The Tor Browser / file comparison
comparison: addon-sdk/source/lib/sdk/deprecated/cortex.js
addon-sdk/source/lib/sdk/deprecated/cortex.js
- branch
- TOR_BUG_9701
- changeset 10
- ac0c01689b40
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| -1:000000000000 | 0:4f1d3a459c50 |
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| 1 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 2 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 4 | |
| 5 "use strict"; | |
| 6 | |
| 7 module.metadata = { | |
| 8 "stability": "deprecated" | |
| 9 }; | |
| 10 | |
| 11 // `var` is being used in the module in order to make it reusable in | |
| 12 // environments in which `let` and `const` is not yet supported. | |
| 13 | |
| 14 // Returns `object`'s property value, where `name` is a name of the property. | |
| 15 function get(object, name) { | |
| 16 return object[name]; | |
| 17 } | |
| 18 | |
| 19 // Assigns `value` to the `object`'s property, where `name` is the name of the | |
| 20 // property. | |
| 21 function set(object, name, value) { | |
| 22 return object[name] = value; | |
| 23 } | |
| 24 | |
| 25 /** | |
| 26 * Given an `object` containing a property with the given `name`, create | |
| 27 * a property descriptor that can be used to define alias/proxy properties | |
| 28 * on other objects. A change in the value of an alias will propagate | |
| 29 * to the aliased property and vice versa. | |
| 30 */ | |
| 31 function createAliasProperty(object, name) { | |
| 32 // Getting own property descriptor of an `object` for the given `name` as | |
| 33 // we are going to create proxy analog. | |
| 34 var property = Object.getOwnPropertyDescriptor(object, name); | |
| 35 var descriptor = { | |
| 36 configurable: property.configurable, | |
| 37 enumerable: property.enumerable, | |
| 38 alias: true | |
| 39 }; | |
| 40 | |
| 41 // If the original property has a getter and/or setter, bind a | |
| 42 // corresponding getter/setter in the alias descriptor to the original | |
| 43 // object, so the `this` object in the getter/setter is the original object | |
| 44 // rather than the alias. | |
| 45 if ("get" in property && property.get) | |
| 46 descriptor.get = property.get.bind(object); | |
| 47 if ("set" in property && property.set) | |
| 48 descriptor.set = property.set.bind(object); | |
| 49 | |
| 50 // If original property was a value property. | |
| 51 if ("value" in property) { | |
| 52 // If original property is a method using it's `object` bounded copy. | |
| 53 if (typeof property.value === "function") { | |
| 54 descriptor.value = property.value.bind(object); | |
| 55 // Also preserving writability of the original property. | |
| 56 descriptor.writable = property.writable; | |
| 57 } | |
| 58 | |
| 59 // If the original property was just a data property, we create proxy | |
| 60 // accessors using our custom get/set functions to propagate changes to the | |
| 61 // original `object` and vice versa. | |
| 62 else { | |
| 63 descriptor.get = get.bind(null, object, name); | |
| 64 descriptor.set = set.bind(null, object, name); | |
| 65 } | |
| 66 } | |
| 67 return descriptor; | |
| 68 } | |
| 69 | |
| 70 // Defines property on `object` object with a name `alias` if given if not | |
| 71 // defaults to `name` that represents an alias of `source[name]`. If aliased | |
| 72 // property was an assessor or a method `this` pseudo-variable will be `source` | |
| 73 // when invoked. If aliased property was a data property changes on any of the | |
| 74 // aliases will propagate to the `source[name]` and also other way round. | |
| 75 function defineAlias(source, target, name, alias) { | |
| 76 return Object.defineProperty(target, alias || name, | |
| 77 createAliasProperty(source, name)); | |
| 78 } | |
| 79 | |
| 80 /** | |
| 81 * Function takes any `object` and returns a proxy for its own public | |
| 82 * properties. By default properties are considered to be public if they don't | |
| 83 * start with `"_"`, but default behavior can be overridden if needed, by | |
| 84 * passing array of public property `names` as a second argument. By default | |
| 85 * returned object will be direct decedent of the given `object`'s prototype, | |
| 86 * but this can be overridden by passing third optional argument, that will be | |
| 87 * used as `prototype` instead. | |
| 88 * @param {Object} object | |
| 89 * Object to create cortex for. | |
| 90 * @param {String[]} [names] | |
| 91 * Optional array of public property names. | |
| 92 * @param {Object} [prototype] | |
| 93 * Optional argument that will be used as `prototype` of the returned object, | |
| 94 * if not provided `Object.getPrototypeOf(object)` is used instead. | |
| 95 */ | |
| 96 exports.Cortex = function Cortex(object, names, prototype) { | |
| 97 // Creating a cortex object from the given `prototype`, if one was not | |
| 98 // provided then `prototype` of a given `object` is used. This allows | |
| 99 // consumer to define expected behavior `instanceof`. In common case | |
| 100 // `prototype` argument can be omitted to preserve same behavior of | |
| 101 // `instanceof` as on original `object`. | |
| 102 var cortex = Object.create(prototype || Object.getPrototypeOf(object)); | |
| 103 // Creating alias properties on the `cortex` object for all the own | |
| 104 // properties of the original `object` that are contained in `names` array. | |
| 105 // If `names` array is not provided then all the properties that don't | |
| 106 // start with `"_"` are aliased. | |
| 107 Object.getOwnPropertyNames(object).forEach(function (name) { | |
| 108 if ((!names && "_" !== name.charAt(0)) || (names && ~names.indexOf(name))) | |
| 109 defineAlias(object, cortex, name); | |
| 110 }); | |
| 111 return cortex; | |
| 112 } |
