Implement Google translator support

This might be legally problematic, it's up to site admin whether to
enable this service.

Fixes issue #136

trans/machine/base.py

@@ -83,8 +83,12 @@ class MachineTranslation(object):
 
         # Read and possibly convert response
         text = handle.read()
+        # Needed for Microsoft
         if text.startswith('\xef\xbb\xbf'):
             text = text.decode('UTF-8-sig')
+        # Needed for Google
+        while ',,' in text:
+            text = text.replace(',,', ',null,')
 
         # Parse JSON
         response = json.loads(text)

trans/machine/google.py

+# -*- coding: utf-8 -*-
+#
+# Copyright © 2012 - 2013 Michal Čihař <michal@cihar.com>
+#
+# This file is part of Weblate <http://weblate.org/>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+from trans.machine.base import MachineTranslation
+
+
+class GoogleTranslation(MachineTranslation):
+    '''
+    Google machine translation support.
+    '''
+    name = 'Google'
+
+    def convert_language(self, language):
+        '''
+        Converts language to service specific code.
+        '''
+        return language.replace('_', '-').lower()
+
+    def is_supported(self, language):
+        '''
+        Any language is supported.
+        '''
+        return True
+
+    def download_translations(self, language, text):
+        '''
+        Downloads list of possible translations from a service.
+        '''
+        response = self.json_req(
+            'http://translate.google.com/translate_a/t',
+            client='t',
+            text=text,
+            sl='en',
+            tl=language,
+        )
+
+        return [(response[0][0][0], 100)]

trans/tests/machine.py

@@ -28,6 +28,7 @@ from trans.machine.apertium import ApertiumTranslation
 from trans.machine.microsoft import (
     MicrosoftTranslation, microsoft_translation_supported
 )
+from trans.machine.google import GoogleTranslation
 
 
 class MachineTranslationTest(TestCase):
@@ -71,3 +72,7 @@ class MachineTranslationTest(TestCase):
     def test_microsoft(self):
         machine = MicrosoftTranslation()
         self.assertGreater(len(machine.translate('cs', 'world')), 0)
+
+    def test_google(self):
+        machine = GoogleTranslation()
+        self.assertGreater(len(machine.translate('cs', 'world')), 0)