Initial source commit to grit-i18n project.

grit/xtb_reader.py

+#!/usr/bin/python2.4
+# Copyright (c) 2006-2008 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.
+
+'''Fast and efficient parser for XTB files.
+'''
+
+
+import sys
+import xml.sax
+import xml.sax.handler
+
+
+class XtbContentHandler(xml.sax.handler.ContentHandler):
+  '''A content handler that calls a given callback function for each
+  translation in the XTB file.
+  '''
+
+  def __init__(self, callback, defs=None, debug=False):
+    self.callback = callback
+    self.debug = debug
+    # 0 if we are not currently parsing a translation, otherwise the message
+    # ID of that translation.
+    self.current_id = 0
+    # Empty if we are not currently parsing a translation, otherwise the
+    # parts we have for that translation - a list of tuples
+    # (is_placeholder, text)
+    self.current_structure = []
+    # Set to the language ID when we see the <translationbundle> node.
+    self.language = ''
+    # Keep track of the if block we're inside.  We can't nest ifs.
+    self.if_expr = None
+    # Root defines to be used with if expr.
+    if defs:
+      self.defines = defs
+    else:
+      self.defines = {}
+
+  def startElement(self, name, attrs):
+    if name == 'translation':
+      assert self.current_id == 0 and len(self.current_structure) == 0, (
+              "Didn't expect a <translation> element here.")
+      self.current_id = attrs.getValue('id')
+    elif name == 'ph':
+      assert self.current_id != 0, "Didn't expect a <ph> element here."
+      self.current_structure.append((True, attrs.getValue('name')))
+    elif name == 'translationbundle':
+      self.language = attrs.getValue('lang')
+    elif name == 'if':
+      assert self.if_expr is None, "Can't nest <if> in xtb files"
+      self.if_expr = attrs.getValue('expr')
+
+  def endElement(self, name):
+    if name == 'translation':
+      assert self.current_id != 0
+
+      defs = self.defines
+      def pp_ifdef(define):
+        return define in defs
+      def pp_if(define):
+        return define in defs and defs[define]
+
+      # If we're in an if block, only call the callback (add the translation)
+      # if the expression is True.
+      should_run_callback = True
+      if self.if_expr:
+        should_run_callback = eval(self.if_expr, {},
+                                   {'os': sys.platform,
+                                    'defs' : defs,
+                                    'pp_ifdef' : pp_ifdef,
+                                    'pp_if' : pp_if})
+      if should_run_callback:
+        self.callback(self.current_id, self.current_structure)
+
+      self.current_id = 0
+      self.current_structure = []
+    elif name == 'if':
+      assert self.if_expr is not None
+      self.if_expr = None
+
+  def characters(self, content):
+    if self.current_id != 0:
+      # We are inside a <translation> node so just add the characters to our
+      # structure.
+      #
+      # This naive way of handling characters is OK because in the XTB format,
+      # <ph> nodes are always empty (always <ph name="XXX"/>) and whitespace
+      # inside the <translation> node should be preserved.
+      self.current_structure.append((False, content))
+
+
+class XtbErrorHandler(xml.sax.handler.ErrorHandler):
+  def error(self, exception):
+    pass
+
+  def fatalError(self, exception):
+    raise exception
+
+  def warning(self, exception):
+    pass
+
+
+def Parse(xtb_file, callback_function, defs={}, debug=False):
+  '''Parse xtb_file, making a call to callback_function for every translation
+  in the XTB file.
+
+  The callback function must have the signature as described below.  The 'parts'
+  parameter is a list of tuples (is_placeholder, text).  The 'text' part is
+  either the raw text (if is_placeholder is False) or the name of the placeholder
+  (if is_placeholder is True).
+
+  Args:
+    xtb_file:           file('fr.xtb')
+    callback_function:  def Callback(msg_id, parts): pass
+
+  Return:
+    The language of the XTB, e.g. 'fr'
+  '''
+  # Start by advancing the file pointer past the DOCTYPE thing, as the TC
+  # uses a path to the DTD that only works in Unix.
+  # TODO(joi) Remove this ugly hack by getting the TC gang to change the
+  # XTB files somehow?
+  front_of_file = xtb_file.read(1024)
+  xtb_file.seek(front_of_file.find('<translationbundle'))
+
+  handler = XtbContentHandler(callback=callback_function, defs=defs,
+                              debug=debug)
+  xml.sax.parse(xtb_file, handler)
+  assert handler.language != ''
+  return handler.language
+