| 1 | // Copyright 2009 The Closure Library Authors. All Rights Reserved. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS-IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | /** |
| 16 | * @fileoverview Useful compiler idioms. |
| 17 | * |
| 18 | * @author johnlenz@google.com (John Lenz) |
| 19 | */ |
| 20 | |
| 21 | goog.provide('goog.reflect'); |
| 22 | |
| 23 | |
| 24 | /** |
| 25 | * Syntax for object literal casts. |
| 26 | * @see http://go/jscompiler-renaming |
| 27 | * @see http://code.google.com/p/closure-compiler/wiki/ |
| 28 | * ExperimentalTypeBasedPropertyRenaming |
| 29 | * |
| 30 | * Use this if you have an object literal whose keys need to have the same names |
| 31 | * as the properties of some class even after they are renamed by the compiler. |
| 32 | * |
| 33 | * @param {!Function} type Type to cast to. |
| 34 | * @param {Object} object Object literal to cast. |
| 35 | * @return {Object} The object literal. |
| 36 | */ |
| 37 | goog.reflect.object = function(type, object) { |
| 38 | return object; |
| 39 | }; |
| 40 | |
| 41 | |
| 42 | /** |
| 43 | * To assert to the compiler that an operation is needed when it would |
| 44 | * otherwise be stripped. For example: |
| 45 | * <code> |
| 46 | * // Force a layout |
| 47 | * goog.reflect.sinkValue(dialog.offsetHeight); |
| 48 | * </code> |
| 49 | * @type {!Function} |
| 50 | */ |
| 51 | goog.reflect.sinkValue = function(x) { |
| 52 | goog.reflect.sinkValue[' '](x); |
| 53 | return x; |
| 54 | }; |
| 55 | |
| 56 | |
| 57 | /** |
| 58 | * The compiler should optimize this function away iff no one ever uses |
| 59 | * goog.reflect.sinkValue. |
| 60 | */ |
| 61 | goog.reflect.sinkValue[' '] = goog.nullFunction; |
| 62 | |
| 63 | |
| 64 | /** |
| 65 | * Check if a property can be accessed without throwing an exception. |
| 66 | * @param {Object} obj The owner of the property. |
| 67 | * @param {string} prop The property name. |
| 68 | * @return {boolean} Whether the property is accessible. Will also return true |
| 69 | * if obj is null. |
| 70 | */ |
| 71 | goog.reflect.canAccessProperty = function(obj, prop) { |
| 72 | /** @preserveTry */ |
| 73 | try { |
| 74 | goog.reflect.sinkValue(obj[prop]); |
| 75 | return true; |
| 76 | } catch (e) {} |
| 77 | return false; |
| 78 | }; |