Use enum instead of pair as result type for Template

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 (nil, nil)
+        return .Success(string: "")
     }
 }