selenium-webdriver/lib/goog/base.js

The official WebDriver JavaScript bindings from the Selenium project

// Copyright 2006 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 Bootstrap for the Google JS Library (Closure).
 *
 * In uncompiled mode base.js will write out Closure's deps file, unless the
 * global <code>CLOSURE_NO_DEPS</code> is set to true.  This allows projects to
 * include their own deps file(s) from different locations.
 *
 *
 * @provideGoog
 */


/**
 * @define {boolean} Overridden to true by the compiler when --closure_pass
 *     or --mark_as_compiled is specified.
 */
var COMPILED = false;


/**
 * Base namespace for the Closure library.  Checks to see goog is already
 * defined in the current scope before assigning to prevent clobbering if
 * base.js is loaded more than once.
 *
 * @const
 */
var goog = goog || {};


/**
 * Reference to the global context.  In most cases this will be 'window'.
 */
goog.global = this;


/**
 * A hook for overriding the define values in uncompiled mode.
 *
 * In uncompiled mode, {@code CLOSURE_UNCOMPILED_DEFINES} may be defined before
 * loading base.js.  If a key is defined in {@code CLOSURE_UNCOMPILED_DEFINES},
 * {@code goog.define} will use the value instead of the default value.  This
 * allows flags to be overwritten without compilation (this is normally
 * accomplished with the compiler's "define" flag).
 *
 * Example:
 * <pre>
 *   var CLOSURE_UNCOMPILED_DEFINES = {'goog.DEBUG': false};
 * </pre>
 *
 * @type {Object.<string, (string|number|boolean)>|undefined}
 */
goog.global.CLOSURE_UNCOMPILED_DEFINES;


/**
 * A hook for overriding the define values in uncompiled or compiled mode,
 * like CLOSURE_UNCOMPILED_DEFINES but effective in compiled code.  In
 * uncompiled code CLOSURE_UNCOMPILED_DEFINES takes precedence.
 *
 * Also unlike CLOSURE_UNCOMPILED_DEFINES the values must be number, boolean or
 * string literals or the compiler will emit an error.
 *
 * While any @define value may be set, only those set with goog.define will be
 * effective for uncompiled code.
 *
 * Example:
 * <pre>
 *   var CLOSURE_DEFINES = {'goog.DEBUG': false};
 * </pre>
 *
 * @type {Object.<string, (string|number|boolean)>|undefined}
 */
goog.global.CLOSURE_DEFINES;


/**
 * Returns true if the specified value is not undefined.
 * WARNING: Do not use this to test if an object has a property. Use the in
 * operator instead.
 *
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is defined.
 */
goog.isDef = function(val) {
  // void 0 always evaluates to undefined and hence we do not need to depend on
  // the definition of the global variable named 'undefined'.
  return val !== void 0;
};


/**
 * Builds an object structure for the provided namespace path, ensuring that
 * names that already exist are not overwritten. For example:
 * "a.b.c" -> a = {};a.b={};a.b.c={};
 * Used by goog.provide and goog.exportSymbol.
 * @param {string} name name of the object that this file defines.
 * @param {*=} opt_object the object to expose at the end of the path.
 * @param {Object=} opt_objectToExportTo The object to add the path to; default
 *     is |goog.global|.
 * @private
 */
goog.exportPath_ = function(name, opt_object, opt_objectToExportTo) {
  var parts = name.split('.');
  var cur = opt_objectToExportTo || goog.global;

  // Internet Explorer exhibits strange behavior when throwing errors from
  // methods externed in this manner.  See the testExportSymbolExceptions in
  // base_test.html for an example.
  if (!(parts[0] in cur) && cur.execScript) {
    cur.execScript('var ' + parts[0]);
  }

  // Certain browsers cannot parse code in the form for((a in b); c;);
  // This pattern is produced by the JSCompiler when it collapses the
  // statement above into the conditional loop below. To prevent this from
  // happening, use a for-loop and reserve the init logic as below.

  // Parentheses added to eliminate strict JS warning in Firefox.
  for (var part; parts.length && (part = parts.shift());) {
    if (!parts.length && goog.isDef(opt_object)) {
      // last part and we have an object; use it
      cur[part] = opt_object;
    } else if (cur[part]) {
      cur = cur[part];
    } else {
      cur = cur[part] = {};
    }
  }
};


/**
 * Defines a named value. In uncompiled mode, the value is retreived from
 * CLOSURE_DEFINES or CLOSURE_UNCOMPILED_DEFINES if the object is defined and
 * has the property specified, and otherwise used the defined defaultValue.
 * When compiled, the default can be overridden using compiler command-line
 * options.
 *
 * @param {string} name The distinguished name to provide.
 * @param {string|number|boolean} defaultValue
 */
goog.define = function(name, defaultValue) {
  var value = defaultValue;
  if (!COMPILED) {
    if (goog.global.CLOSURE_UNCOMPILED_DEFINES &&
        Object.prototype.hasOwnProperty.call(
            goog.global.CLOSURE_UNCOMPILED_DEFINES, name)) {
      value = goog.global.CLOSURE_UNCOMPILED_DEFINES[name];
    } else if (goog.global.CLOSURE_DEFINES &&
        Object.prototype.hasOwnProperty.call(
            goog.global.CLOSURE_DEFINES, name)) {
      value = goog.global.CLOSURE_DEFINES[name];
    }
  }
  goog.exportPath_(name, value);
};


/**
 * @define {boolean} DEBUG is provided as a convenience so that debugging code
 * that should not be included in a production js_binary can be easily stripped
 * by specifying --define goog.DEBUG=false to the JSCompiler. For example, most
 * toString() methods should be declared inside an "if (goog.DEBUG)" conditional
 * because they are generally used for debugging purposes and it is difficult
 * for the JSCompiler to statically determine whether they are used.
 */
goog.DEBUG = true;


/**
 * @define {string} LOCALE defines the locale being used for compilation. It is
 * used to select locale specific data to be compiled in js binary. BUILD rule
 * can specify this value by "--define goog.LOCALE=<locale_name>" as JSCompiler
 * option.
 *
 * Take into account that the locale code format is important. You should use
 * the canonical Unicode format with hyphen as a delimiter. Language must be
 * lowercase, Language Script - Capitalized, Region - UPPERCASE.
 * There are few examples: pt-BR, en, en-US, sr-Latin-BO, zh-Hans-CN.
 *
 * See more info about locale codes here:
 * http://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers
 *
 * For language codes you should use values defined by ISO 693-1. See it here
 * http://www.w3.org/WAI/ER/IG/ert/iso639.htm. There is only one exception from
 * this rule: the Hebrew language. For legacy reasons the old code (iw) should
 * be used instead of the new code (he), see http://wiki/Main/IIISynonyms.
 */
goog.define('goog.LOCALE', 'en');  // default to en


/**
 * @define {boolean} Whether this code is running on trusted sites.
 *
 * On untrusted sites, several native functions can be defined or overridden by
 * external libraries like Prototype, Datejs, and JQuery and setting this flag
 * to false forces closure to use its own implementations when possible.
 *
 * If your JavaScript can be loaded by a third party site and you are wary about
 * relying on non-standard implementations, specify
 * "--define goog.TRUSTED_SITE=false" to the JSCompiler.
 */
goog.define('goog.TRUSTED_SITE', true);


/**
 * @define {boolean} Whether a project is expected to be running in strict mode.
 *
 * This define can be used to trigger alternate implementations compatible with
 * running in EcmaScript Strict mode or warn about unavailable functionality.
 * See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions_and_function_scope/Strict_mode
 */
goog.define('goog.STRICT_MODE_COMPATIBLE', false);


/**
 * Creates object stubs for a namespace.  The presence of one or more
 * goog.provide() calls indicate that the file defines the given
 * objects/namespaces.  Provided objects must not be null or undefined.
 * Build tools also scan for provide/require statements
 * to discern dependencies, build dependency files (see deps.js), etc.
 * @see goog.require
 * @param {string} name Namespace provided by this file in the form
 *     "goog.package.part".
 */
goog.provide = function(name) {
  if (!COMPILED) {
    // Ensure that the same namespace isn't provided twice.
    // A goog.module/goog.provide maps a goog.require to a specific file
    if (goog.isProvided_(name)) {
      throw Error('Namespace "' + name + '" already declared.');
    }
    delete goog.implicitNamespaces_[name];

    var namespace = name;
    while ((namespace = namespace.substring(0, namespace.lastIndexOf('.')))) {
      if (goog.getObjectByName(namespace)) {
        break;
      }
      goog.implicitNamespaces_[namespace] = true;
    }
  }

  goog.exportPath_(name);
};


/**
 * goog.module serves two purposes:
 * - marks a file that must be loaded as a module
 * - reserves a namespace (it can not also be goog.provided)
 * and has three requirements:
 * - goog.module may not be used in the same file as goog.provide.
 * - goog.module must be the first statement in the file.
 * - only one goog.module is allowed per file.
 * When a goog.module annotated file is loaded, it is loaded enclosed in
 * a strict function closure. This means that:
 * - any variable declared in a goog.module file are private to the file,
 * not global. Although the compiler is expected to inline the module.
 * - The code must obey all the rules of "strict" JavaScript.
 * - the file will be marked as "use strict"
 *
 * NOTE: unlike goog.provide, goog.module does not declare any symbols by
 * itself.
 *
 * @param {string} name Namespace provided by this file in the form
 *     "goog.package.part", is expected but not required.
 */
goog.module = function(name) {
  if (!goog.isString(name) || !name) {
    throw Error('Invalid module identifier');
  }
  if (!goog.isInModuleLoader_()) {
    throw Error('Module ' + name + ' has been loaded incorrectly.');
  }
  if (goog.moduleLoaderState_.moduleName) {
    throw Error('goog.module may only be called once per module.');
  }

  // Store the module name for the loader.
  goog.moduleLoaderState_.moduleName = name;
  if (!COMPILED) {
    // Ensure that the same namespace isn't provided twice.
    // A goog.module/goog.provide maps a goog.require to a specific file
    if (goog.isProvided_(name)) {
      throw Error('Namespace "' + name + '" already declared.');
    }
    delete goog.implicitNamespaces_[name];
  }
};


/** @private {{
 *     moduleName:(string|undefined),
 *     exportTestMethods:boolean}|null}}
 */
goog.moduleLoaderState_ = null;


/**
 * @private
 * @return {boolean} Whether a goog.module is currently being initialized.
 */
goog.isInModuleLoader_ = function() {
  return goog.moduleLoaderState_ != null;
};


/**
 * Indicate that a module's exports that are known test methods should
 * be copied to the global object.  This makes the test methods visible to
 * test runners that inspect the global object.
 *
 * TODO(johnlenz): Make the test framework aware of goog.module so
 * that this isn't necessary. Alternately combine this with goog.setTestOnly
 * to minimize boiler plate.
 */
goog.module.exportTestMethods = function() {
  if (!goog.isInModuleLoader_()) {
    throw new Error('goog.module.exportTestMethods must be called from ' +
        'within a goog.module');
  }
  goog.moduleLoaderState_.exportTestMethods = true;
};


/**
 * Marks that the current file should only be used for testing, and never for
 * live code in production.
 *
 * In the case of unit tests, the message may optionally be an exact namespace
 * for the test (e.g. 'goog.stringTest'). The linter will then ignore the extra
 * provide (if not explicitly defined in the code).
 *
 * @param {string=} opt_message Optional message to add to the error that's
 *     raised when used in production code.
 */
goog.setTestOnly = function(opt_message) {
  if (COMPILED && !goog.DEBUG) {
    opt_message = opt_message || '';
    throw Error('Importing test-only code into non-debug environment' +
                (opt_message ? ': ' + opt_message : '.'));
  }
};


/**
 * Forward declares a symbol. This is an indication to the compiler that the
 * symbol may be used in the source yet is not required and may not be provided
 * in compilation.
 *
 * The most common usage of forward declaration is code that takes a type as a
 * function parameter but does not need to require it. By forward declaring
 * instead of requiring, no hard dependency is made, and (if not required
 * elsewhere) the namespace may never be required and thus, not be pulled
 * into the JavaScript binary. If it is required elsewhere, it will be type
 * checked as normal.
 *
 *
 * @param {string} name The namespace to forward declare in the form of
 *     "goog.package.part".
 */
goog.forwardDeclare = function(name) {};


if (!COMPILED) {

  /**
   * Check if the given name has been goog.provided. This will return false for
   * names that are available only as implicit namespaces.
   * @param {string} name name of the object to look for.
   * @return {boolean} Whether the name has been provided.
   * @private
   */
  goog.isProvided_ = function(name) {
    return (name in goog.loadedModules_) ||
        (!goog.implicitNamespaces_[name] &&
            goog.isDefAndNotNull(goog.getObjectByName(name)));
  };

  /**
   * Namespaces implicitly defined by goog.provide. For example,
   * goog.provide('goog.events.Event') implicitly declares that 'goog' and
   * 'goog.events' must be namespaces.
   *
   * @type {Object.<string, (boolean|undefined)>}
   * @private
   */
  goog.implicitNamespaces_ = {'goog.module': true};

  // NOTE: We add goog.module as an implicit namespace as goog.module is defined
  // here and because the existing module package has not been moved yet out of
  // the goog.module namespace. This satisifies both the debug loader and
  // ahead-of-time dependency management.
}


/**
 * Returns an object based on its fully qualified external name.  The object
 * is not found if null or undefined.  If you are using a compilation pass that
 * renames property names beware that using this function will not find renamed
 * properties.
 *
 * @param {string} name The fully qualified name.
 * @param {Object=} opt_obj The object within which to look; default is
 *     |goog.global|.
 * @return {?} The value (object or primitive) or, if not found, null.
 */
goog.getObjectByName = function(name, opt_obj) {
  var parts = name.split('.');
  var cur = opt_obj || goog.global;
  for (var part; part = parts.shift(); ) {
    if (goog.isDefAndNotNull(cur[part])) {
      cur = cur[part];
    } else {
      return null;
    }
  }
  return cur;
};


/**
 * Globalizes a whole namespace, such as goog or goog.lang.
 *
 * @param {Object} obj The namespace to globalize.
 * @param {Object=} opt_global The object to add the properties to.
 * @deprecated Properties may be explicitly exported to the global scope, but
 *     this should no longer be done in bulk.
 */
goog.globalize = function(obj, opt_global) {
  var global = opt_global || goog.global;
  for (var x in obj) {
    global[x] = obj[x];
  }
};


/**
 * Adds a dependency from a file to the files it requires.
 * @param {string} relPath The path to the js file.
 * @param {Array} provides An array of strings with the names of the objects
 *                         this file provides.
 * @param {Array} requires An array of strings with the names of the objects
 *                         this file requires.
 * @param {boolean=} opt_isModule Whether this dependency must be loaded as
 *     a module as declared by goog.module.
 */
goog.addDependency = function(relPath, provides, requires, opt_isModule) {
  if (goog.DEPENDENCIES_ENABLED) {
    var provide, require;
    var path = relPath.replace(/\\/g, '/');
    var deps = goog.dependencies_;
    for (var i = 0; provide = provides[i]; i++) {
      deps.nameToPath[provide] = path;
      deps.pathIsModule[path] = !!opt_isModule;
    }
    for (var j = 0; require = requires[j]; j++) {
      if (!(path in deps.requires)) {
        deps.requires[path] = {};
      }
      deps.requires[path][require] = true;
    }
  }
};




// NOTE(nnaze): The debug DOM loader was included in base.js as an original way
// to do "debug-mode" development.  The dependency system can sometimes be
// confusing, as can the debug DOM loader's asynchronous nature.
//
// With the DOM loader, a call to goog.require() is not blocking -- the script
// will not load until some point after the current script.  If a namespace is
// needed at runtime, it needs to be defined in a previous script, or loaded via
// require() with its registered dependencies.
// User-defined namespaces may need their own deps file.  See http://go/js_deps,
// http://go/genjsdeps, or, externally, DepsWriter.
// https://developers.google.com/closure/library/docs/depswriter
//
// Because of legacy clients, the DOM loader can't be easily removed from
// base.js.  Work is being done to make it disableable or replaceable for
// different environments (DOM-less JavaScript interpreters like Rhino or V8,
// for example). See bootstrap/ for more information.


/**
 * @define {boolean} Whether to enable the debug loader.
 *
 * If enabled, a call to goog.require() will attempt to load the namespace by
 * appending a script tag to the DOM (if the namespace has been registered).
 *
 * If disabled, goog.require() will simply assert that the namespace has been
 * provided (and depend on the fact that some outside tool correctly ordered
 * the script).
 */
goog.define('goog.ENABLE_DEBUG_LOADER', true);


/**
 * @param {string} msg
 * @private
 */
goog.logToConsole_ = function(msg) {
  if (goog.global.console) {
    goog.global.console['error'](msg);
  }
};


/**
 * Implements a system for the dynamic resolution of dependencies that works in
 * parallel with the BUILD system. Note that all calls to goog.require will be
 * stripped by the JSCompiler when the --closure_pass option is used.
 * @see goog.provide
 * @param {string} name Namespace to include (as was given in goog.provide()) in
 *     the form "goog.package.part".
 * @return {?} If called within a goog.module file, the associated namespace or
 *     module otherwise null.
 */
goog.require = function(name) {

  // If the object already exists we do not need do do anything.
  if (!COMPILED) {
    if (goog.isProvided_(name)) {
      if (goog.isInModuleLoader_()) {
        // goog.require only return a value with-in goog.module files.
        return name in goog.loadedModules_ ?
            goog.loadedModules_[name] :
            goog.getObjectByName(name);
      } else {
        return null;
      }
    }

    if (goog.ENABLE_DEBUG_LOADER) {
      var path = goog.getPathFromDeps_(name);
      if (path) {
        goog.included_[path] = true;
        goog.writeScripts_();
        return null;
      }
    }

    var errorMessage = 'goog.require could not find: ' + name;
    goog.logToConsole_(errorMessage);

    throw Error(errorMessage);
  }
};


/**
 * Path for included scripts.
 * @type {string}
 */
goog.basePath = '';


/**
 * A hook for overriding the base path.
 * @type {string|undefined}
 */
goog.global.CLOSURE_BASE_PATH;


/**
 * Whether to write out Closure's deps file. By default, the deps are written.
 * @type {boolean|undefined}
 */
goog.global.CLOSURE_NO_DEPS;


/**
 * A function to import a single script. This is meant to be overridden when
 * Closure is being run in non-HTML contexts, such as web workers. It's defined
 * in the global scope so that it can be set before base.js is loaded, which
 * allows deps.js to be imported properly.
 *
 * The function is passed the script source, which is a relative URI. It should
 * return true if the script was imported, false otherwise.
 * @type {(function(string): boolean)|undefined}
 */
goog.global.CLOSURE_IMPORT_SCRIPT;


/**
 * Null function used for default values of callbacks, etc.
 * @return {void} Nothing.
 */
goog.nullFunction = function() {};


/**
 * The identity function. Returns its first argument.
 *
 * @param {*=} opt_returnValue The single value that will be returned.
 * @param {...*} var_args Optional trailing arguments. These are ignored.
 * @return {?} The first argument. We can't know the type -- just pass it along
 *      without type.
 * @deprecated Use goog.functions.identity instead.
 */
goog.identityFunction = function(opt_returnValue, var_args) {
  return opt_returnValue;
};


/**
 * When defining a class Foo with an abstract method bar(), you can do:
 * Foo.prototype.bar = goog.abstractMethod
 *
 * Now if a subclass of Foo fails to override bar(), an error will be thrown
 * when bar() is invoked.
 *
 * Note: This does not take the name of the function to override as an argument
 * because that would make it more difficult to obfuscate our JavaScript code.
 *
 * @type {!Function}
 * @throws {Error} when invoked to indicate the method should be overridden.
 */
goog.abstractMethod = function() {
  throw Error('unimplemented abstract method');
};


/**
 * Adds a {@code getInstance} static method that always returns the same
 * instance object.
 * @param {!Function} ctor The constructor for the class to add the static
 *     method to.
 */
goog.addSingletonGetter = function(ctor) {
  ctor.getInstance = function() {
    if (ctor.instance_) {
      return ctor.instance_;
    }
    if (goog.DEBUG) {
      // NOTE: JSCompiler can't optimize away Array#push.
      goog.instantiatedSingletons_[goog.instantiatedSingletons_.length] = ctor;
    }
    return ctor.instance_ = new ctor;
  };
};


/**
 * All singleton classes that have been instantiated, for testing. Don't read
 * it directly, use the {@code goog.testing.singleton} module. The compiler
 * removes this variable if unused.
 * @type {!Array.<!Function>}
 * @private
 */
goog.instantiatedSingletons_ = [];


/**
 * @define {boolean} Whether to load goog.modules using {@code eval} when using
 * the debug loader.  This provides a better debugging experience as the
 * source is unmodified and can be edited using Chrome Workspaces or
 * similiar.  However in some environments the use of {@code eval} is banned
 * so we provide an alternative.
 */
goog.define('goog.LOAD_MODULE_USING_EVAL', true);


/**
 * The registry of initialized modules:
 * the module identifier to module exports map.
 * @private @const {Object.<string, ?>}
 */
goog.loadedModules_ = {};


/**
 * True if goog.dependencies_ is available.
 * @const {boolean}
 */
goog.DEPENDENCIES_ENABLED = !COMPILED && goog.ENABLE_DEBUG_LOADER;


if (goog.DEPENDENCIES_ENABLED) {
  /**
   * Object used to keep track of urls that have already been added. This record
   * allows the prevention of circular dependencies.
   * @type {Object}
   * @private
   */
  goog.included_ = {};


  /**
   * This object is used to keep track of dependencies and other data that is
   * used for loading scripts.
   * @private
   * @type {Object}
   */
  goog.dependencies_ = {
    pathIsModule: {}, // 1 to 1
    nameToPath: {}, // many to 1
    requires: {}, // 1 to many
    // Used when resolving dependencies to prevent us from visiting file twice.
    visited: {},
    written: {} // Used to keep track of script files we have written.
  };


  /**
   * Tries to detect whether is in the context of an HTML document.
   * @return {boolean} True if it looks like HTML document.
   * @private
   */
  goog.inHtmlDocument_ = function() {
    var doc = goog.global.document;
    return typeof doc != 'undefined' &&
           'write' in doc;  // XULDocument misses write.
  };


  /**
   * Tries to detect the base path of base.js script that bootstraps Closure.
   * @private
   */
  goog.findBasePath_ = function() {
    if (goog.global.CLOSURE_BASE_PATH) {
      goog.basePath = goog.global.CLOSURE_BASE_PATH;
      return;
    } else if (!goog.inHtmlDocument_()) {
      return;
    }
    var doc = goog.global.document;
    var scripts = doc.getElementsByTagName('script');
    // Search backwards since the current script is in almost all cases the one
    // that has base.js.
    for (var i = scripts.length - 1; i >= 0; --i) {
      var src = scripts[i].src;
      var qmark = src.lastIndexOf('?');
      var l = qmark == -1 ? src.length : qmark;
      if (src.substr(l - 7, 7) == 'base.js') {
        goog.basePath = src.substr(0, l - 7);
        return;
      }
    }
  };


  /**
   * Imports a script if, and only if, that script hasn't already been imported.
   * (Must be called at execution time)
   * @param {string} src Script source.
   * @param {string=} opt_sourceText The optionally source text to evaluate
   * @private
   */
  goog.importScript_ = function(src, opt_sourceText) {
    var importScript = goog.global.CLOSURE_IMPORT_SCRIPT ||
        goog.writeScriptTag_;
    if (importScript(src, opt_sourceText)) {
      goog.dependencies_.written[src] = true;
    }
  };


  /** @const @private {boolean} */
  goog.IS_OLD_IE_ = goog.global.document &&
      goog.global.document.all && !goog.global.atob;


  /**
   * Given a URL initiate retrieval and execution of the module.
   * @param {string} src Script source URL.
   * @private
   */
  goog.importModule_ = function(src) {
    // In an attempt to keep browsers from timing out loading scripts using
    // synchronous XHRs, put each load in its own script block.
    var bootstrap = 'goog.retrieveAndExecModule_("' + src + '");';

    if (goog.importScript_('', bootstrap)) {
      goog.dependencies_.written[src] = true;
    }
  };


  /** @private {Array.<string>} */
  goog.queuedModules_ = [];


  /**
   * Retrieve and execute a module.
   * @param {string} src Script source URL.
   * @private
   */
  goog.retrieveAndExecModule_ = function(src) {
    var importScript = goog.global.CLOSURE_IMPORT_SCRIPT ||
        goog.writeScriptTag_;

    var scriptText = null;

    var xhr = new goog.global['XMLHttpRequest']();

    /** @this {Object} */
    xhr.onload = function() {
      scriptText = this.responseText;
    };
    xhr.open('get', src, false);
    xhr.send();

    scriptText = xhr.responseText;

    if (scriptText != null) {
      var execModuleScript = goog.wrapModule_(src, scriptText);
      var isOldIE = goog.IS_OLD_IE_;
      if (isOldIE) {
        goog.queuedModules_.push(execModuleScript);
      } else {
        importScript(src, execModuleScript);
      }
      goog.dependencies_.written[src] = true;
    } else {
      throw new Error('load of ' + src + 'failed');
    }
  };


  /**
   * Return an appropriate module text. Suitable to insert into
   * a script tag (that is unescaped).
   * @param {string} srcUrl
   * @param {string} scriptText
   * @return {string}
   * @private
   */
  goog.wrapModule_ = function(srcUrl, scriptText) {
    if (!goog.LOAD_MODULE_USING_EVAL || !goog.isDef(goog.global.JSON)) {
      return '' +
          'goog.loadModule(function(exports) {' +
          '"use strict";' +
          scriptText +
          '\n' + // terminate any trailing single line comment.
          ';return exports' +
          '});' +
          '\n//# sourceURL=' + srcUrl + '\n';
    } else {
      return '' +
          'goog.loadModule(' +
          goog.global.JSON.stringify(
              scriptText + '\n//# sourceURL=' + srcUrl + '\n') +
          ');';
    }
  };


  /**
   * Load any deferred goog.module loads.
   * @private
   */
  goog.loadQueuedModules_ = function() {
    var count = goog.queuedModules_.length;
    if (count > 0) {
      var queue = goog.queuedModules_;
      goog.queuedModules_ = [];
      for (var i = 0; i < count; i++) {
        var entry = queue[i];
        goog.globalEval(entry);
      }
    }
  };


  /**
   * @param {function(?):?|string} moduleDef The module definition.
   */
  goog.loadModule = function(moduleDef) {
    // NOTE: we allow function definitions to be either in the from
    // of a string to eval (which keeps the original source intact) or
    // in a eval forbidden environment (CSP) we allow a function definition
    // which in its body must call {@code goog.module}, and return the exports
    // of the module.
    try {
      goog.moduleLoaderState_ = {
          moduleName: undefined, exportTestMethods: false};
      var exports;
      if (goog.isFunction(moduleDef)) {
        exports = moduleDef.call(goog.global, {});
      } else if (goog.isString(moduleDef)) {
        exports = goog.loadModuleFromSource_.call(goog.global, moduleDef);
      } else {
        throw Error('Invalid module definition');
      }

      if (Object.seal) {
        Object.seal(exports);
      }
      var moduleName = goog.moduleLoaderState_.moduleName;
      if (!goog.isString(moduleName) || !moduleName) {
        throw Error('Invalid module name \"' + moduleName + '\"');
      }

      goog.loadedModules_[moduleName] = exports;
      if (goog.moduleLoaderState_.exportTestMethods) {
        for (var entry in exports) {
          if (entry.indexOf('test', 0) === 0 ||
              entry == 'tearDown' ||
              entry == 'setup') {
            goog.global[entry] = exports[entry];
          }
        }
      }
    } finally {
      goog.moduleLoaderState_ = null;
    }
  };


  /**
   * @private @const {function(string):?}
   */
  goog.loadModuleFromSource_ = function() {
    // NOTE: we avoid declaring parameters or local variables here to avoid
    // masking globals or leaking values into the module definition.
    'use strict';
    var exports = {};
    eval(arguments[0]);
    return exports;
  };


  /**
   * The default implementation of the import function. Writes a script tag to
   * import the script.
   *
   * @param {string} src The script url.
   * @param {string=} opt_sourceText The optionally source text to evaluate
   * @return {boolean} True if the script was imported, false otherwise.
   * @private
   */
  goog.writeScriptTag_ = function(src, opt_sourceText) {
    if (goog.inHtmlDocument_()) {
      var doc = goog.global.document;

      // If the user tries to require a new symbol after document load,
      // something has gone terribly wrong. Doing a document.write would
      // wipe out the page.
      if (doc.readyState == 'complete') {
        // Certain test frameworks load base.js multiple times, which tries
        // to write deps.js each time. If that happens, just fail silently.
        // These frameworks wipe the page between each load of base.js, so this
        // is OK.
        var isDeps = /\bdeps.js$/.test(src);
        if (isDeps) {
          return false;
        } else {
          throw Error('Cannot write "' + src + '" after document load');
        }
      }

      var isOldIE = goog.IS_OLD_IE_;

      if (opt_sourceText === undefined) {
        if (!isOldIE) {
          doc.write(
              '<script type="text/javascript" src="' +
                  src + '"></' + 'script>');
        } else {
          var state = " onreadystatechange='goog.onScriptLoad_(this, " +
              ++goog.lastNonModuleScriptIndex_ + ")' ";
          doc.write(
              '<script type="text/javascript" src="' +
                  src + '"' + state + '></' + 'script>');
        }
      } else {
        doc.write(
            '<script type="text/javascript">' +
            opt_sourceText +
            '</' + 'script>');
      }
      return true;
    } else {
      return false;
    }
  };


  /** @private {number} */
  goog.lastNonModuleScriptIndex_ = 0;


  /**
   * A readystatechange handler for legacy IE
   * @param {HTMLScriptElement} script
   * @param {number} scriptIndex
   * @return {boolean}
   * @private
   */
  goog.onScriptLoad_ = function(script, scriptIndex) {
    // for now load the modules when we reach the last script,
    // later allow more inter-mingling.
    if (script.readyState == 'complete' &&
        goog.lastNonModuleScriptIndex_ == scriptIndex) {
      goog.loadQueuedModules_();
    }
    return true;
  };

  /**
   * Resolves dependencies based on the dependencies added using addDependency
   * and calls importScript_ in the correct order.
   * @private
   */
  goog.writeScripts_ = function() {
    // The scripts we need to write this time.
    var scripts = [];
    var seenScript = {};
    var deps = goog.dependencies_;

    function visitNode(path) {
      if (path in deps.written) {
        return;
      }

      // We have already visited this one. We can get here if we have cyclic
      // dependencies.
      if (path in deps.visited) {
        if (!(path in seenScript)) {
          seenScript[path] = true;
          scripts.push(path);
        }
        return;
      }

      deps.visited[path] = true;

      if (path in deps.requires) {
        for (var requireName in deps.requires[path]) {
          // If the required name is defined, we assume that it was already
          // bootstrapped by other means.
          if (!goog.isProvided_(requireName)) {
            if (requireName in deps.nameToPath) {
              visitNode(deps.nameToPath[requireName]);
            } else {
              throw Error('Undefined nameToPath for ' + requireName);
            }
          }
        }
      }

      if (!(path in seenScript)) {
        seenScript[path] = true;
        scripts.push(path);
      }
    }

    for (var path in goog.included_) {
      if (!deps.written[path]) {
        visitNode(path);
      }
    }

    // record that we are going to load all these scripts.
    for (var i = 0; i < scripts.length; i++) {
      var path = scripts[i];
      goog.dependencies_.written[path] = true;
    }

    // If a module is loaded synchronously then we need to
    // clear the current inModuleLoader value, and restore it when we are
    // done loading the current "requires".
    var moduleState = goog.moduleLoaderState_;
    goog.moduleLoaderState_ = null;

    var loadingModule = false;
    for (var i = 0; i < scripts.length; i++) {
      var path = scripts[i];
      if (path) {
        if (!deps.pathIsModule[path]) {
          goog.importScript_(goog.basePath + path);
        } else {
          loadingModule = true;
          goog.importModule_(goog.basePath + path);
        }
      } else {
        goog.moduleLoaderState_ = moduleState;
        throw Error('Undefined script input');
      }
    }

    // restore the current "module loading state"
    goog.moduleLoaderState_ = moduleState;
  };


  /**
   * Looks at the dependency rules and tries to determine the script file that
   * fulfills a particular rule.
   * @param {string} rule In the form goog.namespace.Class or project.script.
   * @return {?string} Url corresponding to the rule, or null.
   * @private
   */
  goog.getPathFromDeps_ = function(rule) {
    if (rule in goog.dependencies_.nameToPath) {
      return goog.dependencies_.nameToPath[rule];
    } else {
      return null;
    }
  };

  goog.findBasePath_();

  // Allow projects to manage the deps files themselves.
  if (!goog.global.CLOSURE_NO_DEPS) {
    goog.importScript_(goog.basePath + 'deps.js');
  }
}



//==============================================================================
// Language Enhancements
//==============================================================================


/**
 * This is a "fixed" version of the typeof operator.  It differs from the typeof
 * operator in such a way that null returns 'null' and arrays return 'array'.
 * @param {*} value The value to get the type of.
 * @return {string} The name of the type.
 */
goog.typeOf = function(value) {
  var s = typeof value;
  if (s == 'object') {
    if (value) {
      // Check these first, so we can avoid calling Object.prototype.toString if
      // possible.
      //
      // IE improperly marshals tyepof across execution contexts, but a
      // cross-context object will still return false for "instanceof Object".
      if (value instanceof Array) {
        return 'array';
      } else if (value instanceof Object) {
        return s;
      }

      // HACK: In order to use an Object prototype method on the arbitrary
      //   value, the compiler requires the value be cast to type Object,
      //   even though the ECMA spec explicitly allows it.
      var className = Object.prototype.toString.call(
          /** @type {Object} */ (value));
      // In Firefox 3.6, attempting to access iframe window objects' length
      // property throws an NS_ERROR_FAILURE, so we need to special-case it
      // here.
      if (className == '[object Window]') {
        return 'object';
      }

      // We cannot always use constructor == Array or instanceof Array because
      // different frames have different Array objects. In IE6, if the iframe
      // where the array was created is destroyed, the array loses its
      // prototype. Then dereferencing val.splice here throws an exception, so
      // we can't use goog.isFunction. Calling typeof directly returns 'unknown'
      // so that will work. In this case, this function will return false and
      // most array functions will still work because the array is still
      // array-like (supports length and []) even though it has lost its
      // prototype.
      // Mark Miller noticed that Object.prototype.toString
      // allows access to the unforgeable [[Class]] property.
      //  15.2.4.2 Object.prototype.toString ( )
      //  When the toString method is called, the following steps are taken:
      //      1. Get the [[Class]] property of this object.
      //      2. Compute a string value by concatenating the three strings
      //         "[object ", Result(1), and "]".
      //      3. Return Result(2).
      // and this behavior survives the destruction of the execution context.
      if ((className == '[object Array]' ||
           // In IE all non value types are wrapped as objects across window
           // boundaries (not iframe though) so we have to do object detection
           // for this edge case.
           typeof value.length == 'number' &&
           typeof value.splice != 'undefined' &&
           typeof value.propertyIsEnumerable != 'undefined' &&
           !value.propertyIsEnumerable('splice')

          )) {
        return 'array';
      }
      // HACK: There is still an array case that fails.
      //     function ArrayImpostor() {}
      //     ArrayImpostor.prototype = [];
      //     var impostor = new ArrayImpostor;
      // this can be fixed by getting rid of the fast path
      // (value instanceof Array) and solely relying on
      // (value && Object.prototype.toString.vall(value) === '[object Array]')
      // but that would require many more function calls and is not warranted
      // unless closure code is receiving objects from untrusted sources.

      // IE in cross-window calls does not correctly marshal the function type
      // (it appears just as an object) so we cannot use just typeof val ==
      // 'function'. However, if the object has a call property, it is a
      // function.
      if ((className == '[object Function]' ||
          typeof value.call != 'undefined' &&
          typeof value.propertyIsEnumerable != 'undefined' &&
          !value.propertyIsEnumerable('call'))) {
        return 'function';
      }

    } else {
      return 'null';
    }

  } else if (s == 'function' && typeof value.call == 'undefined') {
    // In Safari typeof nodeList returns 'function', and on Firefox typeof
    // behaves similarly for HTML{Applet,Embed,Object}, Elements and RegExps. We
    // would like to return object for those and we can detect an invalid
    // function by making sure that the function object has a call method.
    return 'object';
  }
  return s;
};


/**
 * Returns true if the specified value is null.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is null.
 */
goog.isNull = function(val) {
  return val === null;
};


/**
 * Returns true if the specified value is defined and not null.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is defined and not null.
 */
goog.isDefAndNotNull = function(val) {
  // Note that undefined == null.
  return val != null;
};


/**
 * Returns true if the specified value is an array.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is an array.
 */
goog.isArray = function(val) {
  return goog.typeOf(val) == 'array';
};


/**
 * Returns true if the object looks like an array. To qualify as array like
 * the value needs to be either a NodeList or an object with a Number length
 * property.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is an array.
 */
goog.isArrayLike = function(val) {
  var type = goog.typeOf(val);
  return type == 'array' || type == 'object' && typeof val.length == 'number';
};


/**
 * Returns true if the object looks like a Date. To qualify as Date-like the
 * value needs to be an object and have a getFullYear() function.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is a like a Date.
 */
goog.isDateLike = function(val) {
  return goog.isObject(val) && typeof val.getFullYear == 'function';
};


/**
 * Returns true if the specified value is a string.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is a string.
 */
goog.isString = function(val) {
  return typeof val == 'string';
};


/**
 * Returns true if the specified value is a boolean.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is boolean.
 */
goog.isBoolean = function(val) {
  return typeof val == 'boolean';
};


/**
 * Returns true if the specified value is a number.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is a number.
 */
goog.isNumber = function(val) {
  return typeof val == 'number';
};


/**
 * Returns true if the specified value is a function.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is a function.
 */
goog.isFunction = function(val) {
  return goog.typeOf(val) == 'function';
};


/**
 * Returns true if the specified value is an object.  This includes arrays and
 * functions.
 * @param {?} val Variable to test.
 * @return {boolean} Whether variable is an object.
 */
goog.isObject = function(val) {
  var type = typeof val;
  return type == 'object' && val != null || type == 'function';
  // return Object(val) === val also works, but is slower, especially if val is
  // not an object.
};


/**
 * Gets a unique ID for an object. This mutates the object so that further calls
 * with the same object as a parameter returns the same value. The unique ID is
 * guaranteed to be unique across the current session amongst objects that are
 * passed into {@code getUid}. There is no guarantee that the ID is unique or
 * consistent across sessions. It is unsafe to generate unique ID for function
 * prototypes.
 *
 * @param {Object} obj The object to get the unique ID for.
 * @return {number} The unique ID for the object.
 */
goog.getUid = function(obj) {
  // TODO(arv): Make the type stricter, do not accept null.

  // In Opera window.hasOwnProperty exists but always returns false so we avoid
  // using it. As a consequence the unique ID generated for BaseClass.prototype
  // and SubClass.prototype will be the same.
  return obj[goog.UID_PROPERTY_] ||
      (obj[goog.UID_PROPERTY_] = ++goog.uidCounter_);
};


/**
 * Whether the given object is alreay assigned a unique ID.
 *
 * This does not modify the object.
 *
 * @param {Object} obj The object to check.
 * @return {boolean} Whether there an assigned unique id for the object.
 */
goog.hasUid = function(obj) {
  return !!obj[goog.UID_PROPERTY_];
};


/**
 * Removes the unique ID from an object. This is useful if the object was
 * previously mutated using {@code goog.getUid} in which case the mutation is
 * undone.
 * @param {Object} obj The object to remove the unique ID field from.
 */
goog.removeUid = function(obj) {
  // TODO(arv): Make the type stricter, do not accept null.

  // In IE, DOM nodes are not instances of Object and throw an exception if we
  // try to delete.  Instead we try to use removeAttribute.
  if ('removeAttribute' in obj) {
    obj.removeAttribute(goog.UID_PROPERTY_);
  }
  /** @preserveTry */
  try {
    delete obj[goog.UID_PROPERTY_];
  } catch (ex) {
  }
};


/**
 * Name for unique ID property. Initialized in a way to help avoid collisions
 * with other closure JavaScript on the same page.
 * @type {string}
 * @private
 */
goog.UID_PROPERTY_ = 'closure_uid_' + ((Math.random() * 1e9) >>> 0);


/**
 * Counter for UID.
 * @type {number}
 * @private
 */
goog.uidCounter_ = 0;


/**
 * Adds a hash code field to an object. The hash code is unique for the
 * given object.
 * @param {Object} obj The object to get the hash code for.
 * @return {number} The hash code for the object.
 * @deprecated Use goog.getUid instead.
 */
goog.getHashCode = goog.getUid;


/**
 * Removes the hash code field from an object.
 * @param {Object} obj The object to remove the field from.
 * @deprecated Use goog.removeUid instead.
 */
goog.removeHashCode = goog.removeUid;


/**
 * Clones a value. The input may be an Object, Array, or basic type. Objects and
 * arrays will be cloned recursively.
 *
 * WARNINGS:
 * <code>goog.cloneObject</code> does not detect reference loops. Objects that
 * refer to themselves will cause infinite recursion.
 *
 * <code>goog.cloneObject</code> is unaware of unique identifiers, and copies
 * UIDs created by <code>getUid</code> into cloned results.
 *
 * @param {*} obj The value to clone.
 * @return {*} A clone of the input value.
 * @deprecated goog.cloneObject is unsafe. Prefer the goog.object methods.
 */
goog.cloneObject = function(obj) {
  var type = goog.typeOf(obj);
  if (type == 'object' || type == 'array') {
    if (obj.clone) {
      return obj.clone();
    }
    var clone = type == 'array' ? [] : {};
    for (var key in obj) {
      clone[key] = goog.cloneObject(obj[key]);
    }
    return clone;
  }

  return obj;
};


/**
 * A native implementation of goog.bind.
 * @param {Function} fn A function to partially apply.
 * @param {Object|undefined} selfObj Specifies the object which this should
 *     point to when the function is run.
 * @param {...*} var_args Additional arguments that are partially applied to the
 *     function.
 * @return {!Function} A partially-applied form of the function bind() was
 *     invoked as a method of.
 * @private
 * @suppress {deprecated} The compiler thinks that Function.prototype.bind is
 *     deprecated because some people have declared a pure-JS version.
 *     Only the pure-JS version is truly deprecated.
 */
goog.bindNative_ = function(fn, selfObj, var_args) {
  return /** @type {!Function} */ (fn.call.apply(fn.bind, arguments));
};


/**
 * A pure-JS implementation of goog.bind.
 * @param {Function} fn A function to partially apply.
 * @param {Object|undefined} selfObj Specifies the object which this should
 *     point to when the function is run.
 * @param {...*} var_args Additional arguments that are partially applied to the
 *     function.
 * @return {!Function} A partially-applied form of the function bind() was
 *     invoked as a method of.
 * @private
 */
goog.bindJs_ = function(fn, selfObj, var_args) {
  if (!fn) {
    throw new Error();
  }

  if (arguments.length > 2) {
    var boundArgs = Array.prototype.slice.call(arguments, 2);
    return function() {
      // Prepend the bound arguments to the current arguments.
      var newArgs = Array.prototype.slice.call(arguments);
      Array.prototype.unshift.apply(newArgs, boundArgs);
      return fn.apply(selfObj, newArgs);
    };

  } else {
    return function() {
      return fn.apply(selfObj, arguments);
    };
  }
};


/**
 * Partially applies this function to a particular 'this object' and zero or
 * more arguments. The result is a new function with some arguments of the first
 * function pre-filled and the value of this 'pre-specified'.
 *
 * Remaining arguments specified at call-time are appended to the pre-specified
 * ones.
 *
 * Also see: {@link #partial}.
 *
 * Usage:
 * <pre>var barMethBound = bind(myFunction, myObj, 'arg1', 'arg2');
 * barMethBound('arg3', 'arg4');</pre>
 *
 * @param {?function(this:T, ...)} fn A function to partially apply.
 * @param {T} selfObj Specifies the object which this should point to when the
 *     function is run.
 * @param {...*} var_args Additional arguments that are partially applied to the
 *     function.
 * @return {!Function} A partially-applied form of the function bind() was
 *     invoked as a method of.
 * @template T
 * @suppress {deprecated} See above.
 */
goog.bind = function(fn, selfObj, var_args) {
  // TODO(nicksantos): narrow the type signature.
  if (Function.prototype.bind &&
      // NOTE(nicksantos): Somebody pulled base.js into the default Chrome
      // extension environment. This means that for Chrome extensions, they get
      // the implementation of Function.prototype.bind that calls goog.bind
      // instead of the native one. Even worse, we don't want to introduce a
      // circular dependency between goog.bind and Function.prototype.bind, so
      // we have to hack this to make sure it works correctly.
      Function.prototype.bind.toString().indexOf('native code') != -1) {
    goog.bind = goog.bindNative_;
  } else {
    goog.bind = goog.bindJs_;
  }
  return goog.bind.apply(null, arguments);
};


/**
 * Like bind(), except that a 'this object' is not required. Useful when the
 * target function