to register a custom which throws") {
       let template = Template(templateString: "{{ name|repeat }}")
-      let namespace = Namespace()
-      namespace.registerFilter("repeat") { (value: Any?) in
+      let repeatExtension = Extension()
+      repeatExtension.registerFilter("repeat") { (value: Any?) in
         throw TemplateSyntaxError("No Repeat")
       }
 
-      try expect(try template.render(Context(dictionary: context, namespace: namespace))).toThrow(TemplateSyntaxError("No Repeat"))
+      let context = Context(dictionary: context, environment: Environment(extensions: [repeatExtension]))
+      try expect(try template.render(context)).toThrow(TemplateSyntaxError(reason: "No Repeat", token: template.tokens.first))
+    }
+
+    $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: "{{ name | uppercase }}")
-      let result = try template.render(Context(dictionary: ["name": "kyle"]))
-      try expect(result) == "KYLE"
+      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") {
@@ -60,32 +89,45 @@ func testFilter() {
     }
   }
 
+  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"
+      }
 
-  describe("capitalize filter") {
-    let template = Template(templateString: "{{ name|capitalize }}")
+      $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("capitalizes a string") {
-      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\"]"
+      }
 
-  describe("uppercase filter") {
-    let template = Template(templateString: "{{ name|uppercase }}")
+      $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 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"
+      $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\"]"
+      }
     }
   }
 
@@ -107,14 +149,145 @@ func testFilter() {
       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"
+    }
+
+    $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("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"
+    }
   }
 
   describe("join filter") {
     let template = Template(templateString: "{{ value|join:\", \" }}")
 
-    $0.it("transforms a string to be lowercase") {
+    $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"
+    }
+  }
+
+  describe("split filter") {
+    let template = Template(templateString: "{{ value|split:\", \" }}")
+
+    $0.it("split a string into array") {
+      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\"]"
+    }
+  }
+
+
+  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 rangeLine = template.templateString.rangeLine(range)
+      let sourceMap = SourceMap(filename: template.name, line: rangeLine)
+      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")
+    }
+
+  }
+
+
+  describe("indent filter") {
+    $0.it("indents content") {
+      let template = Template(templateString: "{{ value|indent:2 }}")
+      let result = try template.render(Context(dictionary: ["value": "One\nTwo"]))
+      try expect(result) == "One\n  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\nTwo"]))
+      try expect(result) == "One\n\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\nTwo"]))
+      try expect(result) == "  One\n  Two"
+    }
+
+    $0.it("does not indent empty lines") {
+      let template = Template(templateString: "{{ value|indent }}")
+      let result = try template.render(Context(dictionary: ["value": "One\n\n\nTwo\n\n"]))
+      try expect(result) == "One\n\n\n    Two\n\n"
+    }
   }
 }

Tests/StencilTests/FilterTagSpec.swift

@@ -0,0 +1,45 @@
+import Spectre
+import Stencil
+
+
+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"
+    }
+  }
+}

Tests/StencilTests/ForNodeSpec.swift

@@ -8,72 +8,120 @@ func testForNode() {
     let context = Context(dictionary: [
       "items": [1, 2, 3],
       "emptyItems": [Int](),
-    ])
+      "dict": [
+        "one": "I",
+        "two": "II",
+      ],
+      "tuples": [(1, 2, 3), (4, 5, 6)]
+      ])
 
     $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: [])
+      let node = ForNode(resolvable: Variable("items"), loopVariables: ["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)
+      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"), loopVariable: "item", nodes: nodes, emptyNodes: [])
+      let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
       try expect(try node.render(any_context)) == "123"
     }
 
-#if os(OSX)
+    $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"), loopVariable: "item", nodes: nodes, emptyNodes: [])
+      let node = ForNode(resolvable: Variable("items"), loopVariables: ["item"], nodes: nodes, emptyNodes: [])
       try expect(try node.render(nsarray_context)) == "123"
     }
-#endif
+    #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: [])
+      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"), loopVariable: "item", nodes: nodes, emptyNodes: [])
+      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"), loopVariable: "item", nodes: nodes, emptyNodes: [])
+      let node = ForNode(resolvable: Variable("items"), loopVariables: ["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 %}" +
+    $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 }}.\n" +
-        "{% endfor %}\n"
+      "{% endfor %}\n"
 
       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)
@@ -81,11 +129,188 @@ func testForNode() {
       let fixture = "" +
         "- Migrating from OCUnit to XCTest by Kyle Fuller.\n" +
         "- Memory Management with ARC by Kyle Fuller.\n" +
-        "\n"
+      "\n"
 
       try expect(result) == fixture
     }
+
+    $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 }}\n" +
+        "{% endfor %}\n"
+
+        let template = Template(templateString: templateString)
+        let result = try template.render(context)
+
+        let fixture = "1, 2, 3\n4, 5, 6\n\n"
+        try expect(result) == fixture
+      }
+
+      $0.it("can iterate with less number of variables") {
+        let templateString = "{% for first,second in tuples %}" +
+          "{{ first }}, {{ second }}\n" +
+        "{% endfor %}\n"
+
+        let template = Template(templateString: templateString)
+        let result = try template.render(context)
+
+        let fixture = "1, 2\n4, 5\n\n"
+        try expect(result) == fixture
+      }
+
+      $0.it("can use _ to skip variables") {
+        let templateString = "{% for first,_,third in tuples %}" +
+          "{{ first }}, {{ third }}\n" +
+        "{% endfor %}\n"
+
+        let template = Template(templateString: templateString)
+        let result = try template.render(context)
+
+        let fixture = "1, 3\n4, 6\n\n"
+        try expect(result) == fixture
+      }
+
+      $0.it("throws when number of variables is more than number of tuple values") {
+        let templateString = "{% for key,value,smth in dict %}" +
+        "{% endfor %}\n"
+
+        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)
+
+      let sortedResult = result.characters.split(separator: ",").map(String.init).sorted(by: <)
+      try expect(sortedResult) == ["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)
+
+      let sortedResult = result.characters.split(separator: ",").map(String.init).sorted(by: <)
+      try expect(sortedResult) == ["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)
+
+      let sortedResult = result.characters.split(separator: ",").map(String.init).sorted(by: <)
+      try expect(sortedResult) == ["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\nnumber=123\n"
+    }
+
+    $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\ntwo=dva\n"
+    }
+
+    $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\nbaseString=base\nbaseInt=1\n"
+    }
+
+    $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"
+    }
+
   }
+
 }
 
 

Tests/StencilTests/IfNodeSpec.swift

@@ -7,101 +7,281 @@ func testIfNode() {
     $0.describe("parsing") {
       $0.it("can parse an if block") {
         let tokens: [Token] = [
-          .block(value: "if value"),
-          .text(value: "true"),
-          .block(value: "else"),
-          .text(value: "false"),
-          .block(value: "endif")
+          .block(value: "if value", at: .unknown),
+          .text(value: "true", at: .unknown),
+          .block(value: "endif", at: .unknown)
         ]
 
-        let parser = TokenParser(tokens: tokens, namespace: Namespace())
+        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
+        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"
-        try expect(node?.falseNodes.count) == 1
+      }
+
+      $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 complex expression") {
+      $0.it("can parse an if with elif block") {
         let tokens: [Token] = [
-          .block(value: "if value == \"test\" and not name"),
-          .text(value: "true"),
-          .block(value: "else"),
-          .text(value: "false"),
-          .block(value: "endif")
+          .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, namespace: Namespace())
+        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
+        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(node?.falseNodes.count) == 1
+
+        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"),
-          .text(value: "false"),
-          .block(value: "else"),
-          .text(value: "true"),
-          .block(value: "endif")
+          .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, namespace: Namespace())
+        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
+        let conditions = node?.conditions
+        try expect(conditions?.count) == 2
 
-        try expect(nodes.count) == 1
-        try expect(node?.trueNodes.count) == 1
+        try expect(conditions?[0].nodes.count) == 1
+        let trueNode = conditions?[0].nodes.first as? TextNode
         try expect(trueNode?.text) == "true"
-        try expect(node?.falseNodes.count) == 1
+
+        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"),
-        ]
+        let tokens: [Token] = [.block(value: "if value", at: .unknown)]
 
-        let parser = TokenParser(tokens: tokens, namespace: Namespace())
-        let error = TemplateSyntaxError("`endif` was not found.")
+        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"),
-        ]
+        let tokens: [Token] = [.block(value: "ifnot value", at: .unknown)]
 
-        let parser = TokenParser(tokens: tokens, namespace: Namespace())
-        let error = TemplateSyntaxError("`endif` was not found.")
+        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 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 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 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("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|uppercase == \"TEST\"", 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 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

@@ -7,19 +7,20 @@ 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") ]
-        let parser = TokenParser(tokens: tokens, namespace: Namespace())
+        let tokens: [Token] = [ .block(value: "include", at: .unknown) ]
+        let parser = TokenParser(tokens: tokens, environment: Environment())
 
-        let error = TemplateSyntaxError("'include' tag takes one argument, the template file to be included")
+        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)
       }
 
       $0.it("can parse a valid include block") {
-        let tokens: [Token] = [ .block(value: "include \"test.html\"") ]
-        let parser = TokenParser(tokens: tokens, namespace: Namespace())
+        let tokens: [Token] = [ .block(value: "include \"test.html\"", at: .unknown) ]
+        let parser = TokenParser(tokens: tokens, environment: Environment())
 
         let nodes = try parser.parse()
         let node = nodes.first as? IncludeNode
@@ -30,31 +31,38 @@ func testInclude() {
 
     $0.describe("rendering") {
       $0.it("throws an error when rendering without a loader") {
-        let node = IncludeNode(templateName: Variable("\"test.html\""))
+        let node = IncludeNode(templateName: Variable("\"test.html\""), token: .block(value: "", at: .unknown))
 
         do {
           _ = try node.render(Context())
         } catch {
-          try expect("\(error)") == "Template loader not in context"
+          try expect("\(error)") == "Template named `test.html` does not exist. No loaders found"
         }
       }
 
       $0.it("throws an error when it cannot find the included template") {
-        let node = IncludeNode(templateName: Variable("\"unknown.html\""))
+        let node = IncludeNode(templateName: Variable("\"unknown.html\""), token: .block(value: "", at: .unknown))
 
         do {
-          _ = try node.render(Context(dictionary: ["loader": loader]))
+          _ = try node.render(Context(environment: environment))
         } catch {
-          try expect("\(error)".hasPrefix("'unknown.html' template not found")).to.beTrue()
+          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\""))
-        let context = Context(dictionary: ["loader":loader, "target": "World"])
+        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

@@ -7,17 +7,21 @@ 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 context = Context(dictionary: ["loader": loader])
-      let template = try loader.loadTemplate(name: "child.html")
-      try expect(try template?.render(context)) == "Header\nChild"
+      let template = try environment.loadTemplate(name: "child.html")
+      try expect(try template.render()) == "Super_Header Child_Header\nChild_Body"
     }
 
     $0.it("can inherit from another template inheriting from another template") {
-      let context = Context(dictionary: ["loader": loader])
-      let template = try loader.loadTemplate(name: "child-child.html")
-      try expect(try template?.render(context)) == "Child Child Header\nChild"
+      let template = try environment.loadTemplate(name: "child-child.html")
+      try expect(try template.render()) == "Super_Header Child_Header Child_Child_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\nChild_Body"
     }
   }
 }

Tests/StencilTests/LexerSpec.swift

@@ -9,15 +9,15 @@ func testLexer() {
       let tokens = lexer.tokenize()
 
       try expect(tokens.count) == 1
-      try expect(tokens.first) == .text(value: "Hello World")
+      try expect(tokens.first) == .text(value: "Hello World", at: SourceMap(line: ("Hello World", 1, 0)))
     }
 
     $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")
+      try expect(tokens.count) == 1
+      try expect(tokens.first) == .comment(value: "Comment", at: SourceMap(line: ("{# Comment #}", 1, 3)))
     }
 
     $0.it("can tokenize a variable") {
@@ -25,26 +25,70 @@ func testLexer() {
       let tokens = lexer.tokenize()
 
       try expect(tokens.count) == 1
-      try expect(tokens.first) == .variable(value: "Variable")
+      try expect(tokens.first) == .variable(value: "Variable", at: SourceMap(line: ("{{ Variable }}", 1, 3)))
+    }
+
+    $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: SourceMap(line: ("{{ thing", 1, 0)))
     }
 
     $0.it("can tokenize a mixture of content") {
-      let lexer = Lexer(templateString: "My name is {{ name }}.")
+      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 ")
-      try expect(tokens[1]) == Token.variable(value: "name")
-      try expect(tokens[2]) == Token.text(value: ".")
+      try expect(tokens[0]) == Token.text(value: "My name is ", at: SourceMap(line: templateString.rangeLine(templateString.range(of: "My name is ")!)))
+      try expect(tokens[1]) == Token.variable(value: "myname", at: SourceMap(line: templateString.rangeLine(templateString.range(of: "myname")!)))
+      try expect(tokens[2]) == Token.text(value: ".", at: SourceMap(line: templateString.rangeLine(templateString.range(of: ".")!)))
     }
 
     $0.it("can tokenize two variables without being greedy") {
-      let lexer = Lexer(templateString: "{{ thing }}{{ name }}")
+      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")
-      try expect(tokens[1]) == Token.variable(value: "name")
+      try expect(tokens[0]) == Token.variable(value: "thing", at: SourceMap(line: templateString.rangeLine(templateString.range(of: "thing")!)))
+      try expect(tokens[1]) == Token.variable(value: "name", at: SourceMap(line: templateString.rangeLine(templateString.range(of: "name")!)))
+    }
+
+    $0.it("can tokenize an unclosed block") {
+      let lexer = Lexer(templateString: "{%}")
+      let _ = lexer.tokenize()
+    }
+
+    $0.it("can tokenize an empty variable") {
+      let lexer = Lexer(templateString: "{{}}")
+      let _ = lexer.tokenize()
+    }
+
+    $0.it("can tokenize with new lines") {
+      let templateString =
+        "My name is {%\n" +
+          "    if name\n" +
+          "     and\n" +
+          "    name\n" +
+          "%}{{\n" +
+          "name\n" +
+          "}}{%\n" +
+      "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: SourceMap(line: templateString.rangeLine(templateString.range(of: "My name is")!)))
+      try expect(tokens[1]) == Token.block(value: "if name and name", at: SourceMap(line: templateString.rangeLine(templateString.range(of: "{%")!)))
+      try expect(tokens[2]) == Token.variable(value: "name", at: SourceMap(line: templateString.rangeLine(templateString.range(of: "name", options: [.backwards])!)))
+      try expect(tokens[3]) == Token.block(value: "endif", at: SourceMap(line: templateString.rangeLine(templateString.range(of: "endif")!)))
+      try expect(tokens[4]) == Token.text(value: ".", at: SourceMap(line: templateString.rangeLine(templateString.range(of: ".")!)))
     }
   }
 }

Tests/StencilTests/LoaderSpec.swift

@@ -0,0 +1,55 @@
+import Spectre
+import Stencil
+import PathKit
+
+
+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 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()
+    }
+  }
+
+  describe("DictionaryLoader") {
+    let loader = DictionaryLoader(templates: [
+        "index.html": "Hello World"
+    ])
+    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 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 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

@@ -1,8 +1,13 @@
 import Spectre
-import Stencil
+@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")
   }

Tests/StencilTests/NowNodeSpec.swift

@@ -8,8 +8,8 @@ func testNowNode() {
   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, namespace: Namespace())
+        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
@@ -18,8 +18,8 @@ func testNowNode() {
       }
 
       $0.it("parses now with a format") {
-        let tokens: [Token] = [ .block(value: "now \"HH:mm\"") ]
-        let parser = TokenParser(tokens: tokens, namespace: Namespace())
+        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

Tests/StencilTests/ParserSpec.swift

@@ -1,13 +1,13 @@
 import Spectre
-import Stencil
+@testable import Stencil
 
 
 func testTokenParser() {
   describe("TokenParser") {
     $0.it("can parse a text token") {
       let parser = TokenParser(tokens: [
-        .text(value: "Hello World")
-      ], namespace: Namespace())
+        .text(value: "Hello World", at: .unknown)
+      ], environment: Environment())
 
       let nodes = try parser.parse()
       let node = nodes.first as? TextNode
@@ -18,8 +18,8 @@ func testTokenParser() {
 
     $0.it("can parse a variable token") {
       let parser = TokenParser(tokens: [
-        .variable(value: "'name'")
-      ], namespace: Namespace())
+        .variable(value: "'name'", at: .unknown)
+      ], environment: Environment())
 
       let nodes = try parser.parse()
       let node = nodes.first as? VariableNode
@@ -30,33 +30,32 @@ func testTokenParser() {
 
     $0.it("can parse a comment token") {
       let parser = TokenParser(tokens: [
-        .comment(value: "Secret stuff!")
-      ], namespace: Namespace())
+        .comment(value: "Secret stuff!", at: .unknown)
+      ], environment: Environment())
 
       let nodes = try parser.parse()
       try expect(nodes.count) == 0
     }
 
     $0.it("can parse a tag token") {
-      let namespace = Namespace()
-      namespace.registerSimpleTag("known") { _ in
+      let simpleExtension = Extension()
+      simpleExtension.registerSimpleTag("known") { _ in
         return ""
       }
 
       let parser = TokenParser(tokens: [
-        .block(value: "known"),
-      ], namespace: namespace)
+        .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 parser = TokenParser(tokens: [
-        .block(value: "unknown"),
-      ], namespace: Namespace())
+      let tokens: [Token] = [.block(value: "unknown", at: .unknown)]
+      let parser = TokenParser(tokens: tokens, environment: Environment())
 
-      try expect(try parser.parse()).toThrow(TemplateSyntaxError("Unknown template tag 'unknown'"))
+      try expect(try parser.parse()).toThrow(TemplateSyntaxError(reason: "Unknown template tag 'unknown'", token: tokens.first))
     }
   }
 }

Tests/StencilTests/StencilSpec.swift

@@ -2,7 +2,8 @@ import Spectre
 import Stencil
 
 
-fileprivate class CustomNode : NodeType {
+fileprivate struct CustomNode : NodeType {
+  let token: Token?
   func render(_ context:Context) throws -> String {
     return "Hello World"
   }
@@ -17,6 +18,18 @@ fileprivate struct Article {
 
 func testStencil() {
   describe("Stencil") {
+    let exampleExtension = Extension()
+
+    exampleExtension.registerSimpleTag("simpletag") { context in
+      return "Hello World"
+    }
+
+    exampleExtension.registerTag("customtag") { parser, token in
+      return CustomNode(token: token)
+    }
+
+    let environment = Environment(extensions: [exampleExtension])
+
     $0.it("can render the README example") {
 
       let templateString = "There are {{ articles.count }} articles.\n" +
@@ -25,12 +38,12 @@ func testStencil() {
         "    - {{ article.title }} by {{ article.author }}.\n" +
         "{% endfor %}\n"
 
-      let context = Context(dictionary: [
+      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)
@@ -45,28 +58,13 @@ func testStencil() {
     }
 
     $0.it("can render a custom template tag") {
-      let templateString = "{% custom %}"
-      let template = Template(templateString: templateString)
-
-      let namespace = Namespace()
-      namespace.registerTag("custom") { parser, token in
-        return CustomNode()
-      }
-
-      let result = try template.render(Context(namespace: namespace))
+      let result = try environment.renderTemplate(string: "{% customtag %}")
       try expect(result) == "Hello World"
     }
 
     $0.it("can render a simple custom tag") {
-      let templateString = "{% custom %}"
-      let template = Template(templateString: templateString)
-
-      let namespace = Namespace()
-      namespace.registerSimpleTag("custom") { context in
-        return "Hello World"
-      }
-
-      try expect(try template.render(Context(namespace: namespace))) == "Hello World"
+      let result = try environment.renderTemplate(string: "{% simpletag %}")
+      try expect(result) == "Hello World"
     }
   }
 }

Tests/StencilTests/TemplateLoaderSpec.swift

@@ -1,25 +0,0 @@
-import Spectre
-import Stencil
-import PathKit
-
-
-func testTemplateLoader() {
-  describe("TemplateLoader") {
-    let path = Path(#file) + ".."  + "fixtures"
-    let loader = FileSystemLoader(paths: [path])
-
-    $0.it("returns nil when a template cannot be found") {
-      try expect(try loader.loadTemplate(name: "unknown.html")).to.beNil()
-    }
-
-    $0.it("returns nil when an array of templates cannot be found") {
-      try expect(try loader.loadTemplate(names: ["unknown.html", "unknown2.html"])).to.beNil()
-    }
-
-    $0.it("can load a template from a file") {
-      if try loader.loadTemplate(name: "test.html") == nil {
-        throw failure("didn't find the template")
-      }
-    }
-  }
-}

Tests/StencilTests/TemplateSpec.swift

@@ -1,21 +1,20 @@
 import Spectre
-import Stencil
+@testable import Stencil
 
 
 func testTemplate() {
   describe("Template") {
     $0.it("can render a template from a string") {
-      let context = Context(dictionary: [ "name": "Kyle" ])
       let template = Template(templateString: "Hello World")
-      let result = try template.render(context)
+      let result = try template.render([ "name": "Kyle" ])
       try expect(result) == "Hello World"
     }
 
     $0.it("can render a template from a string literal") {
-        let context = Context(dictionary: [ "name": "Kyle" ])
         let template: Template = "Hello World"
-        let result = try template.render(context)
+        let result = try template.render([ "name": "Kyle" ])
         try expect(result) == "Hello World"
     }
+    
   }
 }

Tests/StencilTests/TokenSpec.swift

@@ -1,11 +1,11 @@
 import Spectre
-import Stencil
+@testable import Stencil
 
 
 func testToken() {
   describe("Token") {
     $0.it("can split the contents into components") {
-      let token = Token.text(value: "hello world")
+      let token = Token.text(value: "hello world", at: .unknown)
       let components = token.components()
 
       try expect(components.count) == 2
@@ -14,7 +14,7 @@ func testToken() {
     }
 
     $0.it("can split the contents into components with single quoted strings") {
-      let token = Token.text(value: "hello 'kyle fuller'")
+      let token = Token.text(value: "hello 'kyle fuller'", at: .unknown)
       let components = token.components()
 
       try expect(components.count) == 2
@@ -23,7 +23,7 @@ func testToken() {
     }
 
     $0.it("can split the contents into components with double quoted strings") {
-      let token = Token.text(value: "hello \"kyle fuller\"")
+      let token = Token.text(value: "hello \"kyle fuller\"", at: .unknown)
       let components = token.components()
 
       try expect(components.count) == 2

Tests/StencilTests/VariableSpec.swift

@@ -1,11 +1,14 @@
 import Foundation
 import Spectre
-import Stencil
+@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
 
@@ -17,6 +20,14 @@ fileprivate struct Article {
   let author: Person
 }
 
+fileprivate class WebSite {
+  let url: String = "blog.com"
+}
+
+fileprivate class Blog: WebSite {
+  let articles: [Article] = [Article(author: Person(name: "Kyle"))]
+  let featuring: Article? = Article(author: Person(name: "Jhon"))
+}
 
 func testVariable() {
   describe("Variable") {
@@ -26,12 +37,17 @@ func testVariable() {
       "profiles": [
         "github": "kylef",
       ],
-      "article": Article(author: Person(name: "Kyle"))
+      "counter": [
+        "count": "kylef",
+        ],
+      "article": Article(author: Person(name: "Kyle")),
+      "tuple": (one: 1, two: 2)
     ])
 
 #if os(OSX)
     context["object"] = Object()
 #endif
+    context["blog"] = Blog()
 
     $0.it("can resolve a string literal with double quotes") {
       let variable = Variable("\"name\"")
@@ -45,6 +61,25 @@ func testVariable() {
       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
@@ -95,12 +130,205 @@ func testVariable() {
       try expect(result) == "Kyle"
     }
 
+    $0.it("can get the count of a dictionary") {
+      let variable = Variable("profiles.count")
+      let result = try variable.resolve(context) as? Int
+      try expect(result) == 1
+    }
+
 #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"
+    }
 #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("Subrscripting") {
+      $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()  
+          }
+        }
+      }
+    }
+  }
+
+  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()
+    }
+
   }
 }

Tests/StencilTests/XCTest.swift

@@ -17,6 +17,8 @@ public func stencilTests() {
   testNowNode()
   testInclude()
   testInheritence()
+  testFilterTag()
+  testEnvironment()
   testStencil()
 }
 

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

@@ -0,0 +1,3 @@
+{% extends "base.html" %}
+{% 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/api.rst

@@ -0,0 +1,150 @@
+Template API
+============
+
+This document describes Stencils Swift API, and not the Swift template language.
+
+.. contents:: :depth: 2
+
+Environment
+-----------
+
+An environment contains shared configuration such as custom filters and tags
+along with template loaders.
+
+.. code-block:: swift
+
+    let environment = Environment()
+
+You can optionally provide a loader or extensions when creating an environment:
+
+.. code-block:: swift
+
+    let environment = Environment(loader: ..., extensions: [...])
+
+Rendering a Template
+~~~~~~~~~~~~~~~~~~~~
+
+Environment provides convinience methods to render a template either from a
+string or a template loader.
+
+.. code-block:: swift
+
+    let template = "Hello {{ name }}"
+    let context = ["name": "Kyle"]
+    let rendered = environment.renderTemplate(string: template, context: context)
+
+Rendering a template from the configured loader:
+
+.. code-block:: swift
+
+    let context = ["name": "Kyle"]
+    let rendered = environment.renderTemplate(name: "example.html", context: context)
+
+Loading a Template
+~~~~~~~~~~~~~~~~~~
+
+Environment provides an API to load a template from the configured loader.
+
+.. code-block:: swift
+
+    let template = try environment.loadTemplate(name: "example.html")
+
+Loader
+------
+
+Loaders are responsible for loading templates from a resource such as the file
+system.
+
+Stencil provides a ``FileSytemLoader`` which allows you to load a template
+directly from the file system.
+
+FileSystemLoader
+~~~~~~~~~~~~~~~~
+
+Loads templates from the file system. This loader can find templates in folders
+on the file system.
+
+.. code-block:: swift
+
+    FileSystemLoader(paths: ["./templates"])
+
+.. code-block:: swift
+
+    FileSystemLoader(bundle: [Bundle.main])
+
+
+DictionaryLoader
+~~~~~~~~~~~~~~~~
+
+Loads templates from a dictionary.
+
+.. code-block:: swift
+
+    DictionaryLoader(templates: ["index.html": "Hello World"])
+
+
+Custom Loaders
+~~~~~~~~~~~~~~
+
+``Loader`` is a protocol, so you can implement your own compatible loaders. You
+will need to implement a ``loadTemplate`` method to load the template,
+throwing a ``TemplateDoesNotExist`` when the template is not found.
+
+.. code-block:: swift
+
+    class ExampleMemoryLoader: Loader {
+      func loadTemplate(name: String, environment: Environment) throws -> Template {
+        if name == "index.html" {
+          return Template(templateString: "Hello", environment: environment)
+        }
+
+        throw TemplateDoesNotExist(name: name, loader: self)
+      }
+    }
+
+
+Context
+-------
+
+A ``Context`` is a structure containing any templates you would like to use in
+a template. It’s somewhat like a dictionary, however you can push and pop to
+scope variables. So that means that when iterating over a for loop, you can
+push a new scope into the context to store any variables local to the scope.
+
+You would normally only access the ``Context`` within a custom template tag or
+filter.
+
+Subscripting
+~~~~~~~~~~~~
+
+You can use subscripting to get and set values from the context.
+
+.. code-block:: swift
+
+    context["key"] = value
+    let value = context["key"]
+
+``push()``
+~~~~~~~~~~
+
+A ``Context`` is a stack. You can push a new level onto the ``Context`` so that
+modifications can easily be poped off. This is useful for isolating mutations
+into scope of a template tag. Such as ``{% if %}`` and ``{% for %}`` tags.
+
+.. code-block:: swift
+
+    context.push(["name": "example"]) {
+        // context contains name which is `example`.
+    }
+
+    // name is popped off the context after the duration of the closure.
+
+``flatten()``
+~~~~~~~~~~~~~
+
+Using ``flatten()`` method you can get whole ``Context`` stack as one
+dictionary including all variables.
+
+.. code-block:: swift
+
+    let dictionary = context.flatten()

docs/api/context.rst

@@ -1,51 +0,0 @@
-Context
-=======
-
-A Context is a structure containing any templates you would like to use in a
-template. It’s somewhat like a dictionary, however you can push and pop to
-scope variables. So that means that when iterating over a for loop, you can
-push a new scope into the context to store any variables local to the scope.
-
-You can initialise a ``Context`` with a ``Dictionary``.
-
-.. code-block:: swift
-
-    Context(dictionary: [String: Any]? = nil)
-
-API
-----
-
-Subscripting
-~~~~~~~~~~~~
-
-You can use subscripting to get and set values from the context.
-
-.. code-block:: swift
-
-    context["key"] = value
-    let value = context["key"]
-
-``push()``
-~~~~~~~~~~
-
-A ``Context`` is a stack. You can push a new level onto the ``Context`` so that
-modifications can easily be poped off. This is useful for isolating mutations
-into scope of a template tag. Such as ``{% if %}`` and ``{% for %}`` tags.
-
-.. code-block:: swift
-
-    context.push(["name": "example"]) {
-        // context contains name which is `example`.
-    }
-
-    // name is popped off the context after the duration of the closure.
-
-``flatten()``
-~~~~~~~~~~~~~
-
-Using ``flatten()`` method you can get whole ``Context`` stack as one
-dictionary including all variables.
-
-.. code-block:: swift
-
-    let dictionary = context.flatten()

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
 
@@ -177,6 +231,26 @@ Will be treated as:
 ``now``
 ~~~~~~~
 
+``filter``
+~~~~~~~~~~
+
+Filters the contents of the block.
+
+.. code-block:: html+django
+
+    {% filter lowercase %}
+      This Text Will Be Lowercased.
+    {% endfilter %}
+
+You can chain multiple filters with a pipe (`|`).
+
+.. code-block:: html+django
+
+    {% filter lowercase|capitalize %}
+      This Text Will First Be Lowercased, Then The First Character Will BE
+      Capitalised.
+    {% endfilter %}
+
 ``include``
 ~~~~~~~~~~~
 
@@ -186,20 +260,37 @@ You can include another template using the `include` tag.
 
     {% include "comment.html" %}
 
-The `include` tag requires a FileSystemLoader to be found inside your context with the paths, or bundles used to lookup the template.
+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.
 
 .. code-block:: swift
 
-    let context = Context(dictionary: [
-      "loader": FileSystemLoader(bundle: [NSBundle.mainBundle()])
-    ])
+    let environment = Environment(bundle: [Bundle.main])
+    let template = environment.loadTemplate(name: "index.html")
 
 ``extends``
 ~~~~~~~~~~~
 
+Extends the template from a parent template.
+
+.. code-block:: html+django
+
+    {% extends "base.html" %}
+
+See :ref:`template-inheritance` for more information.
+
 ``block``
 ~~~~~~~~~
 
+Defines a block that can be overridden by child templates. See
+:ref:`template-inheritance` for more information.
+
 .. _built-in-filters:
 
 Built-in Filters
@@ -209,7 +300,7 @@ 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
 
@@ -219,7 +310,7 @@ 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
 
@@ -229,7 +320,7 @@ 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
 
@@ -248,10 +339,37 @@ value of the variable. For example:
 ``join``
 ~~~~~~~~
 
-Join an array with a string.
+Join an array of items.
 
 .. code-block:: html+django
 
     {{ value|join:", " }}
 
-.. note:: The value MUST be an array of Strngs and the separator must be a string.
+.. 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 = '0.12.1'
 # The full version, including alpha/beta/rc tags.
-release = '0.7.0'
+release = '0.12.1'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.

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

@@ -3,13 +3,15 @@ Custom Template Tags and Filters
 
 You can build your own custom filters and tags and pass them down while
 rendering your template. Any custom filters or tags must be registered with a
-namespace which contains all filters and tags available to the template.
+extension which contains all filters and tags available to the template.
 
 .. code-block:: swift
 
-    let namespace = Namespace()
-    // Register your filters and tags with the namespace
-    let rendered = try template.render(context, namespace: namespace)
+    let ext = Extension()
+    // Register your filters and tags with the extension
+
+    let environment = Environment(extensions: [ext])
+    try environment.renderTemplate(name: "example.html")
 
 Custom Filters
 --------------
@@ -18,7 +20,7 @@ Registering custom filters:
 
 .. code-block:: swift
 
-    namespace.registerFilter("double") { (value: Any?) in
+    ext.registerFilter("double") { (value: Any?) in
       if let value = value as? Int {
         return value * 2
       }
@@ -30,7 +32,7 @@ Registering custom filters with arguments:
 
 .. code-block:: swift
 
-    namespace.registerFilter("multiply") { (value: Any?, arguments: [Any?]) in
+    ext.registerFilter("multiply") { (value: Any?, arguments: [Any?]) in
       let amount: Int
 
       if let value = arguments.first as? Int {
@@ -40,7 +42,7 @@ Registering custom filters with arguments:
       }
 
       if let value = value as? Int {
-        return value * 2
+        return value * amount
       }
 
       return value
@@ -54,7 +56,7 @@ write your own custom tags. The following is the simplest form:
 
 .. code-block:: swift
 
-    namespace.registerSimpleTag("custom") { context in
+    ext.registerSimpleTag("custom") { context in
       return "Hello World"
     }
 

docs/getting-started.rst

@@ -0,0 +1,37 @@
+Getting Started
+===============
+
+The easiest way to render a template using Stencil is to create a template and
+call render on it providing a context.
+
+.. code-block:: swift
+
+    let template = Template(templateString: "Hello {{ name }}")
+    try template.render(["name": "kyle"])
+
+For more advanced uses, you would normally create an ``Environment`` and call
+the ``renderTemplate`` convinience method.
+
+.. code-block:: swift
+
+    let environment = Environment()
+
+    let context = ["name": "kyle"]
+    try environment.renderTemplate(string: "Hello {{ name }}", context: context)
+
+Template Loaders
+----------------
+
+A template loader allows you to load files from disk or elsewhere. Using a
+``FileSystemLoader`` we can easily render a template from disk.
+
+For example, to render a template called ``index.html`` inside the
+``templates/`` directory we can use the following:
+
+.. code-block:: swift
+
+    let fsLoader = FileSystemLoader(paths: ["templates/"])
+    let environment = Environment(loader: fsLoader)
+
+    let context = ["name": "kyle"]
+    try environment.renderTemplate(name: "index.html", context: context)

docs/index.rst

@@ -17,32 +17,48 @@ feel right at home with Stencil.
 
 .. code-block:: swift
 
-   struct Article {
-     let title: String
-     let author: String
-   }
+    import Stencil
 
-    let context = Context(dictionary: [
+    struct Article {
+      let title: String
+      let author: String
+    }
+
+    let context = [
       "articles": [
         Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
         Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
       ]
-    ])
+    ]
 
-    do {
-      let template = try Template(named: "template.html")
-      let rendered = try template.render(context)
-      print(rendered)
-    } catch {
-      print("Failed to render template \(error)")
-    }
+    let environment = Environment(loader: FileSystemLoader(paths: ["templates/"])
+    let rendered = try environment.renderTemplate(name: context)
 
-Contents:
+    print(rendered)
+
+The User Guide
+--------------
+
+For Template Writers
+~~~~~~~~~~~~~~~~~~~~
+
+Resources for Stencil template authors to write Stencil templates.
 
 .. toctree::
    :maxdepth: 2
 
    templates
    builtins
-   api/context
+
+For Developers
+~~~~~~~~~~~~~~
+
+Resources to help you integrate Stencil into a Swift project.
+
+.. toctree::
+   :maxdepth: 1
+
+   installation
+   getting-started
+   api
    custom-template-tags-and-filters

docs/installation.rst

@@ -0,0 +1,52 @@
+Installation
+============
+
+Swift Package Manager
+---------------------
+
+If you're using the Swift Package Manager, you can add ``Stencil`` to your
+dependencies inside ``Package.swift``.
+
+.. code-block:: swift
+
+    import PackageDescription
+
+    let package = Package(
+      name: "MyApplication",
+      dependencies: [
+        .Package(url: "https://github.com/kylef/Stencil.git", majorVersion: 0, minor: 8),
+      ]
+    )
+
+CocoaPods
+---------
+
+If you're using CocoaPods, you can add Stencil to your ``Podfile`` and then run
+``pod install``.
+
+.. code-block:: ruby
+
+    pod 'Stencil', '~> 0.8.0'
+
+Carthage
+--------
+
+.. note:: Use at your own risk. We don't offer support for Carthage and instead recommend you use Swift Package Manager.
+
+1) Add ``Stencil`` to your ``Cartfile``:
+
+    .. code-block:: text
+
+        github "kylef/Stencil" ~> 0.8.0
+
+2) Checkout your dependencies, generate the Stencil Xcode project, and then use Carthage to build Stencil:
+
+    .. code-block:: shell
+
+        $ carthage update
+        $ (cd Carthage/Checkouts/Stencil && swift package generate-xcodeproj)
+        $ carthage build
+
+3) Follow the Carthage steps to add the built frameworks to your project.
+
+To learn more about this approach see `Using Swift Package Manager with Carthage <https://fuller.li/posts/using-swift-package-manager-with-carthage/>`_.

docs/templates.rst

@@ -1,5 +1,5 @@
-Templates
-=========
+Language overview
+==================
 
 - ``{{ ... }}`` for variables to print to the template output
 - ``{% ... %}`` for tags
@@ -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
 ~~~~~~~
 
@@ -75,3 +93,93 @@ To comment out part of your template, you can use the following syntax:
 .. code-block:: html+django
 
     {# My comment is completely hidden #}
+
+.. _template-inheritance:
+
+Template inheritance
+--------------------
+
+Template inheritance allows the common components surrounding individual pages
+to be shared across other templates. You can define blocks which can be
+overidden in any child template.
+
+Let's take a look at an example. Here is our base template (``base.html``):
+
+.. code-block:: html+django
+
+    <html>
+      <head>
+        <title>{% block title %}Example{% endblock %}</title>
+      </head>
+
+      <body>
+        <aside>
+          {% block sidebar %}
+            <ul>
+              <li><a href="/">Home</a></li>
+              <li><a href="/notes/">Notes</a></li>
+            </ul>
+          {% endblock %}
+        </aside>
+
+        <section>
+          {% block content %}{% endblock %}
+        </section>
+      </body>
+    </html>
+
+This example declares three blocks, ``title``, ``sidebar`` and ``content``. We
+can use the ``{% extends %}`` template tag to inherit from out base template
+and then use ``{% block %}`` to override any blocks from our base template.
+
+A child template might look like the following:
+
+.. code-block:: html+django
+
+    {% extends "base.html" %}
+
+    {% block title %}Notes{% endblock %}
+
+    {% block content %}
+      {% for note in notes %}
+        <h2>{{ note }}</h2>
+      {% endfor %}
+    {% endblock %}
+
+.. note:: You can use ``{{ block.super }}` inside a block to render the contents of the parent block inline.
+
+Since our child template doesn't declare a sidebar block. The original sidebar
+from our base template will be used. Depending on the content of ``notes`` our
+template might be rendered like the following:
+
+.. code-block:: html
+
+    <html>
+      <head>
+        <title>Notes</title>
+      </head>
+
+      <body>
+        <aside>
+          <ul>
+            <li><a href="/">Home</a></li>
+            <li><a href="/notes/">Notes</a></li>
+          </ul>
+        </aside>
+
+        <section>
+          <h2>Pick up food</h2>
+          <h2>Do laundry</h2>
+        </section>
+      </body>
+    </html>
+
+You can use as many levels of inheritance as needed. One common way of using
+inheritance is the following three-level approach:
+
+* Create a ``base.html`` template that holds the main look-and-feel of your site.
+* Create a ``base_SECTIONNAME.html`` template for each “section” of your site.
+  For example, ``base_news.html``, ``base_news.html``. These templates all
+  extend ``base.html`` and include section-specific styles/design.
+* Create individual templates for each type of page, such as a news article or
+  blog entry. These templates extend the appropriate section template.