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// Copyright 2013 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 Closure user agent detection.
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 * @see http://en.wikipedia.org/wiki/User_agent
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 * For more information on browser brand, platform, or device see the other
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 * sub-namespaces in goog.labs.userAgent (browser, platform, and device).
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 *
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 */
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goog.provide('goog.labs.userAgent.engine');
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goog.require('goog.array');
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goog.require('goog.labs.userAgent.util');
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goog.require('goog.string');
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/**
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 * @return {boolean} Whether the rendering engine is Presto.
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 */
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goog.labs.userAgent.engine.isPresto = function() {
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  return goog.labs.userAgent.util.matchUserAgent('Presto');
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};
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/**
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 * @return {boolean} Whether the rendering engine is Trident.
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 */
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goog.labs.userAgent.engine.isTrident = function() {
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  // IE only started including the Trident token in IE8.
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  return goog.labs.userAgent.util.matchUserAgent('Trident') ||
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      goog.labs.userAgent.util.matchUserAgent('MSIE');
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};
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/**
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 * @return {boolean} Whether the rendering engine is Edge.
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 */
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goog.labs.userAgent.engine.isEdge = function() {
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  return goog.labs.userAgent.util.matchUserAgent('Edge');
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};
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/**
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 * @return {boolean} Whether the rendering engine is WebKit.
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 */
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goog.labs.userAgent.engine.isWebKit = function() {
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  return goog.labs.userAgent.util.matchUserAgentIgnoreCase('WebKit') &&
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      !goog.labs.userAgent.engine.isEdge();
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};
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/**
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 * @return {boolean} Whether the rendering engine is Gecko.
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 */
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goog.labs.userAgent.engine.isGecko = function() {
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  return goog.labs.userAgent.util.matchUserAgent('Gecko') &&
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      !goog.labs.userAgent.engine.isWebKit() &&
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      !goog.labs.userAgent.engine.isTrident() &&
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      !goog.labs.userAgent.engine.isEdge();
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};
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/**
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 * @return {string} The rendering engine's version or empty string if version
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 *     can't be determined.
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 */
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goog.labs.userAgent.engine.getVersion = function() {
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  var userAgentString = goog.labs.userAgent.util.getUserAgent();
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  if (userAgentString) {
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    var tuples = goog.labs.userAgent.util.extractVersionTuples(userAgentString);
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    var engineTuple = goog.labs.userAgent.engine.getEngineTuple_(tuples);
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    if (engineTuple) {
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      // In Gecko, the version string is either in the browser info or the
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      // Firefox version.  See Gecko user agent string reference:
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      // http://goo.gl/mULqa
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      if (engineTuple[0] == 'Gecko') {
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        return goog.labs.userAgent.engine.getVersionForKey_(tuples, 'Firefox');
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      }
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      return engineTuple[1];
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    }
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    // MSIE has only one version identifier, and the Trident version is
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    // specified in the parenthetical. IE Edge is covered in the engine tuple
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    // detection.
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    var browserTuple = tuples[0];
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    var info;
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    if (browserTuple && (info = browserTuple[2])) {
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      var match = /Trident\/([^\s;]+)/.exec(info);
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      if (match) {
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        return match[1];
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      }
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    }
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  }
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  return '';
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};
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/**
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 * @param {!Array<!Array<string>>} tuples Extracted version tuples.
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 * @return {!Array<string>|undefined} The engine tuple or undefined if not
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 *     found.
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 * @private
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 */
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goog.labs.userAgent.engine.getEngineTuple_ = function(tuples) {
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  if (!goog.labs.userAgent.engine.isEdge()) {
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    return tuples[1];
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  }
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  for (var i = 0; i < tuples.length; i++) {
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    var tuple = tuples[i];
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    if (tuple[0] == 'Edge') {
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      return tuple;
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    }
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  }
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};
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/**
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 * @param {string|number} version The version to check.
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 * @return {boolean} Whether the rendering engine version is higher or the same
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 *     as the given version.
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 */
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goog.labs.userAgent.engine.isVersionOrHigher = function(version) {
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  return goog.string.compareVersions(
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             goog.labs.userAgent.engine.getVersion(), version) >= 0;
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};
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/**
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 * @param {!Array<!Array<string>>} tuples Version tuples.
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 * @param {string} key The key to look for.
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 * @return {string} The version string of the given key, if present.
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 *     Otherwise, the empty string.
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 * @private
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 */
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goog.labs.userAgent.engine.getVersionForKey_ = function(tuples, key) {
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  // TODO(nnaze): Move to util if useful elsewhere.
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  var pair = goog.array.find(tuples, function(pair) { return key == pair[0]; });
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  return pair && pair[1] || '';
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};
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