| 1 | // Copyright 2015 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 Simple freelist. |
| 17 | * |
| 18 | * An anterative to goog.structs.SimplePool, it imposes the requirement that the |
| 19 | * objects in the list contain a "next" property that can be used to maintain |
| 20 | * the pool. |
| 21 | */ |
| 22 | |
| 23 | goog.provide('goog.async.FreeList'); |
| 24 | |
| 25 | |
| 26 | /** |
| 27 | * @template ITEM |
| 28 | */ |
| 29 | goog.async.FreeList = goog.defineClass(null, { |
| 30 | /** |
| 31 | * @param {function():ITEM} create |
| 32 | * @param {function(ITEM):void} reset |
| 33 | * @param {number} limit |
| 34 | */ |
| 35 | constructor: function(create, reset, limit) { |
| 36 | /** @const {number} */ |
| 37 | this.limit_ = limit; |
| 38 | /** @const {function()} */ |
| 39 | this.create_ = create; |
| 40 | /** @const {function(ITEM):void} */ |
| 41 | this.reset_ = reset; |
| 42 | |
| 43 | /** @type {number} */ |
| 44 | this.occupants_ = 0; |
| 45 | /** @type {ITEM} */ |
| 46 | this.head_ = null; |
| 47 | }, |
| 48 | |
| 49 | /** |
| 50 | * @return {ITEM} |
| 51 | */ |
| 52 | get: function() { |
| 53 | var item; |
| 54 | if (this.occupants_ > 0) { |
| 55 | this.occupants_--; |
| 56 | item = this.head_; |
| 57 | this.head_ = item.next; |
| 58 | item.next = null; |
| 59 | } else { |
| 60 | item = this.create_(); |
| 61 | } |
| 62 | return item; |
| 63 | }, |
| 64 | |
| 65 | /** |
| 66 | * @param {ITEM} item An item available for possible future reuse. |
| 67 | */ |
| 68 | put: function(item) { |
| 69 | this.reset_(item); |
| 70 | if (this.occupants_ < this.limit_) { |
| 71 | this.occupants_++; |
| 72 | item.next = this.head_; |
| 73 | this.head_ = item; |
| 74 | } |
| 75 | }, |
| 76 | |
| 77 | /** |
| 78 | * Visible for testing. |
| 79 | * @package |
| 80 | * @return {number} |
| 81 | */ |
| 82 | occupants: function() { |
| 83 | return this.occupants_; |
| 84 | } |
| 85 | }); |
| 86 | |
| 87 | |
| 88 | |