text: // 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
  //
  //      https://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 || {}; // Identifies this file as the Closure base.
  
  
  /**
   * Reference to the global context.  In most cases this will be 'window'.
   */
  goog.global = this;
  
  
  /**
   * @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.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.TRUSTED_SITE = true;
  
  
  /**
   * Creates object stubs for a namespace.  The presence of one or more
   * goog.provide() calls indicate that the file defines the given
   * objects/namespaces.  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. This is intended
      // to teach new developers that 'goog.provide' is effectively a variable
      // declaration. And when JSCompiler transforms goog.provide into a real
      // variable declaration, the compiled JS should work the same as the raw
      // JS--even when the raw JS uses goog.provide incorrectly.
      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);
  };
  
  
  /**
   * Marks that the current file should only be used for testing, and never for
   * live code in production.
   * @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 : '.');
    }
  };
  
  
  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 !goog.implicitNamespaces_[name] && !!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}
     * @private
     */
    goog.implicitNamespaces_ = {};
  }
  
  
  /**
   * 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] = {};
      }
    }
  };
  
  
  /**
   * Returns an object based on its fully qualified external name.  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.
   */
  goog.addDependency = function(relPath, provides, requires) {
    if (!COMPILED) {
      var provide, require;
      var path = relPath.replace(/\\/g, '/');
      var deps = goog.dependencies_;
      for (var i = 0; provide = provides[i]; i++) {
        deps.nameToPath[provide] = path;
        if (!(path in deps.pathToNames)) {
          deps.pathToNames[path] = {};
        }
        deps.pathToNames[path][provide] = true;
      }
      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 orignal
  // 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.
  // http://code.google.com/closure/library/docs/depswriter.html
  //
  // 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.ENABLE_DEBUG_LOADER = true;
  
  
  /**
   * 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".
   */
  goog.require = function(name) {
  
    // if the object already exists we do not need do do anything
    // TODO(arv): If we start to support require based on file name this has
    //            to change
    // TODO(arv): If we allow goog.foo.* this has to change
    // TODO(arv): If we implement dynamic load after page load we should probably
    //            not remove this code for the compiled output
    if (!COMPILED) {
      if (goog.isProvided_(name)) {
        return;
      }
  
      if (goog.ENABLE_DEBUG_LOADER) {
        var path = goog.getPathFromDeps_(name);
        if (path) {
          goog.included_[path] = true;
          goog.writeScripts_();
          return;
        }
      }
  
      var errorMessage = 'goog.require could not find: ' + name;
      if (goog.global.console) {
        goog.global.console['error'](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.
   */
  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 return 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_ = [];
  
  
  if (!COMPILED && goog.ENABLE_DEBUG_LOADER) {
    /**
     * 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_ = {
      pathToNames: {}, // 1 to many
      nameToPath: {}, // 1 to 1
      requires: {}, // 1 to many
      // used when resolving dependencies to prevent us from
      // visiting the 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 the 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.
     * @private
     */
    goog.importScript_ = function(src) {
      var importScript = goog.global.CLOSURE_IMPORT_SCRIPT ||
          goog.writeScriptTag_;
      if (!goog.dependencies_.written[src] && importScript(src)) {
        goog.dependencies_.written[src] = true;
      }
    };
  
  
    /**
     * The default implementation of the import function. Writes a script tag to
     * import the script.
     *
     * @param {string} src The script source.
     * @return {boolean} True if the script was imported, false otherwise.
     * @private
     */
    goog.writeScriptTag_ = function(src) {
      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');
          }
        }
  
        doc.write(
            '<script type="text/javascript" src="' + src + '"></' + 'script>');
        return true;
      } else {
        return false;
      }
    };
  
  
    /**
     * 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);
        }
      }
  
      for (var i = 0; i < scripts.length; i++) {
        if (scripts[i]) {
          goog.importScript_(goog.basePath + scripts[i]);
        } else {
          throw Error('Undefined script input');
        }
      }
    };
  
  
    /**
     * 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 not |undefined|.
   * WARNING: Do not use this to test if an object has a property. Use the in
   * operator instead.  Additionally, this function assumes that the global
   * undefined variable has not been redefined.
   * @param {*} val Variable to test.
   * @return {boolean} Whether variable is defined.
   */
  goog.isDef = function(val) {
    return val !== undefined;
  };
  
  
  /**
   * 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_);
  };
  
  
  /**
   * 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.
  
    // DOM nodes in IE are not instance of Object and throws exception
    // for 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'.<br><br>
   *
   * Remaining arguments specified at call-time are appended to the pre-
   * specified ones.<br><br>
   *
   * Also see: {@link #partial}.<br><br>
   *
   * Usage:
   * <pre>var barMethBound = bind(myFunction, myObj, 'arg1', 'arg2');
   * barMethBound('arg3', 'arg4');</pre>
   *
   * @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.
   * @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 is already bound.
   *
   * Usage:
   * var g = partial(f, arg1, arg2);
   * g(arg3, arg4);
   *
   * @param {Function} fn A function to partially apply.
   * @param {...*} var_args Additional arguments that are partially
   *     applied to fn.
   * @return {!Function} A partially-applied form of the function bind() was
   *     invoked as a method of.
   */
  goog.partial = function(fn, var_args) {
    var args = Array.prototype.slice.call(arguments, 1);
    return function() {
      // Prepend the bound arguments to the current arguments.
      var newArgs = Array.prototype.slice.call(arguments);
      newArgs.unshift.apply(newArgs, args);
      return fn.apply(this, newArgs);
    };
  };
  
  
  /**
   * Copies all the members of a source object to a target object. This method
   * does not work on all browsers for all objects that contain keys such as
   * toString or hasOwnProperty. Use goog.object.extend for this purpose.
   * @param {Object} target Target.
   * @param {Object} source Source.
   */
  goog.mixin = function(target, source) {
    for (var x in source) {
      target[x] = source[x];
    }
  
    // For IE7 or lower, the for-in-loop does not contain any properties that are
    // not enumerable on the prototype object (for example, isPrototypeOf from
    // Object.prototype) but also it will not include 'replace' on objects that
    // extend String and change 'replace' (not that it is common for anyone to
    // extend anything except Object).
  };
  
  
  /**
   * @return {number} An integer value representing the number of milliseconds
   *     between midnight, January 1, 1970 and the current time.
   */
  goog.now = (goog.TRUSTED_SITE && Date.now) || (function() {
    // Unary plus operator converts its operand to a number which in the case of
    // a date is done by calling getTime().
    return +new Date();
  });
  
  
  /**
   * Evals javascript in the global scope.  In IE this uses execScript, other
   * browsers use goog.global.eval. If goog.global.eval does not evaluate in the
   * global scope (for example, in Safari), appends a script tag instead.
   * Throws an exception if neither execScript or eval is defined.
   * @param {string} script JavaScript string.
   */
  goog.globalEval = function(script) {
    if (goog.global.execScript) {
      goog.global.execScript(script, 'JavaScript');
    } else if (goog.global.eval) {
      // Test to see if eval works
      if (goog.evalWorksForGlobals_ == null) {
        goog.global.eval('var _et_ = 1;');
        if (typeof goog.global['_et_'] != 'undefined') {
          delete goog.global['_et_'];
          goog.evalWorksForGlobals_ = true;
        } else {
          goog.evalWorksForGlobals_ = false;
        }
      }
  
      if (goog.evalWorksForGlobals_) {
        goog.global.eval(script);
      } else {
        var doc = goog.global.document;
        var scriptElt = doc.createElement('script');
        scriptElt.type = 'text/javascript';
        scriptElt.defer = false;
        // Note(user): can't use .innerHTML since "t('<test>')" will fail and
        // .text doesn't work in Safari 2.  Therefore we append a text node.
        scriptElt.appendChild(doc.createTextNode(script));
        doc.body.appendChild(scriptElt);
        doc.body.removeChild(scriptElt);
      }
    } else {
      throw Error('goog.globalEval not available');
    }
  };
  
  
  /**
   * Indicates whether or not we can call 'eval' directly to eval code in the
   * global scope. Set to a Boolean by the first call to goog.globalEval (which
   * empirically tests whether eval works for globals). @see goog.globalEval
   * @type {?boolean}
   * @private
   */
  goog.evalWorksForGlobals_ = null;
  
  
  /**
   * Optional map of CSS class names to obfuscated names used with
   * goog.getCssName().
   * @type {Object|undefined}
   * @private
   * @see goog.setCssNameMapping
   */
  goog.cssNameMapping_;
  
  
  /**
   * Optional obfuscation style for CSS class names. Should be set to either
   * 'BY_WHOLE' or 'BY_PART' if defined.
   * @type {string|undefined}
   * @private
   * @see goog.setCssNameMapping
   */
  goog.cssNameMappingStyle_;
  
  
  /**
   * Handles strings that are intended to be used as CSS class names.
   *
   * This function works in tandem with @see goog.setCssNameMapping.
   *
   * Without any mapping set, the arguments are simple joined with a
   * hyphen and passed through unaltered.
   *
   * When there is a mapping, there are two possible styles in which
   * these mappings are used. In the BY_PART style, each part (i.e. in
   * between hyphens) of the passed in css name is rewritten according
   * to the map. In the BY_WHOLE style, the full css name is looked up in
   * the map directly. If a rewrite is not specified by the map, the
   * compiler will output a warning.
   *
   * When the mapping is passed to the compiler, it will replace calls
   * to goog.getCssName with the strings from the mapping, e.g.
   *     var x = goog.getCssName('foo');
   *     var y = goog.getCssName(this.baseClass, 'active');
   *  becomes:
   *     var x= 'foo';
   *     var y = this.baseClass + '-active';
   *
   * If one argument is passed it will be processed, if two are passed
   * only the modifier will be processed, as it is assumed the first
   * argument was generated as a result of calling goog.getCssName.
   *
   * @param {string} className The class name.
   * @param {string=} opt_modifier A modifier to be appended to the class name.
   * @return {string} The class name or the concatenation of the class name and
   *     the modifier.
   */
  goog.getCssName = function(className, opt_modifier) {
    var getMapping = function(cssName) {
      return goog.cssNameMapping_[cssName] || cssName;
    };
  
    var renameByParts = function(cssName) {
      // Remap all the parts individually.
      var parts = cssName.split('-');
      var mapped = [];
      for (var i = 0; i < parts.length; i++) {
        mapped.push(getMapping(parts[i]));
      }
      return mapped.join('-');
    };
  
    var rename;
    if (goog.cssNameMapping_) {
      rename = goog.cssNameMappingStyle_ == 'BY_WHOLE' ?
          getMapping : renameByParts;
    } else {
      rename = function(a) {
        return a;
      };
    }
  
    if (opt_modifier) {
      return className + '-' + rename(opt_modifier);
    } else {
      return rename(className);
    }
  };
  
  
  /**
   * Sets the map to check when returning a value from goog.getCssName(). Example:
   * <pre>
   * goog.setCssNameMapping({
   *   "goog": "a",
   *   "disabled": "b",
   * });
   *
   * var x = goog.getCssName('goog');
   * // The following evaluates to: "a a-b".
   * goog.getCssName('goog') + ' ' + goog.getCssName(x, 'disabled')
   * </pre>
   * When declared as a map of string literals to string literals, the JSCompiler
   * will replace all calls to goog.getCssName() using the supplied map if the
   * --closure_pass flag is set.
   *
   * @param {!Object} mapping A map of strings to strings where keys are possible
   *     arguments to goog.getCssName() and values are the corresponding values
   *     that should be returned.
   * @param {string=} opt_style The style of css name mapping. There are two valid
   *     options: 'BY_PART', and 'BY_WHOLE'.
   * @see goog.getCssName for a description.
   */
  goog.setCssNameMapping = function(mapping, opt_style) {
    goog.cssNameMapping_ = mapping;
    goog.cssNameMappingStyle_ = opt_style;
  };
  
  
  /**
   * To use CSS renaming in compiled mode, one of the input files should have a
   * call to goog.setCssNameMapping() with an object literal that the JSCompiler
   * can extract and use to replace all calls to goog.getCssName(). In uncompiled
   * mode, JavaScript code should be loaded before this base.js file that declares
   * a global variable, CLOSURE_CSS_NAME_MAPPING, which is used below. This is
   * to ensure that the mapping is loaded before any calls to goog.getCssName()
   * are made in uncompiled mode.
   *
   * A hook for overriding the CSS name mapping.
   * @type {Object|undefined}
   */
  goog.global.CLOSURE_CSS_NAME_MAPPING;
  
  
  if (!COMPILED && goog.global.CLOSURE_CSS_NAME_MAPPING) {
    // This does not call goog.setCssNameMapping() because the JSCompiler
    // requires that goog.setCssNameMapping() be called with an object literal.
    goog.cssNameMapping_ = goog.global.CLOSURE_CSS_NAME_MAPPING;
  }
  
  
  /**
   * Gets a localized message.
   *
   * This function is a compiler primitive. If you give the compiler a localized
   * message bundle, it will replace the string at compile-time with a localized
   * version, and expand goog.getMsg call to a concatenated string.
   *
   * Messages must be initialized in the form:
   * <code>
   * var MSG_NAME = goog.getMsg('Hello {$placeholder}', {'placeholder': 'world'});
   * </code>
   *
   * @param {string} str Translatable string, places holders in the form {$foo}.
   * @param {Object=} opt_values Map of place holder name to value.
   * @return {string} message with placeholders filled.
   */
  goog.getMsg = function(str, opt_values) {
    var values = opt_values || {};
    for (var key in values) {
      var value = ('' + values[key]).replace(/\$/g, '$$$$');
      str = str.replace(new RegExp('\\{\\$' + key + '\\}', 'gi'), value);
    }
    return str;
  };
  
  
  /**
   * Gets a localized message. If the message does not have a translation, gives a
   * fallback message.
   *
   * This is useful when introducing a new message that has not yet been
   * translated into all languages.
   *
   * This function is a compiler primtive. Must be used in the form:
   * <code>var x = goog.getMsgWithFallback(MSG_A, MSG_B);</code>
   * where MSG_A and MSG_B were initialized with goog.getMsg.
   *
   * @param {string} a The preferred message.
   * @param {string} b The fallback message.
   * @return {string} The best translated message.
   */
  goog.getMsgWithFallback = function(a, b) {
    return a;
  };
  
  
  /**
   * Exposes an unobfuscated global namespace path for the given object.
   * Note that fields of the exported object *will* be obfuscated,
   * unless they are exported in turn via this function or
   * goog.exportProperty
   *
   * <p>Also handy for making public items that are defined in anonymous
   * closures.
   *
   * ex. goog.exportSymbol('public.path.Foo', Foo);
   *
   * ex. goog.exportSymbol('public.path.Foo.staticFunction',
   *                       Foo.staticFunction);
   *     public.path.Foo.staticFunction();
   *
   * ex. goog.exportSymbol('public.path.Foo.prototype.myMethod',
   *                       Foo.prototype.myMethod);
   *     new public.path.Foo().myMethod();
   *
   * @param {string} publicPath Unobfuscated name to export.
   * @param {*} object Object the name should point to.
   * @param {Object=} opt_objectToExportTo The object to add the path to; default
   *     is |goog.global|.
   */
  goog.exportSymbol = function(publicPath, object, opt_objectToExportTo) {
    goog.exportPath_(publicPath, object, opt_objectToExportTo);
  };
  
  
  /**
   * Exports a property unobfuscated into the object's namespace.
   * ex. goog.exportProperty(Foo, 'staticFunction', Foo.staticFunction);
   * ex. goog.exportProperty(Foo.prototype, 'myMethod', Foo.prototype.myMethod);
   * @param {Object} object Object whose static property is being exported.
   * @param {string} publicName Unobfuscated name to export.
   * @param {*} symbol Object the name should point to.
   */
  goog.exportProperty = function(object, publicName, symbol) {
    object[publicName] = symbol;
  };
  
  
  /**
   * Inherit the prototype methods from one constructor into another.
   *
   * Usage:
   * <pre>
   * function ParentClass(a, b) { }
   * ParentClass.prototype.foo = function(a) { }
   *
   * function ChildClass(a, b, c) {
   *   goog.base(this, a, b);
   * }
   * goog.inherits(ChildClass, ParentClass);
   *
   * var child = new ChildClass('a', 'b', 'see');
   * child.foo(); // works
   * </pre>
   *
   * In addition, a superclass' implementation of a method can be invoked
   * as follows:
   *
   * <pre>
   * ChildClass.prototype.foo = function(a) {
   *   ChildClass.superClass_.foo.call(this, a);
   *   // other code
   * };
   * </pre>
   *
   * @param {Function} childCtor Child class.
   * @param {Function} parentCtor Parent class.
   */
  goog.inherits = function(childCtor, parentCtor) {
    /** @constructor */
    function tempCtor() {};
    tempCtor.prototype = parentCtor.prototype;
    childCtor.superClass_ = parentCtor.prototype;
    childCtor.prototype = new tempCtor();
    /** @override */
    childCtor.prototype.constructor = childCtor;
  };
  
  
  /**
   * Call up to the superclass.
   *
   * If this is called from a constructor, then this calls the superclass
   * contructor with arguments 1-N.
   *
   * If this is called from a prototype method, then you must pass
   * the name of the method as the second argument to this function. If
   * you do not, you will get a runtime error. This calls the superclass'
   * method with arguments 2-N.
   *
   * This function only works if you use goog.inherits to express
   * inheritance relationships between your classes.
   *
   * This function is a compiler primitive. At compile-time, the
   * compiler will do macro expansion to remove a lot of
   * the extra overhead that this function introduces. The compiler
   * will also enforce a lot of the assumptions that this function
   * makes, and treat it as a compiler error if you break them.
   *
   * @param {!Object} me Should always be "this".
   * @param {*=} opt_methodName The method name if calling a super method.
   * @param {...*} var_args The rest of the arguments.
   * @return {*} The return value of the superclass method.
   */
  goog.base = function(me, opt_methodName, var_args) {
    var caller = arguments.callee.caller;
    if (caller.superClass_) {
      // This is a constructor. Call the superclass constructor.
      return caller.superClass_.constructor.apply(
          me, Array.prototype.slice.call(arguments, 1));
    }
  
    var args = Array.prototype.slice.call(arguments, 2);
    var foundCaller = false;
    for (var ctor = me.constructor;
         ctor; ctor = ctor.superClass_ && ctor.superClass_.constructor) {
      if (ctor.prototype[opt_methodName] === caller) {
        foundCaller = true;
      } else if (foundCaller) {
        return ctor.prototype[opt_methodName].apply(me, args);
      }
    }
  
    // If we did not find the caller in the prototype chain,
    // then one of two things happened:
    // 1) The caller is an instance method.
    // 2) This method was not called by the right caller.
    if (me[opt_methodName] === caller) {
      return me.constructor.prototype[opt_methodName].apply(me, args);
    } else {
      throw Error(
          'goog.base called from a method of one name ' +
          'to a method of a different name');
    }
  };
  
  
  /**
   * Allow for aliasing within scope functions.  This function exists for
   * uncompiled code - in compiled code the calls will be inlined and the
   * aliases applied.  In uncompiled code the function is simply run since the
   * aliases as written are valid JavaScript.
   * @param {function()} fn Function to call.  This function can contain aliases
   *     to namespaces (e.g. "var dom = goog.dom") or classes
   *    (e.g. "var Timer = goog.Timer").
   */
  goog.scope = function(fn) {
    fn.call(goog.global);
  };
  
  
  