fix(angular.equals): add support for regular expressions

Regular expression objects didn't used to be considered to be equal when using
'angular.equals'. Dirty checking therefore failed to recognize a
property modification.

Closes #2685

Author: bripkens

src/Angular.js

@@ -413,6 +413,18 @@ function isArray(value) {
 function isFunction(value){return typeof value == 'function';}
 
 
+/**
+ * Determines if a value is a regular expression object.
+ *
+ * @private
+ * @param {*} value Reference to check.
+ * @returns {boolean} True if `value` is a `RegExp`.
+ */
+function isRegExp(value) {
+  return toString.apply(value) == '[object RegExp]';
+}
+
+
 /**
  * Checks if `obj` is a window object.
  *
@@ -646,14 +658,17 @@ function shallowCopy(src, dst) {
  * @function
  *
  * @description
- * Determines if two objects or two values are equivalent. Supports value types, arrays and
+ * Determines if two objects or two values are equivalent. Supports value types, regular expressions, arrays and
  * objects.
  *
  * Two objects or values are considered equivalent if at least one of the following is true:
  *
  * * Both objects or values pass `===` comparison.
  * * Both objects or values are of the same type and all of their properties pass `===` comparison.
  * * Both values are NaN. (In JavasScript, NaN == NaN => false. But we consider two NaN as equal)
+ * * Both values represent the same regular expression (In JavasScript,
+ *   /abc/ == /abc/ => false. But we consider two regular expressions as equal when their textual
+ *   representation matches).
  *
  * During a property comparison, properties of `function` type and properties with names
  * that begin with `$` are ignored.
@@ -680,6 +695,8 @@ function equals(o1, o2) {
         }
       } else if (isDate(o1)) {
         return isDate(o2) && o1.getTime() == o2.getTime();
+      } else if (isRegExp(o1) && isRegExp(o2)) {
+        return o1.toString() == o2.toString();
       } else {
         if (isScope(o1) || isScope(o2) || isWindow(o1) || isWindow(o2)) return false;
         keySet = {};
@@ -949,9 +966,9 @@ function encodeUriQuery(val, pctEncodeSpaces) {
  * one ngApp directive can be used per HTML document. The directive
  * designates the root of the application and is typically placed
  * at the root of the page.
- * 
- * The first ngApp found in the document will be auto-bootstrapped. To use multiple applications in an 
- * HTML document you must manually bootstrap them using {@link angular.bootstrap}. 
+ *
+ * The first ngApp found in the document will be auto-bootstrapped. To use multiple applications in an
+ * HTML document you must manually bootstrap them using {@link angular.bootstrap}.
  * Applications cannot be nested.
  *
  * In the example below if the `ngApp` directive would not be placed

test/AngularSpec.js

@@ -278,6 +278,17 @@ describe('angular', function() {
       expect(equals({}, {hasOwnProperty: 1})).toBe(false);
       expect(equals({}, {toString: null})).toBe(false);
     });
+
+    it('should compare regular expressions', function() {
+      expect(equals(/abc/, /abc/)).toBe(true);
+      expect(equals(/abc/i, new RegExp('abc', 'i'))).toBe(true);
+      expect(equals(new RegExp('abc', 'i'), new RegExp('abc', 'i'))).toBe(true);
+      expect(equals(new RegExp('abc', 'i'), new RegExp('abc'))).toBe(false);
+      expect(equals(/abc/i, /abc/)).toBe(false);
+      expect(equals(/abc/, /def/)).toBe(false);
+      expect(equals(/^abc/, /abc/)).toBe(false);
+      expect(equals(/^abc/, '/^abc/')).toBe(false);
+    });
   });
 
   describe('size', function() {
@@ -654,6 +665,23 @@ describe('angular', function() {
     });
   });
 
+
+  describe('isRegExp', function() {
+    it('should return true for RegExp object', function() {
+      expect(isRegExp(/^foobar$/)).toBe(true);
+      expect(isRegExp(new RegExp('^foobar$/'))).toBe(true);
+    });
+
+    it('should return false for non RegExp objects', function() {
+      expect(isRegExp([])).toBe(false);
+      expect(isRegExp('')).toBe(false);
+      expect(isRegExp(23)).toBe(false);
+      expect(isRegExp({})).toBe(false);
+      expect(isRegExp(new Date())).toBe(false);
+    });
+  });
+
+
   describe('compile', function() {
     it('should link to existing node and create scope', inject(function($rootScope, $compile) {
       var template = angular.element('<div>{{greeting = "hello world"}}</div>');