"""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

lastk = k = None

for item in tmsg.splitlines():

item = item.strip()

if not item:

continue

if ':' in item:

k, v = item.split(':', 1)

k = k.strip().lower()

v = v.strip()

self._info[k] = v

lastk = k

elif lastk:

self._info[lastk] += '\n' + item

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