angular.js/src/ng/directive/ngSwitch.js

'use strict';

/**
 * @ngdoc directive
 * @name ng.directive:ngSwitch
 * @restrict EA
 *
 * @description
 * The ngSwitch directive is used to conditionally swap DOM structure on your template based on a scope expression.
 * Elements within ngSwitch but without ngSwitchWhen or ngSwitchDefault directives will be preserved at the location
 * as specified in the template.
 *
 * The directive itself works similar to ngInclude, however, instead of downloading template code (or loading it
 * from the template cache), ngSwitch simply choses one of the nested elements and makes it visible based on which element
 * matches the value obtained from the evaluated expression. In other words, you define a container element
 * (where you place the directive), place an expression on the **on="..." attribute**
 * (or the **ng-switch="..." attribute**), define any inner elements inside of the directive and place
 * a when attribute per element. The when attribute is used to inform ngSwitch which element to display when the on
 * expression is evaluated. If a matching expression is not found via a when attribute then an element with the default
 * attribute is displayed.
 *
 * @animations
 * enter - happens after the ngSwitch contents change and the matched child element is placed inside the container
 * leave - happens just after the ngSwitch contents change and just before the former contents are removed from the DOM
 *
 * @usage
 * <ANY ng-switch="expression">
 *   <ANY ng-switch-when="matchValue1">...</ANY>
 *   <ANY ng-switch-when="matchValue2">...</ANY>
 *   <ANY ng-switch-default>...</ANY>
 * </ANY>
 *
 * @scope
 * @priority 800
 * @param {*} ngSwitch|on expression to match against <tt>ng-switch-when</tt>.
 * @paramDescription
 * On child elements add:
 *
 * * `ngSwitchWhen`: the case statement to match against. If match then this
 *   case will be displayed. If the same match appears multiple times, all the
 *   elements will be displayed.
 * * `ngSwitchDefault`: the default case when no other case match. If there
 *   are multiple default cases, all of them will be displayed when no other
 *   case match.
 *
 *
 * @example
  <example animations="true">
    <file name="index.html">
      <div ng-controller="Ctrl">
        <select ng-model="selection" ng-options="item for item in items">
        </select>
        <tt>selection={{selection}}</tt>
        <hr/>
        <div class="animate-switch-container"
          ng-switch on="selection">
            <div ng-switch-when="settings">Settings Div</div>
            <div ng-switch-when="home">Home Span</div>
            <div ng-switch-default>default</div>
        </div>
      </div>
    </file>
    <file name="script.js">
      function Ctrl($scope) {
        $scope.items = ['settings', 'home', 'other'];
        $scope.selection = $scope.items[0];
      }
    </file>
    <file name="animations.css">
      .animate-switch-container {
        position:relative;
        background:white;
        border:1px solid black;
        height:40px;
        overflow:hidden;
      }

      .animate-switch-container > div {
        padding:10px;
      }

      .animate-switch-container > .ng-enter,
      .animate-switch-container > .ng-leave {
        -webkit-transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;
        -moz-transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;
        -o-transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;
        transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;

        position:absolute;
        top:0;
        left:0;
        right:0;
        bottom:0;
      }

      .animate-switch-container > .ng-enter {
        top:-50px;
      }
      .animate-switch-container > .ng-enter.ng-enter-active {
        top:0;
      }

      .animate-switch-container > .ng-leave {
        top:0;
      }
      .animate-switch-container > .ng-leave.ng-leave-active {
        top:50px;
      }
    </file>
    <file name="scenario.js">
      it('should start in settings', function() {
        expect(element('.doc-example-live [ng-switch]').text()).toMatch(/Settings Div/);
      });
      it('should change to home', function() {
        select('selection').option('home');
        expect(element('.doc-example-live [ng-switch]').text()).toMatch(/Home Span/);
      });
      it('should select default', function() {
        select('selection').option('other');
        expect(element('.doc-example-live [ng-switch]').text()).toMatch(/default/);
      });
    </file>
  </example>
 */
var ngSwitchDirective = ['$animate', function($animate) {
  return {
    restrict: 'EA',
    require: 'ngSwitch',

    // asks for $scope to fool the BC controller module
    controller: ['$scope', function ngSwitchController() {
     this.cases = {};
    }],
    link: function(scope, element, attr, ngSwitchController) {
      var watchExpr = attr.ngSwitch || attr.on,
          selectedTranscludes,
          selectedElements,
          selectedScopes = [];

      scope.$watch(watchExpr, function ngSwitchWatchAction(value) {
        for (var i= 0, ii=selectedScopes.length; i<ii; i++) {
          selectedScopes[i].$destroy();
          $animate.leave(selectedElements[i]);
        }

        selectedElements = [];
        selectedScopes = [];

        if ((selectedTranscludes = ngSwitchController.cases['!' + value] || ngSwitchController.cases['?'])) {
          scope.$eval(attr.change);
          forEach(selectedTranscludes, function(selectedTransclude) {
            var selectedScope = scope.$new();
            selectedScopes.push(selectedScope);
            selectedTransclude.transclude(selectedScope, function(caseElement) {
              var anchor = selectedTransclude.element;

              selectedElements.push(caseElement);
              $animate.enter(caseElement, anchor.parent(), anchor);
            });
          });
        }
      });
    }
  }
}];

var ngSwitchWhenDirective = ngDirective({
  transclude: 'element',
  priority: 800,
  require: '^ngSwitch',
  compile: function(element, attrs, transclude) {
    return function(scope, element, attr, ctrl) {
      ctrl.cases['!' + attrs.ngSwitchWhen] = (ctrl.cases['!' + attrs.ngSwitchWhen] || []);
      ctrl.cases['!' + attrs.ngSwitchWhen].push({ transclude: transclude, element: element });
    };
  }
});

var ngSwitchDefaultDirective = ngDirective({
  transclude: 'element',
  priority: 800,
  require: '^ngSwitch',
  compile: function(element, attrs, transclude) {
    return function(scope, element, attr, ctrl) {
      ctrl.cases['?'] = (ctrl.cases['?'] || []);
      ctrl.cases['?'].push({ transclude: transclude, element: element });
    };
  }
});