[Files.app] Split the JavaScript files into subdirectories: common, background, and foreground

chrome/browser/resources/file_manager/js/metadata/metadata_dispatcher.js

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-'use strict';
-
-// All of these scripts could be imported with a single call to importScripts,
-// but then load and compile time errors would all be reported from the same
-// line.
-importScripts('metadata_parser.js');
-importScripts('byte_reader.js');
-importScripts('../util.js');
-
-/**
- * Dispatches metadata requests to the correct parser.
- *
- * @param {Object} port Worker port.
- * @constructor
- */
-function MetadataDispatcher(port) {
-  this.port_ = port;
-  this.port_.onmessage = this.onMessage.bind(this);
-
-  // Make sure to update component_extension_resources.grd
-  // when adding new parsers.
-  importScripts('exif_parser.js');
-  importScripts('image_parsers.js');
-  importScripts('mpeg_parser.js');
-  importScripts('id3_parser.js');
-
-  var patterns = [];
-
-  this.parserInstances_ = [];
-  for (var i = 0; i < MetadataDispatcher.parserClasses_.length; i++) {
-    var parserClass = MetadataDispatcher.parserClasses_[i];
-    var parser = new parserClass(this);
-    this.parserInstances_.push(parser);
-    patterns.push(parser.urlFilter.source);
-  }
-
-  this.parserRegexp_ = new RegExp('(' + patterns.join('|') + ')', 'i');
-
-  this.messageHandlers_ = {
-    init: this.init_.bind(this),
-    request: this.request_.bind(this)
-  };
-}
-
-/**
- * List of registered parser classes.
- * @private
- */
-MetadataDispatcher.parserClasses_ = [];
-
-/**
- * @param {function} parserClass Parser constructor function.
- */
-MetadataDispatcher.registerParserClass = function(parserClass) {
-  MetadataDispatcher.parserClasses_.push(parserClass);
-};
-
-/**
- * Verbose logging for the dispatcher.
- *
- * Individual parsers also take this as their default verbosity setting.
- */
-MetadataDispatcher.prototype.verbose = false;
-
-/**
- * |init| message handler.
- * @private
- */
-MetadataDispatcher.prototype.init_ = function() {
-  // Inform our owner that we're done initializing.
-  // If we need to pass more data back, we can add it to the param array.
-  this.postMessage('initialized', [this.parserRegexp_]);
-  this.log('initialized with URL filter ' + this.parserRegexp_);
-};
-
-/**
- * |request| message handler.
- * @param {string} fileURL File URL.
- * @private
- */
-MetadataDispatcher.prototype.request_ = function(fileURL) {
-  try {
-    this.processOneFile(fileURL, function callback(metadata) {
-        this.postMessage('result', [fileURL, metadata]);
-    }.bind(this));
-  } catch (ex) {
-    this.error(fileURL, ex);
-  }
-};
-
-/**
- * Indicate to the caller that an operation has failed.
- *
- * No other messages relating to the failed operation should be sent.
- * @param {...Object} var_args Arguments.
- */
-MetadataDispatcher.prototype.error = function(var_args) {
-  var ary = Array.apply(null, arguments);
-  this.postMessage('error', ary);
-};
-
-/**
- * Send a log message to the caller.
- *
- * Callers must not parse log messages for control flow.
- * @param {...Object} var_args Arguments.
- */
-MetadataDispatcher.prototype.log = function(var_args) {
-  var ary = Array.apply(null, arguments);
-  this.postMessage('log', ary);
-};
-
-/**
- * Send a log message to the caller only if this.verbose is true.
- * @param {...Object} var_args Arguments.
- */
-MetadataDispatcher.prototype.vlog = function(var_args) {
-  if (this.verbose)
-    this.log.apply(this, arguments);
-};
-
-/**
- * Post a properly formatted message to the caller.
- * @param {string} verb Message type descriptor.
- * @param {Array.<Object>} args Arguments array.
- */
-MetadataDispatcher.prototype.postMessage = function(verb, args) {
-  this.port_.postMessage({verb: verb, arguments: args});
-};
-
-/**
- * Message handler.
- * @param {Event} event Event object.
- */
-MetadataDispatcher.prototype.onMessage = function(event) {
-  var data = event.data;
-
-  if (this.messageHandlers_.hasOwnProperty(data.verb)) {
-    this.messageHandlers_[data.verb].apply(this, data.arguments);
-  } else {
-    this.log('Unknown message from client: ' + data.verb, data);
-  }
-};
-
-/**
- * @param {string} fileURL File URL.
- * @param {function(Object)} callback Completion callback.
- */
-MetadataDispatcher.prototype.processOneFile = function(fileURL, callback) {
-  var self = this;
-  var currentStep = -1;
-
-  function nextStep(var_args) {
-    self.vlog('nextStep: ' + steps[currentStep + 1].name);
-    steps[++currentStep].apply(self, arguments);
-  }
-
-  var metadata;
-
-  function onError(err, stepName) {
-    self.error(fileURL, stepName || steps[currentStep].name, err.toString(),
-        metadata);
-  }
-
-  var steps =
-  [ // Step one, find the parser matching the url.
-    function detectFormat() {
-      for (var i = 0; i != self.parserInstances_.length; i++) {
-        var parser = self.parserInstances_[i];
-        if (fileURL.match(parser.urlFilter)) {
-          // Create the metadata object as early as possible so that we can
-          // pass it with the error message.
-          metadata = parser.createDefaultMetadata();
-          nextStep(parser);
-          return;
-        }
-      }
-      onError('unsupported format');
-    },
-
-    // Step two, turn the url into an entry.
-    function getEntry(parser) {
-      webkitResolveLocalFileSystemURL(
-          fileURL,
-          function(entry) { nextStep(entry, parser) },
-          onError);
-    },
-
-    // Step three, turn the entry into a file.
-    function getFile(entry, parser) {
-      entry.file(function(file) { nextStep(file, parser) }, onError);
-    },
-
-    // Step four, parse the file content.
-    function parseContent(file, parser) {
-      metadata.fileSize = file.size;
-      try {
-        parser.parse(file, metadata, callback, onError);
-      } catch (e) {
-        onError(e.stack);
-      }
-    }
-  ];
-
-  nextStep();
-};
-
-// Webworker spec says that the worker global object is called self.  That's
-// a terrible name since we use it all over the chrome codebase to capture
-// the 'this' keyword in lambdas.
-var global = self;
-
-if (global.constructor.name == 'SharedWorkerGlobalScope') {
-  global.addEventListener('connect', function(e) {
-    var port = e.ports[0];
-    new MetadataDispatcher(port);
-    port.start();
-  });
-} else {
-  // Non-shared worker.
-  new MetadataDispatcher(global);
-}