compile.js

'use strict';

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 *     Any commits to this file should be reviewed with security in mind.  *
 *   Changes to this file can potentially create security vulnerabilities. *
 *          An approval from 2 Core members with history of modifying      *
 *                         this file is required.                          *
 *                                                                         *
 *  Does the change somehow allow for arbitrary javascript to be executed? *
 *    Or allows for someone to change the prototype of built-in objects?   *
 *     Or gives undesired access to variables likes document or window?    *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/* ! 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 $compile
 * @kind function
 *
 * @description
 * Compiles an HTML string or DOM into a template and produces a template function, which
 * can then be used to link {@link ng.$rootScope.Scope `scope`} and the template together.
 *
 * The compilation is a process of walking the DOM tree and matching DOM elements to
 * {@link ng.$compileProvider#directive directives}.
 *
 * <div class="alert alert-warning">
 * **Note:** This document is an in-depth reference of all directive options.
 * For a gentle introduction to directives with examples of common use cases,
 * see the {@link guide/directive directive guide}.
 * </div>
 *
 * ## Comprehensive Directive API
 *
 * There are many different options for a directive.
 *
 * The difference resides in the return value of the factory function.
 * You can either return a "Directive Definition Object" (see below) that defines the directive properties,
 * or just the `postLink` function (all other properties will have the default values).
 *
 * <div class="alert alert-success">
 * **Best Practice:** It's recommended to use the "directive definition object" form.
 * </div>
 *
 * Here's an example directive declared with a Directive Definition Object:
 *
 * ```js
 *   var myModule = angular.module(...);
 *
 *   myModule.directive('directiveName', function factory(injectables) {
 *     var directiveDefinitionObject = {
 *       priority: 0,
 *       template: '<div></div>', // or // function(tElement, tAttrs) { ... },
 *       // or
 *       // templateUrl: 'directive.html', // or // function(tElement, tAttrs) { ... },
 *       transclude: false,
 *       restrict: 'A',
 *       templateNamespace: 'html',
 *       scope: false,
 *       controller: function($scope, $element, $attrs, $transclude, otherInjectables) { ... },
 *       controllerAs: 'stringIdentifier',
 *       bindToController: false,
 *       require: 'siblingDirectiveName', // or // ['^parentDirectiveName', '?optionalDirectiveName', '?^optionalParent'],
 *       compile: function compile(tElement, tAttrs, transclude) {
 *         return {
 *           pre: function preLink(scope, iElement, iAttrs, controller) { ... },
 *           post: function postLink(scope, iElement, iAttrs, controller) { ... }
 *         }
 *         // or
 *         // return function postLink( ... ) { ... }
 *       },
 *       // or
 *       // link: {
 *       //  pre: function preLink(scope, iElement, iAttrs, controller) { ... },
 *       //  post: function postLink(scope, iElement, iAttrs, controller) { ... }
 *       // }
 *       // or
 *       // link: function postLink( ... ) { ... }
 *     };
 *     return directiveDefinitionObject;
 *   });
 * ```
 *
 * <div class="alert alert-warning">
 * **Note:** Any unspecified options will use the default value. You can see the default values below.
 * </div>
 *
 * Therefore the above can be simplified as:
 *
 * ```js
 *   var myModule = angular.module(...);
 *
 *   myModule.directive('directiveName', function factory(injectables) {
 *     var directiveDefinitionObject = {
 *       link: function postLink(scope, iElement, iAttrs) { ... }
 *     };
 *     return directiveDefinitionObject;
 *     // or
 *     // return function postLink(scope, iElement, iAttrs) { ... }
 *   });
 * ```
 *
 *
 *
 * ### Directive Definition Object
 *
 * The directive definition object provides instructions to the {@link ng.$compile
 * compiler}. The attributes are:
 *
 * #### `multiElement`
 * When this property is set to true, the HTML compiler will collect DOM nodes between
 * nodes with the attributes `directive-name-start` and `directive-name-end`, and group them
 * together as the directive elements. It is recommended that this feature be used on directives
 * which are not strictly behavioral (such as {@link ngClick}), and which
 * do not manipulate or replace child nodes (such as {@link ngInclude}).
 *
 * #### `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). Note that expressions
 * and other directives used in the directive's template will also be excluded from execution.
 *
 * #### `scope`
 * The scope property can be `true`, an object or a falsy value:
 *
 * * **falsy:** No scope will be created for the directive. The directive will use its parent's scope.
 *
 * * **`true`:** A new child scope that prototypically inherits from its parent will be created for
 * the directive's element. 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.
 *
 * * **`{...}` (an object hash):** A new "isolate" scope is created for the directive's element. The
 * 'isolate' scope differs from normal scope in that it does not prototypically inherit from its parent
 * scope. This is useful when creating reusable components, which should not accidentally read or modify
 * data in the parent scope.
 *
 * The 'isolate' scope object hash defines a set of local scope properties derived from attributes on the
 * directive's element. These local properties are useful for aliasing values for templates. The keys in
 * the object hash map to the name of the property on the isolate scope; the values define how the property
 * is bound to the parent scope, via matching attributes on the directive's element:
 *
 * * `@` 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. If
 *   you want to shallow watch for changes (i.e. $watchCollection instead of $watch) you can use
 *   `=*` or `=*attr` (`=*?` or `=*?attr` if the property is 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 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})`.
 *
 * In general it's possible to apply more than one directive to one element, but there might be limitations
 * depending on the type of scope required by the directives. The following points will help explain these limitations.
 * For simplicity only two directives are taken into account, but it is also applicable for several directives:
 *
 * * **no scope** + **no scope** => Two directives which don't require their own scope will use their parent's scope
 * * **child scope** + **no scope** =>  Both directives will share one single child scope
 * * **child scope** + **child scope** =>  Both directives will share one single child scope
 * * **isolated scope** + **no scope** =>  The isolated directive will use it's own created isolated scope. The other directive will use
 * its parent's scope
 * * **isolated scope** + **child scope** =>  **Won't work!** Only one scope can be related to one element. Therefore these directives cannot
 * be applied to the same element.
 * * **isolated scope** + **isolated scope**  =>  **Won't work!** Only one scope can be related to one element. Therefore these directives
 * cannot be applied to the same element.
 *
 *
 * #### `bindToController`
 * When an isolate scope is used for a component (see above), and `controllerAs` is used, `bindToController: true` will
 * allow a component to have its properties bound to the controller, rather than to scope. When the controller
 * is instantiated, the initial values of the isolate scope bindings will be available if the controller is not an ES6 class.
 *
 * #### `controller`
 * Controller constructor function. The controller is instantiated before the
 * pre-linking phase and can be accessed by 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
 * * `$transclude` - A transclude linking function pre-bound to the correct transclusion scope:
 *   `function([scope], cloneLinkingFn, futureParentElement, slotName)`:
 *    * `scope`: (optional) override the scope.
 *    * `cloneLinkingFn`: (optional) argument to create clones of the original transcluded content.
 *    * `futureParentElement` (optional):
 *        * defines the parent to which the `cloneLinkingFn` will add the cloned elements.
 *        * default: `$element.parent()` resp. `$element` for `transclude:'element'` resp. `transclude:true`.
 *        * only needed for transcludes that are allowed to contain non html elements (e.g. SVG elements)
 *          and when the `cloneLinkinFn` is passed,
 *          as those elements need to created and cloned in a special way when they are defined outside their
 *          usual containers (e.g. like `<svg>`).
 *        * See also the `directive.templateNamespace` property.
 *    * `slotName`: (optional) the name of the slot to transclude. If falsy (e.g. `null`, `undefined` or `''`)
 *      then the default translusion is provided.
 *    The `$transclude` function also has a method on it, `$transclude.isSlotFilled(slotName)`, which returns
 *    `true` if the specified slot contains content (i.e. one or more DOM nodes).
 *
 * #### `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 (unless no link function
 * is specified, in which case error checking is skipped). 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 and its parents. Throw an error 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 and its parents or pass
 *   `null` to the `link` fn 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`
 * Identifier name for a reference to the controller in the directive's scope.
 * This allows the controller to be referenced from the directive template. This is especially
 * useful when a directive is used as component, i.e. with an `isolate` scope. It's also possible
 * to use it in a directive without an `isolate` / `new` scope, but you need to be aware that the
 * `controllerAs` reference might overwrite a property that already exists on the parent scope.
 *
 *
 * #### `restrict`
 * String of subset of `EACM` which restricts the directive to a specific directive
 * declaration style. If omitted, the defaults (elements and attributes) are used.
 *
 * * `E` - Element name (default): `<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 -->`
 *
 *
 * #### `templateNamespace`
 * String representing the document type used by the markup in the template.
 * AngularJS needs this information as those elements need to be created and cloned
 * in a special way when they are defined outside their usual containers like `<svg>` and `<math>`.
 *
 * * `html` - All root nodes in the template are HTML. Root nodes may also be
 *   top-level elements such as `<svg>` or `<math>`.
 * * `svg` - The root nodes in the template are SVG elements (excluding `<math>`).
 * * `math` - The root nodes in the template are MathML elements (excluding `<svg>`).
 *
 * If no `templateNamespace` is specified, then the namespace is considered to be `html`.
 *
 * #### `template`
 * HTML markup that may:
 * * Replace the contents of the directive's element (default).
 * * Replace the directive's element itself (if `replace` is true - DEPRECATED).
 * * Wrap the contents of the directive's element (if `transclude` is true).
 *
 * Value may be:
 *
 * * A string. For example `<div red-on-hover>{{delete_str}}</div>`.
 * * A function which takes two arguments `tElement` and `tAttrs` (described in the `compile`
 *   function api below) and returns a string value.
 *
 *
 * #### `templateUrl`
 * This is similar to `template` but the template is loaded from the specified URL, asynchronously.
 *
 * Because template loading is asynchronous the compiler will suspend compilation of directives on that element
 * for later when the template has been resolved.  In the meantime it will continue to compile and link
 * sibling and parent elements as though this element had not contained any directives.
 *
 * The compiler does not suspend the entire compilation to wait for templates to be loaded because this
 * would result in the whole app "stalling" until all templates are loaded asynchronously - even in the
 * case when only one deeply nested directive has `templateUrl`.
 *
 * Template loading is asynchronous even if the template has been preloaded into the {@link $templateCache}
 *
 * 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
 * $sce#getTrustedResourceUrl $sce.getTrustedResourceUrl}.
 *
 *
 * #### `replace` ([*DEPRECATED*!], will be removed in next major release - i.e. v2.0)
 * specify what the template should replace. Defaults to `false`.
 *
 * * `true` - the template will replace the directive's element.
 * * `false` - the template will replace the contents of the directive's element.
 *
 * The replacement process migrates all of the attributes / classes from the old element to the new
 * one. See the {@link guide/directive#template-expanding-directive
 * Directives Guide} for an example.
 *
 * There are very few scenarios where element replacement is required for the application function,
 * the main one being reusable custom components that are used within SVG contexts
 * (because SVG doesn't work with custom elements in the DOM tree).
 *
 * #### `transclude`
 * Extract the contents of the element where the directive appears and make it available to the directive.
 * The contents are compiled and provided to the directive as a **transclusion function**. See the
 * {@link $compile#transclusion Transclusion} section below.
 *
 *
 * #### `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. 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-danger">
 * **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#$watch watches}.
 *
 *   * `iElement` - instance element - The element where the directive is to be used. It is safe to
 *     manipulate the children of the element only in `postLink` function since the children have
 *     already been linked.
 *
 *   * `iAttrs` - instance attributes - Normalized list of attributes declared on this element shared
 *     between all directive linking functions.
 *
 *   * `controller` - the directive's required controller instance(s) - Instances are shared
 *     among all directives, which allows the directives to use the controllers as a communication
 *     channel. The exact value depends on the directive's `require` property:
 *       * no controller(s) required: the directive's own controller, or `undefined` if it doesn't have one
 *       * `string`: the controller instance
 *       * `array`: array of controller instances
 *
 *     If a required controller cannot be found, and it is optional, the instance is `null`,
 *     otherwise the {@link error:$compile:ctreq Missing Required Controller} error is thrown.
 *
 *     Note that you can also require the directive's own controller - it will be made available like
 *     any other controller.
 *
 *   * `transcludeFn` - A transclude linking function pre-bound to the correct transclusion scope.
 *     This is the same as the `$transclude`
 *     parameter of directive controllers, see there for details.
 *     `function([scope], cloneLinkingFn, futureParentElement)`.
 *
 * #### 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.
 *
 * Note that child elements that contain `templateUrl` directives will not have been compiled
 * and linked since they are waiting for their template to load asynchronously and their own
 * compilation and linking has been suspended until that occurs.
 *
 * It is safe to do DOM transformation in the post-linking function on elements that are not waiting
 * for their async templates to be resolved.
 *
 *
 * ### Transclusion
 *
 * Transclusion is the process of extracting a collection of DOM elements from one part of the DOM and
 * copying them to another part of the DOM, while maintaining their connection to the original AngularJS
 * scope from where they were taken.
 *
 * Transclusion is used (often with {@link ngTransclude}) to insert the
 * original contents of a directive's element into a specified place in the template of the directive.
 * The benefit of transclusion, over simply moving the DOM elements manually, is that the transcluded
 * content has access to the properties on the scope from which it was taken, even if the directive
 * has isolated scope.
 * See the {@link guide/directive#creating-a-directive-that-wraps-other-elements Directives Guide}.
 *
 * This makes it possible for the widget to have private state for its template, while the transcluded
 * content has access to its originating scope.
 *
 * <div class="alert alert-warning">
 * **Note:** When testing an element transclude directive you must not place the directive at the root of the
 * DOM fragment that is being compiled. See {@link guide/unit-testing#testing-transclusion-directives
 * Testing Transclusion Directives}.
 * </div>
 *
 * There are three kinds of transclusion depending upon whether you want to transclude just the contents of the
 * directive's element, the entire element or multiple parts of the element contents:
 *
 * * `true` - transclude the content (i.e. the child nodes) of the directive's element.
 * * `'element'` - transclude the whole of the directive's element including any directives on this
 *   element that defined at a lower priority than this directive. When used, the `template`
 *   property is ignored.
 * * **`{...}` (an object hash):** - map elements of the content onto transclusion "slots" in the template.
 *
 * **Mult-slot transclusion** is declared by providing an object for the `transclude` property.
 *
 * This object is a map where the keys are the name of the slot to fill and the value is an element selector
 * used to match the HTML to the slot. The element selector should be in normalized form (e.g. `myElement`)
 * and will match the standard element variants (e.g. `my-element`, `my:element`, `data-my-element`, etc).
 *
 * For further information check out the guide on {@link guide/directive#matching-directives Matching Directives}
 *
 * If the element selector is prefixed with a `?` then that slot is optional.
 *
 * For example, the transclude object `{ slotA: '?myCustomElement' }` maps `<my-custom-element>` elements to
 * the `slotA` slot, which can be accessed via the `$transclude` function or via the {@link ngTransclude} directive.
 *
 * Slots that are not marked as optional (`?`) will trigger a compile time error if there are no matching elements
 * in the transclude content. If you wish to know if an optional slot was filled with content, then you can call
 * `$transclude.isSlotFilled(slotName)` on the transclude function passed to the directive's link function and
 * injectable into the directive's controller.
 *
 *
 * #### Transclusion Functions
 *
 * When a directive requests transclusion, the compiler extracts its contents and provides a **transclusion
 * function** to the directive's `link` function and `controller`. This transclusion function is a special
 * **linking function** that will return the compiled contents linked to a new transclusion scope.
 *
 * <div class="alert alert-info">
 * If you are just using {@link ngTransclude} then you don't need to worry about this function, since
 * ngTransclude will deal with it for us.
 * </div>
 *
 * If you want to manually control the insertion and removal of the transcluded content in your directive
 * then you must use this transclude function. When you call a transclude function it returns a a jqLite/JQuery
 * object that contains the compiled DOM, which is linked to the correct transclusion scope.
 *
 * When you call a transclusion function you can pass in a **clone attach function**. This function accepts
 * two parameters, `function(clone, scope) { ... }`, where the `clone` is a fresh compiled copy of your transcluded
 * content and the `scope` is the newly created transclusion scope, to which the clone is bound.
 *
 * <div class="alert alert-info">
 * **Best Practice**: Always provide a `cloneFn` (clone attach function) when you call a transclude function
 * since you then get a fresh clone of the original DOM and also have access to the new transclusion scope.
 * </div>
 *
 * It is normal practice to attach your transcluded content (`clone`) to the DOM inside your **clone
 * attach function**:
 *
 * ```js
 * var transcludedContent, transclusionScope;
 *
 * $transclude(function(clone, scope) {
 *   element.append(clone);
 *   transcludedContent = clone;
 *   transclusionScope = scope;
 * });
 * ```
 *
 * Later, if you want to remove the transcluded content from your DOM then you should also destroy the
 * associated transclusion scope:
 *
 * ```js
 * transcludedContent.remove();
 * transclusionScope.$destroy();
 * ```
 *
 * <div class="alert alert-info">
 * **Best Practice**: if you intend to add and remove transcluded content manually in your directive
 * (by calling the transclude function to get the DOM and calling `element.remove()` to remove it),
 * then you are also responsible for calling `$destroy` on the transclusion scope.
 * </div>
 *
 * The built-in DOM manipulation directives, such as {@link ngIf}, {@link ngSwitch} and {@link ngRepeat}
 * automatically destroy their transcluded clones as necessary so you do not need to worry about this if
 * you are simply using {@link ngTransclude} to inject the transclusion into your directive.
 *
 *
 * #### Transclusion Scopes
 *
 * When you call a transclude function it returns a DOM fragment that is pre-bound to a **transclusion
 * scope**. This scope is special, in that it is a child of the directive's scope (and so gets destroyed
 * when the directive's scope gets destroyed) but it inherits the properties of the scope from which it
 * was taken.
 *
 * For example consider a directive that uses transclusion and isolated scope. The DOM hierarchy might look
 * like this:
 *
 * ```html
 * <div ng-app>
 *   <div isolate>
 *     <div transclusion>
 *     </div>
 *   </div>
 * </div>
 * ```
 *
 * The `$parent` scope hierarchy will look like this:
 *
   ```
   - $rootScope
     - isolate
       - transclusion
   ```
 *
 * but the scopes will inherit prototypically from different scopes to their `$parent`.
 *
   ```
   - $rootScope
     - transclusion
   - isolate
   ```
 *
 *
 * ### Attributes
 *
 * The {@link ng.$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.$observe('ngModel', function(value) {
 *     console.log('ngModel has changed value to ' + value);
 *   });
 * }
 * ```
 *
 * ## Example
 *
 * <div class="alert alert-warning">
 * **Note**: Typically directives are registered with `module.directive`. The example below is
 * to illustrate how `$compile` works.
 * </div>
 *
 <example module="compileExample">
   <file name="index.html">
    <script>
      angular.module('compileExample', [], 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
                $compile(element.contents())(scope);
              }
            );
          };
        });
      })
      .controller('GreeterController', ['$scope', function($scope) {
        $scope.name = 'Angular';
        $scope.html = 'Hello {{name}}';
      }]);
    </script>
    <div ng-controller="GreeterController">
      <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 - DEPRECATED.
 *
 * <div class="alert alert-danger">
 * **Note:** Passing a `transclude` function to the $compile function is deprecated, as it
 *   e.g. will not use the right outer scope. Please pass the transclude function as a
 *   `parentBoundTranscludeFn` to the link function instead.
 * </div>
 *
 * @param {number} maxPriority only apply directives lower than given priority (Only effects the
 *                 root element(s), not their children)
 * @returns {function(scope, cloneAttachFn=, options=)} a link function which is used to bind template
 * (a DOM element/tree) to a scope. Where:
 *
 *  * `scope` - A {@link ng.$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.
 *
 *  * `options` - An optional object hash with linking options. If `options` is provided, then the following
 *  keys may be used to control linking behavior:
 *
 *      * `parentBoundTranscludeFn` - the transclude function made available to
 *        directives; if given, it will be passed through to the link functions of
 *        directives found in `element` during compilation.
 *      * `transcludeControllers` - an object hash with keys that map controller names
 *        to controller instances; if given, it will make the controllers
 *        available to directives.
 *      * `futureParentElement` - defines the parent to which the `cloneAttachFn` will add
 *        the cloned elements; only needed for transcludes that are allowed to contain non html
 *        elements (e.g. SVG elements). See also the directive.controller property.
 *
 * 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
 *
 * @description
 */
$CompileProvider.$inject = ['$provide', '$$sanitizeUriProvider'];
function $CompileProvider($provide, $$sanitizeUriProvider) {
  var hasDirectives = {},
      Suffix = 'Directive',
      COMMENT_DIRECTIVE_REGEXP = /^\s*directive\:\s*([\w\-]+)\s+(.*)$/,
      CLASS_DIRECTIVE_REGEXP = /(([\w\-]+)(?:\:([^;]+))?;?)/,
      ALL_OR_NOTHING_ATTRS = makeMap('ngSrc,ngSrcset,src,srcset'),
      REQUIRE_PREFIX_REGEXP = /^(?:(\^\^?)?(\?)?(\^\^?)?)?/;

  // 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)$/;

  function parseIsolateBindings(scope, directiveName, isController) {
    var LOCAL_REGEXP = /^\s*([@&]|=(\*?))(\??)\s*(\w*)\s*$/;

    var bindings = {};

    forEach(scope, function(definition, scopeName) {
      var match = definition.match(LOCAL_REGEXP);

      if (!match) {
        throw $compileMinErr('iscp',
            "Invalid {3} for directive '{0}'." +
            " Definition: {... {1}: '{2}' ...}",
            directiveName, scopeName, definition,
            (isController ? "controller bindings definition" :
            "isolate scope definition"));
      }

      bindings[scopeName] = {
        mode: match[1][0],
        collection: match[2] === '*',
        optional: match[3] === '?',
        attrName: match[4] || scopeName
      };
    });

    return bindings;
  }

  function parseDirectiveBindings(directive, directiveName) {
    var bindings = {
      isolateScope: null,
      bindToController: null
    };
    if (isObject(directive.scope)) {
      if (directive.bindToController === true) {
        bindings.bindToController = parseIsolateBindings(directive.scope,
                                                         directiveName, true);
        bindings.isolateScope = {};
      } else {
        bindings.isolateScope = parseIsolateBindings(directive.scope,
                                                     directiveName, false);
      }
    }
    if (isObject(directive.bindToController)) {
      bindings.bindToController =
          parseIsolateBindings(directive.bindToController, directiveName, true);
    }
    if (isObject(bindings.bindToController)) {
      var controller = directive.controller;
      var controllerAs = directive.controllerAs;
      if (!controller) {
        // There is no controller, there may or may not be a controllerAs property
        throw $compileMinErr('noctrl',
              "Cannot bind to controller without directive '{0}'s controller.",
              directiveName);
      } else if (!identifierForController(controller, controllerAs)) {
        // There is a controller, but no identifier or controllerAs property
        throw $compileMinErr('noident',
              "Cannot bind to controller without identifier for directive '{0}'.",
              directiveName);
      }
    }
    return bindings;
  }

  function assertValidDirectiveName(name) {
    var letter = name.charAt(0);
    if (!letter || letter !== lowercase(letter)) {
      throw $compileMinErr('baddir', "Directive name '{0}' is invalid. The first character must be a lowercase letter", name);
    }
    if (name !== name.trim()) {
      throw $compileMinErr('baddir',
            "Directive name '{0}' is invalid. The name should not contain leading or trailing whitespaces",
            name);
    }
  }

  /**
   * @ngdoc method
   * @name $compileProvider#directive
   * @kind 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 the
   *    {@link guide/directive directive guide} and the {@link $compile compile API} for more info.
   * @returns {ng.$compileProvider} Self for chaining.
   */
   this.directive = function registerDirective(name, directiveFactory) {
    assertNotHasOwnProperty(name, 'directive');
    if (isString(name)) {
      assertValidDirectiveName(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 || 'EA';
                var bindings = directive.$$bindings =
                    parseDirectiveBindings(directive, directive.name);
                if (isObject(bindings.isolateScope)) {
                  directive.$$isolateBindings = bindings.isolateScope;
                }
                directive.$$moduleName = directiveFactory.$$moduleName;
                directives.push(directive);
              } catch (e) {
                $exceptionHandler(e);
              }
            });
            return directives;
          }]);
      }
      hasDirectives[name].push(directiveFactory);
    } else {
      forEach(name, reverseParams(registerDirective));
    }
    return this;
  };

  /**
   * @ngdoc method
   * @name $compileProvider#component
   * @module ng
   * @param {string} name Name of the component in camel-case (i.e. myComp which will match as my-comp)
   * @param {Object} options Component definition object (a simplified
   *    {@link ng.$compile#directive-definition-object directive definition object}),
   *    has the following properties (all optional):
   *
   *    - `controller` – `{(string|function()=}` – Controller constructor function that should be
   *      associated with newly created scope or the name of a {@link ng.$compile#-controller-
   *      registered controller} if passed as a string. Empty function by default.
   *    - `controllerAs` – `{string=}` – An identifier name for a reference to the controller.
   *      If present, the controller will be published to scope under the `controllerAs` name.
   *      If not present, this will default to be the same as the component name.
   *    - `template` – `{string=|function()=}` – html template as a string or a function that
   *      returns an html template as a string which should be used as the contents of this component.
   *      Empty string by default.
   *
   *      If `template` is a function, then it is {@link auto.$injector#invoke injected} with
   *      the following locals:
   *
   *      - `$element` - Current element
   *      - `$attrs` - Current attributes object for the element
   *
   *    - `templateUrl` – `{string=|function()=}` – path or function that returns a path to an html
   *      template that should be used  as the contents of this component.
   *
   *      If `templateUrl` is a function, then it is {@link auto.$injector#invoke injected} with
   *      the following locals:
   *
   *      - `$element` - Current element
   *      - `$attrs` - Current attributes object for the element
   *    - `bindings` – `{object=}` – Define DOM attribute binding to component properties.
   *      Component properties are always bound to the component controller and not to the scope.
   *    - `transclude` – `{boolean=}` – Whether {@link $compile#transclusion transclusion} is enabled.
   *      Enabled by default.
   *    - `isolate` – `{boolean=}` – Whether the new scope is isolated. Isolated by default.
   *    - `restrict` - `{string=}` - String of subset of {@link ng.$compile#-restrict- EACM} which
   *      restricts the component to specific directive declaration style. If omitted, this defaults to 'E'.
   *    - `$canActivate` – `{function()=}` – TBD.
   *    - `$routeConfig` – `{object=}` – TBD.
   *
   * @returns {ng.$compileProvider} Self for chaining.
   * @description
   * Register a component definition with the compiler. This is short for registering a specific
   * type of directive which represents a self-contained UI component in your application. Component
   * definitions are very simple and do not require the complexity behind defining directives.
   * Component definitions usually consist only of the template and the controller backing it.
   * In order to make the definition easier, components enforce best practices like controllerAs
   * and default behaviors like scope isolation and restriction to elements.
   *
   * Here are a few examples of how you would usually define components:
   *
   * ```js
   *   var myMod = angular.module(...);
   *   myMod.component('myComp', {
   *     template: '<div>My name is {{myComp.name}}</div>',
   *     controller: function() {
   *       this.name = 'shahar';
   *     }
   *   });
   *
   *   myMod.component('myComp', {
   *     template: '<div>My name is {{myComp.name}}</div>',
   *     bindings: {name: '@'}
   *   });
   *
   *   myMod.component('myComp', {
   *     templateUrl: 'views/my-comp.html',
   *     controller: 'MyCtrl as ctrl',
   *     bindings: {name: '@'}
   *   });
   *
   * ```
   *
   * <br />
   * Components are also useful as route templates (e.g. when using
   * {@link ngRoute ngRoute}):
   *
   * ```js
   *   var myMod = angular.module('myMod', ['ngRoute']);
   *
   *   myMod.component('home', {
   *     template: '<h1>Home</h1><p>Hello, {{ home.user.name }} !</p>',
   *     controller: function() {
   *       this.user = {name: 'world'};
   *     }
   *   });
   *
   *   myMod.config(function($routeProvider) {
   *     $routeProvider.when('/', {
   *       template: '<home></home>'
   *     });
   *   });
   * ```
   *
   * <br />
   * When using {@link ngRoute.$routeProvider $routeProvider}, you can often avoid some
   * boilerplate, by assigning the resolved dependencies directly on the route scope:
   *
   * ```js
   *   var myMod = angular.module('myMod', ['ngRoute']);
   *
   *   myMod.component('home', {
   *     template: '<h1>Home</h1><p>Hello, {{ home.user.name }} !</p>',
   *     bindings: {user: '='}
   *   });
   *
   *   myMod.config(function($routeProvider) {
   *     $routeProvider.when('/', {
   *       template: '<home user="$resolve.user"></home>',
   *       resolve: {user: function($http) { return $http.get('...'); }}
   *     });
   *   });
   * ```
   *
   * <br />
   * See also {@link ng.$compileProvider#directive $compileProvider.directive()}.
   */
  this.component = function registerComponent(name, options) {
    function factory($injector) {
      function makeInjectable(fn) {
        if (isFunction(fn) || Array.isArray(fn)) {
          return function(tElement, tAttrs) {
            return $injector.invoke(fn, this, {$element: tElement, $attrs: tAttrs});
          };
        } else {
          return fn;
        }
      }

      var template = (!options.template && !options.templateUrl ? '' : options.template);
      return {
        controller: options.controller || function() {},
        controllerAs: identifierForController(options.controller) || options.controllerAs || name,
        template: makeInjectable(template),
        templateUrl: makeInjectable(options.templateUrl),
        transclude: options.transclude === undefined ? false : options.transclude,
        scope: options.isolate === false ? true : {},
        bindToController: options.bindings || {},
        restrict: options.restrict || 'E'
      };
    }

    if (options.$canActivate) {
      factory.$canActivate = options.$canActivate;
    }
    if (options.$routeConfig) {
      factory.$routeConfig = options.$routeConfig;
    }
    factory.$inject = ['$injector'];

    return this.directive(name, factory);
  };


  /**
   * @ngdoc method
   * @name $compileProvider#aHrefSanitizationWhitelist
   * @kind function
   *
   * @description
   * Retrieves or overrides the default regular expression that is used for whitelisting of safe
   * urls during a[href] sanitization.
   *
   * The sanitization is a security measure aimed at preventing XSS attacks via html links.
   *
   * Any url about to be assigned to a[href] via data-binding is first normalized and turned into
   * an absolute url. Afterwards, the url is matched against the `aHrefSanitizationWhitelist`
   * regular expression. If a match is found, the original url is written into the dom. Otherwise,
   * the absolute url is prefixed with `'unsafe:'` string and only then is it written into the DOM.
   *
   * @param {RegExp=} regexp New regexp to whitelist urls with.
   * @returns {RegExp|ng.$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 $compileProvider#imgSrcSanitizationWhitelist
   * @kind function
   *
   * @description
   * Retrieves or overrides the default regular expression that is used for whitelisting of safe
   * urls during img[src] sanitization.
   *
   * The sanitization is a security measure aimed at prevent XSS attacks via html links.
   *
   * Any url about to be assigned to img[src] via data-binding is first normalized and turned into
   * an absolute url. Afterwards, the url is matched against the `imgSrcSanitizationWhitelist`
   * regular expression. If a match is found, the original url is written into the dom. Otherwise,
   * the absolute url is prefixed with `'unsafe:'` string and only then is it written into the DOM.
   *
   * @param {RegExp=} regexp New regexp to whitelist urls with.
   * @returns {RegExp|ng.$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();
    }
  };

  /**
   * @ngdoc method
   * @name  $compileProvider#debugInfoEnabled
   *
   * @param {boolean=} enabled update the debugInfoEnabled state if provided, otherwise just return the
   * current debugInfoEnabled state
   * @returns {*} current value if used as getter or itself (chaining) if used as setter
   *
   * @kind function
   *
   * @description
   * Call this method to enable/disable various debug runtime information in the compiler such as adding
   * binding information and a reference to the current scope on to DOM elements.
   * If enabled, the compiler will add the following to DOM elements that have been bound to the scope
   * * `ng-binding` CSS class
   * * `$binding` data property containing an array of the binding expressions
   *
   * You may want to disable this in production for a significant performance boost. See
   * {@link guide/production#disabling-debug-data Disabling Debug Data} for more.
   *
   * The default value is true.
   */
  var debugInfoEnabled = true;
  this.debugInfoEnabled = function(enabled) {
    if (isDefined(enabled)) {
      debugInfoEnabled = enabled;
      return this;
    }
    return debugInfoEnabled;
  };

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

    var SIMPLE_ATTR_NAME = /^\w/;
    var specialAttrHolder = document.createElement('div');
    var Attributes = function(element, attributesToCopy) {
      if (attributesToCopy) {
        var keys = Object.keys(attributesToCopy);
        var i, l, key;

        for (i = 0, l = keys.length; i < l; i++) {
          key = keys[i];
          this[key] = attributesToCopy[key];
        }
      } else {
        this.$attr = {};
      }

      this.$$element = element;
    };

    Attributes.prototype = {
      /**
       * @ngdoc method
       * @name $compile.directive.Attributes#$normalize
       * @kind function
       *
       * @description
       * Converts an attribute name (e.g. dash/colon/underscore-delimited string, optionally prefixed with `x-` or
       * `data-`) to its normalized, camelCase form.
       *
       * Also there is special case for Moz prefix starting with upper case letter.
       *
       * For further information check out the guide on {@link guide/directive#matching-directives Matching Directives}
       *
       * @param {string} name Name to normalize
       */
      $normalize: directiveNormalize,


      /**
       * @ngdoc method
       * @name $compile.directive.Attributes#$addClass
       * @kind 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
       * @kind 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
       * @kind 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);
        if (toAdd && toAdd.length) {
          $animate.addClass(this.$$element, toAdd);
        }

        var toRemove = tokenDifference(oldClasses, newClasses);
        if (toRemove && toRemove.length) {
          $animate.removeClass(this.$$element, 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 node = this.$$element[0],
            booleanKey = getBooleanAttrName(node, key),
            aliasedKey = getAliasedAttrName(key),
            observer = key,
            nodeName;

        if (booleanKey) {
          this.$$element.prop(key, value);
          attrName = booleanKey;
        } else if (aliasedKey) {
          this[aliasedKey] = value;
          observer = aliasedKey;
        }

        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);

        if ((nodeName === 'a' && (key === 'href' || key === 'xlinkHref')) ||
            (nodeName === 'img' && key === 'src')) {
          // sanitize a[href] and img[src] values
          this[key] = value = $$sanitizeUri(value, key === 'src');
        } else if (nodeName === 'img' && key === 'srcset') {
          // sanitize img[srcset] values
          var result = "";

          // first check if there are spaces because it's not the same pattern
          var trimmedSrcset = trim(value);
          //                (   999x   ,|   999w   ,|   ,|,   )
          var srcPattern = /(\s+\d+x\s*,|\s+\d+w\s*,|\s+,|,\s+)/;
          var pattern = /\s/.test(trimmedSrcset) ? srcPattern : /(,)/;

          // split srcset into tuple of uri and descriptor except for the last item
          var rawUris = trimmedSrcset.split(pattern);

          // for each tuples
          var nbrUrisWith2parts = Math.floor(rawUris.length / 2);
          for (var i = 0; i < nbrUrisWith2parts; i++) {
            var innerIdx = i * 2;
            // sanitize the uri
            result += $$sanitizeUri(trim(rawUris[innerIdx]), true);
            // add the descriptor
            result += (" " + trim(rawUris[innerIdx + 1]));
          }

          // split the last item into uri and descriptor
          var lastTuple = trim(rawUris[i * 2]).split(/\s/);

          // sanitize the last uri
          result += $$sanitizeUri(trim(lastTuple[0]), true);

          // and add the last descriptor if any
          if (lastTuple.length === 2) {
            result += (" " + trim(lastTuple[1]));
          }
          this[key] = value = result;
        }

        if (writeAttr !== false) {
          if (value === null || isUndefined(value)) {
            this.$$element.removeAttr(attrName);
          } else {
            if (SIMPLE_ATTR_NAME.test(attrName)) {
              this.$$element.attr(attrName, value);
            } else {
              setSpecialAttr(this.$$element[0], attrName, value);
            }
          }
        }

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


      /**
       * @ngdoc method
       * @name $compile.directive.Attributes#$observe
       * @kind 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/interpolation#how-text-and-attribute-bindings-work Interpolation
       *        guide} for more info.
       * @returns {function()} Returns a deregistration function for this observer.
       */
      $observe: function(key, fn) {
        var attrs = this,
            $$observers = (attrs.$$observers || (attrs.$$observers = createMap())),
            listeners = ($$observers[key] || ($$observers[key] = []));

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

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

    function setSpecialAttr(element, attrName, value) {
      // Attributes names that do not start with letters (such as `(click)`) cannot be set using `setAttribute`
      // so we have to jump through some hoops to get such an attribute
      // https://github.com/angular/angular.js/pull/13318
      specialAttrHolder.innerHTML = "<span " + attrName + ">";
      var attributes = specialAttrHolder.firstChild.attributes;
      var attribute = attributes[0];
      // We have to remove the attribute from its container element before we can add it to the destination element
      attributes.removeNamedItem(attribute.name);
      attribute.value = value;
      element.attributes.setNamedItem(attribute);
    }

    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.
      }
    }


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

    compile.$$addBindingInfo = debugInfoEnabled ? function $$addBindingInfo($element, binding) {
      var bindings = $element.data('$binding') || [];

      if (isArray(binding)) {
        bindings = bindings.concat(binding);
      } else {
        bindings.push(binding);
      }

      $element.data('$binding', bindings);
    } : noop;

    compile.$$addBindingClass = debugInfoEnabled ? function $$addBindingClass($element) {
      safeAddClass($element, 'ng-binding');
    } : noop;

    compile.$$addScopeInfo = debugInfoEnabled ? function $$addScopeInfo($element, scope, isolated, noTemplate) {
      var dataName = isolated ? (noTemplate ? '$isolateScopeNoTemplate' : '$isolateScope') : '$scope';
      $element.data(dataName, scope);
    } : noop;

    compile.$$addScopeClass = debugInfoEnabled ? function $$addScopeClass($element, isolated) {
      safeAddClass($element, isolated ? 'ng-isolate-scope' : 'ng-scope');
    } : noop;

    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);
      }
      // 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>
      forEach($compileNodes, function(node, index) {
        if (node.nodeType == NODE_TYPE_TEXT && node.nodeValue.match(/\S+/) /* non-empty */) {
          $compileNodes[index] = jqLite(node).wrap('<span></span>').parent()[0];
        }
      });
      var compositeLinkFn =
              compileNodes($compileNodes, transcludeFn, $compileNodes,
                           maxPriority, ignoreDirective, previousCompileContext);
      compile.$$addScopeClass($compileNodes);
      var namespace = null;
      return function publicLinkFn(scope, cloneConnectFn, options) {
        assertArg(scope, 'scope');

        if (previousCompileContext && previousCompileContext.needsNewScope) {
          // A parent directive did a replace and a directive on this element asked
          // for transclusion, which caused us to lose a layer of element on which
          // we could hold the new transclusion scope, so we will create it manually
          // here.
          scope = scope.$parent.$new();
        }

        options = options || {};
        var parentBoundTranscludeFn = options.parentBoundTranscludeFn,
          transcludeControllers = options.transcludeControllers,
          futureParentElement = options.futureParentElement;

        // When `parentBoundTranscludeFn` is passed, it is a
        // `controllersBoundTransclude` function (it was previously passed
        // as `transclude` to directive.link) so we must unwrap it to get
        // its `boundTranscludeFn`
        if (parentBoundTranscludeFn && parentBoundTranscludeFn.$$boundTransclude) {
          parentBoundTranscludeFn = parentBoundTranscludeFn.$$boundTransclude;
        }

        if (!namespace) {
          namespace = detectNamespaceForChildElements(futureParentElement);
        }
        var $linkNode;
        if (namespace !== 'html') {
          // When using a directive with replace:true and templateUrl the $compileNodes
          // (or a child element inside of them)
          // might change, so we need to recreate the namespace adapted compileNodes
          // for call to the link function.
          // Note: This will already clone the nodes...
          $linkNode = jqLite(
            wrapTemplate(namespace, jqLite('<div>').append($compileNodes).html())
          );
        } else if (cloneConnectFn) {
          // important!!: we must call our jqLite.clone() since the jQuery one is trying to be smart
          // and sometimes changes the structure of the DOM.
          $linkNode = JQLitePrototype.clone.call($compileNodes);
        } else {
          $linkNode = $compileNodes;
        }

        if (transcludeControllers) {
          for (var controllerName in transcludeControllers) {
            $linkNode.data('$' + controllerName + 'Controller', transcludeControllers[controllerName].instance);
          }
        }

        compile.$$addScopeInfo($linkNode, scope);

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

    function detectNamespaceForChildElements(parentElement) {
      // TODO: Make this detect MathML as well...
      var node = parentElement && parentElement[0];
      if (!node) {
        return 'html';
      } else {
        return nodeName_(node) !== 'foreignobject' && toString.call(node).match(/SVG/) ? 'svg' : 'html';
      }
    }

    /**
     * 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, nodeLinkFnFound;

      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) {
          compile.$$addScopeClass(attrs.$$element);
        }

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

        if (nodeLinkFn || childLinkFn) {
          linkFns.push(i, nodeLinkFn, childLinkFn);
          linkFnFound = true;
          nodeLinkFnFound = nodeLinkFnFound || nodeLinkFn;
        }

        //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, parentBoundTranscludeFn) {
        var nodeLinkFn, childLinkFn, node, childScope, i, ii, idx, childBoundTranscludeFn;
        var stableNodeList;


        if (nodeLinkFnFound) {
          // copy nodeList so that if a nodeLinkFn removes or adds an element at this DOM level our
          // offsets don't get screwed up
          var nodeListLength = nodeList.length;
          stableNodeList = new Array(nodeListLength);

          // create a sparse array by only copying the elements which have a linkFn
          for (i = 0; i < linkFns.length; i+=3) {
            idx = linkFns[i];
            stableNodeList[idx] = nodeList[idx];
          }
        } else {
          stableNodeList = nodeList;
        }

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

          if (nodeLinkFn) {
            if (nodeLinkFn.scope) {
              childScope = scope.$new();
              compile.$$addScopeInfo(jqLite(node), childScope);
            } else {
              childScope = scope;
            }

            if (nodeLinkFn.transcludeOnThisElement) {
              childBoundTranscludeFn = createBoundTranscludeFn(
                  scope, nodeLinkFn.transclude, parentBoundTranscludeFn);

            } else if (!nodeLinkFn.templateOnThisElement && parentBoundTranscludeFn) {
              childBoundTranscludeFn = parentBoundTranscludeFn;

            } else if (!parentBoundTranscludeFn && transcludeFn) {
              childBoundTranscludeFn = createBoundTranscludeFn(scope, transcludeFn);

            } else {
              childBoundTranscludeFn = null;
            }

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

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

    function createBoundTranscludeFn(scope, transcludeFn, previousBoundTranscludeFn) {

      var boundTranscludeFn = function(transcludedScope, cloneFn, controllers, futureParentElement, containingScope) {

        if (!transcludedScope) {
          transcludedScope = scope.$new(false, containingScope);
          transcludedScope.$$transcluded = true;
        }

        return transcludeFn(transcludedScope, cloneFn, {
          parentBoundTranscludeFn: previousBoundTranscludeFn,
          transcludeControllers: controllers,
          futureParentElement: futureParentElement
        });
      };

      // We need  to attach the transclusion slots onto the `boundTranscludeFn`
      // so that they are available inside the `controllersBoundTransclude` function
      var boundSlots = boundTranscludeFn.$$slots = createMap();
      for (var slotName in transcludeFn.$$slots) {
        if (transcludeFn.$$slots[slotName]) {
          boundSlots[slotName] = createBoundTranscludeFn(scope, transcludeFn.$$slots[slotName], previousBoundTranscludeFn);
        } else {
          boundSlots[slotName] = null;
        }
      }

      return boundTranscludeFn;
    }

    /**
     * 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 NODE_TYPE_ELEMENT: /* Element */
          // use the node name: <directive>
          addDirective(directives,
              directiveNormalize(nodeName_(node)), 'E', maxPriority, ignoreDirective);

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

            attr = nAttrs[j];
            name = attr.name;
            value = trim(attr.value);

            // support ngAttr attribute binding
            ngAttrName = directiveNormalize(name);
            if (isNgAttr = NG_ATTR_BINDING.test(ngAttrName)) {
              name = name.replace(PREFIX_REGEXP, '')
                .substr(8).replace(/_(.)/g, function(match, letter) {
                  return letter.toUpperCase();
                });
            }

            var multiElementMatch = ngAttrName.match(MULTI_ELEMENT_DIR_RE);
            if (multiElementMatch && directiveIsMultiElement(multiElementMatch[1])) {
              attrStartName = name;
              attrEndName = name.substr(0, name.length - 5) + 'end';
              name = name.substr(0, name.length - 6);
            }

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

          // use class as directive
          className = node.className;
          if (isObject(className)) {
              // Maybe SVGAnimatedString
              className = className.animVal;
          }
          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 NODE_TYPE_TEXT: /* Text Node */
          if (msie === 11) {
            // Workaround for #11781
            while (node.parentNode && node.nextSibling && node.nextSibling.nodeType === NODE_TYPE_TEXT) {
              node.nodeValue = node.nodeValue + node.nextSibling.nodeValue;
              node.parentNode.removeChild(node.nextSibling);
            }
          }
          addTextInterpolateDirective(directives, node.nodeValue);
          break;
        case NODE_TYPE_COMMENT: /* 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)) {
        do {
          if (!node) {
            throw $compileMinErr('uterdir',
                      "Unterminated attribute, found '{0}' but no matching '{1}' found.",
                      attrStart, attrEnd);
          }
          if (node.nodeType == NODE_TYPE_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);
      };
    }

    /**
     * A function generator that is used to support both eager and lazy compilation
     * linking function.
     * @param eager
     * @param $compileNodes
     * @param transcludeFn
     * @param maxPriority
     * @param ignoreDirective
     * @param previousCompileContext
     * @returns {Function}
     */
    function compilationGenerator(eager, $compileNodes, transcludeFn, maxPriority, ignoreDirective, previousCompileContext) {
        if (eager) {
            return compile($compileNodes, transcludeFn, maxPriority, ignoreDirective, previousCompileContext);
        }

        var compiled;

        return function() {
            if (!compiled) {
                compiled = compile($compileNodes, transcludeFn, maxPriority, ignoreDirective, previousCompileContext);

                // Null out all of these references in order to make them eligible for garbage collection
                // since this is a potentially long lived closure
                $compileNodes = transcludeFn = previousCompileContext = null;
            }

            return compiled.apply(this, arguments);
        };
    }

    /**
     * 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 = previousCompileContext.newScopeDirective,
          controllerDirectives = previousCompileContext.controllerDirectives,
          newIsolateScopeDirective = previousCompileContext.newIsolateScopeDirective,
          templateDirective = previousCompileContext.templateDirective,
          nonTlbTranscludeDirective = previousCompileContext.nonTlbTranscludeDirective,
          hasTranscludeDirective = false,
          hasTemplate = false,
          hasElementTranscludeDirective = previousCompileContext.hasElementTranscludeDirective,
          $compileNode = templateAttrs.$$element = jqLite(compileNode),
          directive,
          directiveName,
          $template,
          replaceDirective = originalReplaceDirective,
          childTranscludeFn = transcludeFn,
          linkFn,
          didScanForMultipleTransclusion = false,
          mightHaveMultipleTransclusionError = false,
          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) {

          // skip the check for directives with async templates, we'll check the derived sync
          // directive when the template arrives
          if (!directive.templateUrl) {
            if (isObject(directiveValue)) {
              // This directive is trying to add an isolated scope.
              // Check that there is no scope of any kind already
              assertNoDuplicate('new/isolated scope', newIsolateScopeDirective || newScopeDirective,
                                directive, $compileNode);
              newIsolateScopeDirective = directive;
            } else {
              // This directive is trying to add a child scope.
              // Check that there is no isolated scope already
              assertNoDuplicate('new/isolated scope', newIsolateScopeDirective, directive,
                                $compileNode);
            }
          }

          newScopeDirective = newScopeDirective || directive;
        }

        directiveName = directive.name;

        // If we encounter a condition that can result in transclusion on the directive,
        // then scan ahead in the remaining directives for others that may cause a multiple
        // transclusion error to be thrown during the compilation process.  If a matching directive
        // is found, then we know that when we encounter a transcluded directive, we need to eagerly
        // compile the `transclude` function rather than doing it lazily in order to throw
        // exceptions at the correct time
        if (!didScanForMultipleTransclusion && ((directive.replace && (directive.templateUrl || directive.template))
            || (directive.transclude && !directive.$$tlb))) {
                var candidateDirective;

                for (var scanningIndex = i + 1; candidateDirective = directives[scanningIndex++];) {
                    if ((candidateDirective.transclude && !candidateDirective.$$tlb)
                        || (candidateDirective.replace && (candidateDirective.templateUrl || candidateDirective.template))) {
                        mightHaveMultipleTransclusionError = true;
                        break;
                    }
                }

                didScanForMultipleTransclusion = true;
        }

        if (!directive.templateUrl && directive.controller) {
          directiveValue = directive.controller;
          controllerDirectives = controllerDirectives || createMap();
          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 = $compileNode;
            $compileNode = templateAttrs.$$element =
                jqLite(document.createComment(' ' + directiveName + ': ' +
                                              templateAttrs[directiveName] + ' '));
            compileNode = $compileNode[0];
            replaceWith(jqCollection, sliceArgs($template), compileNode);

            childTranscludeFn = compilationGenerator(mightHaveMultipleTransclusionError, $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 {

            var slots = createMap();

            $template = jqLite(jqLiteClone(compileNode)).contents();

            if (isObject(directiveValue)) {

              // We have transclusion slots,
              // collect them up, compile them and store their transclusion functions
              $template = [];

              var slotMap = createMap();
              var filledSlots = createMap();

              // Parse the element selectors
              forEach(directiveValue, function(elementSelector, slotName) {
                // If an element selector starts with a ? then it is optional
                var optional = (elementSelector.charAt(0) === '?');
                elementSelector = optional ? elementSelector.substring(1) : elementSelector;

                slotMap[elementSelector] = slotName;

                // We explicitly assign `null` since this implies that a slot was defined but not filled.
                // Later when calling boundTransclusion functions with a slot name we only error if the
                // slot is `undefined`
                slots[slotName] = null;

                // filledSlots contains `true` for all slots that are either optional or have been
                // filled. This is used to check that we have not missed any required slots
                filledSlots[slotName] = optional;
              });

              // Add the matching elements into their slot
              forEach($compileNode.contents(), function(node) {
                var slotName = slotMap[directiveNormalize(nodeName_(node))];
                if (slotName) {
                  filledSlots[slotName] = true;
                  slots[slotName] = slots[slotName] || [];
                  slots[slotName].push(node);
                } else {
                  $template.push(node);
                }
              });

              // Check for required slots that were not filled
              forEach(filledSlots, function(filled, slotName) {
                if (!filled) {
                  throw $compileMinErr('reqslot', 'Required transclusion slot `{0}` was not filled.', slotName);
                }
              });

              for (var slotName in slots) {
                if (slots[slotName]) {
                  // Only define a transclusion function if the slot was filled
                  slots[slotName] = compilationGenerator(mightHaveMultipleTransclusionError, slots[slotName], transcludeFn);
                }
              }
            }

            $compileNode.empty(); // clear contents
            childTranscludeFn = compilationGenerator(mightHaveMultipleTransclusionError, $template, transcludeFn, undefined,
                undefined, { needsNewScope: directive.$$isolateScope || directive.$$newScope});
            childTranscludeFn.$$slots = slots;
          }
        }

        if (directive.template) {
          hasTemplate = true;
          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 = removeComments(wrapTemplate(directive.templateNamespace, trim(directiveValue)));
            }
            compileNode = $template[0];

            if ($template.length != 1 || compileNode.nodeType !== NODE_TYPE_ELEMENT) {
              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 || newScopeDirective) {
              // The original directive caused the current element to be replaced but this element
              // also needs to have a new scope, so we need to tell the template directives
              // that they would need to get their scope from further up, if they require transclusion
              markDirectiveScope(templateDirectives, newIsolateScopeDirective, newScopeDirective);
            }
            directives = directives.concat(templateDirectives).concat(unprocessedDirectives);
            mergeTemplateAttributes(templateAttrs, newTemplateAttrs);

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

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

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

          nodeLinkFn = compileTemplateUrl(directives.splice(i, directives.length - i), $compileNode,
              templateAttrs, jqCollection, hasTranscludeDirective && childTranscludeFn, preLinkFns, postLinkFns, {
                controllerDirectives: controllerDirectives,
                newScopeDirective: (newScopeDirective !== directive) && newScopeDirective,
                newIsolateScopeDirective: newIsolateScopeDirective,
                templateDirective: templateDirective,
                nonTlbTranscludeDirective: nonTlbTranscludeDirective
              });
          ii = directives.length;
        } else if (directive.compile) {
          try {
            linkFn = directive.compile($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.templateOnThisElement = hasTemplate;
      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;

        if (isString(require)) {
          var match = require.match(REQUIRE_PREFIX_REGEXP);
          var name = require.substring(match[0].length);
          var inheritType = match[1] || match[3];
          var optional = match[2] === '?';

          //If only parents then start at the parent element
          if (inheritType === '^^') {
            $element = $element.parent();
          //Otherwise attempt getting the controller from elementControllers in case
          //the element is transcluded (and has no data) and to avoid .data if possible
          } else {
            value = elementControllers && elementControllers[name];
            value = value && value.instance;
          }

          if (!value) {
            var dataName = '$' + name + 'Controller';
            value = inheritType ? $element.inheritedData(dataName) : $element.data(dataName);
          }

          if (!value && !optional) {
            throw $compileMinErr('ctreq',
                "Controller '{0}', required by directive '{1}', can't be found!",
                name, directiveName);
          }
        } else if (isArray(require)) {
          value = [];
          for (var i = 0, ii = require.length; i < ii; i++) {
            value[i] = getControllers(directiveName, require[i], $element, elementControllers);
          }
        }

        return value || null;
      }

      function setupControllers($element, attrs, transcludeFn, controllerDirectives, isolateScope, scope) {
        var elementControllers = createMap();
        for (var controllerKey in controllerDirectives) {
          var directive = controllerDirectives[controllerKey];
          var locals = {
            $scope: directive === newIsolateScopeDirective || directive.$$isolateScope ? isolateScope : scope,
            $element: $element,
            $attrs: attrs,
            $transclude: transcludeFn
          };

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

          var controllerInstance = $controller(controller, locals, true, directive.controllerAs);

          // 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.instance);
          }
        }
        return elementControllers;
      }

      function nodeLinkFn(childLinkFn, scope, linkNode, $rootElement, boundTranscludeFn) {
        var i, ii, linkFn, isolateScope, controllerScope, elementControllers, transcludeFn, $element,
            attrs, removeScopeBindingWatches, removeControllerBindingWatches;

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

        controllerScope = scope;
        if (newIsolateScopeDirective) {
          isolateScope = scope.$new(true);
        } else if (newScopeDirective) {
          controllerScope = scope.$parent;
        }

        if (boundTranscludeFn) {
          // track `boundTranscludeFn` so it can be unwrapped if `transcludeFn`
          // is later passed as `parentBoundTranscludeFn` to `publicLinkFn`
          transcludeFn = controllersBoundTransclude;
          transcludeFn.$$boundTransclude = boundTranscludeFn;
          // expose the slots on the `$transclude` function
          transcludeFn.isSlotFilled = function(slotName) {
            return !!boundTranscludeFn.$$slots[slotName];
          };
        }

        if (controllerDirectives) {
          elementControllers = setupControllers($element, attrs, transcludeFn, controllerDirectives, isolateScope, scope);
        }

        if (newIsolateScopeDirective) {
          // Initialize isolate scope bindings for new isolate scope directive.
          compile.$$addScopeInfo($element, isolateScope, true, !(templateDirective && (templateDirective === newIsolateScopeDirective ||
              templateDirective === newIsolateScopeDirective.$$originalDirective)));
          compile.$$addScopeClass($element, true);
          isolateScope.$$isolateBindings =
              newIsolateScopeDirective.$$isolateBindings;
          removeScopeBindingWatches = initializeDirectiveBindings(scope, attrs, isolateScope,
                                        isolateScope.$$isolateBindings,
                                        newIsolateScopeDirective);
          if (removeScopeBindingWatches) {
            isolateScope.$on('$destroy', removeScopeBindingWatches);
          }
        }

        // Initialize bindToController bindings
        for (var name in elementControllers) {
          var controllerDirective = controllerDirectives[name];
          var controller = elementControllers[name];
          var bindings = controllerDirective.$$bindings.bindToController;

          if (controller.identifier && bindings) {
            removeControllerBindingWatches =
              initializeDirectiveBindings(controllerScope, attrs, controller.instance, bindings, controllerDirective);
          }

          var controllerResult = controller();
          if (controllerResult !== controller.instance) {
            // If the controller constructor has a return value, overwrite the instance
            // from setupControllers
            controller.instance = controllerResult;
            $element.data('$' + controllerDirective.name + 'Controller', controllerResult);
            removeControllerBindingWatches && removeControllerBindingWatches();
            removeControllerBindingWatches =
              initializeDirectiveBindings(controllerScope, attrs, controller.instance, bindings, controllerDirective);
          }
        }

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

        // 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--) {
          linkFn = postLinkFns[i];
          invokeLinkFn(linkFn,
              linkFn.isolateScope ? isolateScope : scope,
              $element,
              attrs,
              linkFn.require && getControllers(linkFn.directiveName, linkFn.require, $element, elementControllers),
              transcludeFn
          );
        }

        // This is the function that is injected as `$transclude`.
        // Note: all arguments are optional!
        function controllersBoundTransclude(scope, cloneAttachFn, futureParentElement, slotName) {
          var transcludeControllers;
          // No scope passed in:
          if (!isScope(scope)) {
            slotName = futureParentElement;
            futureParentElement = cloneAttachFn;
            cloneAttachFn = scope;
            scope = undefined;
          }

          if (hasElementTranscludeDirective) {
            transcludeControllers = elementControllers;
          }
          if (!futureParentElement) {
            futureParentElement = hasElementTranscludeDirective ? $element.parent() : $element;
          }
          if (slotName) {
            // slotTranscludeFn can be one of three things:
            //  * a transclude function - a filled slot
            //  * `null` - an optional slot that was not filled
            //  * `undefined` - a slot that was not declared (i.e. invalid)
            var slotTranscludeFn = boundTranscludeFn.$$slots[slotName];
            if (slotTranscludeFn) {
              return slotTranscludeFn(scope, cloneAttachFn, transcludeControllers, futureParentElement, scopeToChild);
            } else if (isUndefined(slotTranscludeFn)) {
              throw $compileMinErr('noslot',
               'No parent directive that requires a transclusion with slot name "{0}". ' +
               'Element: {1}',
               slotName, startingTag($element));
            }
          } else {
            return boundTranscludeFn(scope, cloneAttachFn, transcludeControllers, futureParentElement, scopeToChild);
          }
        }
      }
    }

    // Depending upon the context in which a directive finds itself it might need to have a new isolated
    // or child scope created. For instance:
    // * if the directive has been pulled into a template because another directive with a higher priority
    // asked for element transclusion
    // * if the directive itself asks for transclusion but it is at the root of a template and the original
    // element was replaced. See https://github.com/angular/angular.js/issues/12936
    function markDirectiveScope(directives, isolateScope, newScope) {
      for (var j = 0, jj = directives.length; j < jj; j++) {
        directives[j] = inherit(directives[j], {$$isolateScope: isolateScope, $$newScope: newScope});
      }
    }

    /**
     * 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 ((isUndefined(maxPriority) || 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;
    }


    /**
     * looks up the directive and returns true if it is a multi-element directive,
     * and therefore requires DOM nodes between -start and -end markers to be grouped
     * together.
     *
     * @param {string} name name of the directive to look up.
     * @returns true if directive was registered as multi-element.
     */
    function directiveIsMultiElement(name) {
      if (hasDirectives.hasOwnProperty(name)) {
        for (var directive, directives = $injector.get(name + Suffix),
            i = 0, ii = directives.length; i < ii; i++) {
          directive = directives[i];
          if (directive.multiElement) {
            return true;
          }
        }
      }
      return false;
    }

    /**
     * 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) != '$') {
          if (src[key] && src[key] !== value) {
            value += (key === 'style' ? ';' : ' ') + src[key];
          }
          dst.$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(),
          derivedSyncDirective = inherit(origAsyncDirective, {
            templateUrl: null, transclude: null, replace: null, $$originalDirective: origAsyncDirective
          }),
          templateUrl = (isFunction(origAsyncDirective.templateUrl))
              ? origAsyncDirective.templateUrl($compileNode, tAttrs)
              : origAsyncDirective.templateUrl,
          templateNamespace = origAsyncDirective.templateNamespace;

      $compileNode.empty();

      $templateRequest(templateUrl)
        .then(function(content) {
          var compileNode, tempTemplateAttrs, $template, childBoundTranscludeFn;

          content = denormalizeTemplate(content);

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

            if ($template.length != 1 || compileNode.nodeType !== NODE_TYPE_ELEMENT) {
              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)) {
              // the original directive that caused the template to be loaded async required
              // an isolate scope
              markDirectiveScope(templateDirectives, true);
            }
            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 (scope.$$destroyed) continue;

            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.transcludeOnThisElement) {
              childBoundTranscludeFn = createBoundTranscludeFn(scope, afterTemplateNodeLinkFn.transclude, boundTranscludeFn);
            } else {
              childBoundTranscludeFn = boundTranscludeFn;
            }
            afterTemplateNodeLinkFn(afterTemplateChildLinkFn, scope, linkNode, $rootElement,
              childBoundTranscludeFn);
          }
          linkQueue = null;
        });

      return function delayedNodeLinkFn(ignoreChildLinkFn, scope, node, rootElement, boundTranscludeFn) {
        var childBoundTranscludeFn = boundTranscludeFn;
        if (scope.$$destroyed) return;
        if (linkQueue) {
          linkQueue.push(scope,
                         node,
                         rootElement,
                         childBoundTranscludeFn);
        } else {
          if (afterTemplateNodeLinkFn.transcludeOnThisElement) {
            childBoundTranscludeFn = createBoundTranscludeFn(scope, afterTemplateNodeLinkFn.transclude, boundTranscludeFn);
          }
          afterTemplateNodeLinkFn(afterTemplateChildLinkFn, scope, node, rootElement, childBoundTranscludeFn);
        }
      };
    }


    /**
     * 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) {

      function wrapModuleNameIfDefined(moduleName) {
        return moduleName ?
          (' (module: ' + moduleName + ')') :
          '';
      }

      if (previousDirective) {
        throw $compileMinErr('multidir', 'Multiple directives [{0}{1}, {2}{3}] asking for {4} on: {5}',
            previousDirective.name, wrapModuleNameIfDefined(previousDirective.$$moduleName),
            directive.name, wrapModuleNameIfDefined(directive.$$moduleName), what, startingTag(element));
      }
    }


    function addTextInterpolateDirective(directives, text) {
      var interpolateFn = $interpolate(text, true);
      if (interpolateFn) {
        directives.push({
          priority: 0,
          compile: function textInterpolateCompileFn(templateNode) {
            var templateNodeParent = templateNode.parent(),
                hasCompileParent = !!templateNodeParent.length;

            // When transcluding a template that has bindings in the root
            // we don't have a parent and thus need to add the class during linking fn.
            if (hasCompileParent) compile.$$addBindingClass(templateNodeParent);

            return function textInterpolateLinkFn(scope, node) {
              var parent = node.parent();
              if (!hasCompileParent) compile.$$addBindingClass(parent);
              compile.$$addBindingInfo(parent, interpolateFn.expressions);
              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, allOrNothing) {
      var trustedContext = getTrustedContext(node, name);
      allOrNothing = ALL_OR_NOTHING_ATTRS[name] || allOrNothing;

      var interpolateFn = $interpolate(value, true, trustedContext, allOrNothing);

      // 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 = createMap()));

                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.");
                }

                // If the attribute has changed since last $interpolate()ed
                var newValue = attr[name];
                if (newValue !== value) {
                  // we need to interpolate again since the attribute value has been updated
                  // (e.g. by another directive's compile function)
                  // ensure unset/empty values make interpolateFn falsy
                  interpolateFn = newValue && $interpolate(newValue, true, trustedContext, allOrNothing);
                  value = newValue;
                }

                // 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;

            // If the replaced element is also the jQuery .context then replace it
            // .context is a deprecated jQuery api, so we should set it only when jQuery set it
            // http://api.jquery.com/context/
            if ($rootElement.context === firstElementToRemove) {
              $rootElement.context = newNode;
            }
            break;
          }
        }
      }

      if (parent) {
        parent.replaceChild(newNode, firstElementToRemove);
      }

      // Append all the `elementsToRemove` to a fragment. This will...
      // - remove them from the DOM
      // - allow them to still be traversed with .nextSibling
      // - allow a single fragment.qSA to fetch all elements being removed
      var fragment = document.createDocumentFragment();
      for (i = 0; i < removeCount; i++) {
        fragment.appendChild(elementsToRemove[i]);
      }

      if (jqLite.hasData(firstElementToRemove)) {
        // Copy over user data (that includes Angular's $scope etc.). Don't copy private
        // data here because there's no public interface in jQuery to do that and copying over
        // event listeners (which is the main use of private data) wouldn't work anyway.
        jqLite.data(newNode, jqLite.data(firstElementToRemove));

        // Remove $destroy event listeners from `firstElementToRemove`
        jqLite(firstElementToRemove).off('$destroy');
      }

      // Cleanup any data/listeners on the elements and children.
      // This includes invoking the $destroy event on any elements with listeners.
      jqLite.cleanData(fragment.querySelectorAll('*'));

      // Update the jqLite collection to only contain the `newNode`
      for (i = 1; i < removeCount; i++) {
        delete elementsToRemove[i];
      }
      elementsToRemove[0] = newNode;
      elementsToRemove.length = 1;
    }


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


    function invokeLinkFn(linkFn, scope, $element, attrs, controllers, transcludeFn) {
      try {
        linkFn(scope, $element, attrs, controllers, transcludeFn);
      } catch (e) {
        $exceptionHandler(e, startingTag($element));
      }
    }


    // Set up $watches for isolate scope and controller bindings. This process
    // only occurs for isolate scopes and new scopes with controllerAs.
    function initializeDirectiveBindings(scope, attrs, destination, bindings, directive) {
      var removeWatchCollection = [];
      forEach(bindings, function(definition, scopeName) {
        var attrName = definition.attrName,
        optional = definition.optional,
        mode = definition.mode, // @, =, or &
        lastValue,
        parentGet, parentSet, compare;

        switch (mode) {

          case '@':
            if (!optional && !hasOwnProperty.call(attrs, attrName)) {
              destination[scopeName] = attrs[attrName] = void 0;
            }
            attrs.$observe(attrName, function(value) {
              if (isString(value)) {
                destination[scopeName] = value;
              }
            });
            attrs.$$observers[attrName].$$scope = scope;
            if (isString(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
              destination[scopeName] = $interpolate(attrs[attrName])(scope);
            }
            break;

          case '=':
            if (!hasOwnProperty.call(attrs, attrName)) {
              if (optional) break;
              attrs[attrName] = void 0;
            }
            if (optional && !attrs[attrName]) break;

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

          case '&':
            // Don't assign Object.prototype method to scope
            parentGet = attrs.hasOwnProperty(attrName) ? $parse(attrs[attrName]) : noop;

            // Don't assign noop to destination if expression is not valid
            if (parentGet === noop && optional) break;

            destination[scopeName] = function(locals) {
              return parentGet(scope, locals);
            };
            break;
        }
      });

      return removeWatchCollection.length && function removeWatches() {
        for (var i = 0, ii = removeWatchCollection.length; i < ii; ++i) {
          removeWatchCollection[i]();
        }
      };
    }
  }];
}

var PREFIX_REGEXP = /^((?:x|data)[\:\-_])/i;
/**
 * Converts all accepted directives format into proper directive name.
 * @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
 *
 * @description
 * 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
 * @kind 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;
}

function removeComments(jqNodes) {
  jqNodes = jqLite(jqNodes);
  var i = jqNodes.length;

  if (i <= 1) {
    return jqNodes;
  }

  while (i--) {
    var node = jqNodes[i];
    if (node.nodeType === NODE_TYPE_COMMENT) {
      splice.call(jqNodes, i, 1);
    }
  }
  return jqNodes;
}