chrome/renderer/resources/extensions/utils.js

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 var createClassWrapper = requireNative('utils').createClassWrapper;
   6 var schemaRegistry = requireNative('schema_registry');
   7 var CHECK = requireNative('logging').CHECK;
   8 var WARNING = requireNative('logging').WARNING;
   9
  10 /**
  11  * An object forEach. Calls |f| with each (key, value) pair of |obj|, using
  12  * |self| as the target.
  13  * @param {Object} obj The object to iterate over.
  14  * @param {function} f The function to call in each iteration.
  15  * @param {Object} self The object to use as |this| in each function call.
  16  */
  17 function forEach(obj, f, self) {
  18   for (var key in obj) {
  19     if ($Object.hasOwnProperty(obj, key))
  20       $Function.call(f, self, key, obj[key]);
  21   }
  22 }
  23
  24 /**
  25  * Assuming |array_of_dictionaries| is structured like this:
  26  * [{id: 1, ... }, {id: 2, ...}, ...], you can use
  27  * lookup(array_of_dictionaries, 'id', 2) to get the dictionary with id == 2.
  28  * @param {Array.<Object.<string, ?>>} array_of_dictionaries
  29  * @param {string} field
  30  * @param {?} value
  31  */
  32 function lookup(array_of_dictionaries, field, value) {
  33   var filter = function (dict) {return dict[field] == value;};
  34   var matches = array_of_dictionaries.filter(filter);
  35   if (matches.length == 0) {
  36     return undefined;
  37   } else if (matches.length == 1) {
  38     return matches[0]
  39   } else {
  40     throw new Error("Failed lookup of field '" + field + "' with value '" +
  41                     value + "'");
  42   }
  43 }
  44
  45 function loadTypeSchema(typeName, defaultSchema) {
  46   var parts = $String.split(typeName, '.');
  47   if (parts.length == 1) {
  48     if (defaultSchema == null) {
  49       WARNING('Trying to reference "' + typeName + '" ' +
  50               'with neither namespace nor default schema.');
  51       return null;
  52     }
  53     var types = defaultSchema.types;
  54   } else {
  55     var schemaName = $Array.join($Array.slice(parts, 0, parts.length - 1), '.');
  56     var types = schemaRegistry.GetSchema(schemaName).types;
  57   }
  58   for (var i = 0; i < types.length; ++i) {
  59     if (types[i].id == typeName)
  60       return types[i];
  61   }
  62   return null;
  63 }
  64
  65 /**
  66  * Takes a private class implementation |cls| and exposes a subset of its
  67  * methods |functions| and properties |properties| and |readonly| in a public
  68  * wrapper class that it returns. Within bindings code, you can access the
  69  * implementation from an instance of the wrapper class using
  70  * privates(instance).impl, and from the implementation class you can access
  71  * the wrapper using this.wrapper (or implInstance.wrapper if you have another
  72  * instance of the implementation class).
  73  * @param {string} name The name of the exposed wrapper class.
  74  * @param {Object} cls The class implementation.
  75  * @param {{functions: ?Array.<string>,
  76  *          properties: ?Array.<string>,
  77  *          readonly: ?Array.<string>}} exposed The names of properties on the
  78  *     implementation class to be exposed. |functions| represents the names of
  79  *     functions which should be delegated to the implementation; |properties|
  80  *     are gettable/settable properties and |readonly| are read-only properties.
  81  */
  82 function expose(name, cls, exposed) {
  83   var publicClass = createClassWrapper(name, cls);
  84
  85   if ('functions' in exposed) {
  86     $Array.forEach(exposed.functions, function(func) {
  87       publicClass.prototype[func] = function() {
  88         var impl = privates(this).impl;
  89         return $Function.apply(impl[func], impl, arguments);
  90       };
  91     });
  92   }
  93
  94   if ('properties' in exposed) {
  95     $Array.forEach(exposed.properties, function(prop) {
  96       $Object.defineProperty(publicClass.prototype, prop, {
  97         enumerable: true,
  98         get: function() {
  99           return privates(this).impl[prop];
 100         },
 101         set: function(value) {
 102           var impl = privates(this).impl;
 103           delete impl[prop];
 104           impl[prop] = value;
 105         }
 106       });
 107     });
 108   }
 109
 110   if ('readonly' in exposed) {
 111     $Array.forEach(exposed.readonly, function(readonly) {
 112       $Object.defineProperty(publicClass.prototype, readonly, {
 113         enumerable: true,
 114         get: function() {
 115           return privates(this).impl[readonly];
 116         },
 117       });
 118     });
 119   }
 120
 121   return publicClass;
 122 }
 123
 124 exports.forEach = forEach;
 125 exports.loadTypeSchema = loadTypeSchema;
 126 exports.lookup = lookup;
 127 exports.expose = expose;