Initial source commit to grit-i18n project.

grit/pseudo_rtl.py

+#!/usr/bin/python
+# Copyright (c) 2011 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.
+
+'''Pseudo RTL, (aka Fake Bidi) support. It simply wraps each word with
+Unicode RTL overrides.
+More info at https://sites.google.com/a/chromium.org/dev/Home/fake-bidi
+'''
+
+import re
+import types
+
+from grit import tclib
+
+ACCENTED_STRINGS = {
+  'a': u"\u00e5", 'e': u"\u00e9", 'i': u"\u00ee", 'o': u"\u00f6",
+  'u': u"\u00fb", 'A': u"\u00c5", 'E': u"\u00c9", 'I': u"\u00ce",
+  'O': u"\u00d6", 'U': u"\u00db", 'c': u"\u00e7", 'd': u"\u00f0",
+  'n': u"\u00f1", 'p': u"\u00fe", 'y': u"\u00fd", 'C': u"\u00c7",
+  'D': u"\u00d0", 'N': u"\u00d1", 'P': u"\u00de", 'Y': u"\u00dd",
+  'f': u"\u0192", 's': u"\u0161", 'S': u"\u0160", 'z': u"\u017e",
+  'Z': u"\u017d", 'g': u"\u011d", 'G': u"\u011c", 'h': u"\u0125",
+  'H': u"\u0124", 'j': u"\u0135", 'J': u"\u0134", 'k': u"\u0137",
+  'K': u"\u0136", 'l': u"\u013c", 'L': u"\u013b", 't': u"\u0163",
+  'T': u"\u0162", 'w': u"\u0175", 'W': u"\u0174",
+  '$': u"\u20ac", '?': u"\u00bf", 'R': u"\u00ae", r'!': u"\u00a1",
+}
+
+# a character set containing the keys in ACCENTED_STRINGS
+# We should not accent characters in an escape sequence such as "\n".
+# To be safe, we assume every character following a backslash is an escaped
+# character. We also need to consider the case like "\\n", which means
+# a blackslash and a character "n", we will accent the character "n".
+TO_ACCENT = re.compile(r'[%s]|\\[a-z\\]' % ''.join(ACCENTED_STRINGS.keys()))
+
+# Lex text so that we don't interfere with html tokens and entities.
+# This lexing scheme will handle all well formed tags and entities, html or
+# xhtml.  It will not handle comments, CDATA sections, or the unescaping tags:
+# script, style, xmp or listing.  If any of those appear in messages,
+# something is wrong.
+TOKENS = [ re.compile(
+                      '^%s' % pattern,  # match at the beginning of input
+                      re.I | re.S  # html tokens are case-insensitive
+                      )
+           for pattern in
+           (
+            # a run of non html special characters
+            r'[^<&]+',
+            # a tag
+            (r'</?[a-z]\w*' # beginning of tag
+             r'(?:\s+\w+(?:\s*=\s*' # attribute start
+             r'(?:[^\s"\'>]+|"[^\"]*"|\'[^\']*\'))?' # attribute value
+             r')*\s*/?>'),
+            # an entity
+            r'&(?:[a-z]\w+|#\d+|#x[\da-f]+);',
+            # an html special character not part of a special sequence
+            r'.'
+           ) ]
+
+ALPHABETIC_RUN = re.compile(r'([^\W0-9_]+)')
+
+RLO = u'\u202e'
+PDF = u'\u202c'
+
+def PseudoRTLString(text):
+  '''Returns a fake bidirectional version of the source string. This code is
+    based on accentString above, in turn copied from Frank Tang.
+    '''
+  parts = []
+  while text:
+    m = None
+    for token in TOKENS:
+      m = token.search(text)
+      if m:
+        part = m.group(0)
+        text = text[len(part):]
+        if part[0] not in ('<', '&'):
+          # not a tag or entity, so accent
+          part = ALPHABETIC_RUN.sub(lambda run: RLO + run.group() + PDF, part)
+        parts.append(part)
+        break
+  return ''.join(parts)
+
+
+def PseudoRTLMessage(message):
+  '''Returns a pseudo-RTL (aka Fake-Bidi) translation of the provided message.
+
+  Args:
+    message: tclib.Message()
+
+  Return:
+    tclib.Translation()
+  '''
+  transl = tclib.Translation()
+  for part in message.GetContent():
+    if isinstance(part, tclib.Placeholder):
+      transl.AppendPlaceholder(part)
+    else:
+      transl.AppendText(PseudoRTLString(part))
+
+  return transl