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- // Copyright 2014 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- var nativeDeepCopy = requireNative('utils').deepCopy;
- /**
- * An object forEach. Calls |f| with each (key, value) pair of |obj|, using
- * |self| as the target.
- * @param {Object} obj The object to iterate over.
- * @param {function} f The function to call in each iteration.
- * @param {Object} self The object to use as |this| in each function call.
- */
- function forEach(obj, f, self) {
- for (var key in obj) {
- if ($Object.hasOwnProperty(obj, key))
- $Function.call(f, self, key, obj[key]);
- }
- }
- /**
- * Assuming |array_of_dictionaries| is structured like this:
- * [{id: 1, ... }, {id: 2, ...}, ...], you can use
- * lookup(array_of_dictionaries, 'id', 2) to get the dictionary with id == 2.
- * @param {Array<Object<?>>} array_of_dictionaries
- * @param {string} field
- * @param {?} value
- */
- function lookup(array_of_dictionaries, field, value) {
- var filter = function (dict) {return dict[field] == value;};
- var matches = $Array.filter(array_of_dictionaries, filter);
- if (matches.length == 0) {
- return undefined;
- } else if (matches.length == 1) {
- return matches[0]
- } else {
- throw new Error("Failed lookup of field '" + field + "' with value '" +
- value + "'");
- }
- }
- /**
- * Sets a property |value| on |obj| with property name |key|. Like
- *
- * obj[key] = value;
- *
- * but without triggering setters.
- */
- function defineProperty(obj, key, value) {
- $Object.defineProperty(obj, key, {
- __proto__: null,
- configurable: true,
- enumerable: true,
- writable: true,
- value: value,
- });
- }
- /**
- * Takes a private class implementation |privateClass| and exposes a subset of
- * its methods |functions| and properties |properties| and |readonly| to a
- * public wrapper class that should be passed in. Within bindings code, you can
- * access the implementation from an instance of the wrapper class using
- * privates(instance).impl, and from the implementation class you can access
- * the wrapper using this.wrapper (or implInstance.wrapper if you have another
- * instance of the implementation class).
- *
- * |publicClass| should be a constructor that calls constructPrivate() like so:
- *
- * privates(publicClass).constructPrivate(this, arguments);
- *
- * @param {function} publicClass The publicly exposed wrapper class. This must
- * be a named function, and the name appears in stack traces.
- * @param {Object} privateClass The class implementation.
- * @param {{superclass: ?Function,
- * functions: ?Array<string>,
- * properties: ?Array<string>,
- * readonly: ?Array<string>}} exposed The names of properties on the
- * implementation class to be exposed. |superclass| represents the
- * constructor of the class to be used as the superclass of the exposed
- * class; |functions| represents the names of functions which should be
- * delegated to the implementation; |properties| are gettable/settable
- * properties and |readonly| are read-only properties.
- */
- function expose(publicClass, privateClass, exposed) {
- $Object.setPrototypeOf(exposed, null);
- // This should be called by publicClass.
- privates(publicClass).constructPrivate = function(self, args) {
- if (!(self instanceof publicClass)) {
- throw new Error('Please use "new ' + publicClass.name + '"');
- }
- // The "instanceof publicClass" check can easily be spoofed, so we check
- // whether the private impl is already set before continuing.
- var privateSelf = privates(self);
- if ('impl' in privateSelf) {
- throw new Error('Object ' + publicClass.name + ' is already constructed');
- }
- var privateObj = $Object.create(privateClass.prototype);
- $Function.apply(privateClass, privateObj, args);
- privateObj.wrapper = self;
- privateSelf.impl = privateObj;
- };
- function getPrivateImpl(self) {
- var impl = privates(self).impl;
- if (!(impl instanceof privateClass)) {
- // Either the object is not constructed, or the property descriptor is
- // used on a target that is not an instance of publicClass.
- throw new Error('impl is not an instance of ' + privateClass.name);
- }
- return impl;
- }
- var publicClassPrototype = {
- // The final prototype will be assigned at the end of this method.
- __proto__: null,
- constructor: publicClass,
- };
- if ('functions' in exposed) {
- $Array.forEach(exposed.functions, function(func) {
- publicClassPrototype[func] = function() {
- var impl = getPrivateImpl(this);
- return $Function.apply(impl[func], impl, arguments);
- };
- });
- }
- if ('properties' in exposed) {
- $Array.forEach(exposed.properties, function(prop) {
- $Object.defineProperty(publicClassPrototype, prop, {
- __proto__: null,
- enumerable: true,
- get: function() {
- return getPrivateImpl(this)[prop];
- },
- set: function(value) {
- var impl = getPrivateImpl(this);
- delete impl[prop];
- impl[prop] = value;
- }
- });
- });
- }
- if ('readonly' in exposed) {
- $Array.forEach(exposed.readonly, function(readonly) {
- $Object.defineProperty(publicClassPrototype, readonly, {
- __proto__: null,
- enumerable: true,
- get: function() {
- return getPrivateImpl(this)[readonly];
- },
- });
- });
- }
- // The prototype properties have been installed. Now we can safely assign an
- // unsafe prototype and export the class to the public.
- var superclass = exposed.superclass || $Object.self;
- $Object.setPrototypeOf(publicClassPrototype, superclass.prototype);
- publicClass.prototype = publicClassPrototype;
- return publicClass;
- }
- /**
- * Returns a deep copy of |value|. The copy will have no references to nested
- * values of |value|.
- */
- function deepCopy(value) {
- return nativeDeepCopy(value);
- }
- exports.$set('forEach', forEach);
- exports.$set('lookup', lookup);
- exports.$set('defineProperty', defineProperty);
- exports.$set('expose', expose);
- exports.$set('deepCopy', deepCopy);
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