Bug 971054 - Part 2. BingTranslator engine. r=florian

browser/components/translation/BingTranslator.jsm

@@ -0,0 +1,189 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
+
+this.EXPORTED_SYMBOLS = [ "BingTranslation" ];
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/Log.jsm");
+Cu.import("resource://gre/modules/Promise.jsm");
+Cu.import("resource://gre/modules/Task.jsm");
+Cu.import("resource://services-common/utils.js");
+
+// The maximum amount of net data allowed per request on Bing's API.
+const MAX_REQUEST_DATA = 5000; // Documentation says 10000 but anywhere
+                               // close to that is refused by the service.
+
+// The maximum number of chunks allowed to be translated in a single
+// request.
+const MAX_REQUEST_CHUNKS = 1000; // Documentation says 2000.
+
+// Self-imposed limit of 15 requests. This means that a page that would need
+// to be broken in more than 15 requests won't be fully translated.
+// The maximum amount of data that we will translate for a single page
+// is MAX_REQUESTS * MAX_REQUEST_DATA.
+const MAX_REQUESTS = 15;
+
+/**
+ * Translates a webpage using Bing's Translation API.
+ *
+ * @param translationDocument  The TranslationDocument object that represents
+ *                             the webpage to be translated
+ * @param sourceLanguage       The source language of the document
+ * @param targetLanguage       The target language for the translation
+ *
+ * @returns {Promise}          A promise that will resolve when the translation
+ *                             task is finished.
+ */
+this.BingTranslation = function(translationDocument, sourceLanguage, targetLanguage) {
+  this.translationDocument = translationDocument;
+  this.sourceLanguage = sourceLanguage;
+  this.targetLanguage = targetLanguage;
+  this._pendingRequests = 0;
+  this._partialSuccess = false;
+};
+
+this.BingTranslation.prototype = {
+  /**
+   * Performs the translation, splitting the document into several chunks
+   * respecting the data limits of the API.
+   *
+   * @returns {Promise}          A promise that will resolve when the translation
+   *                             task is finished.
+   */
+  translate: function() {
+    return Task.spawn(function *() {
+      let currentIndex = 0;
+      this._onFinishedDeferred = Promise.defer();
+
+      // Let's split the document into various requests to be sent to
+      // Bing's Translation API.
+      for (let requestCount = 0; requestCount < MAX_REQUESTS; requestCount++) {
+        // Generating the text for each request can be expensive, so
+        // let's take the opportunity of the chunkification process to
+        // allow for the event loop to attend other pending events
+        // before we continue.
+        yield CommonUtils.laterTickResolvingPromise();
+
+        // Determine the data for the next request.
+        let request = this._generateNextTranslationRequest(currentIndex);
+
+        // Create a real request to the server, and put it on the
+        // pending requests list.
+        let bingRequest = new BingRequest(request.data,
+                                          this.sourceLanguage,
+                                          this.targetLanguage);
+        this._pendingRequests++;
+        bingRequest.fireRequest().then(this._chunkCompleted.bind(this));
+
+        currentIndex = request.lastIndex;
+        if (request.finished) {
+          break;
+        }
+      }
+
+      return this._onFinishedDeferred.promise;
+    }.bind(this));
+  },
+
+  /**
+   * Function called when a request sent to the server is completed.
+   * This function handles determining if the response was successful or not,
+   * calling the function to parse the result, and resolving the promise
+   * returned by the public `translate()` method when all chunks are completed.
+   *
+   * @param   request   The BingRequest sent to the server.
+   */
+  _chunkCompleted: function(bingRequest) {
+     this._pendingRequests--;
+     if (bingRequest.requestSucceeded &&
+         this._parseChunkResult(bingRequest)) {
+       // error on request
+       this._partialSuccess = true;
+     }
+
+    // Check if all pending requests have been
+    // completed and then resolves the promise.
+    // If at least one chunk was successful, the
+    // promise will be resolved positively which will
+    // display the "Success" state for the infobar. Otherwise,
+    // the "Error" state will appear.
+    if (this._pendingRequests == 0) {
+      if (this._partialSuccess) {
+        this._onFinishedDeferred.resolve("success");
+      } else {
+        this._onFinishedDeferred.reject("failure");
+      }
+    }
+  },
+
+  _parseChunkResult() {
+    // note: this function is implemented in the patch from bug 976556
+  },
+
+  /**
+   * This function will determine what is the data to be used for
+   * the Nth request we are generating, based on the input params.
+   *
+   * @param startIndex What is the index, in the roots list, that the
+   *                   chunk should start.
+   */
+  _generateNextTranslationRequest: function(startIndex) {
+    let currentDataSize = 0;
+    let currentChunks = 0;
+    let output = [];
+    let rootsList = this.translationDocument.roots;
+
+    for (let i = startIndex; i < rootsList.length; i++) {
+      let root = rootsList[i];
+      let text = this.translationDocument.generateTextForItem(root);
+      if (!text) {
+        continue;
+      }
+
+      text = escapeXML(text);
+      let newCurSize = currentDataSize + text.length;
+      let newChunks = currentChunks + 1;
+
+      if (newCurSize > MAX_REQUEST_DATA ||
+          newChunks > MAX_REQUEST_CHUNKS) {
+
+        // If we've reached the API limits, let's stop accumulating data
+        // for this request and return. We return information useful for
+        // the caller to pass back on the next call, so that the function
+        // can keep working from where it stopped.
+        return {
+          data: output,
+          finished: false,
+          lastIndex: i
+        };
+      }
+
+      currentDataSize = newCurSize;
+      currentChunks = newChunks;
+      output.push([root, text]);
+    }
+
+    return {
+      data: output,
+      finished: true,
+      lastIndex: 0
+    };
+  }
+};
+
+/**
+ * Escape a string to be valid XML content.
+ */
+function escapeXML(aStr) {
+  return aStr.toString()
+             .replace("&", "&amp;", "g")
+             .replace('"', "&quot;", "g")
+             .replace("'", "&apos;", "g")
+             .replace("<", "&lt;", "g")
+             .replace(">", "&gt;", "g");
+}

browser/components/translation/moz.build

@@ -5,6 +5,7 @@
 JS_MODULES_PATH = 'modules/translation'
 
 EXTRA_JS_MODULES = [
+    'BingTranslator.jsm',
     'cld2/cld-worker.js',
     'cld2/cld-worker.js.mem',
     'LanguageDetector.jsm',