/src/ng/compile.js

'use strict';

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


var NON_ASSIGNABLE_MODEL_EXPRESSION = 'Non-assignable model expression: ';


/**
 * @ngdoc function
 * @name ng.$compile
 * @function
 *
 * @description
 * Compiles a piece of HTML string or DOM into a template and produces a template function, which
 * can then be used to link {@link ng.$rootScope.Scope scope} and the template together.
 *
 * The compilation is a process of walking the DOM tree and trying to match DOM elements to
 * {@link ng.$compileProvider#directive directives}. For each match it
 * executes corresponding template function and collects the
 * instance functions into a single template function which is then returned.
 *
 * The template function can then be used once to produce the view or as it is the case with
 * {@link ng.directive:ngRepeat repeater} many-times, in which
 * case each call results in a view that is a DOM clone of the original template.
 *
 <doc:example module="compile">
   <doc:source>
    <script>
      // declare a new module, and inject the $compileProvider
      angular.module('compile', [], function($compileProvider) {
        // configure new 'compile' directive by passing a directive
        // factory function. The factory function injects the '$compile'
        $compileProvider.directive('compile', function($compile) {
          // directive factory creates a link function
          return function(scope, element, attrs) {
            scope.$watch(
              function(scope) {
                 // watch the 'compile' expression for changes
                return scope.$eval(attrs.compile);
              },
              function(value) {
                // when the 'compile' expression changes
                // assign it into the current DOM
                element.html(value);

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

      function Ctrl($scope) {
        $scope.name = 'Angular';
        $scope.html = 'Hello {{name}}';
      }
    </script>
    <div ng-controller="Ctrl">
      <input ng-model="name"> <br>
      <textarea ng-model="html"></textarea> <br>
      <div compile="html"></div>
    </div>
   </doc:source>
   <doc:scenario>
     it('should auto compile', function() {
       expect(element('div[compile]').text()).toBe('Hello Angular');
       input('html').enter('{{name}}!');
       expect(element('div[compile]').text()).toBe('Angular!');
     });
   </doc:scenario>
 </doc:example>

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


/**
 * @ngdoc service
 * @name ng.$compileProvider
 * @function
 *
 * @description
 */
$CompileProvider.$inject = ['$provide'];
function $CompileProvider($provide) {
  var hasDirectives = {},
      Suffix = 'Directive',
      COMMENT_DIRECTIVE_REGEXP = /^\s*directive\:\s*([\d\w\-_]+)\s+(.*)$/,
      CLASS_DIRECTIVE_REGEXP = /(([\d\w\-_]+)(?:\:([^;]+))?;?)/,
      MULTI_ROOT_TEMPLATE_ERROR = 'Template must have exactly one root element. was: ';


  /**
   * @ngdoc function
   * @name ng.$compileProvider#directive
   * @methodOf ng.$compileProvider
   * @function
   *
   * @description
   * Register a new directives with the compiler.
   *
   * @param {string} name Name of the directive in camel-case. (ie <code>ngBind</code> which will match as
   *                <code>ng-bind</code>).
   * @param {function} directiveFactory An injectable directive factroy function. See {@link guide/directive} for more
   *                info.
   * @returns {ng.$compileProvider} Self for chaining.
   */
   this.directive = function registerDirective(name, directiveFactory) {
    if (isString(name)) {
      assertArg(directiveFactory, 'directive');
      if (!hasDirectives.hasOwnProperty(name)) {
        hasDirectives[name] = [];
        $provide.factory(name + Suffix, ['$injector', '$exceptionHandler',
          function($injector, $exceptionHandler) {
            var directives = [];
            forEach(hasDirectives[name], function(directiveFactory) {
              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.name = directive.name || name;
                directive.require = directive.require || (directive.controller && directive.name);
                directive.restrict = directive.restrict || 'A';
                directives.push(directive);
              } catch (e) {
                $exceptionHandler(e);
              }
            });
            return directives;
          }]);
      }
      hasDirectives[name].push(directiveFactory);
    } else {
      forEach(name, reverseParams(registerDirective));
    }
    return this;
  };


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

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

    Attributes.prototype = {
      $normalize: directiveNormalize,


      /**
       * 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) {
        var booleanKey = getBooleanAttrName(this.$$element[0], key),
            $$observers = this.$$observers;

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

        this[key] = value;

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

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

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


      /**
       * Observe an interpolated attribute.
       * The observer will never be called, if given attribute is not interpolated.
       *
       * @param {string} key Normalized key. (ie ngAttribute) .
       * @param {function(*)} fn Function that will be called whenever the attribute value changes.
       * @returns {function(*)} the `fn` Function passed in.
       */
      $observe: function(key, fn) {
        var attrs = this,
            $$observers = (attrs.$$observers || (attrs.$$observers = {})),
            listeners = ($$observers[key] || ($$observers[key] = []));

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

    var startSymbol = $interpolate.startSymbol(),
        endSymbol = $interpolate.endSymbol(),
        denormalizeTemplate = (startSymbol == '{{' || endSymbol  == '}}')
            ? identity
            : function denormalizeTemplate(template) {
              return template.replace(/\{\{/g, startSymbol).replace(/}}/g, endSymbol);
            };


    return compile;

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

    function compile($compileNodes, transcludeFn, maxPriority) {
      if (!($compileNodes instanceof jqLite)) {
        // jquery always rewraps, where as 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 == 3 /* text node */) {
          $compileNodes[index] = jqLite(node).wrap('<span></span>').parent()[0];
        }
      });
      var compositeLinkFn = compileNodes($compileNodes, transcludeFn, $compileNodes, maxPriority);
      return function publicLinkFn(scope, cloneConnectFn){
        assertArg(scope, 'scope');
        // important!!: we must call our jqLite.clone() since the jQuery one is trying to be smart
        // and sometimes changes the structure of the DOM.
        var $linkNode = cloneConnectFn
          ? JQLitePrototype.clone.call($compileNodes) // IMPORTANT!!!
          : $compileNodes;
        $linkNode.data('$scope', scope);
        safeAddClass($linkNode, 'ng-scope');
        if (cloneConnectFn) cloneConnectFn($linkNode, scope);
        if (compositeLinkFn) compositeLinkFn(scope, $linkNode, $linkNode);
        return $linkNode;
      };
    }

    function wrongMode(localName, mode) {
      throw Error("Unsupported '" + mode + "' for '" + localName + "'.");
    }

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

    /**
     * Compile function matches each node in nodeList against the directives. Once all directives
     * for a particular node are collected their compile functions are executed. The compile
     * functions return values - the linking functions - are combined into a composite linking
     * function, which is the a linking function for the node.
     *
     * @param {NodeList} nodeList an array of nodes 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=} max directive priority
     * @returns {?function} A composite linking function of all of the matched directives or null.
     */
    function compileNodes(nodeList, transcludeFn, $rootElement, maxPriority) {
     var linkFns = [],
         nodeLinkFn, childLinkFn, directives, attrs, linkFnFound;

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

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

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

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

       linkFns.push(nodeLinkFn);
       linkFns.push(childLinkFn);
       linkFnFound = (linkFnFound || nodeLinkFn || childLinkFn);
     }

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

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

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

         if (nodeLinkFn) {
           if (nodeLinkFn.scope) {
             childScope = scope.$new(isObject(nodeLinkFn.scope));
             jqLite(node).data('$scope', childScope);
           } else {
             childScope = scope;
           }
           childTranscludeFn = nodeLinkFn.transclude;
           if (childTranscludeFn || (!boundTranscludeFn && transcludeFn)) {
             nodeLinkFn(childLinkFn, childScope, node, $rootElement,
                 (function(transcludeFn) {
                   return function(cloneFn) {
                     var transcludeScope = scope.$new();

                     return transcludeFn(transcludeScope, cloneFn).
                         bind('$destroy', bind(transcludeScope, transcludeScope.$destroy));
                    };
                  })(childTranscludeFn || transcludeFn)
             );
           } else {
             nodeLinkFn(childLinkFn, childScope, node, undefined, boundTranscludeFn);
           }
         } else if (childLinkFn) {
           childLinkFn(scope, node.childNodes, undefined, 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) {
      var nodeType = node.nodeType,
          attrsMap = attrs.$attr,
          match,
          className;

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

          // iterate over the attributes
          for (var attr, name, nName, value, nAttrs = node.attributes,
                   j = 0, jj = nAttrs && nAttrs.length; j < jj; j++) {
            attr = nAttrs[j];
            if (attr.specified) {
              name = attr.name;
              nName = directiveNormalize(name.toLowerCase());
              attrsMap[nName] = name;
              attrs[nName] = value = trim((msie && name == 'href')
                ? decodeURIComponent(node.getAttribute(name, 2))
                : attr.value);
              if (getBooleanAttrName(node, nName)) {
                attrs[nName] = true; // presence means true
              }
              addAttrInterpolateDirective(node, directives, value, nName);
              addDirective(directives, nName, 'A', maxPriority);
            }
          }

          // use class as directive
          className = node.className;
          if (isString(className) && className !== '') {
            while (match = CLASS_DIRECTIVE_REGEXP.exec(className)) {
              nName = directiveNormalize(match[2]);
              if (addDirective(directives, nName, 'C', maxPriority)) {
                attrs[nName] = trim(match[3]);
              }
              className = className.substr(match.index + match[0].length);
            }
          }
          break;
        case 3: /* Text Node */
          addTextInterpolateDirective(directives, node.nodeValue);
          break;
        case 8: /* Comment */
          try {
            match = COMMENT_DIRECTIVE_REGEXP.exec(node.nodeValue);
            if (match) {
              nName = directiveNormalize(match[1]);
              if (addDirective(directives, nName, 'M', maxPriority)) {
                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;
    }


    /**
     * Once the directives have been collected their compile functions is 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 {DOMElement} $rootElement If we are working on the root of the compile tree then this
     *        argument has the root jqLite array so that we can replace widgets on it.
     * @returns linkFn
     */
    function applyDirectivesToNode(directives, compileNode, templateAttrs, transcludeFn, $rootElement) {
      var terminalPriority = -Number.MAX_VALUE,
          preLinkFns = [],
          postLinkFns = [],
          newScopeDirective = null,
          newIsolateScopeDirective = null,
          templateDirective = null,
          $compileNode = templateAttrs.$$element = jqLite(compileNode),
          directive,
          directiveName,
          $template,
          transcludeDirective,
          childTranscludeFn = transcludeFn,
          controllerDirectives,
          linkFn,
          directiveValue;

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

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

        if (directiveValue = directive.scope) {
          assertNoDuplicate('isolated scope', newIsolateScopeDirective, directive, $compileNode);
          if (isObject(directiveValue)) {
            safeAddClass($compileNode, 'ng-isolate-scope');
            newIsolateScopeDirective = directive;
          }
          safeAddClass($compileNode, 'ng-scope');
          newScopeDirective = newScopeDirective || directive;
        }

        directiveName = directive.name;

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

        if (directiveValue = directive.transclude) {
          assertNoDuplicate('transclusion', transcludeDirective, directive, $compileNode);
          transcludeDirective = directive;
          terminalPriority = directive.priority;
          if (directiveValue == 'element') {
            $template = jqLite(compileNode);
            $compileNode = templateAttrs.$$element =
                jqLite('<!-- ' + directiveName + ': ' + templateAttrs[directiveName]  + ' -->');
            compileNode = $compileNode[0];
            replaceWith($rootElement, jqLite($template[0]), compileNode);
            childTranscludeFn = compile($template, transcludeFn, terminalPriority);
          } else {
            $template = jqLite(JQLiteClone(compileNode)).contents();
            $compileNode.html(''); // clear contents
            childTranscludeFn = compile($template, transcludeFn);
          }
        }

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

          if (directive.replace) {
            $template = jqLite('<div>' +
                                 trim(directiveValue) +
                               '</div>').contents();
            compileNode = $template[0];

            if ($template.length != 1 || compileNode.nodeType !== 1) {
              throw new Error(MULTI_ROOT_TEMPLATE_ERROR + directiveValue);
            }

            replaceWith($rootElement, $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 were already applied and those that weren't
            // - collect directives from the template, add them to the second group and sort them
            // - append the second group with new directives to the first group
            directives = directives.concat(
                collectDirectives(
                    compileNode,
                    directives.splice(i + 1, directives.length - (i + 1)),
                    newTemplateAttrs
                )
            );
            mergeTemplateAttributes(templateAttrs, newTemplateAttrs);

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

        if (directive.templateUrl) {
          assertNoDuplicate('template', templateDirective, directive, $compileNode);
          templateDirective = directive;
          nodeLinkFn = compileTemplateUrl(directives.splice(i, directives.length - i),
              nodeLinkFn, $compileNode, templateAttrs, $rootElement, directive.replace,
              childTranscludeFn);
          ii = directives.length;
        } else if (directive.compile) {
          try {
            linkFn = directive.compile($compileNode, templateAttrs, childTranscludeFn);
            if (isFunction(linkFn)) {
              addLinkFns(null, linkFn);
            } else if (linkFn) {
              addLinkFns(linkFn.pre, linkFn.post);
            }
          } catch (e) {
            $exceptionHandler(e, startingTag($compileNode));
          }
        }

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

      }

      nodeLinkFn.scope = newScopeDirective && newScopeDirective.scope;
      nodeLinkFn.transclude = transcludeDirective && childTranscludeFn;

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

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

      function addLinkFns(pre, post) {
        if (pre) {
          pre.require = directive.require;
          preLinkFns.push(pre);
        }
        if (post) {
          post.require = directive.require;
          postLinkFns.push(post);
        }
      }


      function getControllers(require, $element) {
        var value, retrievalMethod = 'data', optional = false;
        if (isString(require)) {
          while((value = require.charAt(0)) == '^' || value == '?') {
            require = require.substr(1);
            if (value == '^') {
              retrievalMethod = 'inheritedData';
            }
            optional = optional || value == '?';
          }
          value = $element[retrievalMethod]('$' + require + 'Controller');
          if (!value && !optional) {
            throw Error("No controller: " + require);
          }
          return value;
        } else if (isArray(require)) {
          value = [];
          forEach(require, function(require) {
            value.push(getControllers(require, $element));
          });
        }
        return value;
      }


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

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

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

          var parentScope = scope.$parent || scope;

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

            switch (mode) {

              case '@': {
                attrs.$observe(attrName, function(value) {
                  scope[scopeName] = value;
                });
                attrs.$$observers[attrName].$$scope = parentScope;
                break;
              }

              case '=': {
                parentGet = $parse(attrs[attrName]);
                parentSet = parentGet.assign || function() {
                  // reset the change, or we will throw this exception on every $digest
                  lastValue = scope[scopeName] = parentGet(parentScope);
                  throw Error(NON_ASSIGNABLE_MODEL_EXPRESSION + attrs[attrName] +
                      ' (directive: ' + newIsolateScopeDirective.name + ')');
                };
                lastValue = scope[scopeName] = parentGet(parentScope);
                scope.$watch(function parentValueWatch() {
                  var parentValue = parentGet(parentScope);

                  if (parentValue !== scope[scopeName]) {
                    // we are out of sync and need to copy
                    if (parentValue !== lastValue) {
                      // parent changed and it has precedence
                      lastValue = scope[scopeName] = parentValue;
                    } else {
                      // if the parent can be assigned then do so
                      parentSet(parentScope, parentValue = lastValue = scope[scopeName]);
                    }
                  }
                  return parentValue;
                });
                break;
              }

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

              default: {
                throw Error('Invalid isolate scope definition for directive ' +
                    newIsolateScopeDirective.name + ': ' + definiton);
              }
            }
          });
        }

        if (controllerDirectives) {
          forEach(controllerDirectives, function(directive) {
            var locals = {
              $scope: scope,
              $element: $element,
              $attrs: attrs,
              $transclude: boundTranscludeFn
            };

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

            $element.data(
                '$' + directive.name + 'Controller',
                $controller(controller, locals));
          });
        }

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

        // RECURSION
        childLinkFn && childLinkFn(scope, linkNode.childNodes, undefined, boundTranscludeFn);

        // POSTLINKING
        for(i = 0, ii = postLinkFns.length; i < ii; i++) {
          try {
            linkFn = postLinkFns[i];
            linkFn(scope, $element, attrs,
                linkFn.require && getControllers(linkFn.require, $element));
          } catch (e) {
            $exceptionHandler(e, startingTag($element));
          }
        }
      }
    }


    /**
     * 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 true if directive was added.
     */
    function addDirective(tDirectives, name, location, maxPriority) {
      var match = false;
      if (hasDirectives.hasOwnProperty(name)) {
        for(var directive, directives = $injector.get(name + Suffix),
            i = 0, ii = directives.length; i<ii; i++) {
          try {
            directive = directives[i];
            if ( (maxPriority === undefined || maxPriority > directive.priority) &&
                 directive.restrict.indexOf(location) != -1) {
              tDirectives.push(directive);
              match = true;
            }
          } catch(e) { $exceptionHandler(e); }
        }
      }
      return match;
    }


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

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

      // copy the new attributes on the old attrs object
      forEach(src, function(value, key) {
        if (key == 'class') {
          safeAddClass($element, value);
          dst['class'] = (dst['class'] ? dst['class'] + ' ' : '') + value;
        } else if (key == 'style') {
          $element.attr('style', $element.attr('style') + ';' + value);
        } else if (key.charAt(0) != '$' && !dst.hasOwnProperty(key)) {
          dst[key] = value;
          dstAttr[key] = srcAttr[key];
        }
      });
    }


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

      $compileNode.html('');

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

          content = denormalizeTemplate(content);

          if (replace) {
            $template = jqLite('<div>' + trim(content) + '</div>').contents();
            compileNode = $template[0];

            if ($template.length != 1 || compileNode.nodeType !== 1) {
              throw new Error(MULTI_ROOT_TEMPLATE_ERROR + content);
            }

            tempTemplateAttrs = {$attr: {}};
            replaceWith($rootElement, $compileNode, compileNode);
            collectDirectives(compileNode, directives, tempTemplateAttrs);
            mergeTemplateAttributes(tAttrs, tempTemplateAttrs);
          } else {
            compileNode = beforeTemplateCompileNode;
            $compileNode.html(content);
          }

          directives.unshift(derivedSyncDirective);
          afterTemplateNodeLinkFn = applyDirectivesToNode(directives, $compileNode, tAttrs, childTranscludeFn);
          afterTemplateChildLinkFn = compileNodes($compileNode.contents(), childTranscludeFn);


          while(linkQueue.length) {
            var controller = linkQueue.pop(),
                linkRootElement = linkQueue.pop(),
                beforeTemplateLinkNode = linkQueue.pop(),
                scope = linkQueue.pop(),
                linkNode = compileNode;

            if (beforeTemplateLinkNode !== beforeTemplateCompileNode) {
              // it was cloned therefore we have to clone as well.
              linkNode = JQLiteClone(compileNode);
              replaceWith(linkRootElement, jqLite(beforeTemplateLinkNode), linkNode);
            }

            afterTemplateNodeLinkFn(function() {
              beforeTemplateNodeLinkFn(afterTemplateChildLinkFn, scope, linkNode, $rootElement, controller);
            }, scope, linkNode, $rootElement, controller);
          }
          linkQueue = null;
        }).
        error(function(response, code, headers, config) {
          throw Error('Failed to load template: ' + config.url);
        });

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


    /**
     * Sorting function for bound directives.
     */
    function byPriority(a, b) {
      return b.priority - a.priority;
    }


    function assertNoDuplicate(what, previousDirective, directive, element) {
      if (previousDirective) {
        throw Error('Multiple directives [' + previousDirective.name + ', ' +
          directive.name + '] asking for ' + what + ' on: ' +  startingTag(element));
      }
    }


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


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


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

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

          if (name === 'class') {
            // we need to interpolate classes again, in the case the element was replaced
            // and therefore the two class attrs got merged - we want to interpolate the result
            interpolateFn = $interpolate(attr[name], true);
          }

          attr[name] = undefined;
          ($$observers[name] || ($$observers[name] = [])).$$inter = true;
          (attr.$$observers && attr.$$observers[name].$$scope || scope).
            $watch(interpolateFn, function interpolateFnWatchAction(value) {
              attr.$set(name, value);
            });
        })
      });
    }


    /**
     * 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} $element The jqLite element which we are going to replace. We keep the shell,
     *    but replace its DOM node reference.
     * @param {Node} newNode The new DOM node.
     */
    function replaceWith($rootElement, $element, newNode) {
      var oldNode = $element[0],
          parent = oldNode.parentNode,
          i, ii;

      if ($rootElement) {
        for(i = 0, ii = $rootElement.length; i < ii; i++) {
          if ($rootElement[i] == oldNode) {
            $rootElement[i] = newNode;
            break;
          }
        }
      }

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

      newNode[jqLite.expando] = oldNode[jqLite.expando];
      $element[0] = newNode;
    }
  }];
}

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

/**
 * @ngdoc object
 * @name ng.$compile.directive.Attributes
 * @description
 *
 * A shared object between directive compile / linking functions which contains normalized DOM element
 * attributes. The 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 ng.$compile.directive.Attributes#$attr
 * @propertyOf ng.$compile.directive.Attributes
 * @returns {object} A map of DOM element attribute names to the normalized name. This is
 *          needed to do reverse lookup from normalized name back to actual name.
 */


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



/**
 * 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
){}