michael@0: /* this source code form is subject to the terms of the mozilla public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /**
michael@0:  * ObservableObject
michael@0:  *
michael@0:  * An observable object is a JSON-like object that throws
michael@0:  * events when its direct properties or properties of any
michael@0:  * contained objects, are getting accessed or set.
michael@0:  *
michael@0:  * Inherits from EventEmitter.
michael@0:  *
michael@0:  * Properties:
michael@0:  * ⬩ object: JSON-like object
michael@0:  *
michael@0:  * Events:
michael@0:  * ⬩ "get" / path (array of property names)
michael@0:  * ⬩ "set" / path / new value
michael@0:  *
michael@0:  * Example:
michael@0:  *
michael@0:  *   let emitter = new ObservableObject({ x: { y: [10] } });
michael@0:  *   emitter.on("set", console.log);
michael@0:  *   emitter.on("get", console.log);
michael@0:  *   let obj = emitter.object;
michael@0:  *   obj.x.y[0] = 50;
michael@0:  *
michael@0:  */
michael@0: 
michael@0: "use strict";
michael@0: 
michael@0: const EventEmitter = require("devtools/toolkit/event-emitter");
michael@0: 
michael@0: function ObservableObject(object = {}) {
michael@0:   EventEmitter.decorate(this);
michael@0:   let handler = new Handler(this);
michael@0:   this.object = new Proxy(object, handler);
michael@0:   handler._wrappers.set(this.object, object);
michael@0:   handler._paths.set(object, []);
michael@0: }
michael@0: 
michael@0: module.exports = ObservableObject;
michael@0: 
michael@0: function isObject(x) {
michael@0:   if (typeof x === "object")
michael@0:     return x !== null;
michael@0:   return typeof x === "function";
michael@0: }
michael@0: 
michael@0: function Handler(emitter) {
michael@0:   this._emitter = emitter;
michael@0:   this._wrappers = new WeakMap();
michael@0:   this._values = new WeakMap();
michael@0:   this._paths = new WeakMap();
michael@0: }
michael@0: 
michael@0: Handler.prototype = {
michael@0:   wrap: function(target, key, value) {
michael@0:     let path;
michael@0:     if (!isObject(value)) {
michael@0:       path = this._paths.get(target).concat(key);
michael@0:     } else if (this._wrappers.has(value)) {
michael@0:       path = this._paths.get(value);
michael@0:     } else if (this._paths.has(value)) {
michael@0:       path = this._paths.get(value);
michael@0:       value = this._values.get(value);
michael@0:     } else {
michael@0:       path = this._paths.get(target).concat(key);
michael@0:       this._paths.set(value, path);
michael@0:       let wrapper = new Proxy(value, this);
michael@0:       this._wrappers.set(wrapper, value);
michael@0:       this._values.set(value, wrapper);
michael@0:       value = wrapper;
michael@0:     }
michael@0:     return [value, path];
michael@0:   },
michael@0:   unwrap: function(target, key, value) {
michael@0:     if (!isObject(value) || !this._wrappers.has(value)) {
michael@0:       return [value, this._paths.get(target).concat(key)];
michael@0:     }
michael@0:     return [this._wrappers.get(value), this._paths.get(target).concat(key)];
michael@0:   },
michael@0:   get: function(target, key) {
michael@0:     let value = target[key];
michael@0:     let [wrapped, path] = this.wrap(target, key, value);
michael@0:     this._emitter.emit("get", path, value);
michael@0:     return wrapped;
michael@0:   },
michael@0:   set: function(target, key, value) {
michael@0:     let [wrapped, path] = this.unwrap(target, key, value);
michael@0:     target[key] = value;
michael@0:     this._emitter.emit("set", path, value);
michael@0:   },
michael@0:   getOwnPropertyDescriptor: function(target, key) {
michael@0:     let desc = Object.getOwnPropertyDescriptor(target, key);
michael@0:     if (desc) {
michael@0:       if ("value" in desc) {
michael@0:         let [wrapped, path] = this.wrap(target, key, desc.value);
michael@0:         desc.value = wrapped;
michael@0:         this._emitter.emit("get", path, desc.value);
michael@0:       } else {
michael@0:         if ("get" in desc) {
michael@0:           [desc.get] = this.wrap(target, "get "+key, desc.get);
michael@0:         }
michael@0:         if ("set" in desc) {
michael@0:           [desc.set] = this.wrap(target, "set "+key, desc.set);
michael@0:         }
michael@0:       }
michael@0:     }
michael@0:     return desc;
michael@0:   },
michael@0:   defineProperty: function(target, key, desc) {
michael@0:     if ("value" in desc) {
michael@0:       let [unwrapped, path] = this.unwrap(target, key, desc.value);
michael@0:       desc.value = unwrapped;
michael@0:       Object.defineProperty(target, key, desc);
michael@0:       this._emitter.emit("set", path, desc.value);
michael@0:     } else {
michael@0:       if ("get" in desc) {
michael@0:         [desc.get] = this.unwrap(target, "get "+key, desc.get);
michael@0:       }
michael@0:       if ("set" in desc) {
michael@0:         [desc.set] = this.unwrap(target, "set "+key, desc.set);
michael@0:       }
michael@0:       Object.defineProperty(target, key, desc);
michael@0:     }
michael@0:   }
michael@0: };