angular.js/src/directives.js

'use strict';

/**
 * @ngdoc overview
 * @name angular.directive
 * @description
 *
 * Angular directives create custom attributes for DOM elements. A directive can modify the
 * behavior of the element in which it is specified. Do not use directives to add elements to the
 * DOM; instead, use {@link angular.widget widgets} to add DOM elements.
 *
 * Following is the list of built-in Angular directives:
 *
 * * {@link angular.directive.ng:autobind ng:autobind} - An Angular bootstrap parameter that can
 * act as a directive.
 * * {@link angular.directive.ng:bind ng:bind} - Creates a data-binding between an HTML text value
 * and a data model.
 * * {@link angular.directive.ng:bind-attr ng:bind-attr} - Creates a data-binding in a way similar
 * to `ng:bind`, but uses JSON key / value pairs to do so.
 * * {@link angular.directive.ng:bind-template ng:bind-template} - Replaces the text value of an
 * element with a specified template.
 * * {@link angular.directive.ng:change ng:change} - Executes an expression when the value of an
 * input widget changes.
 * * {@link angular.directive.ng:class ng:class} - Conditionally set a CSS class on an element.
 * * {@link angular.directive.ng:class-even ng:class-even} - Like `ng:class`, but works in
 * conjunction with {@link angular.widget.@ng:repeat} to affect even rows in a collection.
 * * {@link angular.directive.ng:class-odd ng:class-odd} - Like `ng:class`, but works with {@link
 * angular.widget.@ng:repeat}  to affect odd rows.
 * * {@link angular.directive.ng:click ng:click} - Executes custom behavior when an element is
 * clicked.
 * * {@link angular.directive.ng:controller ng:controller} - Creates a scope object linked to the
 * DOM element and assigns behavior to the scope.
 * * {@link angular.directive.ng:hide ng:hide} - Conditionally hides a portion of HTML.
 * * {@link angular.directive.ng:href ng:href} - Places an href in the Angular namespace.
 * * {@link angular.directive.ng:init} - Initialization tasks run before a template is executed.
 * * {@link angular.directive.ng:show ng:show} - Conditionally displays a portion of HTML.
 * * {@link angular.directive.ng:src ng:src} - Places a `src` attribute into the Angular namespace.
 * * {@link angular.directive.ng:style ng:style} - Conditionally set CSS styles on an element.
 * * {@link angular.directive.ng:submit} - Binds Angular expressions to `onSubmit` events.
 *
 * For more information about how Angular directives work, and to learn how to create your own
 * directives, see {@link guide/dev_guide.compiler.directives Understanding Angular Directives} in
 * the Angular Developer Guide.
 */

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:init
 *
 * @description
 * The `ng:init` attribute specifies initialization tasks to be executed
 *  before the template enters execution mode during bootstrap.
 *
 * @element ANY
 * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval.
 *
 * @example
   <doc:example>
     <doc:source>
    <div ng:init="greeting='Hello'; person='World'">
      {{greeting}} {{person}}!
    </div>
     </doc:source>
     <doc:scenario>
       it('should check greeting', function(){
         expect(binding('greeting')).toBe('Hello');
         expect(binding('person')).toBe('World');
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:init", function(expression){
  return function(element){
    this.$eval(expression);
  };
});

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:controller
 *
 * @description
 * The `ng:controller` directive assigns behavior to a scope. This is a key aspect of how angular
 * supports the principles behind the Model-View-Controller design pattern.
 *
 * MVC components in angular:
 *
 * * Model — The Model is data in scope properties; scopes are attached to the DOM.
 * * View — The template (HTML with data bindings) is rendered into the View.
 * * Controller — The `ng:controller` directive specifies a Controller class; the class has
 *   methods that typically express the business logic behind the application.
 *
 * Note that an alternative way to define controllers is via the `{@link angular.service.$route}`
 * service.
 *
 * @element ANY
 * @param {expression} expression Name of a globally accessible constructor function or an
 *     {@link guide/dev_guide.expressions expression} that on the current scope evaluates to a
 *     constructor function.
 *
 * @example
 * Here is a simple form for editing user contact information. Adding, removing, clearing, and
 * greeting are methods declared on the controller (see source tab). These methods can
 * easily be called from the angular markup. Notice that the scope becomes the `this` for the
 * controller's instance. This allows for easy access to the view data from the controller. Also
 * notice that any changes to the data are automatically reflected in the View without the need
 * for a manual update.
   <doc:example>
     <doc:source>
      <script type="text/javascript">
        function SettingsController() {
          this.name = "John Smith";
          this.contacts = [
            {type:'phone', value:'408 555 1212'},
            {type:'email', value:'john.smith@example.org'} ];
        }
        SettingsController.prototype = {
         greet: function(){
           alert(this.name);
         },
         addContact: function(){
           this.contacts.push({type:'email', value:'yourname@example.org'});
         },
         removeContact: function(contactToRemove) {
           angular.Array.remove(this.contacts, contactToRemove);
         },
         clearContact: function(contact) {
           contact.type = 'phone';
           contact.value = '';
         }
        };
      </script>
      <div ng:controller="SettingsController">
        Name: <input type="text" name="name"/>
        [ <a href="" ng:click="greet()">greet</a> ]<br/>
        Contact:
        <ul>
          <li ng:repeat="contact in contacts">
            <select name="contact.type">
               <option>phone</option>
               <option>email</option>
            </select>
            <input type="text" name="contact.value"/>
            [ <a href="" ng:click="clearContact(contact)">clear</a>
            | <a href="" ng:click="removeContact(contact)">X</a> ]
          </li>
          <li>[ <a href="" ng:click="addContact()">add</a> ]</li>
       </ul>
      </div>
     </doc:source>
     <doc:scenario>
       it('should check controller', function(){
         expect(element('.doc-example-live div>:input').val()).toBe('John Smith');
         expect(element('.doc-example-live li[ng\\:repeat-index="0"] input').val())
           .toBe('408 555 1212');
         expect(element('.doc-example-live li[ng\\:repeat-index="1"] input').val())
           .toBe('john.smith@example.org');

         element('.doc-example-live li:first a:contains("clear")').click();
         expect(element('.doc-example-live li:first input').val()).toBe('');

         element('.doc-example-live li:last a:contains("add")').click();
         expect(element('.doc-example-live li[ng\\:repeat-index="2"] input').val())
           .toBe('yourname@example.org');
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:controller", function(expression){
  this.scope(function(scope){
    var Controller =
      getter(scope, expression, true) ||
      getter(window, expression, true);
    assertArgFn(Controller, expression);
    return Controller;
  });
  return noop;
});

/**
 * @ngdoc directive
 * @name angular.directive.ng:bind
 *
 * @description
 * The `ng:bind` attribute tells Angular to replace the text content of the specified HTML element
 * with the value of a given expression, and to update the text content when the value of that
 * expression changes.
 *
 * Typically, you don't use `ng:bind` directly, but instead you use the double curly markup like
 * `{{ expression }}` and let the Angular compiler transform it to
 * `<span ng:bind="expression"></span>` when the template is compiled.
 *
 * @element ANY
 * @param {expression} expression {@link guide/dev_guide.expressions Expression} to evaluate.
 *
 * @example
 * Enter a name in the Live Preview text box; the greeting below the text box changes instantly.
   <doc:example>
     <doc:source>
       Enter name: <input type="text" name="name" value="Whirled"> <br>
       Hello <span ng:bind="name"></span>!
     </doc:source>
     <doc:scenario>
       it('should check ng:bind', function(){
         expect(using('.doc-example-live').binding('name')).toBe('Whirled');
         using('.doc-example-live').input('name').enter('world');
         expect(using('.doc-example-live').binding('name')).toBe('world');
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:bind", function(expression, element){
  element.addClass('ng-binding');
  var exprFn = parser(expression).statements();
  return function(element) {
    var lastValue = noop, lastError = noop;
    this.$watch(function(scope) {
      // TODO(misko): remove error handling https://github.com/angular/angular.js/issues/347
      var error, value, html, isHtml, isDomElement,
          hadOwnElement = scope.hasOwnProperty('$element'),
          oldElement = scope.$element;
      // TODO(misko): get rid of $element https://github.com/angular/angular.js/issues/348
      scope.$element = element;
      try {
        value = exprFn(scope);
      } catch (e) {
        scope.$service('$exceptionHandler')(e);
        error = formatError(e);
      } finally {
        if (hadOwnElement) {
          scope.$element = oldElement;
        } else {
          delete scope.$element;
        }
      }
      // If we are HTML, then save the raw HTML data so that we don't
      // recompute sanitization since that is expensive.
      // TODO: turn this into a more generic way to compute this
      if ((isHtml = (value instanceof HTML)))
        value = (html = value).html;
      if (lastValue === value && lastError == error) return;
      isDomElement = isElement(value);
      if (!isHtml && !isDomElement && isObject(value)) {
        value = toJson(value, true);
      }
      if (value != lastValue || error != lastError) {
        lastValue = value;
        lastError = error;
        elementError(element, NG_EXCEPTION, error);
        if (error) value = error;
        if (isHtml) {
          element.html(html.get());
        } else if (isDomElement) {
          element.html('');
          element.append(value);
        } else {
          element.text(value == undefined ? '' : value);
        }
      }
    });
  };
});

var bindTemplateCache = {};
function compileBindTemplate(template){
  var fn = bindTemplateCache[template];
  if (!fn) {
    var bindings = [];
    forEach(parseBindings(template), function(text){
      var exp = binding(text);
      bindings.push(exp
        ? function(scope, element) {
            var error, value;
            try {
              value = scope.$eval(exp);
            } catch(e) {
              scope.$service('$exceptionHandler')(e);
              error = toJson(e);
            }
            elementError(element, NG_EXCEPTION, error);
            return error ? error : value;
          }
        : function() {
            return text;
          });
    });
    bindTemplateCache[template] = fn = function(scope, element, prettyPrintJson) {
      var parts = [],
          hadOwnElement = scope.hasOwnProperty('$element'),
          oldElement = scope.$element;

      // TODO(misko): get rid of $element
      scope.$element = element;
      try {
        for (var i = 0; i < bindings.length; i++) {
          var value = bindings[i](scope, element);
          if (isElement(value))
            value = '';
          else if (isObject(value))
            value = toJson(value, prettyPrintJson);
          parts.push(value);
        }
        return parts.join('');
      } finally {
        if (hadOwnElement) {
          scope.$element = oldElement;
        } else {
          delete scope.$element;
        }
      }
    };
  }
  return fn;
}

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:bind-template
 *
 * @description
 * The `ng:bind-template` attribute specifies that the element
 * text should be replaced with the template in ng:bind-template.
 * Unlike ng:bind the ng:bind-template can contain multiple `{{` `}}`
 * expressions. (This is required since some HTML elements
 * can not have SPAN elements such as TITLE, or OPTION to name a few.)
 *
 * @element ANY
 * @param {string} template of form
 *   <tt>{{</tt> <tt>expression</tt> <tt>}}</tt> to eval.
 *
 * @example
 * Try it here: enter text in text box and watch the greeting change.
   <doc:example>
     <doc:source>
      Salutation: <input type="text" name="salutation" value="Hello"><br/>
      Name: <input type="text" name="name" value="World"><br/>
      <pre ng:bind-template="{{salutation}} {{name}}!"></pre>
     </doc:source>
     <doc:scenario>
       it('should check ng:bind', function(){
         expect(using('.doc-example-live').binding('{{salutation}} {{name}}')).
           toBe('Hello World!');
         using('.doc-example-live').input('salutation').enter('Greetings');
         using('.doc-example-live').input('name').enter('user');
         expect(using('.doc-example-live').binding('{{salutation}} {{name}}')).
           toBe('Greetings user!');
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:bind-template", function(expression, element){
  element.addClass('ng-binding');
  var templateFn = compileBindTemplate(expression);
  return function(element) {
    var lastValue;
    this.$watch(function(scope) {
      var value = templateFn(scope, element, true);
      if (value != lastValue) {
        element.text(value);
        lastValue = value;
      }
    });
  };
});

var REMOVE_ATTRIBUTES = {
  'disabled':'disabled',
  'readonly':'readOnly',
  'checked':'checked',
  'selected':'selected',
  'multiple':'multiple'
};
/**
 * @ngdoc directive
 * @name angular.directive.ng:bind-attr
 *
 * @description
 * The `ng:bind-attr` attribute specifies that a
 * {@link guide/dev_guide.templates.databinding databinding}  should be created between a particular
 * element attribute and a given expression. Unlike `ng:bind`, the `ng:bind-attr` contains one or
 * more JSON key value pairs; each pair specifies an attribute and the
 * {@link guide/dev_guide.expressions expression} to which it will be mapped.
 *
 * Instead of writing `ng:bind-attr` statements in your HTML, you can use double-curly markup to
 * specify an <tt ng:non-bindable>{{expression}}</tt> for the value of an attribute.
 * At compile time, the attribute is translated into an `<span ng:bind-attr="{attr:expression}"/>`
 *
 * The following HTML snippet shows how to specify `ng:bind-attr`:
 * <pre>
 *   <a href="http://www.google.com/search?q={{query}}">Google</a>
 * </pre>
 *
 * During compilation, the snippet gets translated to the following:
 * <pre>
 *   <a ng:bind-attr='{"href":"http://www.google.com/search?q={{query}}"}'>Google</a>
 * </pre>
 *
 * @element ANY
 * @param {string} attribute_json one or more JSON key-value pairs representing
 *    the attributes to replace with expressions. Each key matches an attribute
 *    which needs to be replaced. Each value is a text template of
 *    the attribute with the embedded
 *    <tt ng:non-bindable>{{expression}}</tt>s. Any number of
 *    key-value pairs can be specified.
 *
 * @example
 * Enter a search string in the Live Preview text box and then click "Google". The search executes instantly.
   <doc:example>
     <doc:source>
      Google for:
      <input type="text" name="query" value="AngularJS"/>
      <a href="http://www.google.com/search?q={{query}}">Google</a>
     </doc:source>
     <doc:scenario>
       it('should check ng:bind-attr', function(){
         expect(using('.doc-example-live').element('a').attr('href')).
           toBe('http://www.google.com/search?q=AngularJS');
         using('.doc-example-live').input('query').enter('google');
         expect(using('.doc-example-live').element('a').attr('href')).
           toBe('http://www.google.com/search?q=google');
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:bind-attr", function(expression){
  return function(element){
    var lastValue = {};
    this.$watch(function(scope){
      var values = scope.$eval(expression);
      for(var key in values) {
        var value = compileBindTemplate(values[key])(scope, element),
            specialName = REMOVE_ATTRIBUTES[lowercase(key)];
        if (lastValue[key] !== value) {
          lastValue[key] = value;
          if (specialName) {
            if (toBoolean(value)) {
              element.attr(specialName, specialName);
              element.attr('ng-' + specialName, value);
            } else {
              element.removeAttr(specialName);
              element.removeAttr('ng-' + specialName);
            }
            (element.data($$validate)||noop)();
          } else {
            element.attr(key, value);
          }
        }
      }
    });
  };
});


/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:click
 *
 * @description
 * The ng:click allows you to specify custom behavior when
 * element is clicked.
 *
 * @element ANY
 * @param {expression} expression {@link guide/dev_guide.expressions Expression} to evaluate upon
 * click.
 *
 * @example
   <doc:example>
     <doc:source>
      <button ng:click="count = count + 1" ng:init="count=0">
        Increment
      </button>
      count: {{count}}
     </doc:source>
     <doc:scenario>
       it('should check ng:click', function(){
         expect(binding('count')).toBe('0');
         element('.doc-example-live :button').click();
         expect(binding('count')).toBe('1');
       });
     </doc:scenario>
   </doc:example>
 */
/*
 * A directive that allows creation of custom onclick handlers that are defined as angular
 * expressions and are compiled and executed within the current scope.
 *
 * Events that are handled via these handler are always configured not to propagate further.
 *
 * TODO: maybe we should consider allowing users to control event propagation in the future.
 */
angularDirective("ng:click", function(expression, element){
  return function(element){
    var self = this;
    element.bind('click', function(event){
      self.$apply(expression);
      event.stopPropagation();
    });
  };
});


/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:submit
 *
 * @description
 * Enables binding angular expressions to onsubmit events.
 *
 * Additionally it prevents the default action (which for form means sending the request to the
 * server and reloading the current page).
 *
 * @element form
 * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval.
 *
 * @example
   <doc:example>
     <doc:source>
      <form ng:submit="list.push(text);text='';" ng:init="list=[]">
        Enter text and hit enter:
        <input type="text" name="text" value="hello"/>
        <input type="submit" id="submit" value="Submit" />
      </form>
      <pre>list={{list}}</pre>
     </doc:source>
     <doc:scenario>
       it('should check ng:submit', function(){
         expect(binding('list')).toBe('list=[]');
         element('.doc-example-live #submit').click();
         expect(binding('list')).toBe('list=["hello"]');
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:submit", function(expression, element) {
  return function(element) {
    var self = this;
    element.bind('submit', function(event) {
      self.$apply(expression);
      event.preventDefault();
    });
  };
});


function ngClass(selector) {
  return function(expression, element) {
    return function(element) {
      this.$watch(expression, function(scope, newVal, oldVal) {
        if (selector(scope.$index)) {
          element.removeClass(isArray(oldVal) ? oldVal.join(' ') : oldVal)
          element.addClass(isArray(newVal) ? newVal.join(' ') : newVal);
        }
      });
    };
  };
}

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:class
 *
 * @description
 * The `ng:class` allows you to set CSS class on HTML element dynamically by databinding an
 * expression that represents all classes to be added.
 *
 * The directive won't add duplicate classes if a particular class was already set.
 *
 * When the expression changes, the previously added classes are removed and only then the classes
 * new classes are added.
 *
 * @element ANY
 * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval. The result
 *   of the evaluation can be a string representing space delimited class names or an array.
 *
 * @example
   <doc:example>
     <doc:source>
      <input type="button" value="set" ng:click="myVar='ng-input-indicator-wait'">
      <input type="button" value="clear" ng:click="myVar=''">
      <br>
      <span ng:class="myVar">Sample Text &nbsp;&nbsp;&nbsp;&nbsp;</span>
     </doc:source>
     <doc:scenario>
       it('should check ng:class', function(){
         expect(element('.doc-example-live span').prop('className')).not().
           toMatch(/ng-input-indicator-wait/);

         using('.doc-example-live').element(':button:first').click();

         expect(element('.doc-example-live span').prop('className')).
           toMatch(/ng-input-indicator-wait/);

         using('.doc-example-live').element(':button:last').click();

         expect(element('.doc-example-live span').prop('className')).not().
           toMatch(/ng-input-indicator-wait/);
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:class", ngClass(function(){return true;}));

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:class-odd
 *
 * @description
 * The `ng:class-odd` and `ng:class-even` works exactly as
 * {@link angular.directive.ng:class ng:class}, except it works in conjunction with `ng:repeat` and
 * takes affect only on odd (even) rows.
 *
 * This directive can be applied only within a scope of an
 * {@link angular.widget.@ng:repeat ng:repeat}.
 *
 * @element ANY
 * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval. The result
 *   of the evaluation can be a string representing space delimited class names or an array.
 *
 * @example
   <doc:example>
     <doc:source>
        <ol ng:init="names=['John', 'Mary', 'Cate', 'Suz']">
          <li ng:repeat="name in names">
           <span ng:class-odd="'ng-format-negative'"
                 ng:class-even="'ng-input-indicator-wait'">
             {{name}} &nbsp; &nbsp; &nbsp;
           </span>
          </li>
        </ol>
     </doc:source>
     <doc:scenario>
       it('should check ng:class-odd and ng:class-even', function(){
         expect(element('.doc-example-live li:first span').prop('className')).
           toMatch(/ng-format-negative/);
         expect(element('.doc-example-live li:last span').prop('className')).
           toMatch(/ng-input-indicator-wait/);
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:class-odd", ngClass(function(i){return i % 2 === 0;}));

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:class-even
 *
 * @description
 * The `ng:class-odd` and `ng:class-even` works exactly as
 * {@link angular.directive.ng:class ng:class}, except it works in conjunction with `ng:repeat` and
 * takes affect only on odd (even) rows.
 *
 * This directive can be applied only within a scope of an
 * {@link angular.widget.@ng:repeat ng:repeat}.
 *
 * @element ANY
 * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval. The result
 *   of the evaluation can be a string representing space delimited class names or an array.
 *
 * @example
   <doc:example>
     <doc:source>
        <ol ng:init="names=['John', 'Mary', 'Cate', 'Suz']">
          <li ng:repeat="name in names">
           <span ng:class-odd="'ng-format-negative'"
                 ng:class-even="'ng-input-indicator-wait'">
             {{name}} &nbsp; &nbsp; &nbsp;
           </span>
          </li>
        </ol>
     </doc:source>
     <doc:scenario>
       it('should check ng:class-odd and ng:class-even', function(){
         expect(element('.doc-example-live li:first span').prop('className')).
           toMatch(/ng-format-negative/);
         expect(element('.doc-example-live li:last span').prop('className')).
           toMatch(/ng-input-indicator-wait/);
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:class-even", ngClass(function(i){return i % 2 === 1;}));

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:show
 *
 * @description
 * The `ng:show` and `ng:hide` directives show or hide a portion of the DOM tree (HTML)
 * conditionally.
 *
 * @element ANY
 * @param {expression} expression If the {@link guide/dev_guide.expressions expression} is truthy
 *     then the element is shown or hidden respectively.
 *
 * @example
   <doc:example>
     <doc:source>
        Click me: <input type="checkbox" name="checked"><br/>
        Show: <span ng:show="checked">I show up when your checkbox is checked.</span> <br/>
        Hide: <span ng:hide="checked">I hide when your checkbox is checked.</span>
     </doc:source>
     <doc:scenario>
       it('should check ng:show / ng:hide', function(){
         expect(element('.doc-example-live span:first:hidden').count()).toEqual(1);
         expect(element('.doc-example-live span:last:visible').count()).toEqual(1);

         input('checked').check();

         expect(element('.doc-example-live span:first:visible').count()).toEqual(1);
         expect(element('.doc-example-live span:last:hidden').count()).toEqual(1);
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:show", function(expression, element){
  return function(element){
    this.$watch(expression, function(scope, value){
      element.css('display', toBoolean(value) ? '' : 'none');
    });
  };
});

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:hide
 *
 * @description
 * The `ng:hide` and `ng:show` directives hide or show a portion
 * of the HTML conditionally.
 *
 * @element ANY
 * @param {expression} expression If the {@link guide/dev_guide.expressions expression} truthy then
 *     the element is shown or hidden respectively.
 *
 * @example
   <doc:example>
     <doc:source>
        Click me: <input type="checkbox" name="checked"><br/>
        Show: <span ng:show="checked">I show up when you checkbox is checked?</span> <br/>
        Hide: <span ng:hide="checked">I hide when you checkbox is checked?</span>
     </doc:source>
     <doc:scenario>
       it('should check ng:show / ng:hide', function(){
         expect(element('.doc-example-live span:first:hidden').count()).toEqual(1);
         expect(element('.doc-example-live span:last:visible').count()).toEqual(1);

         input('checked').check();

         expect(element('.doc-example-live span:first:visible').count()).toEqual(1);
         expect(element('.doc-example-live span:last:hidden').count()).toEqual(1);
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:hide", function(expression, element){
  return function(element){
    this.$watch(expression, function(scope, value){
      element.css('display', toBoolean(value) ? 'none' : '');
    });
  };
});

/**
 * @workInProgress
 * @ngdoc directive
 * @name angular.directive.ng:style
 *
 * @description
 * The ng:style allows you to set CSS style on an HTML element conditionally.
 *
 * @element ANY
 * @param {expression} expression {@link guide/dev_guide.expressions Expression} which evals to an
 *      object whose keys are CSS style names and values are corresponding values for those CSS
 *      keys.
 *
 * @example
   <doc:example>
     <doc:source>
        <input type="button" value="set" ng:click="myStyle={color:'red'}">
        <input type="button" value="clear" ng:click="myStyle={}">
        <br/>
        <span ng:style="myStyle">Sample Text</span>
        <pre>myStyle={{myStyle}}</pre>
     </doc:source>
     <doc:scenario>
       it('should check ng:style', function(){
         expect(element('.doc-example-live span').css('color')).toBe('rgb(0, 0, 0)');
         element('.doc-example-live :button[value=set]').click();
         expect(element('.doc-example-live span').css('color')).toBe('rgb(255, 0, 0)');
         element('.doc-example-live :button[value=clear]').click();
         expect(element('.doc-example-live span').css('color')).toBe('rgb(0, 0, 0)');
       });
     </doc:scenario>
   </doc:example>
 */
angularDirective("ng:style", function(expression, element){
  // TODO(i): this is inefficient (runs on every $digest) and obtrusive (overrides 3rd part css)
  //   we should change it in a similar way as I changed ng:class
  return function(element){
    var resetStyle = getStyle(element);
    this.$watch(function(scope){
      var style = scope.$eval(expression) || {}, key, mergedStyle = {};
      for(key in style) {
        if (resetStyle[key] === undefined) resetStyle[key] = '';
        mergedStyle[key] = style[key];
      }
      for(key in resetStyle) {
        mergedStyle[key] = mergedStyle[key] || resetStyle[key];
      }
      element.css(mergedStyle);
    });
  };
});


/**
 * @ngdoc directive
 * @name angular.directive.ng:cloak
 *
 * @description
 * The `ng:cloak` directive is used to prevent the Angular html template from being briefly
 * displayed by the browser in its raw (uncompiled) form while your application is loading. Use this
 * directive to avoid the undesirable flicker effect caused by the html template display.
 *
 * The directive can be applied to the `<body>` element, but typically a fine-grained application is
 * prefered in order to benefit from progressive rendering of the browser view.
 *
 * `ng:cloak` works in cooperation with a css rule that is embedded within `angular.js` and
 *  `angular.min.js` files. Following is the css rule:
 *
 * <pre>
 * [ng\:cloak], .ng-cloak {
 *   display: none;
 * }
 * </pre>
 *
 * When this css rule is loaded by the browser, all html elements (including their children) that
 * are tagged with the `ng:cloak` directive are hidden. When Angular comes across this directive
 * during the compilation of the template it deletes the `ng:cloak` element attribute, which
 * makes the compiled element visible.
 *
 * For the best result, `angular.js` script must be loaded in the head section of the html file;
 * alternatively, the css rule (above) must be included in the external stylesheet of the
 * application.
 *
 * Legacy browsers, like IE7, do not provide attribute selector support (added in CSS 2.1) so they
 * cannot match the `[ng\:cloak]` selector. To work around this limitation, you must add the css
 * class `ng-cloak` in addition to `ng:cloak` directive as shown in the example below.
 *
 * @element ANY
 *
 * @example
   <doc:example>
     <doc:source>
        <div id="template1" ng:cloak>{{ 'hello' }}</div>
        <div id="template2" ng:cloak class="ng-cloak">{{ 'hello IE7' }}</div>
     </doc:source>
     <doc:scenario>
       it('should remove the template directive and css class', function() {
         expect(element('.doc-example-live #template1').attr('ng:cloak')).
           not().toBeDefined();
         expect(element('.doc-example-live #template2').attr('ng:cloak')).
           not().toBeDefined();
       });
     </doc:scenario>
   </doc:example>
 *
 */
angularDirective("ng:cloak", function(expression, element) {
  element.removeAttr('ng:cloak');
  element.removeClass('ng-cloak');
});