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// Copyright 2006 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview Creates a pool of XhrIo objects to use. This allows multiple
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 * XhrIo objects to be grouped together and requests will use next available
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 * XhrIo object.
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 *
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 */
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goog.provide('goog.net.XhrIoPool');
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goog.require('goog.net.XhrIo');
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goog.require('goog.structs.PriorityPool');
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/**
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 * A pool of XhrIo objects.
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 * @param {goog.structs.Map=} opt_headers Map of default headers to add to every
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 *     request.
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 * @param {number=} opt_minCount Minimum number of objects (Default: 0).
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 * @param {number=} opt_maxCount Maximum number of objects (Default: 10).
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 * @param {boolean=} opt_withCredentials Add credentials to every request
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 *     (Default: false).
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 * @constructor
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 * @extends {goog.structs.PriorityPool}
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 */
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goog.net.XhrIoPool = function(
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    opt_headers, opt_minCount, opt_maxCount, opt_withCredentials) {
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  /**
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   * Map of default headers to add to every request.
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   * @type {goog.structs.Map|undefined}
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   * @private
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   */
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  this.headers_ = opt_headers;
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  /**
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   * Whether a "credentialed" requests are to be sent (ones that is aware of
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   * cookies and authentication). This is applicable only for cross-domain
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   * requests and more recent browsers that support this part of the HTTP Access
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   * Control standard.
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   *
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   * @see http://www.w3.org/TR/XMLHttpRequest/#the-withcredentials-attribute
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   *
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   * @private {boolean}
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   */
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  this.withCredentials_ = !!opt_withCredentials;
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  // Must break convention of putting the super-class's constructor first. This
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  // is because the super-class constructor calls adjustForMinMax, which calls
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  // this class' createObject. In this class's implementation, it assumes that
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  // there is a headers_, and will lack those if not yet present.
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  goog.structs.PriorityPool.call(this, opt_minCount, opt_maxCount);
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};
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goog.inherits(goog.net.XhrIoPool, goog.structs.PriorityPool);
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/**
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 * Creates an instance of an XhrIo object to use in the pool.
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 * @return {!goog.net.XhrIo} The created object.
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 * @override
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 */
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goog.net.XhrIoPool.prototype.createObject = function() {
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  var xhrIo = new goog.net.XhrIo();
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  var headers = this.headers_;
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  if (headers) {
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    headers.forEach(function(value, key) { xhrIo.headers.set(key, value); });
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  }
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  if (this.withCredentials_) {
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    xhrIo.setWithCredentials(true);
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  }
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  return xhrIo;
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};
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/**
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 * Determine if an object has become unusable and should not be used.
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 * @param {Object} obj The object to test.
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 * @return {boolean} Whether the object can be reused, which is true if the
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 *     object is not disposed and not active.
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 * @override
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 */
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goog.net.XhrIoPool.prototype.objectCanBeReused = function(obj) {
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  // An active XhrIo object should never be used.
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  var xhr = /** @type {goog.net.XhrIo} */ (obj);
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  return !xhr.isDisposed() && !xhr.isActive();
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};
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