compile.js

'use strict';

/* ! VARIABLE/FUNCTION NAMING CONVENTIONS THAT APPLY TO THIS FILE!
 *
 * DOM-related variables:
 *
 * - "node" - DOM Node
 * - "element" - DOM Element or Node
 * - "$node" or "$element" - jqLite-wrapped node or element
 *
 *
 * Compiler related stuff:
 *
 * - "linkFn" - linking fn of a single directive
 * - "nodeLinkFn" - function that aggregates all linking fns for a particular node
 * - "childLinkFn" -  function that aggregates all linking fns for child nodes of a particular node
 * - "compositeLinkFn" - function that aggregates all linking fns for a compilation root (nodeList)
 */


/**
 * @ngdoc service
 * @name $compile
 * @function
 *
 * @description
 * Compiles an HTML string or DOM into a template and produces a template function, which
 * can then be used to link {@link ng.$rootScope.Scope `scope`} and the template together.
 *
 * The compilation is a process of walking the DOM tree and matching DOM elements to
 * {@link ng.$compileProvider#directive directives}.
 *
 * <div class="alert alert-warning">
 * **Note:** This document is an in-depth reference of all directive options.
 * For a gentle introduction to directives with examples of common use cases,
 * see the {@link guide/directive directive guide}.
 * </div>
 *
 * ## Comprehensive Directive API
 *
 * There are many different options for a directive.
 *
 * The difference resides in the return value of the factory function.
 * You can either return a "Directive Definition Object" (see below) that defines the directive properties,
 * or just the `postLink` function (all other properties will have the default values).
 *
 * <div class="alert alert-success">
 * **Best Practice:** It's recommended to use the "directive definition object" form.
 * </div>
 *
 * Here's an example directive declared with a Directive Definition Object:
 *
 * ```js
 *   var myModule = angular.module(...);
 *
 *   myModule.directive('directiveName', function factory(injectables) {
 *     var directiveDefinitionObject = {
 *       priority: 0,
 *       template: '<div></div>', // or // function(tElement, tAttrs) { ... },
 *       // or
 *       // templateUrl: 'directive.html', // or // function(tElement, tAttrs) { ... },
 *       replace: false,
 *       transclude: false,
 *       restrict: 'A',
 *       scope: false,
 *       controller: function($scope, $element, $attrs, $transclude, otherInjectables) { ... },
 *       controllerAs: 'stringAlias',
 *       require: 'siblingDirectiveName', // or // ['^parentDirectiveName', '?optionalDirectiveName', '?^optionalParent'],
 *       compile: function compile(tElement, tAttrs, transclude) {
 *         return {
 *           pre: function preLink(scope, iElement, iAttrs, controller) { ... },
 *           post: function postLink(scope, iElement, iAttrs, controller) { ... }
 *         }
 *         // or
 *         // return function postLink( ... ) { ... }
 *       },
 *       // or
 *       // link: {
 *       //  pre: function preLink(scope, iElement, iAttrs, controller) { ... },
 *       //  post: function postLink(scope, iElement, iAttrs, controller) { ... }
 *       // }
 *       // or
 *       // link: function postLink( ... ) { ... }
 *     };
 *     return directiveDefinitionObject;
 *   });
 * ```
 *
 * <div class="alert alert-warning">
 * **Note:** Any unspecified options will use the default value. You can see the default values below.
 * </div>
 *
 * Therefore the above can be simplified as:
 *
 * ```js
 *   var myModule = angular.module(...);
 *
 *   myModule.directive('directiveName', function factory(injectables) {
 *     var directiveDefinitionObject = {
 *       link: function postLink(scope, iElement, iAttrs) { ... }
 *     };
 *     return directiveDefinitionObject;
 *     // or
 *     // return function postLink(scope, iElement, iAttrs) { ... }
 *   });
 * ```
 *
 *
 *
 * ### Directive Definition Object
 *
 * The directive definition object provides instructions to the {@link ng.$compile
 * compiler}. The attributes are:
 *
 * #### `priority`
 * When there are multiple directives defined on a single DOM element, sometimes it
 * is necessary to specify the order in which the directives are applied. The `priority` is used
 * to sort the directives before their `compile` functions get called. Priority is defined as a
 * number. Directives with greater numerical `priority` are compiled first. Pre-link functions
 * are also run in priority order, but post-link functions are run in reverse order. The order
 * of directives with the same priority is undefined. The default priority is `0`.
 *
 * #### `terminal`
 * If set to true then the current `priority` will be the last set of directives
 * which will execute (any directives at the current priority will still execute
 * as the order of execution on same `priority` is undefined).
 *
 * #### `scope`
 * **If set to `true`,** then a new scope will be created for this directive. If multiple directives on the
 * same element request a new scope, only one new scope is created. The new scope rule does not
 * apply for the root of the template since the root of the template always gets a new scope.
 *
 * **If set to `{}` (object hash),** then a new "isolate" scope is created. The 'isolate' scope differs from
 * normal scope in that it does not prototypically inherit from the parent scope. This is useful
 * when creating reusable components, which should not accidentally read or modify data in the
 * parent scope.
 *
 * The 'isolate' scope takes an object hash which defines a set of local scope properties
 * derived from the parent scope. These local properties are useful for aliasing values for
 * templates. Locals definition is a hash of local scope property to its source:
 *
 * * `@` or `@attr` - bind a local scope property to the value of DOM attribute. The result is
 *   always a string since DOM attributes are strings. If no `attr` name is specified  then the
 *   attribute name is assumed to be the same as the local name.
 *   Given `<widget my-attr="hello {{name}}">` and widget definition
 *   of `scope: { localName:'@myAttr' }`, then widget scope property `localName` will reflect
 *   the interpolated value of `hello {{name}}`. As the `name` attribute changes so will the
 *   `localName` property on the widget scope. The `name` is read from the parent scope (not
 *   component scope).
 *
 * * `=` or `=attr` - set up bi-directional binding between a local scope property and the
 *   parent scope property of name defined via the value of the `attr` attribute. If no `attr`
 *   name is specified then the attribute name is assumed to be the same as the local name.
 *   Given `<widget my-attr="parentModel">` and widget definition of
 *   `scope: { localModel:'=myAttr' }`, then widget scope property `localModel` will reflect the
 *   value of `parentModel` on the parent scope. Any changes to `parentModel` will be reflected
 *   in `localModel` and any changes in `localModel` will reflect in `parentModel`. If the parent
 *   scope property doesn't exist, it will throw a NON_ASSIGNABLE_MODEL_EXPRESSION exception. You
 *   can avoid this behavior using `=?` or `=?attr` in order to flag the property as optional.
 *
 * * `&` or `&attr` - provides a way to execute an expression in the context of the parent scope.
 *   If no `attr` name is specified then the attribute name is assumed to be the same as the
 *   local name. Given `<widget my-attr="count = count + value">` and widget definition of
 *   `scope: { localFn:'&myAttr' }`, then isolate scope property `localFn` will point to
 *   a function wrapper for the `count = count + value` expression. Often it's desirable to
 *   pass data from the isolated scope via an expression and to the parent scope, this can be
 *   done by passing a map of local variable names and values into the expression wrapper fn.
 *   For example, if the expression is `increment(amount)` then we can specify the amount value
 *   by calling the `localFn` as `localFn({amount: 22})`.
 *
 *
 *
 * #### `controller`
 * Controller constructor function. The controller is instantiated before the
 * pre-linking phase and it is shared with other directives (see
 * `require` attribute). This allows the directives to communicate with each other and augment
 * each other's behavior. The controller is injectable (and supports bracket notation) with the following locals:
 *
 * * `$scope` - Current scope associated with the element
 * * `$element` - Current element
 * * `$attrs` - Current attributes object for the element
 * * `$transclude` - A transclude linking function pre-bound to the correct transclusion scope.
 *    The scope can be overridden by an optional first argument.
 *   `function([scope], cloneLinkingFn)`.
 *
 *
 * #### `require`
 * Require another directive and inject its controller as the fourth argument to the linking function. The
 * `require` takes a string name (or array of strings) of the directive(s) to pass in. If an array is used, the
 * injected argument will be an array in corresponding order. If no such directive can be
 * found, or if the directive does not have a controller, then an error is raised. The name can be prefixed with:
 *
 * * (no prefix) - Locate the required controller on the current element. Throw an error if not found.
 * * `?` - Attempt to locate the required controller or pass `null` to the `link` fn if not found.
 * * `^` - Locate the required controller by searching the element's parents. Throw an error if not found.
 * * `?^` - Attempt to locate the required controller by searching the element's parents or pass `null` to the
 *   `link` fn if not found.
 *
 *
 * #### `controllerAs`
 * Controller alias at the directive scope. An alias for the controller so it
 * can be referenced at the directive template. The directive needs to define a scope for this
 * configuration to be used. Useful in the case when directive is used as component.
 *
 *
 * #### `restrict`
 * String of subset of `EACM` which restricts the directive to a specific directive
 * declaration style. If omitted, the default (attributes only) is used.
 *
 * * `E` - Element name: `<my-directive></my-directive>`
 * * `A` - Attribute (default): `<div my-directive="exp"></div>`
 * * `C` - Class: `<div class="my-directive: exp;"></div>`
 * * `M` - Comment: `<!-- directive: my-directive exp -->`
 *
 *
 * #### `type`
 * String representing the document type used by the markup. This is useful for templates where the root
 * node is non-HTML content (such as SVG or MathML). The default value is "html".
 *
 * * `html` - All root template nodes are HTML, and don't need to be wrapped. Root nodes may also be
 *   top-level elements such as `<svg>` or `<math>`.
 * * `svg` - The template contains only SVG content, and must be wrapped in an `<svg>` node prior to
 *   processing.
 * * `math` - The template contains only MathML content, and must be wrapped in an `<math>` node prior to
 *   processing.
 *
 * If no `type` is specified, then the type is considered to be html.
 *
 * #### `template`
 * replace the current element with the contents of the HTML. The replacement process
 * migrates all of the attributes / classes from the old element to the new one. See the
 * {@link guide/directive#creating-custom-directives_creating-directives_template-expanding-directive
 * Directives Guide} for an example.
 *
 * You can specify `template` as a string representing the template or as a function which takes
 * two arguments `tElement` and `tAttrs` (described in the `compile` function api below) and
 * returns a string value representing the template.
 *
 *
 * #### `templateUrl`
 * Same as `template` but the template is loaded from the specified URL. Because
 * the template loading is asynchronous the compilation/linking is suspended until the template
 * is loaded.
 *
 * You can specify `templateUrl` as a string representing the URL or as a function which takes two
 * arguments `tElement` and `tAttrs` (described in the `compile` function api below) and returns
 * a string value representing the url.  In either case, the template URL is passed through {@link
 * api/ng.$sce#getTrustedResourceUrl $sce.getTrustedResourceUrl}.
 *
 *
 * #### `replace`
 * specify where the template should be inserted. Defaults to `false`.
 *
 * * `true` - the template will replace the current element.
 * * `false` - the template will replace the contents of the current element.
 *
 *
 * #### `transclude`
 * compile the content of the element and make it available to the directive.
 * Typically used with {@link ng.directive:ngTransclude
 * ngTransclude}. The advantage of transclusion is that the linking function receives a
 * transclusion function which is pre-bound to the correct scope. In a typical setup the widget
 * creates an `isolate` scope, but the transclusion is not a child, but a sibling of the `isolate`
 * scope. This makes it possible for the widget to have private state, and the transclusion to
 * be bound to the parent (pre-`isolate`) scope.
 *
 * * `true` - transclude the content of the directive.
 * * `'element'` - transclude the whole element including any directives defined at lower priority.
 *
 *
 * #### `compile`
 *
 * ```js
 *   function compile(tElement, tAttrs, transclude) { ... }
 * ```
 *
 * The compile function deals with transforming the template DOM. Since most directives do not do
 * template transformation, it is not used often. Examples that require compile functions are
 * directives that transform template DOM, such as {@link
 * api/ng.directive:ngRepeat ngRepeat}, or load the contents
 * asynchronously, such as {@link ngRoute.directive:ngView ngView}. The
 * compile function takes the following arguments.
 *
 *   * `tElement` - template element - The element where the directive has been declared. It is
 *     safe to do template transformation on the element and child elements only.
 *
 *   * `tAttrs` - template attributes - Normalized list of attributes declared on this element shared
 *     between all directive compile functions.
 *
 *   * `transclude` -  [*DEPRECATED*!] A transclude linking function: `function(scope, cloneLinkingFn)`
 *
 * <div class="alert alert-warning">
 * **Note:** The template instance and the link instance may be different objects if the template has
 * been cloned. For this reason it is **not** safe to do anything other than DOM transformations that
 * apply to all cloned DOM nodes within the compile function. Specifically, DOM listener registration
 * should be done in a linking function rather than in a compile function.
 * </div>

 * <div class="alert alert-warning">
 * **Note:** The compile function cannot handle directives that recursively use themselves in their
 * own templates or compile functions. Compiling these directives results in an infinite loop and a
 * stack overflow errors.
 *
 * This can be avoided by manually using $compile in the postLink function to imperatively compile
 * a directive's template instead of relying on automatic template compilation via `template` or
 * `templateUrl` declaration or manual compilation inside the compile function.
 * </div>
 *
 * <div class="alert alert-error">
 * **Note:** The `transclude` function that is passed to the compile function is deprecated, as it
 *   e.g. does not know about the right outer scope. Please use the transclude function that is passed
 *   to the link function instead.
 * </div>

 * A compile function can have a return value which can be either a function or an object.
 *
 * * returning a (post-link) function - is equivalent to registering the linking function via the
 *   `link` property of the config object when the compile function is empty.
 *
 * * returning an object with function(s) registered via `pre` and `post` properties - allows you to
 *   control when a linking function should be called during the linking phase. See info about
 *   pre-linking and post-linking functions below.
 *
 *
 * #### `link`
 * This property is used only if the `compile` property is not defined.
 *
 * ```js
 *   function link(scope, iElement, iAttrs, controller, transcludeFn) { ... }
 * ```
 *
 * The link function is responsible for registering DOM listeners as well as updating the DOM. It is
 * executed after the template has been cloned. This is where most of the directive logic will be
 * put.
 *
 *   * `scope` - {@link ng.$rootScope.Scope Scope} - The scope to be used by the
 *     directive for registering {@link ng.$rootScope.Scope#$watch watches}.
 *
 *   * `iElement` - instance element - The element where the directive is to be used. It is safe to
 *     manipulate the children of the element only in `postLink` function since the children have
 *     already been linked.
 *
 *   * `iAttrs` - instance attributes - Normalized list of attributes declared on this element shared
 *     between all directive linking functions.
 *
 *   * `controller` - a controller instance - A controller instance if at least one directive on the
 *     element defines a controller. The controller is shared among all the directives, which allows
 *     the directives to use the controllers as a communication channel.
 *
 *   * `transcludeFn` - A transclude linking function pre-bound to the correct transclusion scope.
 *     The scope can be overridden by an optional first argument. This is the same as the `$transclude`
 *     parameter of directive controllers.
 *     `function([scope], cloneLinkingFn)`.
 *
 *
 * #### Pre-linking function
 *
 * Executed before the child elements are linked. Not safe to do DOM transformation since the
 * compiler linking function will fail to locate the correct elements for linking.
 *
 * #### Post-linking function
 *
 * Executed after the child elements are linked. It is safe to do DOM transformation in the post-linking function.
 *
 * <a name="Attributes"></a>
 * ### Attributes
 *
 * The {@link ng.$compile.directive.Attributes Attributes} object - passed as a parameter in the
 * `link()` or `compile()` functions. It has a variety of uses.
 *
 * accessing *Normalized attribute names:*
 * Directives like 'ngBind' can be expressed in many ways: 'ng:bind', `data-ng-bind`, or 'x-ng-bind'.
 * the attributes object allows for normalized access to
 *   the attributes.
 *
 * * *Directive inter-communication:* All directives share the same instance of the attributes
 *   object which allows the directives to use the attributes object as inter directive
 *   communication.
 *
 * * *Supports interpolation:* Interpolation attributes are assigned to the attribute object
 *   allowing other directives to read the interpolated value.
 *
 * * *Observing interpolated attributes:* Use `$observe` to observe the value changes of attributes
 *   that contain interpolation (e.g. `src="{{bar}}"`). Not only is this very efficient but it's also
 *   the only way to easily get the actual value because during the linking phase the interpolation
 *   hasn't been evaluated yet and so the value is at this time set to `undefined`.
 *
 * ```js
 * function linkingFn(scope, elm, attrs, ctrl) {
 *   // get the attribute value
 *   console.log(attrs.ngModel);
 *
 *   // change the attribute
 *   attrs.$set('ngModel', 'new value');
 *
 *   // observe changes to interpolated attribute
 *   attrs.$observe('ngModel', function(value) {
 *     console.log('ngModel has changed value to ' + value);
 *   });
 * }
 * ```
 *
 * Below is an example using `$compileProvider`.
 *
 * <div class="alert alert-warning">
 * **Note**: Typically directives are registered with `module.directive`. The example below is
 * to illustrate how `$compile` works.
 * </div>
 *
 <example module="compile">
   <file name="index.html">
    <script>
      angular.module('compile', [], function($compileProvider) {
        // configure new 'compile' directive by passing a directive
        // factory function. The factory function injects the '$compile'
        $compileProvider.directive('compile', function($compile) {
          // directive factory creates a link function
          return function(scope, element, attrs) {
            scope.$watch(
              function(scope) {
                 // watch the 'compile' expression for changes
                return scope.$eval(attrs.compile);
              },
              function(value) {
                // when the 'compile' expression changes
                // assign it into the current DOM
                element.html(value);

                // compile the new DOM and link it to the current
                // scope.
                // NOTE: we only compile .childNodes so that
                // we don't get into infinite loop compiling ourselves
                $compile(element.contents())(scope);
              }
            );
          };
        })
      });

      function Ctrl($scope) {
        $scope.name = 'Angular';
        $scope.html = 'Hello {{name}}';
      }
    </script>
    <div ng-controller="Ctrl">
      <input ng-model="name"> <br>
      <textarea ng-model="html"></textarea> <br>
      <div compile="html"></div>
    </div>
   </file>
   <file name="protractor.js" type="protractor">
     it('should auto compile', function() {
       var textarea = $('textarea');
       var output = $('div[compile]');
       // The initial state reads 'Hello Angular'.
       expect(output.getText()).toBe('Hello Angular');
       textarea.clear();
       textarea.sendKeys('{{name}}!');
       expect(output.getText()).toBe('Angular!');
     });
   </file>
 </example>

 *
 *
 * @param {string|DOMElement} element Element or HTML string to compile into a template function.
 * @param {function(angular.Scope, cloneAttachFn=)} transclude function available to directives.
 * @param {number} maxPriority only apply directives lower than given priority (Only effects the
 *                 root element(s), not their children)
 * @returns {function(scope, cloneAttachFn=)} a link function which is used to bind template
 * (a DOM element/tree) to a scope. Where:
 *
 *  * `scope` - A {@link ng.$rootScope.Scope Scope} to bind to.
 *  * `cloneAttachFn` - If `cloneAttachFn` is provided, then the link function will clone the
 *  `template` and call the `cloneAttachFn` function allowing the caller to attach the
 *  cloned elements to the DOM document at the appropriate place. The `cloneAttachFn` is
 *  called as: <br> `cloneAttachFn(clonedElement, scope)` where:
 *
 *      * `clonedElement` - is a clone of the original `element` passed into the compiler.
 *      * `scope` - is the current scope with which the linking function is working with.
 *
 * Calling the linking function returns the element of the template. It is either the original
 * element passed in, or the clone of the element if the `cloneAttachFn` is provided.
 *
 * After linking the view is not updated until after a call to $digest which typically is done by
 * Angular automatically.
 *
 * If you need access to the bound view, there are two ways to do it:
 *
 * - If you are not asking the linking function to clone the template, create the DOM element(s)
 *   before you send them to the compiler and keep this reference around.
 *   ```js
 *     var element = $compile('<p>{{total}}</p>')(scope);
 *   ```
 *
 * - if on the other hand, you need the element to be cloned, the view reference from the original
 *   example would not point to the clone, but rather to the original template that was cloned. In
 *   this case, you can access the clone via the cloneAttachFn:
 *   ```js
 *     var templateElement = angular.element('<p>{{total}}</p>'),
 *         scope = ....;
 *
 *     var clonedElement = $compile(templateElement)(scope, function(clonedElement, scope) {
 *       //attach the clone to DOM document at the right place
 *     });
 *
 *     //now we have reference to the cloned DOM via `clonedElement`
 *   ```
 *
 *
 * For information on how the compiler works, see the
 * {@link guide/compiler Angular HTML Compiler} section of the Developer Guide.
 */

var $compileMinErr = minErr('$compile');

/**
 * @ngdoc provider
 * @name $compileProvider
 * @function
 *
 * @description
 */
$CompileProvider.$inject = ['$provide', '$$sanitizeUriProvider'];
function $CompileProvider($provide, $$sanitizeUriProvider) {
  var hasDirectives = {},
      Suffix = 'Directive',
      COMMENT_DIRECTIVE_REGEXP = /^\s*directive\:\s*([\d\w_\-]+)\s+(.*)$/,
      CLASS_DIRECTIVE_REGEXP = /(([\d\w_\-]+)(?:\:([^;]+))?;?)/,
      ALL_OR_NOTHING_ATTRS = makeMap('ngSrc,ngSrcset,src,srcset');

  // Ref: http://developers.whatwg.org/webappapis.html#event-handler-idl-attributes
  // The assumption is that future DOM event attribute names will begin with
  // 'on' and be composed of only English letters.
  var EVENT_HANDLER_ATTR_REGEXP = /^(on[a-z]+|formaction)$/;

  /**
   * @ngdoc method
   * @name $compileProvider#directive
   * @function
   *
   * @description
   * Register a new directive with the compiler.
   *
   * @param {string|Object} name Name of the directive in camel-case (i.e. <code>ngBind</code> which
   *    will match as <code>ng-bind</code>), or an object map of directives where the keys are the
   *    names and the values are the factories.
   * @param {Function|Array} directiveFactory An injectable directive factory function. See
   *    {@link guide/directive} for more info.
   * @returns {ng.$compileProvider} Self for chaining.
   */
   this.directive = function registerDirective(name, directiveFactory) {
    assertNotHasOwnProperty(name, 'directive');
    if (isString(name)) {
      assertArg(directiveFactory, 'directiveFactory');
      if (!hasDirectives.hasOwnProperty(name)) {
        hasDirectives[name] = [];
        $provide.factory(name + Suffix, ['$injector', '$exceptionHandler',
          function($injector, $exceptionHandler) {
            var directives = [];
            forEach(hasDirectives[name], function(directiveFactory, index) {
              try {
                var directive = $injector.invoke(directiveFactory);
                if (isFunction(directive)) {
                  directive = { compile: valueFn(directive) };
                } else if (!directive.compile && directive.link) {
                  directive.compile = valueFn(directive.link);
                }
                directive.priority = directive.priority || 0;
                directive.index = index;
                directive.name = directive.name || name;
                directive.require = directive.require || (directive.controller && directive.name);
                directive.restrict = directive.restrict || 'A';
                directives.push(directive);
              } catch (e) {
                $exceptionHandler(e);
              }
            });
            return directives;
          }]);
      }
      hasDirectives[name].push(directiveFactory);
    } else {
      forEach(name, reverseParams(registerDirective));
    }
    return this;
  };


  /**
   * @ngdoc method
   * @name $compileProvider#aHrefSanitizationWhitelist
   * @function
   *
   * @description
   * Retrieves or overrides the default regular expression that is used for whitelisting of safe
   * urls during a[href] sanitization.
   *
   * The sanitization is a security measure aimed at prevent XSS attacks via html links.
   *
   * Any url about to be assigned to a[href] via data-binding is first normalized and turned into
   * an absolute url. Afterwards, the url is matched against the `aHrefSanitizationWhitelist`
   * regular expression. If a match is found, the original url is written into the dom. Otherwise,
   * the absolute url is prefixed with `'unsafe:'` string and only then is it written into the DOM.
   *
   * @param {RegExp=} regexp New regexp to whitelist urls with.
   * @returns {RegExp|ng.$compileProvider} Current RegExp if called without value or self for
   *    chaining otherwise.
   */
  this.aHrefSanitizationWhitelist = function(regexp) {
    if (isDefined(regexp)) {
      $$sanitizeUriProvider.aHrefSanitizationWhitelist(regexp);
      return this;
    } else {
      return $$sanitizeUriProvider.aHrefSanitizationWhitelist();
    }
  };


  /**
   * @ngdoc method
   * @name $compileProvider#imgSrcSanitizationWhitelist
   * @function
   *
   * @description
   * Retrieves or overrides the default regular expression that is used for whitelisting of safe
   * urls during img[src] sanitization.
   *
   * The sanitization is a security measure aimed at prevent XSS attacks via html links.
   *
   * Any url about to be assigned to img[src] via data-binding is first normalized and turned into
   * an absolute url. Afterwards, the url is matched against the `imgSrcSanitizationWhitelist`
   * regular expression. If a match is found, the original url is written into the dom. Otherwise,
   * the absolute url is prefixed with `'unsafe:'` string and only then is it written into the DOM.
   *
   * @param {RegExp=} regexp New regexp to whitelist urls with.
   * @returns {RegExp|ng.$compileProvider} Current RegExp if called without value or self for
   *    chaining otherwise.
   */
  this.imgSrcSanitizationWhitelist = function(regexp) {
    if (isDefined(regexp)) {
      $$sanitizeUriProvider.imgSrcSanitizationWhitelist(regexp);
      return this;
    } else {
      return $$sanitizeUriProvider.imgSrcSanitizationWhitelist();
    }
  };

  this.$get = [
            '$injector', '$interpolate', '$exceptionHandler', '$http', '$templateCache', '$parse',
            '$controller', '$rootScope', '$document', '$sce', '$animate', '$$sanitizeUri',
    function($injector,   $interpolate,   $exceptionHandler,   $http,   $templateCache,   $parse,
             $controller,   $rootScope,   $document,   $sce,   $animate,   $$sanitizeUri) {

    var Attributes = function(element, attr) {
      this.$$element = element;
      this.$attr = attr || {};
    };

    Attributes.prototype = {
      $normalize: directiveNormalize,


      /**
       * @ngdoc method
       * @name $compile.directive.Attributes#$addClass
       * @function
       *
       * @description
       * Adds the CSS class value specified by the classVal parameter to the element. If animations
       * are enabled then an animation will be triggered for the class addition.
       *
       * @param {string} classVal The className value that will be added to the element
       */
      $addClass : function(classVal) {
        if(classVal && classVal.length > 0) {
          $animate.addClass(this.$$element, classVal);
        }
      },

      /**
       * @ngdoc method
       * @name $compile.directive.Attributes#$removeClass
       * @function
       *
       * @description
       * Removes the CSS class value specified by the classVal parameter from the element. If
       * animations are enabled then an animation will be triggered for the class removal.
       *
       * @param {string} classVal The className value that will be removed from the element
       */
      $removeClass : function(classVal) {
        if(classVal && classVal.length > 0) {
          $animate.removeClass(this.$$element, classVal);
        }
      },

      /**
       * @ngdoc method
       * @name $compile.directive.Attributes#$updateClass
       * @function
       *
       * @description
       * Adds and removes the appropriate CSS class values to the element based on the difference
       * between the new and old CSS class values (specified as newClasses and oldClasses).
       *
       * @param {string} newClasses The current CSS className value
       * @param {string} oldClasses The former CSS className value
       */
      $updateClass : function(newClasses, oldClasses) {
        var toAdd = tokenDifference(newClasses, oldClasses);
        var toRemove = tokenDifference(oldClasses, newClasses);

        if(toAdd.length === 0) {
          $animate.removeClass(this.$$element, toRemove);
        } else if(toRemove.length === 0) {
          $animate.addClass(this.$$element, toAdd);
        } else {
          $animate.setClass(this.$$element, toAdd, toRemove);
        }
      },

      /**
       * Set a normalized attribute on the element in a way such that all directives
       * can share the attribute. This function properly handles boolean attributes.
       * @param {string} key Normalized key. (ie ngAttribute)
       * @param {string|boolean} value The value to set. If `null` attribute will be deleted.
       * @param {boolean=} writeAttr If false, does not write the value to DOM element attribute.
       *     Defaults to true.
       * @param {string=} attrName Optional none normalized name. Defaults to key.
       */
      $set: function(key, value, writeAttr, attrName) {
        // TODO: decide whether or not to throw an error if "class"
        //is set through this function since it may cause $updateClass to
        //become unstable.

        var booleanKey = getBooleanAttrName(this.$$element[0], key),
            normalizedVal,
            nodeName;

        if (booleanKey) {
          this.$$element.prop(key, value);
          attrName = booleanKey;
        }

        this[key] = value;

        // translate normalized key to actual key
        if (attrName) {
          this.$attr[key] = attrName;
        } else {
          attrName = this.$attr[key];
          if (!attrName) {
            this.$attr[key] = attrName = snake_case(key, '-');
          }
        }

        nodeName = nodeName_(this.$$element);

        // sanitize a[href] and img[src] values
        if ((nodeName === 'A' && key === 'href') ||
            (nodeName === 'IMG' && key === 'src')) {
          this[key] = value = $$sanitizeUri(value, key === 'src');
        }

        if (writeAttr !== false) {
          if (value === null || value === undefined) {
            this.$$element.removeAttr(attrName);
          } else {
            this.$$element.attr(attrName, value);
          }
        }

        // fire observers
        var $$observers = this.$$observers;
        $$observers && forEach($$observers[key], function(fn) {
          try {
            fn(value);
          } catch (e) {
            $exceptionHandler(e);
          }
        });
      },


      /**
       * @ngdoc method
       * @name $compile.directive.Attributes#$observe
       * @function
       *
       * @description
       * Observes an interpolated attribute.
       *
       * The observer function will be invoked once during the next `$digest` following
       * compilation. The observer is then invoked whenever the interpolated value
       * changes.
       *
       * @param {string} key Normalized key. (ie ngAttribute) .
       * @param {function(interpolatedValue)} fn Function that will be called whenever
                the interpolated value of the attribute changes.
       *        See the {@link guide/directive#Attributes Directives} guide for more info.
       * @returns {function()} Returns a deregistration function for this observer.
       */
      $observe: function(key, fn) {
        var attrs = this,
            $$observers = (attrs.$$observers || (attrs.$$observers = {})),
            listeners = ($$observers[key] || ($$observers[key] = []));

        listeners.push(fn);
        $rootScope.$evalAsync(function() {
          if (!listeners.$$inter) {
            // no one registered attribute interpolation function, so lets call it manually
            fn(attrs[key]);
          }
        });

        return function() {
          arrayRemove(listeners, fn);
        };
      }
    };

    var startSymbol = $interpolate.startSymbol(),
        endSymbol = $interpolate.endSymbol(),
        denormalizeTemplate = (startSymbol == '{{' || endSymbol  == '}}')
            ? identity
            : function denormalizeTemplate(template) {
              return template.replace(/\{\{/g, startSymbol).replace(/}}/g, endSymbol);
        },
        NG_ATTR_BINDING = /^ngAttr[A-Z]/;


    return compile;

    //================================

    function compile($compileNodes, transcludeFn, maxPriority, ignoreDirective,
                        previousCompileContext) {
      if (!($compileNodes instanceof jqLite)) {
        // jquery always rewraps, whereas we need to preserve the original selector so that we can
        // modify it.
        $compileNodes = jqLite($compileNodes);
      }

      var isText = function(node) {
        return node && node.nodeType === Node.TEXT_NODE;
      };

      var normalizeNode = function(node) {
        var child, combined, lastSibling, _i, _len, _ref, _results;
        lastSibling = null;
        _ref = (node != null ? node.childNodes : void 0) || [];
        _results = [];
        for (_i = 0, _len = _ref.length; _i < _len; _i++) {
          child = _ref[_i];
          if (isText(child) && isText(lastSibling)) {
            combined = lastSibling.nodeValue + child.nodeValue;
            child.nodeValue = combined;
            node.removeChild(lastSibling);
          } else {
            normalizeNode(child);
          }
          _results.push(lastSibling = child);
        }
        return _results;
      };

      // We can not compile top level text elements since text nodes can be merged and we will
      // not be able to attach scope data to them, so we will wrap them in <span>
      // We also need to call `normalize` on the nodes, because in some cases
      // browsers (like IE11) allocate multiple text nodes when parsing a single block of HTML.
      forEach($compileNodes, function(node, index){
        normalizeNode(node);

        if (node.nodeType == 3 /* text node */ && node.nodeValue.match(/\S+/) /* non-empty */ ) {
          $compileNodes[index] = node = jqLite(node).wrap('<span></span>').parent()[0];
        }
      });
      var compositeLinkFn =
              compileNodes($compileNodes, transcludeFn, $compileNodes,
                           maxPriority, ignoreDirective, previousCompileContext);
      safeAddClass($compileNodes, 'ng-scope');
      return function publicLinkFn(scope, cloneConnectFn, transcludeControllers){
        assertArg(scope, 'scope');
        // important!!: we must call our jqLite.clone() since the jQuery one is trying to be smart
        // and sometimes changes the structure of the DOM.
        var $linkNode = cloneConnectFn
          ? JQLitePrototype.clone.call($compileNodes) // IMPORTANT!!!
          : $compileNodes;

        forEach(transcludeControllers, function(instance, name) {
          $linkNode.data('$' + name + 'Controller', instance);
        });

        // Attach scope only to non-text nodes.
        for(var i = 0, ii = $linkNode.length; i<ii; i++) {
          var node = $linkNode[i],
              nodeType = node.nodeType;
          if (nodeType === 1 /* element */ || nodeType === 9 /* document */) {
            $linkNode.eq(i).data('$scope', scope);
          }
        }

        if (cloneConnectFn) cloneConnectFn($linkNode, scope);
        if (compositeLinkFn) compositeLinkFn(scope, $linkNode, $linkNode);
        return $linkNode;
      };
    }

    function safeAddClass($element, className) {
      try {
        $element.addClass(className);
      } catch(e) {
        // ignore, since it means that we are trying to set class on
        // SVG element, where class name is read-only.
      }
    }

    /**
     * Compile function matches each node in nodeList against the directives. Once all directives
     * for a particular node are collected their compile functions are executed. The compile
     * functions return values - the linking functions - are combined into a composite linking
     * function, which is the a linking function for the node.
     *
     * @param {NodeList} nodeList an array of nodes or NodeList to compile
     * @param {function(angular.Scope, cloneAttachFn=)} transcludeFn A linking function, where the
     *        scope argument is auto-generated to the new child of the transcluded parent scope.
     * @param {DOMElement=} $rootElement If the nodeList is the root of the compilation tree then
     *        the rootElement must be set the jqLite collection of the compile root. This is
     *        needed so that the jqLite collection items can be replaced with widgets.
     * @param {number=} maxPriority Max directive priority.
     * @returns {Function} A composite linking function of all of the matched directives or null.
     */
    function compileNodes(nodeList, transcludeFn, $rootElement, maxPriority, ignoreDirective,
                            previousCompileContext) {
      var linkFns = [],
          attrs, directives, nodeLinkFn, childNodes, childLinkFn, linkFnFound;

      for (var i = 0; i < nodeList.length; i++) {
        attrs = new Attributes();

        // we must always refer to nodeList[i] since the nodes can be replaced underneath us.
        directives = collectDirectives(nodeList[i], [], attrs, i === 0 ? maxPriority : undefined,
                                        ignoreDirective);

        nodeLinkFn = (directives.length)
            ? applyDirectivesToNode(directives, nodeList[i], attrs, transcludeFn, $rootElement,
                                      null, [], [], previousCompileContext)
            : null;

        if (nodeLinkFn && nodeLinkFn.scope) {
          safeAddClass(jqLite(nodeList[i]), 'ng-scope');
        }

        childLinkFn = (nodeLinkFn && nodeLinkFn.terminal ||
                      !(childNodes = nodeList[i].childNodes) ||
                      !childNodes.length)
            ? null
            : compileNodes(childNodes,
                 nodeLinkFn ? nodeLinkFn.transclude : transcludeFn);

        linkFns.push(nodeLinkFn, childLinkFn);
        linkFnFound = linkFnFound || nodeLinkFn || childLinkFn;
        //use the previous context only for the first element in the virtual group
        previousCompileContext = null;
      }

      // return a linking function if we have found anything, null otherwise
      return linkFnFound ? compositeLinkFn : null;

      function compositeLinkFn(scope, nodeList, $rootElement, boundTranscludeFn) {
        var nodeLinkFn, childLinkFn, node, $node, childScope, i, ii, n;

        // copy nodeList so that linking doesn't break due to live list updates.
        var nodeListLength = nodeList.length,
            stableNodeList = new Array(nodeListLength);
        for (i = 0; i < nodeListLength; i++) {
          stableNodeList[i] = nodeList[i];
        }

        for(i = 0, n = 0, ii = linkFns.length; i < ii; n++) {
          node = stableNodeList[n];
          nodeLinkFn = linkFns[i++];
          childLinkFn = linkFns[i++];
          $node = jqLite(node);

          if (nodeLinkFn) {
            if (nodeLinkFn.scope) {
              childScope = scope.$new();
              $node.data('$scope', childScope);
            } else {
              childScope = scope;
            }

            // We need to create a new boundTranscludeFn if
            //  - a directive on this element wants to transclude
            //  or
            //  - there is no boundTranscludeFn already and a transcludeFn was passed in
            if ( nodeLinkFn.transcludeOnThisElement || (!boundTranscludeFn && transcludeFn) ) {
              boundTranscludeFn = createBoundTranscludeFn(scope, nodeLinkFn.transclude || transcludeFn);
            }

            nodeLinkFn(childLinkFn, childScope, node, $rootElement, boundTranscludeFn);

          } else if (childLinkFn) {
            childLinkFn(scope, node.childNodes, undefined, boundTranscludeFn);
          }
        }
      }
    }

    function createBoundTranscludeFn(scope, transcludeFn) {
      return function boundTranscludeFn(transcludedScope, cloneFn, controllers) {
        var scopeCreated = false;

        if (!transcludedScope) {
          transcludedScope = scope.$new();
          transcludedScope.$$transcluded = true;
          scopeCreated = true;
        }

        var clone = transcludeFn(transcludedScope, cloneFn, controllers);
        if (scopeCreated) {
          clone.on('$destroy', bind(transcludedScope, transcludedScope.$destroy));
        }
        return clone;
      };
    }

    /**
     * Looks for directives on the given node and adds them to the directive collection which is
     * sorted.
     *
     * @param node Node to search.
     * @param directives An array to which the directives are added to. This array is sorted before
     *        the function returns.
     * @param attrs The shared attrs object which is used to populate the normalized attributes.
     * @param {number=} maxPriority Max directive priority.
     */
    function collectDirectives(node, directives, attrs, maxPriority, ignoreDirective) {
      var nodeType = node.nodeType,
          attrsMap = attrs.$attr,
          match,
          className;

      switch(nodeType) {
        case 1: /* Element */
          // use the node name: <directive>
          addDirective(directives,
              directiveNormalize(nodeName_(node).toLowerCase()), 'E', maxPriority, ignoreDirective);

          // iterate over the attributes
          for (var attr, name, nName, ngAttrName, value, nAttrs = node.attributes,
                   j = 0, jj = nAttrs && nAttrs.length; j < jj; j++) {
            var attrStartName = false;
            var attrEndName = false;

            attr = nAttrs[j];
            if (!msie || msie >= 8 || attr.specified) {
              name = attr.name;
              // support ngAttr attribute binding
              ngAttrName = directiveNormalize(name);
              if (NG_ATTR_BINDING.test(ngAttrName)) {
                name = snake_case(ngAttrName.substr(6), '-');
              }

              var directiveNName = ngAttrName.replace(/(Start|End)$/, '');
              if (ngAttrName === directiveNName + 'Start') {
                attrStartName = name;
                attrEndName = name.substr(0, name.length - 5) + 'end';
                name = name.substr(0, name.length - 6);
              }

              nName = directiveNormalize(name.toLowerCase());
              attrsMap[nName] = name;
              attrs[nName] = value = trim(attr.value);
              if (getBooleanAttrName(node, nName)) {
                attrs[nName] = true; // presence means true
              }
              addAttrInterpolateDirective(node, directives, value, nName);
              addDirective(directives, nName, 'A', maxPriority, ignoreDirective, attrStartName,
                            attrEndName);
            }
          }

          // use class as directive
          className = node.className;
          if (isString(className) && className !== '') {
            while (match = CLASS_DIRECTIVE_REGEXP.exec(className)) {
              nName = directiveNormalize(match[2]);
              if (addDirective(directives, nName, 'C', maxPriority, ignoreDirective)) {
                attrs[nName] = trim(match[3]);
              }
              className = className.substr(match.index + match[0].length);
            }
          }
          break;
        case 3: /* Text Node */
          addTextInterpolateDirective(directives, node.nodeValue);
          break;
        case 8: /* Comment */
          try {
            match = COMMENT_DIRECTIVE_REGEXP.exec(node.nodeValue);
            if (match) {
              nName = directiveNormalize(match[1]);
              if (addDirective(directives, nName, 'M', maxPriority, ignoreDirective)) {
                attrs[nName] = trim(match[2]);
              }
            }
          } catch (e) {
            // turns out that under some circumstances IE9 throws errors when one attempts to read
            // comment's node value.
            // Just ignore it and continue. (Can't seem to reproduce in test case.)
          }
          break;
      }

      directives.sort(byPriority);
      return directives;
    }

    /**
     * Given a node with an directive-start it collects all of the siblings until it finds
     * directive-end.
     * @param node
     * @param attrStart
     * @param attrEnd
     * @returns {*}
     */
    function groupScan(node, attrStart, attrEnd) {
      var nodes = [];
      var depth = 0;
      if (attrStart && node.hasAttribute && node.hasAttribute(attrStart)) {
        var startNode = node;
        do {
          if (!node) {
            throw $compileMinErr('uterdir',
                      "Unterminated attribute, found '{0}' but no matching '{1}' found.",
                      attrStart, attrEnd);
          }
          if (node.nodeType == 1 /** Element **/) {
            if (node.hasAttribute(attrStart)) depth++;
            if (node.hasAttribute(attrEnd)) depth--;
          }
          nodes.push(node);
          node = node.nextSibling;
        } while (depth > 0);
      } else {
        nodes.push(node);
      }

      return jqLite(nodes);
    }

    /**
     * Wrapper for linking function which converts normal linking function into a grouped
     * linking function.
     * @param linkFn
     * @param attrStart
     * @param attrEnd
     * @returns {Function}
     */
    function groupElementsLinkFnWrapper(linkFn, attrStart, attrEnd) {
      return function(scope, element, attrs, controllers, transcludeFn) {
        element = groupScan(element[0], attrStart, attrEnd);
        return linkFn(scope, element, attrs, controllers, transcludeFn);
      };
    }

    /**
     * Once the directives have been collected, their compile functions are executed. This method
     * is responsible for inlining directive templates as well as terminating the application
     * of the directives if the terminal directive has been reached.
     *
     * @param {Array} directives Array of collected directives to execute their compile function.
     *        this needs to be pre-sorted by priority order.
     * @param {Node} compileNode The raw DOM node to apply the compile functions to
     * @param {Object} templateAttrs The shared attribute function
     * @param {function(angular.Scope, cloneAttachFn=)} transcludeFn A linking function, where the
     *                                                  scope argument is auto-generated to the new
     *                                                  child of the transcluded parent scope.
     * @param {JQLite} jqCollection If we are working on the root of the compile tree then this
     *                              argument has the root jqLite array so that we can replace nodes
     *                              on it.
     * @param {Object=} originalReplaceDirective An optional directive that will be ignored when
     *                                           compiling the transclusion.
     * @param {Array.<Function>} preLinkFns
     * @param {Array.<Function>} postLinkFns
     * @param {Object} previousCompileContext Context used for previous compilation of the current
     *                                        node
     * @returns {Function} linkFn
     */
    function applyDirectivesToNode(directives, compileNode, templateAttrs, transcludeFn,
                                   jqCollection, originalReplaceDirective, preLinkFns, postLinkFns,
                                   previousCompileContext) {
      previousCompileContext = previousCompileContext || {};

      var terminalPriority = -Number.MAX_VALUE,
          newScopeDirective,
          controllerDirectives = previousCompileContext.controllerDirectives,
          newIsolateScopeDirective = previousCompileContext.newIsolateScopeDirective,
          templateDirective = previousCompileContext.templateDirective,
          nonTlbTranscludeDirective = previousCompileContext.nonTlbTranscludeDirective,
          hasTranscludeDirective = false,
          hasElementTranscludeDirective = previousCompileContext.hasElementTranscludeDirective,
          $compileNode = templateAttrs.$$element = jqLite(compileNode),
          directive,
          directiveName,
          $template,
          replaceDirective = originalReplaceDirective,
          childTranscludeFn = transcludeFn,
          linkFn,
          directiveValue;

      // executes all directives on the current element
      for(var i = 0, ii = directives.length; i < ii; i++) {
        directive = directives[i];
        var attrStart = directive.$$start;
        var attrEnd = directive.$$end;

        // collect multiblock sections
        if (attrStart) {
          $compileNode = groupScan(compileNode, attrStart, attrEnd);
        }
        $template = undefined;

        if (terminalPriority > directive.priority) {
          break; // prevent further processing of directives
        }

        if (directiveValue = directive.scope) {
          newScopeDirective = newScopeDirective || directive;

          // skip the check for directives with async templates, we'll check the derived sync
          // directive when the template arrives
          if (!directive.templateUrl) {
            assertNoDuplicate('new/isolated scope', newIsolateScopeDirective, directive,
                              $compileNode);
            if (isObject(directiveValue)) {
              newIsolateScopeDirective = directive;
            }
          }
        }

        directiveName = directive.name;

        if (!directive.templateUrl && directive.controller) {
          directiveValue = directive.controller;
          controllerDirectives = controllerDirectives || {};
          assertNoDuplicate("'" + directiveName + "' controller",
              controllerDirectives[directiveName], directive, $compileNode);
          controllerDirectives[directiveName] = directive;
        }

        if (directiveValue = directive.transclude) {
          hasTranscludeDirective = true;

          // Special case ngIf and ngRepeat so that we don't complain about duplicate transclusion.
          // This option should only be used by directives that know how to safely handle element transclusion,
          // where the transcluded nodes are added or replaced after linking.
          if (!directive.$$tlb) {
            assertNoDuplicate('transclusion', nonTlbTranscludeDirective, directive, $compileNode);
            nonTlbTranscludeDirective = directive;
          }

          if (directiveValue == 'element') {
            hasElementTranscludeDirective = true;
            terminalPriority = directive.priority;
            $template = groupScan(compileNode, attrStart, attrEnd);
            $compileNode = templateAttrs.$$element =
                jqLite(document.createComment(' ' + directiveName + ': ' +
                                              templateAttrs[directiveName] + ' '));
            compileNode = $compileNode[0];
            replaceWith(jqCollection, jqLite(sliceArgs($template)), compileNode);

            childTranscludeFn = compile($template, transcludeFn, terminalPriority,
                                        replaceDirective && replaceDirective.name, {
                                          // Don't pass in:
                                          // - controllerDirectives - otherwise we'll create duplicates controllers
                                          // - newIsolateScopeDirective or templateDirective - combining templates with
                                          //   element transclusion doesn't make sense.
                                          //
                                          // We need only nonTlbTranscludeDirective so that we prevent putting transclusion
                                          // on the same element more than once.
                                          nonTlbTranscludeDirective: nonTlbTranscludeDirective
                                        });
          } else {
            $template = jqLite(jqLiteClone(compileNode)).contents();
            $compileNode.empty(); // clear contents
            childTranscludeFn = compile($template, transcludeFn);
          }
        }

        if (directive.template) {
          assertNoDuplicate('template', templateDirective, directive, $compileNode);
          templateDirective = directive;

          directiveValue = (isFunction(directive.template))
              ? directive.template($compileNode, templateAttrs)
              : directive.template;

          directiveValue = denormalizeTemplate(directiveValue);

          if (directive.replace) {
            replaceDirective = directive;
            if (jqLiteIsTextNode(directiveValue)) {
              $template = [];
            } else {
              $template = jqLite(wrapTemplate(directive.type, trim(directiveValue)));
            }
            compileNode = $template[0];

            if ($template.length != 1 || compileNode.nodeType !== 1) {
              throw $compileMinErr('tplrt',
                  "Template for directive '{0}' must have exactly one root element. {1}",
                  directiveName, '');
            }

            replaceWith(jqCollection, $compileNode, compileNode);

            var newTemplateAttrs = {$attr: {}};

            // combine directives from the original node and from the template:
            // - take the array of directives for this element
            // - split it into two parts, those that already applied (processed) and those that weren't (unprocessed)
            // - collect directives from the template and sort them by priority
            // - combine directives as: processed + template + unprocessed
            var templateDirectives = collectDirectives(compileNode, [], newTemplateAttrs);
            var unprocessedDirectives = directives.splice(i + 1, directives.length - (i + 1));

            if (newIsolateScopeDirective) {
              markDirectivesAsIsolate(templateDirectives);
            }
            directives = directives.concat(templateDirectives).concat(unprocessedDirectives);
            mergeTemplateAttributes(templateAttrs, newTemplateAttrs);

            ii = directives.length;
          } else {
            $compileNode.html(directiveValue);
          }
        }

        if (directive.templateUrl) {
          assertNoDuplicate('template', templateDirective, directive, $compileNode);
          templateDirective = directive;

          if (directive.replace) {
            replaceDirective = directive;
          }

          nodeLinkFn = compileTemplateUrl(directives.splice(i, directives.length - i), $compileNode,
              templateAttrs, jqCollection, childTranscludeFn, preLinkFns, postLinkFns, {
                controllerDirectives: controllerDirectives,
                newIsolateScopeDirective: newIsolateScopeDirective,
                templateDirective: templateDirective,
                nonTlbTranscludeDirective: nonTlbTranscludeDirective
              });
          ii = directives.length;
        } else if (directive.compile) {
          try {
            linkFn = directive.compile($compileNode, templateAttrs, childTranscludeFn);
            if (isFunction(linkFn)) {
              addLinkFns(null, linkFn, attrStart, attrEnd);
            } else if (linkFn) {
              addLinkFns(linkFn.pre, linkFn.post, attrStart, attrEnd);
            }
          } catch (e) {
            $exceptionHandler(e, startingTag($compileNode));
          }
        }

        if (directive.terminal) {
          nodeLinkFn.terminal = true;
          terminalPriority = Math.max(terminalPriority, directive.priority);
        }

      }

      nodeLinkFn.scope = newScopeDirective && newScopeDirective.scope === true;
      nodeLinkFn.transcludeOnThisElement = hasTranscludeDirective;
      nodeLinkFn.transclude = childTranscludeFn;

      previousCompileContext.hasElementTranscludeDirective = hasElementTranscludeDirective;

      // might be normal or delayed nodeLinkFn depending on if templateUrl is present
      return nodeLinkFn;

      ////////////////////

      function addLinkFns(pre, post, attrStart, attrEnd) {
        if (pre) {
          if (attrStart) pre = groupElementsLinkFnWrapper(pre, attrStart, attrEnd);
          pre.require = directive.require;
          pre.directiveName = directiveName;
          if (newIsolateScopeDirective === directive || directive.$$isolateScope) {
            pre = cloneAndAnnotateFn(pre, {isolateScope: true});
          }
          preLinkFns.push(pre);
        }
        if (post) {
          if (attrStart) post = groupElementsLinkFnWrapper(post, attrStart, attrEnd);
          post.require = directive.require;
          post.directiveName = directiveName;
          if (newIsolateScopeDirective === directive || directive.$$isolateScope) {
            post = cloneAndAnnotateFn(post, {isolateScope: true});
          }
          postLinkFns.push(post);
        }
      }


      function getControllers(directiveName, require, $element, elementControllers) {
        var value, retrievalMethod = 'data', optional = false;
        if (isString(require)) {
          while((value = require.charAt(0)) == '^' || value == '?') {
            require = require.substr(1);
            if (value == '^') {
              retrievalMethod = 'inheritedData';
            }
            optional = optional || value == '?';
          }
          value = null;

          if (elementControllers && retrievalMethod === 'data') {
            value = elementControllers[require];
          }
          value = value || $element[retrievalMethod]('$' + require + 'Controller');

          if (!value && !optional) {
            throw $compileMinErr('ctreq',
                "Controller '{0}', required by directive '{1}', can't be found!",
                require, directiveName);
          }
          return value;
        } else if (isArray(require)) {
          value = [];
          forEach(require, function(require) {
            value.push(getControllers(directiveName, require, $element, elementControllers));
          });
        }
        return value;
      }


      function nodeLinkFn(childLinkFn, scope, linkNode, $rootElement, boundTranscludeFn) {
        var attrs, $element, i, ii, linkFn, controller, isolateScope, elementControllers = {}, transcludeFn;

        if (compileNode === linkNode) {
          attrs = templateAttrs;
        } else {
          attrs = shallowCopy(templateAttrs, new Attributes(jqLite(linkNode), templateAttrs.$attr));
        }
        $element = attrs.$$element;

        if (newIsolateScopeDirective) {
          var LOCAL_REGEXP = /^\s*([@=&])(\??)\s*(\w*)\s*$/;
          var $linkNode = jqLite(linkNode);

          isolateScope = scope.$new(true);

          if (templateDirective && (templateDirective === newIsolateScopeDirective ||
              templateDirective === newIsolateScopeDirective.$$originalDirective)) {
            $linkNode.data('$isolateScope', isolateScope) ;
          } else {
            $linkNode.data('$isolateScopeNoTemplate', isolateScope);
          }



          safeAddClass($linkNode, 'ng-isolate-scope');

          forEach(newIsolateScopeDirective.scope, function(definition, scopeName) {
            var match = definition.match(LOCAL_REGEXP) || [],
                attrName = match[3] || scopeName,
                optional = (match[2] == '?'),
                mode = match[1], // @, =, or &
                lastValue,
                parentGet, parentSet, compare;

            isolateScope.$$isolateBindings[scopeName] = mode + attrName;

            switch (mode) {

              case '@':
                attrs.$observe(attrName, function(value) {
                  isolateScope[scopeName] = value;
                });
                attrs.$$observers[attrName].$$scope = scope;
                if( attrs[attrName] ) {
                  // If the attribute has been provided then we trigger an interpolation to ensure
                  // the value is there for use in the link fn
                  isolateScope[scopeName] = $interpolate(attrs[attrName])(scope);
                }
                break;

              case '=':
                if (optional && !attrs[attrName]) {
                  return;
                }
                parentGet = $parse(attrs[attrName]);
                if (parentGet.literal) {
                  compare = equals;
                } else {
                  compare = function(a,b) { return a === b; };
                }
                parentSet = parentGet.assign || function() {
                  // reset the change, or we will throw this exception on every $digest
                  lastValue = isolateScope[scopeName] = parentGet(scope);
                  throw $compileMinErr('nonassign',
                      "Expression '{0}' used with directive '{1}' is non-assignable!",
                      attrs[attrName], newIsolateScopeDirective.name);
                };
                lastValue = isolateScope[scopeName] = parentGet(scope);
                isolateScope.$watch(function parentValueWatch() {
                  var parentValue = parentGet(scope);
                  if (!compare(parentValue, isolateScope[scopeName])) {
                    // we are out of sync and need to copy
                    if (!compare(parentValue, lastValue)) {
                      // parent changed and it has precedence
                      isolateScope[scopeName] = parentValue;
                    } else {
                      // if the parent can be assigned then do so
                      parentSet(scope, parentValue = isolateScope[scopeName]);
                    }
                  }
                  return lastValue = parentValue;
                }, null, parentGet.literal);
                break;

              case '&':
                parentGet = $parse(attrs[attrName]);
                isolateScope[scopeName] = function(locals) {
                  return parentGet(scope, locals);
                };
                break;

              default:
                throw $compileMinErr('iscp',
                    "Invalid isolate scope definition for directive '{0}'." +
                    " Definition: {... {1}: '{2}' ...}",
                    newIsolateScopeDirective.name, scopeName, definition);
            }
          });
        }
        transcludeFn = boundTranscludeFn && controllersBoundTransclude;
        if (controllerDirectives) {
          forEach(controllerDirectives, function(directive) {
            var locals = {
              $scope: directive === newIsolateScopeDirective || directive.$$isolateScope ? isolateScope : scope,
              $element: $element,
              $attrs: attrs,
              $transclude: transcludeFn
            }, controllerInstance;

            controller = directive.controller;
            if (controller == '@') {
              controller = attrs[directive.name];
            }

            controllerInstance = $controller(controller, locals);
            // For directives with element transclusion the element is a comment,
            // but jQuery .data doesn't support attaching data to comment nodes as it's hard to
            // clean up (http://bugs.jquery.com/ticket/8335).
            // Instead, we save the controllers for the element in a local hash and attach to .data
            // later, once we have the actual element.
            elementControllers[directive.name] = controllerInstance;
            if (!hasElementTranscludeDirective) {
              $element.data('$' + directive.name + 'Controller', controllerInstance);
            }

            if (directive.controllerAs) {
              locals.$scope[directive.controllerAs] = controllerInstance;
            }
          });
        }

        // PRELINKING
        for(i = 0, ii = preLinkFns.length; i < ii; i++) {
          try {
            linkFn = preLinkFns[i];
            linkFn(linkFn.isolateScope ? isolateScope : scope, $element, attrs,
                linkFn.require && getControllers(linkFn.directiveName, linkFn.require, $element, elementControllers), transcludeFn);
          } catch (e) {
            $exceptionHandler(e, startingTag($element));
          }
        }

        // RECURSION
        // We only pass the isolate scope, if the isolate directive has a template,
        // otherwise the child elements do not belong to the isolate directive.
        var scopeToChild = scope;
        if (newIsolateScopeDirective && (newIsolateScopeDirective.template || newIsolateScopeDirective.templateUrl === null)) {
          scopeToChild = isolateScope;
        }
        childLinkFn && childLinkFn(scopeToChild, linkNode.childNodes, undefined, boundTranscludeFn);

        // POSTLINKING
        for(i = postLinkFns.length - 1; i >= 0; i--) {
          try {
            linkFn = postLinkFns[i];
            linkFn(linkFn.isolateScope ? isolateScope : scope, $element, attrs,
                linkFn.require && getControllers(linkFn.directiveName, linkFn.require, $element, elementControllers), transcludeFn);
          } catch (e) {
            $exceptionHandler(e, startingTag($element));
          }
        }

        // This is the function that is injected as `$transclude`.
        function controllersBoundTransclude(scope, cloneAttachFn) {
          var transcludeControllers;

          // no scope passed
          if (arguments.length < 2) {
            cloneAttachFn = scope;
            scope = undefined;
          }

          if (hasElementTranscludeDirective) {
            transcludeControllers = elementControllers;
          }

          return boundTranscludeFn(scope, cloneAttachFn, transcludeControllers);
        }
      }
    }

    function markDirectivesAsIsolate(directives) {
      // mark all directives as needing isolate scope.
      for (var j = 0, jj = directives.length; j < jj; j++) {
        directives[j] = inherit(directives[j], {$$isolateScope: true});
      }
    }

    /**
     * looks up the directive and decorates it with exception handling and proper parameters. We
     * call this the boundDirective.
     *
     * @param {string} name name of the directive to look up.
     * @param {string} location The directive must be found in specific format.
     *   String containing any of theses characters:
     *
     *   * `E`: element name
     *   * `A': attribute
     *   * `C`: class
     *   * `M`: comment
     * @returns {boolean} true if directive was added.
     */
    function addDirective(tDirectives, name, location, maxPriority, ignoreDirective, startAttrName,
                          endAttrName) {
      if (name === ignoreDirective) return null;
      var match = null;
      if (hasDirectives.hasOwnProperty(name)) {
        for(var directive, directives = $injector.get(name + Suffix),
            i = 0, ii = directives.length; i<ii; i++) {
          try {
            directive = directives[i];
            if ( (maxPriority === undefined || maxPriority > directive.priority) &&
                 directive.restrict.indexOf(location) != -1) {
              if (startAttrName) {
                directive = inherit(directive, {$$start: startAttrName, $$end: endAttrName});
              }
              tDirectives.push(directive);
              match = directive;
            }
          } catch(e) { $exceptionHandler(e); }
        }
      }
      return match;
    }


    /**
     * When the element is replaced with HTML template then the new attributes
     * on the template need to be merged with the existing attributes in the DOM.
     * The desired effect is to have both of the attributes present.
     *
     * @param {object} dst destination attributes (original DOM)
     * @param {object} src source attributes (from the directive template)
     */
    function mergeTemplateAttributes(dst, src) {
      var srcAttr = src.$attr,
          dstAttr = dst.$attr,
          $element = dst.$$element;

      // reapply the old attributes to the new element
      forEach(dst, function(value, key) {
        if (key.charAt(0) != '$') {
          if (src[key]) {
            value += (key === 'style' ? ';' : ' ') + src[key];
          }
          dst.$set(key, value, true, srcAttr[key]);
        }
      });

      // copy the new attributes on the old attrs object
      forEach(src, function(value, key) {
        if (key == 'class') {
          safeAddClass($element, value);
          dst['class'] = (dst['class'] ? dst['class'] + ' ' : '') + value;
        } else if (key == 'style') {
          $element.attr('style', $element.attr('style') + ';' + value);
          dst['style'] = (dst['style'] ? dst['style'] + ';' : '') + value;
          // `dst` will never contain hasOwnProperty as DOM parser won't let it.
          // You will get an "InvalidCharacterError: DOM Exception 5" error if you
          // have an attribute like "has-own-property" or "data-has-own-property", etc.
        } else if (key.charAt(0) != '$' && !dst.hasOwnProperty(key)) {
          dst[key] = value;
          dstAttr[key] = srcAttr[key];
        }
      });
    }


    function compileTemplateUrl(directives, $compileNode, tAttrs,
        $rootElement, childTranscludeFn, preLinkFns, postLinkFns, previousCompileContext) {
      var linkQueue = [],
          afterTemplateNodeLinkFn,
          afterTemplateChildLinkFn,
          beforeTemplateCompileNode = $compileNode[0],
          origAsyncDirective = directives.shift(),
          // The fact that we have to copy and patch the directive seems wrong!
          derivedSyncDirective = extend({}, origAsyncDirective, {
            templateUrl: null, transclude: null, replace: null, $$originalDirective: origAsyncDirective
          }),
          templateUrl = (isFunction(origAsyncDirective.templateUrl))
              ? origAsyncDirective.templateUrl($compileNode, tAttrs)
              : origAsyncDirective.templateUrl,
          type = origAsyncDirective.type;

      $compileNode.empty();

      $http.get($sce.getTrustedResourceUrl(templateUrl), {cache: $templateCache}).
        success(function(content) {
          var compileNode, tempTemplateAttrs, $template, childBoundTranscludeFn;

          content = denormalizeTemplate(content);

          if (origAsyncDirective.replace) {
            if (jqLiteIsTextNode(content)) {
              $template = [];
            } else {
              $template = jqLite(wrapTemplate(type, trim(content)));
            }
            compileNode = $template[0];

            if ($template.length != 1 || compileNode.nodeType !== 1) {
              throw $compileMinErr('tplrt',
                  "Template for directive '{0}' must have exactly one root element. {1}",
                  origAsyncDirective.name, templateUrl);
            }

            tempTemplateAttrs = {$attr: {}};
            replaceWith($rootElement, $compileNode, compileNode);
            var templateDirectives = collectDirectives(compileNode, [], tempTemplateAttrs);

            if (isObject(origAsyncDirective.scope)) {
              markDirectivesAsIsolate(templateDirectives);
            }
            directives = templateDirectives.concat(directives);
            mergeTemplateAttributes(tAttrs, tempTemplateAttrs);
          } else {
            compileNode = beforeTemplateCompileNode;
            $compileNode.html(content);
          }

          directives.unshift(derivedSyncDirective);

          afterTemplateNodeLinkFn = applyDirectivesToNode(directives, compileNode, tAttrs,
              childTranscludeFn, $compileNode, origAsyncDirective, preLinkFns, postLinkFns,
              previousCompileContext);
          forEach($rootElement, function(node, i) {
            if (node == compileNode) {
              $rootElement[i] = $compileNode[0];
            }
          });
          afterTemplateChildLinkFn = compileNodes($compileNode[0].childNodes, childTranscludeFn);


          while(linkQueue.length) {
            var scope = linkQueue.shift(),
                beforeTemplateLinkNode = linkQueue.shift(),
                linkRootElement = linkQueue.shift(),
                boundTranscludeFn = linkQueue.shift(),
                linkNode = $compileNode[0];

            if (beforeTemplateLinkNode !== beforeTemplateCompileNode) {
              var oldClasses = beforeTemplateLinkNode.className;

              if (!(previousCompileContext.hasElementTranscludeDirective &&
                  origAsyncDirective.replace)) {
                // it was cloned therefore we have to clone as well.
                linkNode = jqLiteClone(compileNode);
              }

              replaceWith(linkRootElement, jqLite(beforeTemplateLinkNode), linkNode);

              // Copy in CSS classes from original node
              safeAddClass(jqLite(linkNode), oldClasses);
            }
            if (afterTemplateNodeLinkFn.transclude) {
              childBoundTranscludeFn = createBoundTranscludeFn(scope, afterTemplateNodeLinkFn.transclude);
            } else {
              childBoundTranscludeFn = boundTranscludeFn;
            }
            afterTemplateNodeLinkFn(afterTemplateChildLinkFn, scope, linkNode, $rootElement,
              childBoundTranscludeFn);
          }
          linkQueue = null;
        }).
        error(function(response, code, headers, config) {
          throw $compileMinErr('tpload', 'Failed to load template: {0}', config.url);
        });

      return function delayedNodeLinkFn(ignoreChildLinkFn, scope, node, rootElement, boundTranscludeFn) {
        if (linkQueue) {
          linkQueue.push(scope);
          linkQueue.push(node);
          linkQueue.push(rootElement);
          linkQueue.push(boundTranscludeFn);
        } else {
          afterTemplateNodeLinkFn(afterTemplateChildLinkFn, scope, node, rootElement, boundTranscludeFn);
        }
      };
    }


    /**
     * Sorting function for bound directives.
     */
    function byPriority(a, b) {
      var diff = b.priority - a.priority;
      if (diff !== 0) return diff;
      if (a.name !== b.name) return (a.name < b.name) ? -1 : 1;
      return a.index - b.index;
    }


    function assertNoDuplicate(what, previousDirective, directive, element) {
      if (previousDirective) {
        throw $compileMinErr('multidir', 'Multiple directives [{0}, {1}] asking for {2} on: {3}',
            previousDirective.name, directive.name, what, startingTag(element));
      }
    }


    function addTextInterpolateDirective(directives, text) {
      var interpolateFn = $interpolate(text, true);
      if (interpolateFn) {
        directives.push({
          priority: 0,
          compile: valueFn(function textInterpolateLinkFn(scope, node) {
            var parent = node.parent(),
                bindings = parent.data('$binding') || [];
            bindings.push(interpolateFn);
            safeAddClass(parent.data('$binding', bindings), 'ng-binding');
            scope.$watch(interpolateFn, function interpolateFnWatchAction(value) {
              node[0].nodeValue = value;
            });
          })
        });
      }
    }


    function wrapTemplate(type, template) {
      type = lowercase(type || 'html');
      switch(type) {
      case 'svg':
      case 'math':
        var wrapper = document.createElement('div');
        wrapper.innerHTML = '<'+type+'>'+template+'</'+type+'>';
        return wrapper.childNodes[0].childNodes;
      default:
        return template;
      }
    }


    function getTrustedContext(node, attrNormalizedName) {
      if (attrNormalizedName == "srcdoc") {
        return $sce.HTML;
      }
      var tag = nodeName_(node);
      // maction[xlink:href] can source SVG.  It's not limited to <maction>.
      if (attrNormalizedName == "xlinkHref" ||
          (tag == "FORM" && attrNormalizedName == "action") ||
          (tag != "IMG" && (attrNormalizedName == "src" ||
                            attrNormalizedName == "ngSrc"))) {
        return $sce.RESOURCE_URL;
      }
    }


    function addAttrInterpolateDirective(node, directives, value, name) {
      var interpolateFn = $interpolate(value, true);

      // no interpolation found -> ignore
      if (!interpolateFn) return;


      if (name === "multiple" && nodeName_(node) === "SELECT") {
        throw $compileMinErr("selmulti",
            "Binding to the 'multiple' attribute is not supported. Element: {0}",
            startingTag(node));
      }

      directives.push({
        priority: 100,
        compile: function() {
            return {
              pre: function attrInterpolatePreLinkFn(scope, element, attr) {
                var $$observers = (attr.$$observers || (attr.$$observers = {}));

                if (EVENT_HANDLER_ATTR_REGEXP.test(name)) {
                  throw $compileMinErr('nodomevents',
                      "Interpolations for HTML DOM event attributes are disallowed.  Please use the " +
                          "ng- versions (such as ng-click instead of onclick) instead.");
                }

                // we need to interpolate again, in case the attribute value has been updated
                // (e.g. by another directive's compile function)
                interpolateFn = $interpolate(attr[name], true, getTrustedContext(node, name),
                    ALL_OR_NOTHING_ATTRS[name]);

                // if attribute was updated so that there is no interpolation going on we don't want to
                // register any observers
                if (!interpolateFn) return;

                // initialize attr object so that it's ready in case we need the value for isolate
                // scope initialization, otherwise the value would not be available from isolate
                // directive's linking fn during linking phase
                attr[name] = interpolateFn(scope);

                ($$observers[name] || ($$observers[name] = [])).$$inter = true;
                (attr.$$observers && attr.$$observers[name].$$scope || scope).
                  $watch(interpolateFn, function interpolateFnWatchAction(newValue, oldValue) {
                    //special case for class attribute addition + removal
                    //so that class changes can tap into the animation
                    //hooks provided by the $animate service. Be sure to
                    //skip animations when the first digest occurs (when
                    //both the new and the old values are the same) since
                    //the CSS classes are the non-interpolated values
                    if(name === 'class' && newValue != oldValue) {
                      attr.$updateClass(newValue, oldValue);
                    } else {
                      attr.$set(name, newValue);
                    }
                  });
              }
            };
          }
      });
    }


    /**
     * This is a special jqLite.replaceWith, which can replace items which
     * have no parents, provided that the containing jqLite collection is provided.
     *
     * @param {JqLite=} $rootElement The root of the compile tree. Used so that we can replace nodes
     *                               in the root of the tree.
     * @param {JqLite} elementsToRemove The jqLite element which we are going to replace. We keep
     *                                  the shell, but replace its DOM node reference.
     * @param {Node} newNode The new DOM node.
     */
    function replaceWith($rootElement, elementsToRemove, newNode) {
      var firstElementToRemove = elementsToRemove[0],
          removeCount = elementsToRemove.length,
          parent = firstElementToRemove.parentNode,
          i, ii;

      if ($rootElement) {
        for(i = 0, ii = $rootElement.length; i < ii; i++) {
          if ($rootElement[i] == firstElementToRemove) {
            $rootElement[i++] = newNode;
            for (var j = i, j2 = j + removeCount - 1,
                     jj = $rootElement.length;
                 j < jj; j++, j2++) {
              if (j2 < jj) {
                $rootElement[j] = $rootElement[j2];
              } else {
                delete $rootElement[j];
              }
            }
            $rootElement.length -= removeCount - 1;
            break;
          }
        }
      }

      if (parent) {
        parent.replaceChild(newNode, firstElementToRemove);
      }
      var fragment = document.createDocumentFragment();
      fragment.appendChild(firstElementToRemove);
      newNode[jqLite.expando] = firstElementToRemove[jqLite.expando];
      for (var k = 1, kk = elementsToRemove.length; k < kk; k++) {
        var element = elementsToRemove[k];
        jqLite(element).remove(); // must do this way to clean up expando
        fragment.appendChild(element);
        delete elementsToRemove[k];
      }

      elementsToRemove[0] = newNode;
      elementsToRemove.length = 1;
    }


    function cloneAndAnnotateFn(fn, annotation) {
      return extend(function() { return fn.apply(null, arguments); }, fn, annotation);
    }
  }];
}

var PREFIX_REGEXP = /^(x[\:\-_]|data[\:\-_])/i;
/**
 * Converts all accepted directives format into proper directive name.
 * All of these will become 'myDirective':
 *   my:Directive
 *   my-directive
 *   x-my-directive
 *   data-my:directive
 *
 * Also there is special case for Moz prefix starting with upper case letter.
 * @param name Name to normalize
 */
function directiveNormalize(name) {
  return camelCase(name.replace(PREFIX_REGEXP, ''));
}

/**
 * @ngdoc type
 * @name $compile.directive.Attributes
 *
 * @description
 * A shared object between directive compile / linking functions which contains normalized DOM
 * element attributes. The values reflect current binding state `{{ }}`. The normalization is
 * needed since all of these are treated as equivalent in Angular:
 *
 * ```
 *    <span ng:bind="a" ng-bind="a" data-ng-bind="a" x-ng-bind="a">
 * ```
 */

/**
 * @ngdoc property
 * @name $compile.directive.Attributes#$attr
 * @returns {object} A map of DOM element attribute names to the normalized name. This is
 *                   needed to do reverse lookup from normalized name back to actual name.
 */


/**
 * @ngdoc method
 * @name $compile.directive.Attributes#$set
 * @function
 *
 * @description
 * Set DOM element attribute value.
 *
 *
 * @param {string} name Normalized element attribute name of the property to modify. The name is
 *          reverse-translated using the {@link ng.$compile.directive.Attributes#$attr $attr}
 *          property to the original name.
 * @param {string} value Value to set the attribute to. The value can be an interpolated string.
 */



/**
 * Closure compiler type information
 */

function nodesetLinkingFn(
  /* angular.Scope */ scope,
  /* NodeList */ nodeList,
  /* Element */ rootElement,
  /* function(Function) */ boundTranscludeFn
){}

function directiveLinkingFn(
  /* nodesetLinkingFn */ nodesetLinkingFn,
  /* angular.Scope */ scope,
  /* Node */ node,
  /* Element */ rootElement,
  /* function(Function) */ boundTranscludeFn
){}

function tokenDifference(str1, str2) {
  var values = '',
      tokens1 = str1.split(/\s+/),
      tokens2 = str2.split(/\s+/);

  outer:
  for(var i = 0; i < tokens1.length; i++) {
    var token = tokens1[i];
    for(var j = 0; j < tokens2.length; j++) {
      if(token == tokens2[j]) continue outer;
    }
    values += (values.length > 0 ? ' ' : '') + token;
  }
  return values;
}