Include node protocol along with text and variable nodes

Stencil/Node.swift

@@ -0,0 +1,61 @@
+//
+//  Node.swift
+//  Stencil
+//
+//  Created by Kyle Fuller on 23/10/2014.
+//  Copyright (c) 2014 Cocode. All rights reserved.
+//
+
+import Foundation
+
+public protocol Error : Printable {
+
+}
+
+public protocol Node : Equatable {
+    func render(context:Context) -> (String?, Error?)
+}
+
+public class TextNode : Node {
+    public let text:String
+
+    public init(text:String) {
+        self.text = text
+    }
+
+    public func render(context:Context) -> (String?, Error?) {
+        return (self.text, nil)
+    }
+}
+
+public func ==(lhs:TextNode, rhs:TextNode) -> Bool {
+    return true
+}
+
+public class VariableNode : Node {
+    let variable:Variable
+
+    public init(variable:Variable) {
+        self.variable = variable
+    }
+
+    public init(variable:String) {
+        self.variable = Variable(variable)
+    }
+
+    public func render(context:Context) -> (String?, Error?) {
+        let result:AnyObject? = variable.resolve(context)
+
+        if let result = result as? String {
+            return (result, nil)
+        } else if let result = result as? NSObject {
+            return (result.description, nil)
+        }
+
+        return (nil, nil)
+    }
+}
+
+public func ==(lhs:VariableNode, rhs:VariableNode) -> Bool {
+    return true
+}