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| 1 // Copyright 2014 The Chromium Authors. All rights reserved. | 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 /** | 5 /** |
| 6 * @fileoverview Provides a system for memoizing computations applied to | 6 * @fileoverview Provides a system for memoizing computations applied to |
| 7 * DOM nodes within the same call stack. | 7 * DOM nodes within the same call stack. |
| 8 * | 8 * |
| 9 * To make a function memoizable - suppose you have a function | 9 * To make a function memoizable - suppose you have a function |
| 10 * isAccessible that takes a node and returns a boolean: | 10 * isAccessible that takes a node and returns a boolean: |
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| 36 */ | 36 */ |
| 37 | 37 |
| 38 | 38 |
| 39 goog.provide('cvox.Memoize'); | 39 goog.provide('cvox.Memoize'); |
| 40 | 40 |
| 41 | 41 |
| 42 /** | 42 /** |
| 43 * Create the namespace. | 43 * Create the namespace. |
| 44 * @constructor | 44 * @constructor |
| 45 */ | 45 */ |
| 46 cvox.Memoize = function() { | 46 cvox.Memoize = function() {}; |
| 47 }; | |
| 48 | 47 |
| 49 /** | 48 /** |
| 50 * The cache: a map from string function name to a WeakMap from DOM node | 49 * The cache: a map from string function name to a WeakMap from DOM node |
| 51 * to function result. This variable is null when we're out of scope, and it's | 50 * to function result. This variable is null when we're out of scope, and it's |
| 52 * a map from string to WeakMap to result when we're in scope. | 51 * a map from string to WeakMap to result when we're in scope. |
| 53 * | 52 * |
| 54 * @type {?Object<WeakMap<Node, *> >} | 53 * @type {?Object<WeakMap<Node, *> >} |
| 55 * @private | 54 * @private |
| 56 */ | 55 */ |
| 57 cvox.Memoize.nodeMap_ = null; | 56 cvox.Memoize.nodeMap_ = null; |
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| 124 if (result === undefined) { | 123 if (result === undefined) { |
| 125 result = functionClosure(node); | 124 result = functionClosure(node); |
| 126 if (result === undefined) { | 125 if (result === undefined) { |
| 127 throw 'A memoized function cannot return undefined.'; | 126 throw 'A memoized function cannot return undefined.'; |
| 128 } | 127 } |
| 129 cvox.Memoize.nodeMap_[functionName].set(node, result); | 128 cvox.Memoize.nodeMap_[functionName].set(node, result); |
| 130 } | 129 } |
| 131 | 130 |
| 132 return result; | 131 return result; |
| 133 }; | 132 }; |
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