mirror of https://github.com/python/cpython.git
319 lines
10 KiB
Python
319 lines
10 KiB
Python
"""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. In order to
|
||
provide multilingual messages for your Python programs, you need to take the
|
||
following steps:
|
||
|
||
- prepare your program by specially marking translatable strings
|
||
- run a suite of tools over your marked program files to generate raw
|
||
messages catalogs
|
||
- create language specific translations of the message catalogs
|
||
- use this module so that message strings are properly translated
|
||
|
||
In order to prepare your program for I18N, you need to look at all the strings
|
||
in your program. Any string that needs to be translated should be marked by
|
||
wrapping it in _('...') -- i.e. a call to the function `_'. For example:
|
||
|
||
filename = 'mylog.txt'
|
||
message = _('writing a log message')
|
||
fp = open(filename, 'w')
|
||
fp.write(message)
|
||
fp.close()
|
||
|
||
In this example, the string `writing a log message' is marked as a candidate
|
||
for translation, while the strings `mylog.txt' and `w' are not.
|
||
|
||
The GNU gettext package provides a tool, called xgettext, that scans C and C++
|
||
source code looking for these specially marked strings. xgettext generates
|
||
what are called `.pot' files, essentially structured human readable files
|
||
which contain every marked string in the source code. These .pot files are
|
||
copied and handed over to translators who write language-specific versions for
|
||
every supported language.
|
||
|
||
For I18N Python programs however, xgettext won't work; it doesn't understand
|
||
the myriad of string types support by Python. The standard Python
|
||
distribution provides a tool called pygettext that does though (found in the
|
||
Tools/i18n directory). This is a command line script that supports a similar
|
||
interface as xgettext; see its documentation for details. Once you've used
|
||
pygettext to create your .pot files, you can use the standard GNU gettext
|
||
tools to generate your machine-readable .mo files, which are what's used by
|
||
this module.
|
||
|
||
In the simple case, to use this module then, you need only add the following
|
||
bit of code to the main driver file of your application:
|
||
|
||
import gettext
|
||
gettext.install()
|
||
|
||
This sets everything up so that your _('...') function calls Just Work. In
|
||
other words, it installs `_' in the builtins namespace for convenience. You
|
||
can skip this step and do it manually by the equivalent code:
|
||
|
||
import gettext
|
||
import __builtin__
|
||
__builtin__['_'] = gettext.gettext
|
||
|
||
Once you've done this, you probably want to call bindtextdomain() and
|
||
textdomain() to get the domain set up properly. Again, for convenience, you
|
||
can pass the domain and localedir to install to set everything up in one fell
|
||
swoop:
|
||
|
||
import gettext
|
||
gettext.install('mydomain', '/my/locale/dir')
|
||
|
||
If your program needs to support many languages at the same time, you will
|
||
want to create Translation objects explicitly, like so:
|
||
|
||
import gettext
|
||
gettext.install()
|
||
|
||
lang1 = gettext.Translations(open('/path/to/my/lang1/messages.mo'))
|
||
lang2 = gettext.Translations(open('/path/to/my/lang2/messages.mo'))
|
||
lang3 = gettext.Translations(open('/path/to/my/lang3/messages.mo'))
|
||
|
||
gettext.set(lang1)
|
||
# all _() will now translate to language 1
|
||
gettext.set(lang2)
|
||
# all _() will now translate to language 2
|
||
|
||
Currently, only GNU gettext format binary .mo files are supported.
|
||
|
||
"""
|
||
|
||
# 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.
|
||
|
||
import os
|
||
import sys
|
||
import struct
|
||
from UserDict import UserDict
|
||
|
||
|
||
|
||
# globals
|
||
_translations = {}
|
||
_current_translation = None
|
||
_current_domain = 'messages'
|
||
|
||
# Domain to directory mapping, for use by bindtextdomain()
|
||
_localedirs = {}
|
||
|
||
|
||
|
||
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 GNUTranslations(UserDict):
|
||
# Magic number of .mo files
|
||
MAGIC = 0x950412de
|
||
|
||
def __init__(self, fp):
|
||
if fp is None:
|
||
d = {}
|
||
else:
|
||
d = self._parse(fp)
|
||
UserDict.__init__(self, d)
|
||
|
||
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.
|
||
catalog = {}
|
||
buf = fp.read()
|
||
magic, version, msgcount, masteridx, transidx = unpack(
|
||
'<5i', buf[:20])
|
||
if magic <> self.MAGIC:
|
||
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):
|
||
mstart = unpack('<i', buf[masteridx+4:masteridx+8])[0]
|
||
mend = mstart + unpack('<i', buf[masteridx:masteridx+4])[0]
|
||
tstart = unpack('<i', buf[transidx+4:transidx+8])[0]
|
||
tend = tstart + unpack('<i', buf[transidx:transidx+4])[0]
|
||
if mend < len(buf) and tend < len(buf):
|
||
catalog[buf[mstart:mend]] = buf[tstart:tend]
|
||
else:
|
||
raise IOError(0, 'File is corrupt', filename)
|
||
#
|
||
# advance to next entry in the seek tables
|
||
masteridx += 8
|
||
transidx += 8
|
||
return catalog
|
||
|
||
|
||
|
||
# By default, use GNU gettext format .mo files
|
||
Translations = GNUTranslations
|
||
|
||
# Locate a .mo file using the gettext strategy
|
||
def _find(localedir=None, languages=None, domain=None):
|
||
global _current_domain
|
||
global _localedirs
|
||
# Get some reasonable defaults for arguments that were not supplied
|
||
if domain is None:
|
||
domain = _current_domain
|
||
if localedir is None:
|
||
localedir = _localedirs.get(
|
||
domain,
|
||
# TBD: The default localedir is actually system dependent. I
|
||
# don't know of a good platform-consistent and portable way to
|
||
# default it, so instead, we'll just use sys.prefix. Most
|
||
# programs should be calling bindtextdomain() or such explicitly
|
||
# anyway.
|
||
os.path.join(sys.prefix, 'share', 'locale'))
|
||
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
|
||
langdict = {}
|
||
for lang in languages:
|
||
for nelang in _expand_lang(lang):
|
||
langdict[nelang] = nelang
|
||
languages = langdict.keys()
|
||
# select a language
|
||
for lang in languages:
|
||
if lang == 'C':
|
||
break
|
||
mofile = os.path.join(localedir, lang, 'LC_MESSAGES', '%s.mo' % domain)
|
||
# see if it's in the cache
|
||
mo = _translations.get(mofile)
|
||
if mo:
|
||
return mo
|
||
fp = None
|
||
try:
|
||
try:
|
||
fp = open(mofile, 'rb')
|
||
t = Translations(fp)
|
||
_translations[mofile] = t
|
||
return t
|
||
except IOError:
|
||
pass
|
||
finally:
|
||
if fp:
|
||
fp.close()
|
||
return {}
|
||
|
||
|
||
|
||
def bindtextdomain(domain=None, localedir=None):
|
||
"""Bind domain to a file in the specified directory."""
|
||
global _localedirs
|
||
if domain is None:
|
||
return None
|
||
if localedir is None:
|
||
return _localedirs.get(domain, _localedirs.get('C'))
|
||
_localedirs[domain] = localedir
|
||
return localedir
|
||
|
||
|
||
def textdomain(domain=None):
|
||
"""Change or query the current global domain."""
|
||
global _current_domain
|
||
if domain is None:
|
||
return _current_domain
|
||
else:
|
||
_current_domain = domain
|
||
return domain
|
||
|
||
|
||
def gettext(message):
|
||
"""Return localized version of a message."""
|
||
return _find().get(message, message)
|
||
|
||
|
||
def dgettext(domain, message):
|
||
"""Like gettext(), but look up message in specified domain."""
|
||
return _find(domain=domain).get(message, message)
|
||
|
||
|
||
|
||
# A higher level API
|
||
def set(translation):
|
||
global _current_translation
|
||
_current_translation = translation
|
||
|
||
|
||
def get():
|
||
global _current_translation
|
||
return _current_translation
|
||
|
||
|
||
def install(domain=None, localedir=None):
|
||
import __builtin__
|
||
__builtin__.__dict__['_'] = gettext
|
||
if domain is not None:
|
||
bindtextdomain(domain, localedir)
|
||
textdomain(domain)
|