Made diff records immutable

Also, updated package.json for devDependencies.

Readme.md

@@ -127,9 +127,11 @@ observableDiff(lhs, rhs, function (d) {
 ```
 
 ## API Documentation
-A startard import of `var diff = require('diff')` is assumed in all of the code examples. The import results in an object having the following publid properties:
+A standard import of `var diff = require('diff')` is assumed in all of the code examples. The import results in an object having the following public properties:
 
 * `diff`           - a function that calculates the differences between two objects.
 * `observableDiff` - a function that calculates the differences between two objects and reports each to an observer function.
 * `applyDiff`      - a function that applies any structural differences from one object to another.
-* `applyChange`    - applies a single change record to an origin object.
+* `applyChange`    - a function that applies a single change record to an origin object.
+
+

lib/diff.js

@@ -3,6 +3,41 @@
 	: function(F) { F(require,exports,module); } }).  // Node.js
 	define(function (require, exports, module) {
 		"use strict";
+
+		var util = require('util');
+
+		function Diff(kind, path) {
+			Object.defineProperty(this, 'kind', { value: kind, enumerable: true });
+			if (path && path.length) {
+				Object.defineProperty(this, 'path', { value: path, enumerable: true });
+			}
+		}
+		function DiffEdit(path, origin, value) {
+			DiffEdit.super_.call(this, 'E', path);
+
+			Object.defineProperty(this, 'lhs', { value: origin, enumerable: true });
+			Object.defineProperty(this, 'rhs', { value: value, enumerable: true });
+		}
+		util.inherits(DiffEdit, Diff); 
+		function DiffNew(path, value) {
+			DiffNew.super_.call(this, 'N', path);
+
+			Object.defineProperty(this, 'rhs', { value: value, enumerable: true });
+		}
+		util.inherits(DiffNew, Diff); 
+		function DiffDeleted(path, value) {
+			DiffDeleted.super_.call(this, 'D', path);
+
+			Object.defineProperty(this, 'lhs', { value: value, enumerable: true });
+		}
+		util.inherits(DiffDeleted, Diff); 
+		function DiffArray(path, index, item) {
+			DiffArray.super_.call(this, 'A', path);
+
+			Object.defineProperty(this, 'index', { value: index, enumerable: true });
+			Object.defineProperty(this, 'item', { value: item, enumerable: true });
+		}
+		util.inherits(DiffArray, Diff); 
 
 		function arrayRemove(arr, from, to) {
 			var rest = arr.slice((to || from) + 1 || arr.length);
@@ -21,48 +56,29 @@
 			var rtype = typeof rhs;
 			if (ltype === 'undefined') {
 				if (rtype !== 'undefined') { 
-					changes({kind: 'N', path: currentPath, rhs: rhs });
+					changes(new DiffNew(currentPath, rhs ));
 				}
 			} else if (rtype === 'undefined') {
-				changes({kind: 'D', path: currentPath, lhs: lhs});
+				changes(new DiffDeleted(currentPath, lhs));
 			} else if (ltype !== rtype) { 
-				changes({kind: 'E', path: currentPath, lhs: lhs, rhs: rhs});
+				changes(new DiffEdit(currentPath, lhs, rhs));
 			} else if (ltype === 'object') {
 				stack = stack || [];
 				if (stack.indexOf(lhs) < 0) {
 					stack.push(lhs);
 					if (Array.isArray(lhs)) {
 						var i, ea = function(d) {
-							changes({
-								kind: 'A', 
-								path: currentPath, 
-								index: i,
-								item: d
-							});
+							changes(new DiffArray(currentPath, i, d));
 						};
 						for(i = 0; i < lhs.length; i++) {
 							if (i >= rhs.length) {
-								changes({
-									kind: 'A', 
-									path: currentPath, 
-									index: i,
-									item: { 
-										kind: 'D',
-										lhs: lhs[i] }
-								});
+								changes(new DiffArray(currentPath, i, new DiffDeleted(undefined, lhs[i]))); 
 							} else {
 								deepDiff(lhs[i], rhs[i], ea, [], null, stack);
 							} 
 						}
 						while(i < rhs.length) {
-							changes({
-								kind: 'A', 
-								path: currentPath, 
-								index: i,
-								item: { 
-									kind: 'N',
-									rhs: rhs[i++] }
-							}); 
+							changes(new DiffArray(currentPath, i, new DiffNew(undefined, rhs[i++]))); 
 						}
 					} else { 
 						var akeys = Object.keys(lhs);
@@ -83,7 +99,7 @@
 					stack.length = stack.length - 1;
 				}
 			} else if (lhs !== rhs) {
-				changes({kind: 'E', path: currentPath, lhs: lhs, rhs: rhs});
+				changes(new DiffEdit(currentPath, lhs, rhs));
 			}
 		}
 
@@ -143,6 +159,9 @@
 		}
 
 		function applyChange(target, source, change) {
+			if (!(change instanceof Diff)) {
+				throw new TypeError('[Object] change must be instanceof Diff');
+			}
 			if (target && source && change) {
 				var it = target, i, u;
 				u = change.path.length - 1; 

package.json

@@ -19,19 +19,25 @@
 		"test": "./test"
 	},
 	"devDependencies" : {
-    "should": {
-      "version": "1.2.0"
-    },
-    "vows": {
-      "version": "0.6.4",
-      "dependencies": {
-        "eyes": {
-          "version": "0.1.8"
-        },
-        "diff": {
-          "version": "1.0.4"
-        }
-      }
+		"lodash": {
+			"version": "0.9.2"
+		},
+		"extend": {
+			"version": "1.1.1"
+		},
+		"should": {
+			"version": "1.2.1"
+		},
+		"vows": {
+			"version": "0.6.4",
+			"dependencies": {
+				"eyes": {
+					"version": "0.1.8"
+				},
+				"diff": {
+					"version": "1.0.4"
+				}
+			}
 		}
 	},
 	"scripts": {