Use enum instead of pair as result type for Template

Stencil.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		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 */; };
@@ -36,6 +37,7 @@
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
+		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>"; };
@@ -97,14 +99,15 @@
 		77FAAE5419F91E480029DC5E /* Stencil */ = {
 			isa = PBXGroup;
 			children = (
-				77FAAE5719F91E480029DC5E /* Stencil.h */,
 				77FAAE6E19F920750029DC5E /* Context.swift */,
-				7725B3CC19F92B61002CF74B /* Variable.swift */,
+				77EB082A19FA8600001870F1 /* Lexer.swift */,
-				7725B3CE19F94214002CF74B /* Tokenizer.swift */,
 				7725B3D419F9438F002CF74B /* Node.swift */,
 				7725B3D619F94A43002CF74B /* Parser.swift */,
-				77EB082A19FA8600001870F1 /* Lexer.swift */,
+				71CE4C0919FD29D000B9E0C5 /* Result.swift */,
+				77FAAE5719F91E480029DC5E /* Stencil.h */,
 				77EB082419F96E88001870F1 /* Template.swift */,
+				7725B3CE19F94214002CF74B /* Tokenizer.swift */,
+				7725B3CC19F92B61002CF74B /* Variable.swift */,
 				77FAAE5519F91E480029DC5E /* Supporting Files */,
 			);
 			path = Stencil;
@@ -254,6 +257,7 @@
 				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 */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Stencil/Node.swift

@@ -8,10 +8,6 @@
 
 import Foundation
 
-public protocol Error : Printable {
-
-}
-
 struct NodeError : Error {
     let token:Token
     let message:String

Stencil/Result.swift

@@ -0,0 +1,33 @@
+//
+//  Result.swift
+//  Stencil
+//
+//  Created by Marius Rackwitz on 26/10/14.
+//  Copyright (c) 2014 Cocode. All rights reserved.
+//
+
+import Foundation
+
+public protocol Error : Printable {
+    
+}
+
+public func ==(lhs:Error, rhs:Error) -> Bool {
+    return lhs.description == rhs.description
+}
+
+public enum Result : Equatable {
+    case Success(string: String)
+    case Error(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

@@ -44,15 +44,19 @@ public class Template {
         parser = TokenParser(tokens: tokens)
     }
 
-    public func render(context:Context) -> (string:String?, error:Error?) {
+    public func render(context:Context) -> Result {
         let (nodes, error) = parser.parse()
 
         if let error = error {
-            return (nil, error)
+            return .Error(error: error)
         } else if let nodes = nodes {
-            return renderNodes(nodes, context)
+            let result = renderNodes(nodes, context)
+            if let string = result.0 {
+                return .Success(string: string)
+            } else {
+                return .Error(error: result.1!)
+            }
         }
-
+        return .Success(string: "")
-        return (nil, nil)
     }
 }

StencilTests/StencilTests.swift

@@ -34,6 +34,6 @@ class StencilTests: XCTestCase {
             "    - Memory Management with ARC by Kyle Fuller.\n" +
             "\n"
 
-        XCTAssertEqual(result.string!, fixture)
+        XCTAssertEqual(result, Result.Success(string: fixture))
     }
 }

StencilTests/TemplateTests.swift

@@ -15,9 +15,8 @@ class TemplateTests: XCTestCase {
     func testTemplate() {
         let context = Context(dictionary: [ "name": "Kyle" ])
         let template = Template(templateString: "Hello World")
-        let (string, error) = template.render(context)
+        let result = template.render(context)
-        XCTAssertEqual(string!, "Hello World")
+        XCTAssertEqual(result, Result.Success(string: "Hello World"))
-        XCTAssertTrue(error == nil)
     }
 
 }