foam-framework/core/visitor.js

MVC metaprogramming framework

/**
 * @license
 * Copyright 2012 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
var Visitor = {
  create: function() {
    return { __proto__: this, stack: [] };
  },

  push: function(o) { this.stack.push(o); },

  pop: function() { return this.stack.pop(); },

  top: function() {
    return this.stack.length && this.stack[this.stack.length-1];
  },

  visit: function(o) {
    return Array.isArray(o)           ? this.visitArray(o)    :
           ( typeof o === 'string' )  ? this.visitString(o)   :
           ( typeof o === 'number' )  ? this.visitNumber(o)   :
           ( o instanceof Function )  ? this.visitFunction(o) :
           ( o instanceof Date )      ? this.visitDate(o)     :
           ( o === true )             ? this.visitTrue()      :
           ( o === false )            ? this.visitFalse()     :
           ( o === null )             ? this.visitNull()      :
           ( o instanceof Object )    ? ( o.model_            ?
             this.visitObject(o)      :
             this.visitMap(o)
           )                          : this.visitUndefined() ;
  },

  visitArray: function(o) {
    var len = o.length;
    for ( var i = 0 ; i < len ; i++ ) this.visitArrayElement(o, i);
    return o;
  },
  visitArrayElement: function (arr, i) { this.visit(arr[i]); },

  visitString: function(o) { return o; },

  visitFunction: function(o) { return o; },

  visitNumber: function(o) { return o; },

  visitDate: function(o) { return o; },

  visitObject: function(o) {
    var properties = o.model_.getRuntimeProperties();
    for ( var key in properties ) {
      var prop = properties[key];

      if ( prop.name in o.instance_ ) {
        this.visitProperty(o, prop);
      }
    }
    return o;
  },
  visitProperty: function(o, prop) { this.visit(o[prop.name]); },

  visitMap: function(o) {
    for ( var key in o ) { this.visitMapElement(key, o[key]); };
    return o;
  },
  visitMapElement: function(key, value) { },

  visitTrue: function() { return true; },

  visitFalse: function() { return false; },

  visitNull: function() { return null; },

  visitUndefined: function() { return undefined; }

};