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// Copyright 2015 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 Simple freelist.
*
* An anterative to goog.structs.SimplePool, it imposes the requirement that the
* objects in the list contain a "next" property that can be used to maintain
* the pool.
*/
goog.provide('goog.async.FreeList');
/**
* @template ITEM
*/
goog.async.FreeList = goog.defineClass(null, {
/**
* @param {function():ITEM} create
* @param {function(ITEM):void} reset
* @param {number} limit
*/
constructor: function(create, reset, limit) {
/** @private @const {number} */
this.limit_ = limit;
/** @private @const {function()} */
this.create_ = create;
/** @private @const {function(ITEM):void} */
this.reset_ = reset;
/** @private {number} */
this.occupants_ = 0;
/** @private {ITEM} */
this.head_ = null;
},
/**
* @return {ITEM}
*/
get: function() {
var item;
if (this.occupants_ > 0) {
this.occupants_--;
item = this.head_;
this.head_ = item.next;
item.next = null;
} else {
item = this.create_();
}
return item;
},
/**
* @param {ITEM} item An item available for possible future reuse.
*/
put: function(item) {
this.reset_(item);
if (this.occupants_ < this.limit_) {
this.occupants_++;
item.next = this.head_;
this.head_ = item;
}
},
/**
* Visible for testing.
* @package
* @return {number}
*/
occupants: function() { return this.occupants_; }
});
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