src/third_party/closure_library/closure/goog/reflect/reflect.js

// Copyright 2009 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 Useful compiler idioms.
 *
 * @author johnlenz@google.com (John Lenz)
 */

goog.provide('goog.reflect');


/**
 * Syntax for object literal casts.
 * @see http://go/jscompiler-renaming
 * @see http://code.google.com/p/closure-compiler/wiki/
 *      ExperimentalTypeBasedPropertyRenaming
 *
 * Use this if you have an object literal whose keys need to have the same names
 * as the properties of some class even after they are renamed by the compiler.
 *
 * @param {!Function} type Type to cast to.
 * @param {Object} object Object literal to cast.
 * @return {Object} The object literal.
 */
goog.reflect.object = function(type, object) {
  return object;
};


/**
 * To assert to the compiler that an operation is needed when it would
 * otherwise be stripped. For example:
 * <code>
 *     // Force a layout
 *     goog.reflect.sinkValue(dialog.offsetHeight);
 * </code>
 * @type {!Function}
 */
goog.reflect.sinkValue = function(x) {
  goog.reflect.sinkValue[' '](x);
  return x;
};


/**
 * The compiler should optimize this function away iff no one ever uses
 * goog.reflect.sinkValue.
 */
goog.reflect.sinkValue[' '] = goog.nullFunction;


/**
 * Check if a property can be accessed without throwing an exception.
 * @param {Object} obj The owner of the property.
 * @param {string} prop The property name.
 * @return {boolean} Whether the property is accessible. Will also return true
 *     if obj is null.
 */
goog.reflect.canAccessProperty = function(obj, prop) {
  /** @preserveTry */
  try {
    goog.reflect.sinkValue(obj[prop]);
    return true;
  } catch (e) {}
  return false;
};