Function resolveElementClasses

test/angular/1.4/angular-animate.js:267–323

(existing, toAdd, toRemove)

}

function resolveElementClasses(existing, toAdd, toRemove) {
  var ADD_CLASS = 1;
  var REMOVE_CLASS = -1;

  var flags = {};
  existing = splitClassesToLookup(existing);

  toAdd = splitClassesToLookup(toAdd);
  forEach(toAdd, function(value, key) {
    flags[key] = ADD_CLASS;
  });

  toRemove = splitClassesToLookup(toRemove);
  forEach(toRemove, function(value, key) {
    flags[key] = flags[key] === ADD_CLASS ? null : REMOVE_CLASS;
  });

  var classes = {
    addClass: '',
    removeClass: ''
  };

  forEach(flags, function(val, klass) {
    var prop, allow;
    if (val === ADD_CLASS) {
      prop = 'addClass';
      allow = !existing[klass];
    } else if (val === REMOVE_CLASS) {
      prop = 'removeClass';
      allow = existing[klass];
    }
    if (allow) {
      if (classes[prop].length) {
        classes[prop] += ' ';
      }
      classes[prop] += klass;
    }
  });

  function splitClassesToLookup(classes) {
    if (isString(classes)) {
      classes = classes.split(' ');
    }

    var obj = {};
    forEach(classes, function(klass) {
      // sometimes the split leaves empty string values
      // incase extra spaces were applied to the options
      if (klass.length) {
        obj[klass] = true;
      }
    });
    return obj;
  }

  return classes;
}