disposable.js

// Copyright 2005 The Closure Library Authors. 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.

/**
 * @fileoverview Implements the disposable interface. The dispose method is used
 * to clean up references and resources.
 */


goog.provide('goog.Disposable');
goog.provide('goog.dispose');

goog.require('goog.disposable.IDisposable');



/**
 * Class that provides the basic implementation for disposable objects. If your
 * class holds one or more references to COM objects, DOM nodes, or other
 * disposable objects, it should extend this class or implement the disposable
 * interface (defined in goog.disposable.IDisposable).
 * @constructor
 * @implements {goog.disposable.IDisposable}
 */
goog.Disposable = function() {
  if (goog.Disposable.ENABLE_MONITORING) {
    goog.Disposable.instances_[goog.getUid(this)] = this;
  }
};


/**
 * @define {boolean} Whether to enable the monitoring of the goog.Disposable
 *     instances. Switching on the monitoring is only recommended for debugging
 *     because it has a significant impact on performance and memory usage.
 *     If switched off, the monitoring code compiles down to 0 bytes.
 *     The monitoring expects that all disposable objects call the
 *     {@code goog.Disposable} base constructor.
 */
goog.Disposable.ENABLE_MONITORING = false;


/**
 * Maps the unique ID of every undisposed {@code goog.Disposable} object to
 * the object itself.
 * @type {!Object.<number, !goog.Disposable>}
 * @private
 */
goog.Disposable.instances_ = {};


/**
 * @return {!Array.<!goog.Disposable>} All {@code goog.Disposable} objects that
 *     haven't been disposed of.
 */
goog.Disposable.getUndisposedObjects = function() {
  var ret = [];
  for (var id in goog.Disposable.instances_) {
    if (goog.Disposable.instances_.hasOwnProperty(id)) {
      ret.push(goog.Disposable.instances_[Number(id)]);
    }
  }
  return ret;
};


/**
 * Clears the registry of undisposed objects but doesn't dispose of them.
 */
goog.Disposable.clearUndisposedObjects = function() {
  goog.Disposable.instances_ = {};
};


/**
 * Whether the object has been disposed of.
 * @type {boolean}
 * @private
 */
goog.Disposable.prototype.disposed_ = false;


/**
 * Disposables that should be disposed when this object is disposed.
 * @type {Array.<goog.disposable.IDisposable>}
 * @private
 */
goog.Disposable.prototype.dependentDisposables_;


/**
 * @return {boolean} Whether the object has been disposed of.
 */
goog.Disposable.prototype.isDisposed = function() {
  return this.disposed_;
};


/**
 * @return {boolean} Whether the object has been disposed of.
 * @deprecated Use {@link #isDisposed} instead.
 */
goog.Disposable.prototype.getDisposed = goog.Disposable.prototype.isDisposed;


/**
 * Disposes of the object. If the object hasn't already been disposed of, calls
 * {@link #disposeInternal}. Classes that extend {@code goog.Disposable} should
 * override {@link #disposeInternal} in order to delete references to COM
 * objects, DOM nodes, and other disposable objects. Reentrant.
 *
 * @return {void} Nothing.
 */
goog.Disposable.prototype.dispose = function() {
  if (!this.disposed_) {
    // Set disposed_ to true first, in case during the chain of disposal this
    // gets disposed recursively.
    this.disposed_ = true;
    this.disposeInternal();
    if (goog.Disposable.ENABLE_MONITORING) {
      var uid = goog.getUid(this);
      if (!goog.Disposable.instances_.hasOwnProperty(uid)) {
        throw Error(this + ' did not call the goog.Disposable base ' +
            'constructor or was disposed of after a clearUndisposedObjects ' +
            'call');
      }
      delete goog.Disposable.instances_[uid];
    }
  }
};


/**
 * Associates a disposable object with this object so that they will be disposed
 * together.
 * @param {goog.disposable.IDisposable} disposable that will be disposed when
 *     this object is disposed.
 */
goog.Disposable.prototype.registerDisposable = function(disposable) {
  if (!this.dependentDisposables_) {
    this.dependentDisposables_ = [];
  }
  this.dependentDisposables_.push(disposable);
};


/**
 * Deletes or nulls out any references to COM objects, DOM nodes, or other
 * disposable objects. Classes that extend {@code goog.Disposable} should
 * override this method.
 * Not reentrant. To avoid calling it twice, it must only be called from the
 * subclass' {@code disposeInternal} method. Everywhere else the public
 * {@code dispose} method must be used.
 * For example:
 * <pre>
 *   mypackage.MyClass = function() {
 *     goog.base(this);
 *     // Constructor logic specific to MyClass.
 *     ...
 *   };
 *   goog.inherits(mypackage.MyClass, goog.Disposable);
 *
 *   mypackage.MyClass.prototype.disposeInternal = function() {
 *     goog.base(this, 'disposeInternal');
 *     // Dispose logic specific to MyClass.
 *     ...
 *   };
 * </pre>
 * @protected
 */
goog.Disposable.prototype.disposeInternal = function() {
  if (this.dependentDisposables_) {
    goog.disposeAll.apply(null, this.dependentDisposables_);
  }
};


/**
 * Calls {@code dispose} on the argument if it supports it. If obj is not an
 *     object with a dispose() method, this is a no-op.
 * @param {*} obj The object to dispose of.
 */
goog.dispose = function(obj) {
  if (obj && typeof obj.dispose == 'function') {
    obj.dispose();
  }
};


/**
 * Calls {@code dispose} on each member of the list that supports it. (If the
 * member is an ArrayLike, then {@code goog.disposeAll()} will be called
 * recursively on each of its members.) If the member is not an object with a
 * {@code dispose()} method, then it is ignored.
 * @param {...*} var_args The list.
 */
goog.disposeAll = function(var_args) {
  for (var i = 0, len = arguments.length; i < len; ++i) {
    var disposable = arguments[i];
    if (goog.isArrayLike(disposable)) {
      goog.disposeAll.apply(null, disposable);
    } else {
      goog.dispose(disposable);
    }
  }
};