Remove custom Result type and throw errors

ARCHITECTURE.md

@@ -106,7 +106,7 @@ Here’s an example. Registering a template tag called `custom` which just rende
 
 ```swift
 parser.registerSimpleTag("custom") { context in
-  return .Success("Hello World")
+  return "Hello World"
 }
 ```
 
@@ -144,7 +144,7 @@ class DebugNode : Node {
     self.nodes = nodes
   }
 
-  func render(context: Context) -> Result {
+  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?
@@ -155,7 +155,7 @@ class DebugNode : Node {
     }
 
     // Debug is turned off, so let's not render anything
-    return .Success("")
+    return ""
   }
 }
 ```
@@ -163,15 +163,10 @@ class DebugNode : Node {
 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
-parser.registerTag("debug") { (parser, token) -> TokenParser.Result in
+parser.registerTag("debug") { parser, token in
   // Use the parser to parse every token up until the `enddebug` block.
-  switch parser.parse(until(["enddebug"]))
+  let nodes = try until(["enddebug"]))
-    case .Success(let nodes):
+  return DebugNode(nodes)
-      nodes
-    case .Error(let error):
-      // There was an error, this is most-likely due to another template block returning an error.
-      return .Error(error)
-    }
 }
 ```
 

README.md

@@ -25,14 +25,12 @@ let context = Context(dictionary: [
   ]
 ])
 
-let template = try? Template(named: "template.stencil")
+do {
-let result = template!.render(context)
+  let template = Template(named: "template.stencil")
-
+  let rendered = template.render(context)
-switch result {
+  print(rendered)
-    case .Error(let error):
+} catch {
-        println("There was an error rendering your template (\(error)).")
+  print("Failed to render template \(error)")
-    case .Success(let string):
-        println("\(string)")
 }
 ```
 
@@ -157,13 +155,13 @@ you to write your own custom tags. The following is the simplest form:
 
 ```swift
 template.parser.registerSimpleTag("custom") { context in
-  return .Success("Hello World")
+  return "Hello World"
 }
 ```
 
 When your tag is used via `{% custom %}` it will execute the registered block
 of code allowing you to modify or retrieve a value from the context. Then
-return either a string rendered in your template, or an error.
+return either a string rendered in your template, or throw an error.
 
 If you want to accept arguments or to capture different tokens between two sets
 of template tags. You will need to call the `registerTag` API which accepts a

Stencil.xcodeproj/project.pbxproj

@@ -16,7 +16,6 @@
 		27CE0AFA1A50C963004A105B /* test.html in Resources */ = {isa = PBXBuildFile; fileRef = 27CE0AF91A50C963004A105B /* test.html */; };
 		27CE0B011A50CBD1004A105B /* Include.swift in Sources */ = {isa = PBXBuildFile; fileRef = 27CE0B001A50CBD1004A105B /* Include.swift */; };
 		27CE0B041A50CBEA004A105B /* IncludeTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 27CE0B031A50CBEA004A105B /* IncludeTests.swift */; };
-		71CE4C0A19FD29D000B9E0C5 /* Result.swift in Sources */ = {isa = PBXBuildFile; fileRef = 71CE4C0919FD29D000B9E0C5 /* Result.swift */; };
 		7725B3CB19F92B4F002CF74B /* VariableTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7725B3CA19F92B4F002CF74B /* VariableTests.swift */; };
 		7725B3CD19F92B61002CF74B /* Variable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7725B3CC19F92B61002CF74B /* Variable.swift */; };
 		7725B3CF19F94214002CF74B /* Tokenizer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7725B3CE19F94214002CF74B /* Tokenizer.swift */; };
@@ -59,7 +58,6 @@
 		27CE0AF91A50C963004A105B /* test.html */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.html; path = test.html; sourceTree = "<group>"; };
 		27CE0B001A50CBD1004A105B /* Include.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Include.swift; sourceTree = "<group>"; };
 		27CE0B031A50CBEA004A105B /* IncludeTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = IncludeTests.swift; sourceTree = "<group>"; };
-		71CE4C0919FD29D000B9E0C5 /* Result.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Result.swift; sourceTree = "<group>"; };
 		7725B3CA19F92B4F002CF74B /* VariableTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = VariableTests.swift; sourceTree = "<group>"; };
 		7725B3CC19F92B61002CF74B /* Variable.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Variable.swift; sourceTree = "<group>"; };
 		7725B3CE19F94214002CF74B /* Tokenizer.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Tokenizer.swift; sourceTree = "<group>"; };
@@ -154,7 +152,6 @@
 				77EB082A19FA8600001870F1 /* Lexer.swift */,
 				7725B3D419F9438F002CF74B /* Node.swift */,
 				7725B3D619F94A43002CF74B /* Parser.swift */,
-				71CE4C0919FD29D000B9E0C5 /* Result.swift */,
 				77EB082419F96E88001870F1 /* Template.swift */,
 				27CE0ADD1A50BEC3004A105B /* TemplateLoader.swift */,
 				7725B3CE19F94214002CF74B /* Tokenizer.swift */,
@@ -422,7 +419,6 @@
 				7725B3D719F94A43002CF74B /* Parser.swift in Sources */,
 				77EB082519F96E88001870F1 /* Template.swift in Sources */,
 				7725B3CD19F92B61002CF74B /* Variable.swift in Sources */,
-				71CE4C0A19FD29D000B9E0C5 /* Result.swift in Sources */,
 				7725B3D519F9438F002CF74B /* Node.swift in Sources */,
 				27CE0ADE1A50BEC3004A105B /* TemplateLoader.swift in Sources */,
 				27A848E41B42240E004ACA13 /* Inheritence.swift in Sources */,

Stencil/Node.swift

@@ -1,83 +1,52 @@
 import Foundation
 
-struct NodeError : Error {
+public struct TemplateSyntaxError : ErrorType, Equatable, CustomStringConvertible {
-  let token:Token
+  public let description:String
-  let message:String
 
-  init(token:Token, message:String) {
+  public init(_ description:String) {
-    self.token = token
+    self.description = description
-    self.message = message
-  }
-
-  var description:String {
-    return "\(token.components().first!): \(message)"
   }
 }
 
-public protocol Node {
+public func ==(lhs:TemplateSyntaxError, rhs:TemplateSyntaxError) -> Bool {
-  /// Return the node rendered as a string, or returns a failure
+  return lhs.description == rhs.description
-  func render(context:Context) -> Result
 }
 
-extension Array {
+public protocol NodeType {
-  func map<U>(block:((Element) -> (U?, Error?))) -> ([U]?, Error?) {
+  /// Render the node in the given context
-    var results = [U]()
+  func render(context:Context) throws -> String
-
-    for item in self {
-      let (result, error) = block(item)
-
-      if let error = error {
-        return (nil, error)
-      } else if (result != nil) {
-        // let result = result exposing a bug in the Swift compier :(
-        results.append(result!)
-      }
-    }
-
-    return (results, nil)
-  }
 }
 
-public func renderNodes(nodes:[Node], context:Context) -> Result {
+/// Render the collection of nodes in the given context
-  var result = ""
+public func renderNodes(nodes:[NodeType], _ context:Context) throws -> String {
-
+  return try nodes.map { try $0.render(context) }.joinWithSeparator("")
-  for item in nodes {
-    switch item.render(context) {
-    case .Success(let string):
-      result += string
-    case .Error(let error):
-      return .Error(error)
-    }
-  }
-
-  return .Success(result)
 }
 
-public class SimpleNode : Node {
+public class SimpleNode : NodeType {
-  let handler:(Context) -> (Result)
+  let handler:Context throws -> String
 
-  public init(handler:((Context) -> (Result))) {
+  public init(handler:Context throws -> String) {
     self.handler = handler
   }
 
-  public func render(context:Context) -> Result {
+  public func render(context: Context) throws -> String {
-    return handler(context)
+    return try handler(context)
   }
 }
 
-public class TextNode : Node {
+public class TextNode : NodeType {
   public let text:String
 
   public init(text:String) {
     self.text = text
   }
 
-  public func render(context:Context) -> Result {
+  public func render(context:Context) throws -> String {
-    return .Success(self.text)
+    return self.text
   }
 }
 
-public class VariableNode : Node {
+public class VariableNode : NodeType {
   public let variable:Variable
 
   public init(variable:Variable) {
@@ -88,23 +57,23 @@ public class VariableNode : Node {
     self.variable = Variable(variable)
   }
 
-  public func render(context:Context) -> Result {
+  public func render(context:Context) throws -> String {
     let result:AnyObject? = variable.resolve(context)
 
     if let result = result as? String {
-      return .Success(result)
+      return result
     } else if let result = result as? NSObject {
-      return .Success(result.description)
+      return result.description
     }
 
-    return .Success("")
+    return ""
   }
 }
 
-public class NowNode : Node {
+public class NowNode : NodeType {
   public let format:Variable
 
-  public class func parse(parser:TokenParser, token:Token) -> TokenParser.Result {
+  public class func parse(parser:TokenParser, token:Token) -> NodeType {
     var format:Variable?
 
     let components = token.components()
@@ -112,7 +81,7 @@ public class NowNode : Node {
       format = Variable(components[1])
     }
 
-    return .Success(node:NowNode(format:format))
+    return NowNode(format:format)
   }
 
   public init(format:Variable?) {
@@ -123,7 +92,7 @@ public class NowNode : Node {
     }
   }
 
-  public func render(context: Context) -> Result {
+  public func render(context: Context) throws -> String {
     let date = NSDate()
     let format: AnyObject? = self.format.resolve(context)
     var formatter:NSDateFormatter?
@@ -134,156 +103,115 @@ public class NowNode : Node {
       formatter = NSDateFormatter()
       formatter!.dateFormat = format
     } else {
-      return .Success("")
+      return ""
     }
 
-    return .Success(formatter!.stringFromDate(date))
+    return formatter!.stringFromDate(date)
   }
 }
 
-public class ForNode : Node {
+public class ForNode : NodeType {
   let variable:Variable
   let loopVariable:String
-  let nodes:[Node]
+  let nodes:[NodeType]
 
-  public class func parse(parser:TokenParser, token:Token) -> TokenParser.Result {
+  public class func parse(parser:TokenParser, token:Token) throws -> NodeType {
     let components = token.components()
 
     if components.count == 4 && components[2] == "in" {
       let loopVariable = components[1]
       let variable = components[3]
 
-      var forNodes:[Node]!
+      var emptyNodes = [NodeType]()
-      var emptyNodes = [Node]()
 
-      switch parser.parse(until(["endfor", "empty"])) {
+      let forNodes = try parser.parse(until(["endfor", "empty"]))
-      case .Success(let nodes):
-        forNodes = nodes
-      case .Error(let error):
-        return .Error(error: error)
-      }
 
       if let token = parser.nextToken() {
         if token.contents == "empty" {
-          switch parser.parse(until(["endfor"])) {
+          emptyNodes = try parser.parse(until(["endfor"]))
-          case .Success(let nodes):
-            emptyNodes = nodes
-          case .Error(let error):
-            return .Error(error: error)
-          }
-
           parser.nextToken()
         }
       } else {
-        return .Error(error: NodeError(token: token, message: "`endfor` was not found."))
+        throw TemplateSyntaxError("`endfor` was not found.")
       }
 
-      return .Success(node:ForNode(variable: variable, loopVariable: loopVariable, nodes: forNodes, emptyNodes:emptyNodes))
+      return ForNode(variable: variable, loopVariable: loopVariable, nodes: forNodes, emptyNodes:emptyNodes)
     }
 
-    return .Error(error: NodeError(token: token, message: "Invalid syntax. Expected `for x in y`."))
+    throw TemplateSyntaxError("'for' statements should use the following 'for x in y' `\(token.contents)`.")
   }
 
-  public init(variable:String, loopVariable:String, nodes:[Node], emptyNodes:[Node]) {
+  public init(variable:String, loopVariable:String, nodes:[NodeType], emptyNodes:[NodeType]) {
     self.variable = Variable(variable)
     self.loopVariable = loopVariable
     self.nodes = nodes
   }
 
-  public func render(context: Context) -> Result {
+  public func render(context: Context) throws -> String {
-    let values = variable.resolve(context) as? [AnyObject]
+    if let values = variable.resolve(context) as? [AnyObject] {
-    var output = ""
+      return try values.map { item in
-
-    if let values = values {
-      for item in values {
         context.push()
         context[loopVariable] = item
-        let result = renderNodes(nodes, context: context)
+        let result = try renderNodes(nodes, context)
         context.pop()
-
+        return result
-        switch result {
+      }.joinWithSeparator("")
-        case .Success(let string):
-          output += string
-        case .Error(let error):
-          return .Error(error)
-        }
-      }
     }
 
-    return .Success(output)
+    return ""
   }
 }
 
-public class IfNode : Node {
+public class IfNode : NodeType {
   public let variable:Variable
-  public let trueNodes:[Node]
+  public let trueNodes:[NodeType]
-  public let falseNodes:[Node]
+  public let falseNodes:[NodeType]
 
-  public class func parse(parser:TokenParser, token:Token) -> TokenParser.Result {
+  public class func parse(parser:TokenParser, token:Token) throws -> NodeType {
     let variable = token.components()[1]
-    var trueNodes = [Node]()
+    var trueNodes = [NodeType]()
-    var falseNodes = [Node]()
+    var falseNodes = [NodeType]()
 
-    switch parser.parse(until(["endif", "else"])) {
+    trueNodes = try parser.parse(until(["endif", "else"]))
-    case .Success(let nodes):
-      trueNodes = nodes
-    case .Error(let error):
-      return .Error(error: error)
-    }
 
     if let token = parser.nextToken() {
       if token.contents == "else" {
-        switch parser.parse(until(["endif"])) {
+        falseNodes = try parser.parse(until(["endif"]))
-        case .Success(let nodes):
-          falseNodes = nodes
-        case .Error(let error):
-          return .Error(error: error)
-        }
         parser.nextToken()
       }
     } else {
-      return .Error(error:NodeError(token: token, message: "`endif` was not found."))
+      throw TemplateSyntaxError("`endif` was not found.")
     }
 
-    return .Success(node:IfNode(variable: variable, trueNodes: trueNodes, falseNodes: falseNodes))
+    return IfNode(variable: variable, trueNodes: trueNodes, falseNodes: falseNodes)
   }
 
-  public class func parse_ifnot(parser:TokenParser, token:Token) -> TokenParser.Result {
+  public class func parse_ifnot(parser:TokenParser, token:Token) throws -> NodeType {
     let variable = token.components()[1]
-    var trueNodes = [Node]()
+    var trueNodes = [NodeType]()
-    var falseNodes = [Node]()
+    var falseNodes = [NodeType]()
 
-    switch parser.parse(until(["endif", "else"])) {
+    falseNodes = try parser.parse(until(["endif", "else"]))
-    case .Success(let nodes):
-      falseNodes = nodes
-    case .Error(let error):
-      return .Error(error: error)
-    }
 
     if let token = parser.nextToken() {
       if token.contents == "else" {
-        switch parser.parse(until(["endif"])) {
+        trueNodes = try parser.parse(until(["endif"]))
-        case .Success(let nodes):
-          trueNodes = nodes
-        case .Error(let error):
-          return .Error(error: error)
-        }
         parser.nextToken()
       }
     } else {
-      return .Error(error:NodeError(token: token, message: "`endif` was not found."))
+      throw TemplateSyntaxError("`endif` was not found.")
     }
 
-    return .Success(node:IfNode(variable: variable, trueNodes: trueNodes, falseNodes: falseNodes))
+    return IfNode(variable: variable, trueNodes: trueNodes, falseNodes: falseNodes)
   }
 
-  public init(variable:String, trueNodes:[Node], falseNodes:[Node]) {
+  public init(variable:String, trueNodes:[NodeType], falseNodes:[NodeType]) {
     self.variable = Variable(variable)
     self.trueNodes = trueNodes
     self.falseNodes = falseNodes
   }
 
-  public func render(context: Context) -> Result {
+  public func render(context: Context) throws -> String {
     let result: AnyObject? = variable.resolve(context)
     var truthy = false
 
@@ -296,7 +224,12 @@ public class IfNode : Node {
     }
 
     context.push()
-    let output = renderNodes(truthy ? trueNodes : falseNodes, context: context)
+    let output:String
+    if truthy {
+      output = try renderNodes(trueNodes, context)
+    } else {
+      output = try renderNodes(falseNodes, context)
+    }
     context.pop()
 
     return output

Stencil/Parser.swift

@@ -1,5 +1,3 @@
-import Foundation
-
 public func until(tags:[String])(parser:TokenParser, token:Token) -> Bool {
   if let name = token.components().first {
     for tag in tags {
@@ -14,18 +12,7 @@ public func until(tags:[String])(parser:TokenParser, token:Token) -> Bool {
 
 /// A class for parsing an array of tokens and converts them into a collection of Node's
 public class TokenParser {
-  public typealias TagParser = (TokenParser, Token) -> Result
+  public typealias TagParser = (TokenParser, Token) throws -> NodeType
-  public typealias NodeList = [Node]
-
-  public enum Result {
-    case Success(node: Node)
-    case Error(error: Stencil.Error)
-  }
-
-  public enum Results {
-    case Success(nodes: NodeList)
-    case Error(error: Stencil.Error)
-  }
 
   private var tokens:[Token]
   private var tags = [String:TagParser]()
@@ -47,19 +34,19 @@ public class TokenParser {
   }
 
   /// Registers a simple template tag with a name and a handler
-  public func registerSimpleTag(name:String, handler:((Context) -> (Stencil.Result))) {
+  public func registerSimpleTag(name:String, handler:(Context throws -> String)) {
-    registerTag(name, parser: { (parser, token) -> TokenParser.Result in
+    registerTag(name, parser: { parser, token in
-      return .Success(node:SimpleNode(handler: handler))
+      return SimpleNode(handler: handler)
     })
   }
 
   /// Parse the given tokens into nodes
-  public func parse() -> Results {
+  public func parse() throws -> [NodeType] {
-    return parse(nil)
+    return try parse(nil)
   }
 
-  public func parse(parse_until:((parser:TokenParser, token:Token) -> (Bool))?) -> TokenParser.Results {
+  public func parse(parse_until:((parser:TokenParser, token:Token) -> (Bool))?) throws -> [NodeType] {
-    var nodes = NodeList()
+    var nodes = [NodeType]()
 
     while tokens.count > 0 {
       let token = nextToken()!
@@ -75,26 +62,19 @@ public class TokenParser {
         if let parse_until = parse_until {
           if parse_until(parser: self, token: token) {
             prependToken(token)
-            return .Success(nodes:nodes)
+            return nodes
           }
         }
 
-        if let tag = tag {
+        if let tag = tag, let parser = self.tags[tag] {
-          if let parser = self.tags[tag] {
+          nodes.append(try parser(self, token))
-            switch parser(self, token) {
-            case .Success(let node):
-              nodes.append(node)
-            case .Error(let error):
-              return .Error(error:error)
-            }
-          }
         }
       case .Comment:
         continue
       }
     }
 
-    return .Success(nodes:nodes)
+    return nodes
   }
 
   public func nextToken() -> Token? {

Stencil/Result.swift

@@ -1,25 +0,0 @@
-import Foundation
-
-public protocol Error : CustomStringConvertible {
-
-}
-
-public func ==(lhs:Error, rhs:Error) -> Bool {
-  return lhs.description == rhs.description
-}
-
-public enum Result : Equatable {
-  case Success(String)
-  case Error(Stencil.Error)
-}
-
-public func ==(lhs:Result, rhs:Result) -> Bool {
-  switch (lhs, rhs) {
-  case (.Success(let lhsValue), .Success(let rhsValue)):
-    return lhsValue == rhsValue
-  case (.Error(let lhsValue), .Error(let rhsValue)):
-    return lhsValue == rhsValue
-  default:
-    return false
-  }
-}

Stencil/Template.swift

@@ -12,15 +12,15 @@ public class Template {
 
   /// Create a template with the given name inside the given bundle
   public convenience init(named:String, inBundle bundle:NSBundle?) throws {
-    var url:NSURL?
+    let url:NSURL
 
     if let bundle = bundle {
-      url = bundle.URLForResource(named, withExtension: nil)
+      url = bundle.URLForResource(named, withExtension: nil)!
     } else {
-      url = NSBundle.mainBundle().URLForResource(named, withExtension: nil)
+      url = NSBundle.mainBundle().URLForResource(named, withExtension: nil)!
     }
 
-    try self.init(URL:url!)
+    try self.init(URL:url)
   }
 
   /// Create a template with a file found at the given URL
@@ -40,20 +40,9 @@ public class Template {
     parser = TokenParser(tokens: tokens)
   }
 
-  /// Render the given template in a context
+  /// Render the given template
-  public func render(context:Context) -> Result {
+  public func render(context:Context? = nil) throws -> String {
-    switch parser.parse() {
+    let nodes = try parser.parse()
-    case .Success(let nodes):
+    return try renderNodes(nodes, context ?? Context())
-      return renderNodes(nodes, context: context)
-
-    case .Error(let error):
-      return .Error(error)
-    }
-  }
-
-  /// Render the given template without a context
-  public func render() -> Result {
-    let context = Context()
-    return render(context)
   }
 }

Stencil/TemplateLoader.swift

@@ -1,11 +1,3 @@
-//
-//  TemplateLoader.swift
-//  Stencil
-//
-//  Created by Kyle Fuller on 28/12/2014.
-//  Copyright (c) 2014 Cocode. All rights reserved.
-//
-
 import Foundation
 import PathKit
 

Stencil/TemplateLoader/Include.swift

@@ -1,44 +1,37 @@
 import Foundation
 import PathKit
 
-extension String : Error {
-  public var description:String {
-    return self
-  }
-}
 
-public class IncludeNode : Node {
+public class IncludeNode : NodeType {
   public let templateName:String
 
-  public class func parse(parser:TokenParser, token:Token) -> TokenParser.Result {
+  public class func parse(parser:TokenParser, token:Token) throws -> NodeType {
     let bits = token.contents.componentsSeparatedByString("\"")
 
     if bits.count != 3 {
-      return .Error(error:NodeError(token: token, message: "Tag takes one argument, the template file to be included"))
+      throw TemplateSyntaxError("'include' tag takes one argument, the template file to be included")
     }
 
-    return .Success(node:IncludeNode(templateName: bits[1]))
+    return IncludeNode(templateName: bits[1])
   }
 
   public init(templateName:String) {
     self.templateName = templateName
   }
 
-  public func render(context: Context) -> Result {
+  public func render(context: Context) throws -> String {
     if let loader =  context["loader"] as? TemplateLoader {
       if let template = loader.loadTemplate(templateName) {
-        return template.render(context)
+        return try template.render(context)
       }
 
       let paths:String = loader.paths.map { path in
         return path.description
       }.joinWithSeparator(", ")
-      let error = "Template '\(templateName)' not found in \(paths)"
+      throw TemplateSyntaxError("'\(templateName)' template not found in \(paths)")
-      return .Error(error)
     }
 
-    let error = "Template loader not in context"
+    throw TemplateSyntaxError("Template loader not in context")
-    return .Error(error)
   }
 }
 

Stencil/TemplateLoader/Inheritence.swift

@@ -24,36 +24,32 @@ func any<Element>(elements:[Element], closure:(Element -> Bool)) -> Element? {
   return nil
 }
 
-class ExtendsNode : Node {
+class ExtendsNode : NodeType {
   let templateName:String
   let blocks:[String:BlockNode]
 
-  class func parse(parser:TokenParser, token:Token) -> TokenParser.Result {
+  class func parse(parser:TokenParser, token:Token) throws -> NodeType {
     let bits = token.contents.componentsSeparatedByString("\"")
 
     if bits.count != 3 {
-      return .Error(error:NodeError(token: token, message: "Tag takes one argument, the template file to be extended"))
+      throw TemplateSyntaxError("'extends' takes one argument, the template file to be extended")
     }
 
-    switch parser.parse() {
+    let parsedNodes = try parser.parse()
-    case .Success(let nodes):
+    if (any(parsedNodes) { ($0 as? ExtendsNode) != nil }) != nil {
-      if (any(nodes) { ($0 as? ExtendsNode) != nil }) != nil {
+      throw TemplateSyntaxError("'extends' cannot appear more than once in the same template")
-        return .Error(error:"'extends' cannot appear more than once in the same template")
     }
 
-      let blockNodes = nodes.filter { node in node is BlockNode }
+    let blockNodes = parsedNodes.filter { node in node is BlockNode }
 
-      let nodes = blockNodes.reduce([String:BlockNode](), combine: { (accumulator, node:Node) -> [String:BlockNode] in
+    let nodes = blockNodes.reduce([String:BlockNode](), combine: { (accumulator, node:NodeType) -> [String:BlockNode] in
       let node = (node as! BlockNode)
       var dict = accumulator
       dict[node.name] = node
       return dict
     })
 
-      return .Success(node:ExtendsNode(templateName: bits[1], blocks: nodes))
+    return ExtendsNode(templateName: bits[1], blocks: nodes)
-    case .Error(let error):
-      return .Error(error:error)
-    }
   }
 
   init(templateName:String, blocks:[String:BlockNode]) {
@@ -61,12 +57,12 @@ class ExtendsNode : Node {
     self.blocks = blocks
   }
 
-  func render(context: Context) -> Result {
+  func render(context: Context) throws -> String {
     if let loader =  context["loader"] as? TemplateLoader {
       if let template = loader.loadTemplate(templateName) {
         let blockContext = BlockContext(blocks: blocks)
         context.push([BlockContext.contextKey: blockContext])
-        let result = template.render(context)
+        let result = try template.render(context)
         context.pop()
         return result
       }
@@ -74,51 +70,39 @@ class ExtendsNode : Node {
       let paths:String = loader.paths.map { path in
         return path.description
         }.joinWithSeparator(", ")
-      let error = "Template '\(templateName)' not found in \(paths)"
+      throw TemplateSyntaxError("'\(templateName)' template not found in \(paths)")
-      return .Error(error)
     }
 
-    let error = "Template loader not in context"
+    throw TemplateSyntaxError("Template loader not in context")
-    return .Error(error)
   }
 }
 
-class BlockNode : Node {
+class BlockNode : NodeType {
   let name:String
-  let nodes:[Node]
+  let nodes:[NodeType]
 
-  class func parse(parser:TokenParser, token:Token) -> TokenParser.Result {
+  class func parse(parser:TokenParser, token:Token) throws -> NodeType {
     let bits = token.components()
 
     if bits.count != 2 {
-      return .Error(error:NodeError(token: token, message: "Tag takes one argument, the template file to be included"))
+      throw TemplateSyntaxError("'block' tag takes one argument, the template file to be included")
     }
 
     let blockName = bits[1]
-    var nodes = [Node]()
+    let nodes = try parser.parse(until(["endblock"]))
-
+    return BlockNode(name:blockName, nodes:nodes)
-    switch parser.parse(until(["endblock"])) {
-    case .Success(let blockNodes):
-      nodes = blockNodes
-    case .Error(let error):
-      return .Error(error: error)
   }
 
-    return .Success(node:BlockNode(name:blockName, nodes:nodes))
+  init(name:String, nodes:[NodeType]) {
-  }
-
-  init(name:String, nodes:[Node]) {
     self.name = name
     self.nodes = nodes
   }
 
-  func render(context: Context) -> Result {
+  func render(context: Context) throws -> String {
-    if let blockContext = context[BlockContext.contextKey] as? BlockContext {
+    if let blockContext = context[BlockContext.contextKey] as? BlockContext, node = blockContext.pop(name) {
-      if let node = blockContext.pop(name) {
+      return try node.render(context)
-        return node.render(context)
-      }
     }
 
-    return renderNodes(nodes, context: context)
+    return try renderNodes(nodes, context)
   }
 }

Stencil/Tokenizer.swift

@@ -1,6 +1,3 @@
-import Foundation
-
-
 public enum Token : Equatable {
   /// A token representing a piece of text.
   case Text(value:String)

StencilTests/NodeTests.swift

@@ -2,16 +2,10 @@ import Foundation
 import XCTest
 import Stencil
 
-class ErrorNodeError : Error {
-  var description: String {
-    return "Node Error"
-  }
-}
 
-class ErrorNode : Node {
+class ErrorNode : NodeType {
-  func render(context: Context) -> Result {
+  func render(context: Context) throws -> String {
-
+    throw TemplateSyntaxError("Custom Error")
-    return .Error(ErrorNodeError())
   }
 }
 
@@ -30,73 +24,39 @@ class NodeTests: XCTestCase {
 class TextNodeTests: NodeTests {
   func testTextNodeResolvesText() {
     let node = TextNode(text:"Hello World")
-    let _ = node.render(context)
+    XCTAssertEqual(try? node.render(context), "Hello World")
-
-    switch node.render(context) {
-    case .Success(let string):
-      XCTAssertEqual(string, "Hello World")
-    case .Error:
-      XCTAssert(false, "Unexpected error")
-    }
   }
 }
 
 class VariableNodeTests: NodeTests {
   func testVariableNodeResolvesVariable() {
     let node = VariableNode(variable:Variable("name"))
-
+    XCTAssertEqual(try? node.render(context), "Kyle")
-    switch node.render(context) {
-    case .Success(let string):
-      XCTAssertEqual(string, "Kyle")
-    case .Error:
-      XCTAssert(false, "Unexpected error")
-    }
   }
 
   func testVariableNodeResolvesNonStringVariable() {
     let node = VariableNode(variable:Variable("age"))
-
+    XCTAssertEqual(try? node.render(context), "27")
-    switch node.render(context) {
-    case .Success(let string):
-      XCTAssertEqual(string, "27")
-    case .Error:
-      XCTAssert(false, "Unexpected error")
-    }
   }
 }
 
 class RenderNodeTests: NodeTests {
   func testRenderingNodes() {
-    let nodes = [TextNode(text:"Hello "), VariableNode(variable: "name")] as [Node]
+    let nodes = [TextNode(text:"Hello "), VariableNode(variable: "name")] as [NodeType]
-    switch renderNodes(nodes, context: context) {
+    XCTAssertEqual(try? renderNodes(nodes, context), "Hello Kyle")
-    case .Success(let result):
-      XCTAssertEqual(result, "Hello Kyle")
-    case .Error:
-      XCTAssert(false, "Unexpected error")
-    }
   }
 
   func testRenderingNodesWithFailure() {
-    let nodes = [TextNode(text:"Hello "), VariableNode(variable: "name"), ErrorNode()] as [Node]
+    let nodes = [TextNode(text:"Hello "), VariableNode(variable: "name"), ErrorNode()] as [NodeType]
 
-    switch renderNodes(nodes, context: context) {
+    assertFailure(try renderNodes(nodes, context), TemplateSyntaxError("Custom Error"))
-    case .Success:
-      XCTAssert(false, "Unexpected success")
-    case .Error(let error):
-      XCTAssertEqual("\(error)", "Node Error")
-    }
   }
 }
 
 class ForNodeTests: NodeTests {
   func testForNodeRender() {
     let node = ForNode(variable: "items", loopVariable: "item", nodes: [VariableNode(variable: "item")], emptyNodes:[])
-    switch node.render(context) {
+    XCTAssertEqual(try? node.render(context), "123")
-    case .Success(let string):
-      XCTAssertEqual(string, "123")
-    case .Error:
-      XCTAssert(false, "Unexpected error")
-    }
   }
 }
 
@@ -114,7 +74,7 @@ class IfNodeTests: NodeTests {
     ]
 
     let parser = TokenParser(tokens: tokens)
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       let node = nodes.first as! IfNode
       let trueNode = node.trueNodes.first as! TextNode
       let falseNode = node.falseNodes.first as! TextNode
@@ -138,7 +98,7 @@ class IfNodeTests: NodeTests {
     ]
 
     let parser = TokenParser(tokens: tokens)
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       let node = nodes.first as! IfNode
       let trueNode = node.trueNodes.first as! TextNode
       let falseNode = node.falseNodes.first as! TextNode
@@ -158,7 +118,7 @@ class IfNodeTests: NodeTests {
     ]
 
     let parser = TokenParser(tokens: tokens)
-    assertFailure(parser.parse(), description: "if: `endif` was not found.")
+    assertFailure(try parser.parse(), TemplateSyntaxError("`endif` was not found."))
   }
 
   func testParseIfNotWithoutEndIfError() {
@@ -167,31 +127,19 @@ class IfNodeTests: NodeTests {
     ]
 
     let parser = TokenParser(tokens: tokens)
-    assertFailure(parser.parse(), description: "ifnot: `endif` was not found.")
+    assertFailure(try parser.parse(), TemplateSyntaxError("`endif` was not found."))
   }
 
   // MARK: Rendering
 
   func testIfNodeRenderTruth() {
     let node = IfNode(variable: "items", trueNodes: [TextNode(text: "true")], falseNodes: [TextNode(text: "false")])
-
+    XCTAssertEqual(try? node.render(context), "true")
-    switch node.render(context) {
-    case .Success(let string):
-      XCTAssertEqual(string, "true")
-    case .Error:
-      XCTAssert(false, "Unexpected error")
-    }
   }
 
   func testIfNodeRenderFalse() {
     let node = IfNode(variable: "unknown", trueNodes: [TextNode(text: "true")], falseNodes: [TextNode(text: "false")])
-
+    XCTAssertEqual(try? node.render(context), "false")
-    switch node.render(context) {
-    case .Success(let string):
-      XCTAssertEqual(string, "false")
-    case .Error:
-      XCTAssert(false, "Unexpected error")
-    }
   }
 
 }
@@ -204,7 +152,7 @@ class NowNodeTests: NodeTests {
     let tokens = [ Token.Block(value: "now") ]
     let parser = TokenParser(tokens: tokens)
 
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       let node = nodes.first as! NowNode
       XCTAssertEqual(nodes.count, 1)
       XCTAssertEqual(node.format.variable, "\"yyyy-MM-dd 'at' HH:mm\"")
@@ -215,7 +163,7 @@ class NowNodeTests: NodeTests {
     let tokens = [ Token.Block(value: "now \"HH:mm\"") ]
     let parser = TokenParser(tokens: tokens)
 
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       let node = nodes.first as! NowNode
       XCTAssertEqual(nodes.count, 1)
       XCTAssertEqual(node.format.variable, "\"HH:mm\"")
@@ -231,13 +179,6 @@ class NowNodeTests: NodeTests {
     formatter.dateFormat = "yyyy-MM-dd"
     let date = formatter.stringFromDate(NSDate())
 
-    switch node.render(context) {
+    XCTAssertEqual(try? node.render(context), date)
-    case .Success(let string):
-      XCTAssertEqual(string, date)
-    case .Error:
-      XCTAssert(false, "Unexpected error")
   }
-  }
-
 }
-

StencilTests/ParserTests.swift

@@ -8,7 +8,7 @@ class TokenParserTests: XCTestCase {
       Token.Text(value: "Hello World")
       ])
 
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       let node = nodes.first as! TextNode
       XCTAssertEqual(nodes.count, 1)
       XCTAssertEqual(node.text, "Hello World")
@@ -20,7 +20,7 @@ class TokenParserTests: XCTestCase {
       Token.Variable(value: "name")
       ])
 
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       let node = nodes.first as! VariableNode
       XCTAssertEqual(nodes.count, 1)
       XCTAssertEqual(node.variable, Variable("name"))
@@ -32,7 +32,7 @@ class TokenParserTests: XCTestCase {
       Token.Comment(value: "Secret stuff!")
       ])
 
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       XCTAssertEqual(nodes.count, 0)
     }
   }
@@ -42,7 +42,7 @@ class TokenParserTests: XCTestCase {
       Token.Block(value: "now"),
       ])
 
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       XCTAssertEqual(nodes.count, 1)
     }
   }

StencilTests/StencilTests.swift

@@ -2,27 +2,27 @@ import Foundation
 import XCTest
 import Stencil
 
-func assertSuccess(result:TokenParser.Results, block:(([Node]) -> ())) {
+func assertSuccess<T>(@autoclosure closure:() throws -> (T), block:(T -> ())) {
-  switch result {
+  do {
-  case .Success(let nodes):
+    block(try closure())
-    block(nodes)
+  } catch {
-  case .Error:
+    XCTFail("Unexpected error \(error)")
-    XCTAssert(false, "Unexpected error")
   }
 }
 
-func assertFailure(result:TokenParser.Results, description:String) {
+func assertFailure<T, U : Equatable>(@autoclosure closure:() throws -> (T), _ error:U) {
-  switch result {
+  do {
-  case .Success:
+    try closure()
-    XCTAssert(false, "Unexpected error")
+  } catch let e as U {
-  case .Error(let error):
+    XCTAssertEqual(e, error)
-    XCTAssertEqual("\(error)", description)
+  } catch {
+    XCTFail()
   }
 }
 
-class CustomNode : Node {
+class CustomNode : NodeType {
-  func render(context:Context) -> Result {
+  func render(context:Context) throws -> String {
-    return .Success("Hello World")
+    return "Hello World"
   }
 }
 
@@ -42,7 +42,7 @@ class StencilTests: XCTestCase {
       ])
 
     let template = Template(templateString:templateString)
-    let result = template.render(context)
+    let result = try? template.render(context)
 
     let fixture = "There are 2 articles.\n" +
       "\n" +
@@ -50,7 +50,7 @@ class StencilTests: XCTestCase {
       "    - Memory Management with ARC by Kyle Fuller.\n" +
     "\n"
 
-    XCTAssertEqual(result, Result.Success(fixture))
+    XCTAssertEqual(result, fixture)
   }
 
   func testCustomTag() {
@@ -58,11 +58,10 @@ class StencilTests: XCTestCase {
     let template = Template(templateString:templateString)
 
     template.parser.registerTag("custom") { parser, token in
-      return .Success(node:CustomNode())
+      return CustomNode()
     }
 
-    let result = template.render()
+    XCTAssertEqual(try? template.render(), "Hello World")
-    XCTAssertEqual(result, Result.Success("Hello World"))
   }
 
   func testSimpleCustomTag() {
@@ -70,10 +69,9 @@ class StencilTests: XCTestCase {
     let template = Template(templateString:templateString)
 
     template.parser.registerSimpleTag("custom") { context in
-      return .Success("Hello World")
+      return "Hello World"
     }
 
-    let result = template.render()
+    XCTAssertEqual(try? template.render(), "Hello World")
-    XCTAssertEqual(result, Result.Success("Hello World"))
   }
 }

StencilTests/TemplateLoader/IncludeTests.swift

@@ -20,14 +20,14 @@ class IncludeTests: NodeTests {
     let tokens = [ Token.Block(value: "include") ]
     let parser = TokenParser(tokens: tokens)
 
-    assertFailure(parser.parse(), description: "include: Tag takes one argument, the template file to be included")
+    assertFailure(try parser.parse(), TemplateSyntaxError("'include' tag takes one argument, the template file to be included"))
   }
 
   func testParse() {
     let tokens = [ Token.Block(value: "include \"test.html\"") ]
     let parser = TokenParser(tokens: tokens)
 
-    assertSuccess(parser.parse()) { nodes in
+    assertSuccess(try parser.parse()) { nodes in
       let node = nodes.first as! IncludeNode
       XCTAssertEqual(nodes.count, 1)
       XCTAssertEqual(node.templateName, "test.html")
@@ -38,38 +38,27 @@ class IncludeTests: NodeTests {
 
   func testRenderWithoutLoader() {
     let node = IncludeNode(templateName: "test.html")
-    let result = node.render(Context())
 
-    switch result {
+    do {
-    case .Success:
+      try node.render(Context())
-      XCTAssert(false, "Unexpected error")
+    } catch {
-    case .Error(let error):
       XCTAssertEqual("\(error)", "Template loader not in context")
     }
   }
 
   func testRenderWithoutTemplateNamed() {
     let node = IncludeNode(templateName: "unknown.html")
-    let result = node.render(Context(dictionary:["loader":loader]))
 
-    switch result {
+    do {
-    case .Success:
+      try node.render(Context(dictionary:["loader":loader]))
-      XCTAssert(false, "Unexpected error")
+    } catch {
-    case .Error(let error):
+      XCTAssertTrue("\(error)".hasPrefix("'unknown.html' template not found"))
-      XCTAssertTrue("\(error)".hasPrefix("Template 'unknown.html' not found"))
     }
   }
 
   func testRender() {
     let node = IncludeNode(templateName: "test.html")
-    let result = node.render(Context(dictionary:["loader":loader, "target": "World"]))
+    let value = try? node.render(Context(dictionary:["loader":loader, "target": "World"]))
-
+    XCTAssertEqual(value, "Hello World!")
-    switch result {
-    case .Success(let string):
-      XCTAssertEqual(string, "Hello World!")
-    case .Error(let error):
-      XCTAssert(false, "Unexpected error: \(error)")
   }
-  }
-
 }

StencilTests/TemplateLoader/InheritenceTests.swift

@@ -16,14 +16,7 @@ class InheritenceTests: NodeTests {
   func testInheritence() {
     context = Context(dictionary: ["loader": loader])
     let template = loader.loadTemplate("child.html")!
-    let result = template.render(context)
+    XCTAssertEqual(try? template.render(context), "Header\nChild")
-
-    switch result {
-    case .Success(let rendered):
-      XCTAssertEqual(rendered, "Header\nChild")
-    case .Error:
-      XCTAssert(false, "Unexpected error")
-    }
   }
 }
 

StencilTests/TemplateTests.swift

@@ -3,12 +3,10 @@ import XCTest
 import Stencil
 
 class TemplateTests: XCTestCase {
-
   func testTemplate() {
     let context = Context(dictionary: [ "name": "Kyle" ])
     let template = Template(templateString: "Hello World")
-    let result = template.render(context)
+    let result = try? template.render(context)
-    XCTAssertEqual(result, Result.Success("Hello World"))
+    XCTAssertEqual(result, "Hello World")
   }
-
 }