diff -r 000000000000 -r b97547f5f1fa gettext.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gettext.py	Wed Nov 05 15:52:50 2008 +0100
@@ -0,0 +1,492 @@
+"""Internationalization and localization support.
+
+This module provides internationalization (I18N) and localization (L10N)
+support for your Python programs by providing an interface to the GNU gettext
+message catalog library.
+
+I18N refers to the operation by which a program is made aware of multiple
+languages.  L10N refers to the adaptation of your program, once
+internationalized, to the local language and cultural habits.
+
+"""
+
+# This module represents the integration of work, contributions, feedback, and
+# suggestions from the following people:
+#
+# Martin von Loewis, who wrote the initial implementation of the underlying
+# C-based libintlmodule (later renamed _gettext), along with a skeletal
+# gettext.py implementation.
+#
+# Peter Funk, who wrote fintl.py, a fairly complete wrapper around intlmodule,
+# which also included a pure-Python implementation to read .mo files if
+# intlmodule wasn't available.
+#
+# James Henstridge, who also wrote a gettext.py module, which has some
+# interesting, but currently unsupported experimental features: the notion of
+# a Catalog class and instances, and the ability to add to a catalog file via
+# a Python API.
+#
+# Barry Warsaw integrated these modules, wrote the .install() API and code,
+# and conformed all C and Python code to Python's coding standards.
+#
+# Francois Pinard and Marc-Andre Lemburg also contributed valuably to this
+# module.
+#
+# J. David Ibanez implemented plural forms. Bruno Haible fixed some bugs.
+#
+# TODO:
+# - Lazy loading of .mo files.  Currently the entire catalog is loaded into
+#   memory, but that's probably bad for large translated programs.  Instead,
+#   the lexical sort of original strings in GNU .mo files should be exploited
+#   to do binary searches and lazy initializations.  Or you might want to use
+#   the undocumented double-hash algorithm for .mo files with hash tables, but
+#   you'll need to study the GNU gettext code to do this.
+#
+# - Support Solaris .mo file formats.  Unfortunately, we've been unable to
+#   find this format documented anywhere.
+
+
+import copy, os, re, struct, sys
+from errno import ENOENT
+
+
+__all__ = ['NullTranslations', 'GNUTranslations', 'Catalog',
+           'find', 'translation', 'install', 'textdomain', 'bindtextdomain',
+           'dgettext', 'dngettext', 'gettext', 'ngettext',
+           ]
+
+_default_localedir = os.path.join(sys.prefix, 'share', 'locale')
+
+
+def test(condition, true, false):
+    """
+    Implements the C expression:
+
+      condition ? true : false
+
+    Required to correctly interpret plural forms.
+    """
+    if condition:
+        return true
+    else:
+        return false
+
+
+def c2py(plural):
+    """Gets a C expression as used in PO files for plural forms and returns a
+    Python lambda function that implements an equivalent expression.
+    """
+    # Security check, allow only the "n" identifier
+    from StringIO import StringIO
+    import token, tokenize
+    tokens = tokenize.generate_tokens(StringIO(plural).readline)
+    try:
+        danger = [x for x in tokens if x[0] == token.NAME and x[1] != 'n']
+    except tokenize.TokenError:
+        raise ValueError, \
+              'plural forms expression error, maybe unbalanced parenthesis'
+    else:
+        if danger:
+            raise ValueError, 'plural forms expression could be dangerous'
+
+    # Replace some C operators by their Python equivalents
+    plural = plural.replace('&&', ' and ')
+    plural = plural.replace('||', ' or ')
+
+    expr = re.compile(r'\!([^=])')
+    plural = expr.sub(' not \\1', plural)
+
+    # Regular expression and replacement function used to transform
+    # "a?b:c" to "test(a,b,c)".
+    expr = re.compile(r'(.*?)\?(.*?):(.*)')
+    def repl(x):
+        return "test(%s, %s, %s)" % (x.group(1), x.group(2),
+                                     expr.sub(repl, x.group(3)))
+
+    # Code to transform the plural expression, taking care of parentheses
+    stack = ['']
+    for c in plural:
+        if c == '(':
+            stack.append('')
+        elif c == ')':
+            if len(stack) == 1:
+                # Actually, we never reach this code, because unbalanced
+                # parentheses get caught in the security check at the
+                # beginning.
+                raise ValueError, 'unbalanced parenthesis in plural form'
+            s = expr.sub(repl, stack.pop())
+            stack[-1] += '(%s)' % s
+        else:
+            stack[-1] += c
+    plural = expr.sub(repl, stack.pop())
+
+    return eval('lambda n: int(%s)' % plural)
+
+
+
+def _expand_lang(locale):
+    from locale import normalize
+    locale = normalize(locale)
+    COMPONENT_CODESET   = 1 << 0
+    COMPONENT_TERRITORY = 1 << 1
+    COMPONENT_MODIFIER  = 1 << 2
+    # split up the locale into its base components
+    mask = 0
+    pos = locale.find('@')
+    if pos >= 0:
+        modifier = locale[pos:]
+        locale = locale[:pos]
+        mask |= COMPONENT_MODIFIER
+    else:
+        modifier = ''
+    pos = locale.find('.')
+    if pos >= 0:
+        codeset = locale[pos:]
+        locale = locale[:pos]
+        mask |= COMPONENT_CODESET
+    else:
+        codeset = ''
+    pos = locale.find('_')
+    if pos >= 0:
+        territory = locale[pos:]
+        locale = locale[:pos]
+        mask |= COMPONENT_TERRITORY
+    else:
+        territory = ''
+    language = locale
+    ret = []
+    for i in range(mask+1):
+        if not (i & ~mask):  # if all components for this combo exist ...
+            val = language
+            if i & COMPONENT_TERRITORY: val += territory
+            if i & COMPONENT_CODESET:   val += codeset
+            if i & COMPONENT_MODIFIER:  val += modifier
+            ret.append(val)
+    ret.reverse()
+    return ret
+
+
+
+class NullTranslations:
+    def __init__(self, fp=None):
+        self._info = {}
+        self._charset = None
+        self._fallback = None
+        if fp is not None:
+            self._parse(fp)
+
+    def _parse(self, fp):
+        pass
+
+    def add_fallback(self, fallback):
+        if self._fallback:
+            self._fallback.add_fallback(fallback)
+        else:
+            self._fallback = fallback
+
+    def gettext(self, message):
+        if self._fallback:
+            return self._fallback.gettext(message)
+        return message
+
+    def ngettext(self, msgid1, msgid2, n):
+        if self._fallback:
+            return self._fallback.ngettext(msgid1, msgid2, n)
+        if n == 1:
+            return msgid1
+        else:
+            return msgid2
+
+    def ugettext(self, message):
+        if self._fallback:
+            return self._fallback.ugettext(message)
+        return unicode(message)
+
+    def ungettext(self, msgid1, msgid2, n):
+        if self._fallback:
+            return self._fallback.ungettext(msgid1, msgid2, n)
+        if n == 1:
+            return unicode(msgid1)
+        else:
+            return unicode(msgid2)
+
+    def info(self):
+        return self._info
+
+    def charset(self):
+        return self._charset
+
+    def install(self, unicode=False):
+        import __builtin__
+        __builtin__.__dict__['_'] = unicode and self.ugettext or self.gettext
+
+
+class GNUTranslations(NullTranslations):
+    # Magic number of .mo files
+    LE_MAGIC = 0x950412deL
+    BE_MAGIC = 0xde120495L
+
+    def _parse(self, fp):
+        """Override this method to support alternative .mo formats."""
+        unpack = struct.unpack
+        filename = getattr(fp, 'name', '')
+        # Parse the .mo file header, which consists of 5 little endian 32
+        # bit words.
+        self._catalog = catalog = {}
+        self.plural = lambda n: int(n != 1) # germanic plural by default
+        buf = fp.read()
+        buflen = len(buf)
+        # Are we big endian or little endian?
+        magic = unpack('<I', buf[:4])[0]
+        if magic == self.LE_MAGIC:
+            version, msgcount, masteridx, transidx = unpack('<4I', buf[4:20])
+            ii = '<II'
+        elif magic == self.BE_MAGIC:
+            version, msgcount, masteridx, transidx = unpack('>4I', buf[4:20])
+            ii = '>II'
+        else:
+            raise IOError(0, 'Bad magic number', filename)
+        # Now put all messages from the .mo file buffer into the catalog
+        # dictionary.
+        for i in xrange(0, msgcount):
+            mlen, moff = unpack(ii, buf[masteridx:masteridx+8])
+            mend = moff + mlen
+            tlen, toff = unpack(ii, buf[transidx:transidx+8])
+            tend = toff + tlen
+            if mend < buflen and tend < buflen:
+                msg = buf[moff:mend]
+                tmsg = buf[toff:tend]
+            else:
+                raise IOError(0, 'File is corrupt', filename)
+            # See if we're looking at GNU .mo conventions for metadata
+            if mlen == 0:
+                # Catalog description
+                # don't handle multi-lines fields here, and skip
+                # lines which don't look like a header description
+                # (e.g. "header: value")
+                lastk = k = None
+                for item in tmsg.splitlines():
+                    item = item.strip()
+                    if not item or not ':' in item:
+                        continue
+                    k, v = item.split(':', 1)
+                    k = k.strip().lower()
+                    v = v.strip()
+                    self._info[k] = v
+                    if k == 'content-type':
+                        self._charset = v.split('charset=')[1]
+                    elif k == 'plural-forms':
+                        v = v.split(';')
+                        plural = v[1].split('plural=')[1]
+                        self.plural = c2py(plural)
+            # Note: we unconditionally convert both msgids and msgstrs to
+            # Unicode using the character encoding specified in the charset
+            # parameter of the Content-Type header.  The gettext documentation
+            # strongly encourages msgids to be us-ascii, but some appliations
+            # require alternative encodings (e.g. Zope's ZCML and ZPT).  For
+            # traditional gettext applications, the msgid conversion will
+            # cause no problems since us-ascii should always be a subset of
+            # the charset encoding.  We may want to fall back to 8-bit msgids
+            # if the Unicode conversion fails.
+            if msg.find('\x00') >= 0:
+                # Plural forms
+                msgid1, msgid2 = msg.split('\x00')
+                tmsg = tmsg.split('\x00')
+                if self._charset:
+                    msgid1 = unicode(msgid1, self._charset)
+                    tmsg = [unicode(x, self._charset) for x in tmsg]
+                for i in range(len(tmsg)):
+                    catalog[(msgid1, i)] = tmsg[i]
+            else:
+                if self._charset:
+                    msg = unicode(msg, self._charset)
+                    tmsg = unicode(tmsg, self._charset)
+                catalog[msg] = tmsg
+            # advance to next entry in the seek tables
+            masteridx += 8
+            transidx += 8
+
+    def gettext(self, message):
+        missing = object()
+        tmsg = self._catalog.get(message, missing)
+        if tmsg is missing:
+            if self._fallback:
+                return self._fallback.gettext(message)
+            return message
+        # Encode the Unicode tmsg back to an 8-bit string, if possible
+        if self._charset:
+            return tmsg.encode(self._charset)
+        return tmsg
+
+    def ngettext(self, msgid1, msgid2, n):
+        try:
+            tmsg = self._catalog[(msgid1, self.plural(n))]
+            if self._charset:
+                return tmsg.encode(self._charset)
+            return tmsg
+        except KeyError:
+            if self._fallback:
+                return self._fallback.ngettext(msgid1, msgid2, n)
+            if n == 1:
+                return msgid1
+            else:
+                return msgid2
+
+    def ugettext(self, message):
+        missing = object()
+        tmsg = self._catalog.get(message, missing)
+        if tmsg is missing:
+            if self._fallback:
+                return self._fallback.ugettext(message)
+            return unicode(message)
+        return tmsg
+
+    def ungettext(self, msgid1, msgid2, n):
+        try:
+            tmsg = self._catalog[(msgid1, self.plural(n))]
+        except KeyError:
+            if self._fallback:
+                return self._fallback.ungettext(msgid1, msgid2, n)
+            if n == 1:
+                tmsg = unicode(msgid1)
+            else:
+                tmsg = unicode(msgid2)
+        return tmsg
+
+
+# Locate a .mo file using the gettext strategy
+def find(domain, localedir=None, languages=None, all=0):
+    # Get some reasonable defaults for arguments that were not supplied
+    if localedir is None:
+        localedir = _default_localedir
+    if languages is None:
+        languages = []
+        for envar in ('LANGUAGE', 'LC_ALL', 'LC_MESSAGES', 'LANG'):
+            val = os.environ.get(envar)
+            if val:
+                languages = val.split(':')
+                break
+        if 'C' not in languages:
+            languages.append('C')
+    # now normalize and expand the languages
+    nelangs = []
+    for lang in languages:
+        for nelang in _expand_lang(lang):
+            if nelang not in nelangs:
+                nelangs.append(nelang)
+    # select a language
+    if all:
+        result = []
+    else:
+        result = None
+    for lang in nelangs:
+        if lang == 'C':
+            break
+        mofile = os.path.join(localedir, lang, 'LC_MESSAGES', '%s.mo' % domain)
+        if os.path.exists(mofile):
+            if all:
+                result.append(mofile)
+            else:
+                return mofile
+    return result
+
+
+
+# a mapping between absolute .mo file path and Translation object
+_translations = {}
+
+def translation(domain, localedir=None, languages=None,
+                class_=None, fallback=False):
+    if class_ is None:
+        class_ = GNUTranslations
+    mofiles = find(domain, localedir, languages, all=1)
+    if not mofiles:
+        if fallback:
+            return NullTranslations()
+        raise IOError(ENOENT, 'No translation file found for domain', domain)
+    # TBD: do we need to worry about the file pointer getting collected?
+    # Avoid opening, reading, and parsing the .mo file after it's been done
+    # once.
+    result = None
+    for mofile in mofiles:
+        key = os.path.abspath(mofile)
+        t = _translations.get(key)
+        if t is None:
+            t = _translations.setdefault(key, class_(open(mofile, 'rb')))
+        # Copy the translation object to allow setting fallbacks.
+        # All other instance data is shared with the cached object.
+        t = copy.copy(t)
+        if result is None:
+            result = t
+        else:
+            result.add_fallback(t)
+    return result
+
+
+def install(domain, localedir=None, unicode=False):
+    translation(domain, localedir, fallback=True).install(unicode)
+
+
+
+# a mapping b/w domains and locale directories
+_localedirs = {}
+# current global domain, `messages' used for compatibility w/ GNU gettext
+_current_domain = 'messages'
+
+
+def textdomain(domain=None):
+    global _current_domain
+    if domain is not None:
+        _current_domain = domain
+    return _current_domain
+
+
+def bindtextdomain(domain, localedir=None):
+    global _localedirs
+    if localedir is not None:
+        _localedirs[domain] = localedir
+    return _localedirs.get(domain, _default_localedir)
+
+
+def dgettext(domain, message):
+    try:
+        t = translation(domain, _localedirs.get(domain, None))
+    except IOError:
+        return message
+    return t.gettext(message)
+
+
+def dngettext(domain, msgid1, msgid2, n):
+    try:
+        t = translation(domain, _localedirs.get(domain, None))
+    except IOError:
+        if n == 1:
+            return msgid1
+        else:
+            return msgid2
+    return t.ngettext(msgid1, msgid2, n)
+
+
+def gettext(message):
+    return dgettext(_current_domain, message)
+
+
+def ngettext(msgid1, msgid2, n):
+    return dngettext(_current_domain, msgid1, msgid2, n)
+
+
+# dcgettext() has been deemed unnecessary and is not implemented.
+
+# James Henstridge's Catalog constructor from GNOME gettext.  Documented usage
+# was:
+#
+#    import gettext
+#    cat = gettext.Catalog(PACKAGE, localedir=LOCALEDIR)
+#    _ = cat.gettext
+#    print _('Hello World')
+
+# The resulting catalog object currently don't support access through a
+# dictionary API, which was supported (but apparently unused) in GNOME
+# gettext.
+
+Catalog = translation