Function classDirective

test/angular/1.4/angular.js:23147–23268

(name, selector)

});

function classDirective(name, selector) {
  name = 'ngClass' + name;
  return ['$animate', function($animate) {
    return {
      restrict: 'AC',
      link: function(scope, element, attr) {
        var oldVal;

        scope.$watch(attr[name], ngClassWatchAction, true);

        attr.$observe('class', function(value) {
          ngClassWatchAction(scope.$eval(attr[name]));
        });


        if (name !== 'ngClass') {
          scope.$watch('$index', function($index, old$index) {
            // jshint bitwise: false
            var mod = $index & 1;
            if (mod !== (old$index & 1)) {
              var classes = arrayClasses(scope.$eval(attr[name]));
              mod === selector ?
                addClasses(classes) :
                removeClasses(classes);
            }
          });
        }

        function addClasses(classes) {
          var newClasses = digestClassCounts(classes, 1);
          attr.$addClass(newClasses);
        }

        function removeClasses(classes) {
          var newClasses = digestClassCounts(classes, -1);
          attr.$removeClass(newClasses);
        }

        function digestClassCounts(classes, count) {
          // Use createMap() to prevent class assumptions involving property
          // names in Object.prototype
          var classCounts = element.data('$classCounts') || createMap();
          var classesToUpdate = [];
          forEach(classes, function(className) {
            if (count > 0 || classCounts[className]) {
              classCounts[className] = (classCounts[className] || 0) + count;
              if (classCounts[className] === +(count > 0)) {
                classesToUpdate.push(className);
              }
            }
          });
          element.data('$classCounts', classCounts);
          return classesToUpdate.join(' ');
        }

        function updateClasses(oldClasses, newClasses) {
          var toAdd = arrayDifference(newClasses, oldClasses);
          var toRemove = arrayDifference(oldClasses, newClasses);