Source code for gettext
From Get docs
Python/docs/3.7/ modules/gettext
Source code for gettext
"""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 os
import re
import sys
__all__ = ['NullTranslations', 'GNUTranslations', 'Catalog',
'find', 'translation', 'install', 'textdomain', 'bindtextdomain',
'bind_textdomain_codeset',
'dgettext', 'dngettext', 'gettext', 'lgettext', 'ldgettext',
'ldngettext', 'lngettext', 'ngettext',
'pgettext', 'dpgettext', 'npgettext', 'dnpgettext',
]
_default_localedir = os.path.join(sys.base_prefix, 'share', 'locale')
# Expression parsing for plural form selection.
#
# The gettext library supports a small subset of C syntax. The only
# incompatible difference is that integer literals starting with zero are
# decimal.
#
# https://www.gnu.org/software/gettext/manual/gettext.html#Plural-forms
# http://git.savannah.gnu.org/cgit/gettext.git/tree/gettext-runtime/intl/plural.y
_token_pattern = re.compile(r"""
(?P<WHITESPACES>[ \t]+) | # spaces and horizontal tabs
(?P<NUMBER>[0-9]+\b) | # decimal integer
(?P<NAME>n\b) | # only n is allowed
(?P<PARENTHESIS>[()]) |
(?P<OPERATOR>[-*/%+?:]|[><!]=?|==|&&|\|\|) | # !, *, /, %, +, -, <, >,
# <=, >=, ==, !=, &&, ||,
# ? :
# unary and bitwise ops
# not allowed
(?P<INVALID>\w+|.) # invalid token
""", re.VERBOSE|re.DOTALL)
def _tokenize(plural):
for mo in re.finditer(_token_pattern, plural):
kind = mo.lastgroup
if kind == 'WHITESPACES':
continue
value = mo.group(kind)
if kind == 'INVALID':
raise ValueError('invalid token in plural form: %s' % value)
yield value
yield ''
def _error(value):
if value:
return ValueError('unexpected token in plural form: %s' % value)
else:
return ValueError('unexpected end of plural form')
_binary_ops = (
('||',),
('&&',),
('==', '!='),
('<', '>', '<=', '>='),
('+', '-'),
('*', '/', '%'),
)
_binary_ops = {op: i for i, ops in enumerate(_binary_ops, 1) for op in ops}
_c2py_ops = {'||': 'or', '&&': 'and', '/': '//'}
def _parse(tokens, priority=-1):
result = ''
nexttok = next(tokens)
while nexttok == '!':
result += 'not '
nexttok = next(tokens)
if nexttok == '(':
sub, nexttok = _parse(tokens)
result = '%s(%s)' % (result, sub)
if nexttok != ')':
raise ValueError('unbalanced parenthesis in plural form')
elif nexttok == 'n':
result = '%s%s' % (result, nexttok)
else:
try:
value = int(nexttok, 10)
except ValueError:
raise _error(nexttok) from None
result = '%s%d' % (result, value)
nexttok = next(tokens)
j = 100
while nexttok in _binary_ops:
i = _binary_ops[nexttok]
if i < priority:
break
# Break chained comparisons
if i in (3, 4) and j in (3, 4): # '==', '!=', '<', '>', '<=', '>='
result = '(%s)' % result
# Replace some C operators by their Python equivalents
op = _c2py_ops.get(nexttok, nexttok)
right, nexttok = _parse(tokens, i + 1)
result = '%s %s %s' % (result, op, right)
j = i
if j == priority == 4: # '<', '>', '<=', '>='
result = '(%s)' % result
if nexttok == '?' and priority <= 0:
if_true, nexttok = _parse(tokens, 0)
if nexttok != ':':
raise _error(nexttok)
if_false, nexttok = _parse(tokens)
result = '%s if %s else %s' % (if_true, result, if_false)
if priority == 0:
result = '(%s)' % result
return result, nexttok
def _as_int(n):
try:
i = round(n)
except TypeError:
raise TypeError('Plural value must be an integer, got %s' %
(n.__class__.__name__,)) from None
import warnings
warnings.warn('Plural value must be an integer, got %s' %
(n.__class__.__name__,),
DeprecationWarning, 4)
return n
def c2py(plural):
"""Gets a C expression as used in PO files for plural forms and returns a
Python function that implements an equivalent expression.
"""
if len(plural) > 1000:
raise ValueError('plural form expression is too long')
try:
result, nexttok = _parse(_tokenize(plural))
if nexttok:
raise _error(nexttok)
depth = 0
for c in result:
if c == '(':
depth += 1
if depth > 20:
# Python compiler limit is about 90.
# The most complex example has 2.
raise ValueError('plural form expression is too complex')
elif c == ')':
depth -= 1
ns = {'_as_int': _as_int}
exec('''if True:
def func(n):
if not isinstance(n, int):
n = _as_int(n)
return int(%s)
''' % result, ns)
return ns['func']
except RecursionError:
# Recursion error can be raised in _parse() or exec().
raise ValueError('plural form expression is too complex')
def _expand_lang(loc):
import locale
loc = locale.normalize(loc)
COMPONENT_CODESET = 1 << 0
COMPONENT_TERRITORY = 1 << 1
COMPONENT_MODIFIER = 1 << 2
# split up the locale into its base components
mask = 0
pos = loc.find('@')
if pos >= 0:
modifier = loc[pos:]
loc = loc[:pos]
mask |= COMPONENT_MODIFIER
else:
modifier = ''
pos = loc.find('.')
if pos >= 0:
codeset = loc[pos:]
loc = loc[:pos]
mask |= COMPONENT_CODESET
else:
codeset = ''
pos = loc.find('_')
if pos >= 0:
territory = loc[pos:]
loc = loc[:pos]
mask |= COMPONENT_TERRITORY
else:
territory = ''
language = loc
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
[docs]class NullTranslations:
def __init__(self, fp=None):
self._info = {}
self._charset = None
self._output_charset = None
self._fallback = None
if fp is not None:
self._parse(fp)
[docs] def _parse(self, fp):
pass
[docs] def add_fallback(self, fallback):
if self._fallback:
self._fallback.add_fallback(fallback)
else:
self._fallback = fallback
[docs] def gettext(self, message):
if self._fallback:
return self._fallback.gettext(message)
return message
[docs] def lgettext(self, message):
import warnings
warnings.warn('lgettext() is deprecated, use gettext() instead',
DeprecationWarning, 2)
import locale
if self._fallback:
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\blgettext\b.*',
DeprecationWarning)
return self._fallback.lgettext(message)
if self._output_charset:
return message.encode(self._output_charset)
return message.encode(locale.getpreferredencoding())
[docs] def ngettext(self, msgid1, msgid2, n):
if self._fallback:
return self._fallback.ngettext(msgid1, msgid2, n)
if n == 1:
return msgid1
else:
return msgid2
[docs] def lngettext(self, msgid1, msgid2, n):
import warnings
warnings.warn('lngettext() is deprecated, use ngettext() instead',
DeprecationWarning, 2)
import locale
if self._fallback:
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\blngettext\b.*',
DeprecationWarning)
return self._fallback.lngettext(msgid1, msgid2, n)
if n == 1:
tmsg = msgid1
else:
tmsg = msgid2
if self._output_charset:
return tmsg.encode(self._output_charset)
return tmsg.encode(locale.getpreferredencoding())
def pgettext(self, context, message):
if self._fallback:
return self._fallback.pgettext(context, message)
return message
def npgettext(self, context, msgid1, msgid2, n):
if self._fallback:
return self._fallback.npgettext(context, msgid1, msgid2, n)
if n == 1:
return msgid1
else:
return msgid2
[docs] def info(self):
return self._info
[docs] def charset(self):
return self._charset
[docs] def output_charset(self):
import warnings
warnings.warn('output_charset() is deprecated',
DeprecationWarning, 2)
return self._output_charset
[docs] def set_output_charset(self, charset):
import warnings
warnings.warn('set_output_charset() is deprecated',
DeprecationWarning, 2)
self._output_charset = charset
[docs] def install(self, names=None):
import builtins
builtins.__dict__['_'] = self.gettext
if names is not None:
allowed = {'gettext', 'lgettext', 'lngettext',
'ngettext', 'npgettext', 'pgettext'}
for name in allowed & set(names):
builtins.__dict__[name] = getattr(self, name)
[docs]class GNUTranslations(NullTranslations):
# Magic number of .mo files
LE_MAGIC = 0x950412de
BE_MAGIC = 0xde120495
# The encoding of a msgctxt and a msgid in a .mo file is
# msgctxt + "\x04" + msgid (gettext version >= 0.15)
CONTEXT = "%s\x04%s"
# Acceptable .mo versions
VERSIONS = (0, 1)
def _get_versions(self, version):
"""Returns a tuple of major version, minor version"""
return (version >> 16, version & 0xffff)
def _parse(self, fp):
"""Override this method to support alternative .mo formats."""
# Delay struct import for speeding up gettext import when .mo files
# are not used.
from struct import 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 OSError(0, 'Bad magic number', filename)
major_version, minor_version = self._get_versions(version)
if major_version not in self.VERSIONS:
raise OSError(0, 'Bad version number ' + str(major_version), filename)
# Now put all messages from the .mo file buffer into the catalog
# dictionary.
for i in range(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 OSError(0, 'File is corrupt', filename)
# See if we're looking at GNU .mo conventions for metadata
if mlen == 0:
# Catalog description
lastk = None
for b_item in tmsg.split(b'\n'):
item = b_item.decode().strip()
if not item:
continue
# Skip over comment lines:
if item.startswith('#-#-#-#-#') and item.endswith('#-#-#-#-#'):
continue
k = v = None
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 applications
# 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.
charset = self._charset or 'ascii'
if b'\x00' in msg:
# Plural forms
msgid1, msgid2 = msg.split(b'\x00')
tmsg = tmsg.split(b'\x00')
msgid1 = str(msgid1, charset)
for i, x in enumerate(tmsg):
catalog[(msgid1, i)] = str(x, charset)
else:
catalog[str(msg, charset)] = str(tmsg, charset)
# advance to next entry in the seek tables
masteridx += 8
transidx += 8
[docs] def lgettext(self, message):
import warnings
warnings.warn('lgettext() is deprecated, use gettext() instead',
DeprecationWarning, 2)
import locale
missing = object()
tmsg = self._catalog.get(message, missing)
if tmsg is missing:
if self._fallback:
return self._fallback.lgettext(message)
tmsg = message
if self._output_charset:
return tmsg.encode(self._output_charset)
return tmsg.encode(locale.getpreferredencoding())
[docs] def lngettext(self, msgid1, msgid2, n):
import warnings
warnings.warn('lngettext() is deprecated, use ngettext() instead',
DeprecationWarning, 2)
import locale
try:
tmsg = self._catalog[(msgid1, self.plural(n))]
except KeyError:
if self._fallback:
return self._fallback.lngettext(msgid1, msgid2, n)
if n == 1:
tmsg = msgid1
else:
tmsg = msgid2
if self._output_charset:
return tmsg.encode(self._output_charset)
return tmsg.encode(locale.getpreferredencoding())
[docs] 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
return tmsg
[docs] def ngettext(self, msgid1, msgid2, n):
try:
tmsg = self._catalog[(msgid1, self.plural(n))]
except KeyError:
if self._fallback:
return self._fallback.ngettext(msgid1, msgid2, n)
if n == 1:
tmsg = msgid1
else:
tmsg = msgid2
return tmsg
def pgettext(self, context, message):
ctxt_msg_id = self.CONTEXT % (context, message)
missing = object()
tmsg = self._catalog.get(ctxt_msg_id, missing)
if tmsg is missing:
if self._fallback:
return self._fallback.pgettext(context, message)
return message
return tmsg
def npgettext(self, context, msgid1, msgid2, n):
ctxt_msg_id = self.CONTEXT % (context, msgid1)
try:
tmsg = self._catalog[ctxt_msg_id, self.plural(n)]
except KeyError:
if self._fallback:
return self._fallback.npgettext(context, msgid1, msgid2, n)
if n == 1:
tmsg = msgid1
else:
tmsg = msgid2
return tmsg
# Locate a .mo file using the gettext strategy
[docs]def find(domain, localedir=None, languages=None, all=False):
# 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 = {}
_unspecified = ['unspecified']
[docs]def translation(domain, localedir=None, languages=None,
class_=None, fallback=False, codeset=_unspecified):
if class_ is None:
class_ = GNUTranslations
mofiles = find(domain, localedir, languages, all=True)
if not mofiles:
if fallback:
return NullTranslations()
from errno import ENOENT
raise FileNotFoundError(ENOENT,
'No translation file found for domain', domain)
# Avoid opening, reading, and parsing the .mo file after it's been done
# once.
result = None
for mofile in mofiles:
key = (class_, os.path.abspath(mofile))
t = _translations.get(key)
if t is None:
with open(mofile, 'rb') as fp:
t = _translations.setdefault(key, class_(fp))
# Copy the translation object to allow setting fallbacks and
# output charset. All other instance data is shared with the
# cached object.
# Delay copy import for speeding up gettext import when .mo files
# are not used.
import copy
t = copy.copy(t)
if codeset is not _unspecified:
import warnings
warnings.warn('parameter codeset is deprecated',
DeprecationWarning, 2)
if codeset:
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\bset_output_charset\b.*',
DeprecationWarning)
t.set_output_charset(codeset)
if result is None:
result = t
else:
result.add_fallback(t)
return result
[docs]def install(domain, localedir=None, codeset=_unspecified, names=None):
t = translation(domain, localedir, fallback=True, codeset=codeset)
t.install(names)
# a mapping b/w domains and locale directories
_localedirs = {}
# a mapping b/w domains and codesets
_localecodesets = {}
# current global domain, `messages' used for compatibility w/ GNU gettext
_current_domain = 'messages'
[docs]def textdomain(domain=None):
global _current_domain
if domain is not None:
_current_domain = domain
return _current_domain
[docs]def bindtextdomain(domain, localedir=None):
global _localedirs
if localedir is not None:
_localedirs[domain] = localedir
return _localedirs.get(domain, _default_localedir)
[docs]def bind_textdomain_codeset(domain, codeset=None):
import warnings
warnings.warn('bind_textdomain_codeset() is deprecated',
DeprecationWarning, 2)
global _localecodesets
if codeset is not None:
_localecodesets[domain] = codeset
return _localecodesets.get(domain)
[docs]def dgettext(domain, message):
try:
t = translation(domain, _localedirs.get(domain, None))
except OSError:
return message
return t.gettext(message)
[docs]def ldgettext(domain, message):
import warnings
warnings.warn('ldgettext() is deprecated, use dgettext() instead',
DeprecationWarning, 2)
import locale
codeset = _localecodesets.get(domain)
try:
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\bparameter codeset\b.*',
DeprecationWarning)
t = translation(domain, _localedirs.get(domain, None), codeset=codeset)
except OSError:
return message.encode(codeset or locale.getpreferredencoding())
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\blgettext\b.*',
DeprecationWarning)
return t.lgettext(message)
[docs]def dngettext(domain, msgid1, msgid2, n):
try:
t = translation(domain, _localedirs.get(domain, None))
except OSError:
if n == 1:
return msgid1
else:
return msgid2
return t.ngettext(msgid1, msgid2, n)
[docs]def ldngettext(domain, msgid1, msgid2, n):
import warnings
warnings.warn('ldngettext() is deprecated, use dngettext() instead',
DeprecationWarning, 2)
import locale
codeset = _localecodesets.get(domain)
try:
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\bparameter codeset\b.*',
DeprecationWarning)
t = translation(domain, _localedirs.get(domain, None), codeset=codeset)
except OSError:
if n == 1:
tmsg = msgid1
else:
tmsg = msgid2
return tmsg.encode(codeset or locale.getpreferredencoding())
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\blngettext\b.*',
DeprecationWarning)
return t.lngettext(msgid1, msgid2, n)
def dpgettext(domain, context, message):
try:
t = translation(domain, _localedirs.get(domain, None))
except OSError:
return message
return t.pgettext(context, message)
def dnpgettext(domain, context, msgid1, msgid2, n):
try:
t = translation(domain, _localedirs.get(domain, None))
except OSError:
if n == 1:
return msgid1
else:
return msgid2
return t.npgettext(context, msgid1, msgid2, n)
[docs]def gettext(message):
return dgettext(_current_domain, message)
[docs]def lgettext(message):
import warnings
warnings.warn('lgettext() is deprecated, use gettext() instead',
DeprecationWarning, 2)
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\bldgettext\b.*',
DeprecationWarning)
return ldgettext(_current_domain, message)
[docs]def ngettext(msgid1, msgid2, n):
return dngettext(_current_domain, msgid1, msgid2, n)
[docs]def lngettext(msgid1, msgid2, n):
import warnings
warnings.warn('lngettext() is deprecated, use ngettext() instead',
DeprecationWarning, 2)
with warnings.catch_warnings():
warnings.filterwarnings('ignore', r'.*\bldngettext\b.*',
DeprecationWarning)
return ldngettext(_current_domain, msgid1, msgid2, n)
def pgettext(context, message):
return dpgettext(_current_domain, context, message)
def npgettext(context, msgid1, msgid2, n):
return dnpgettext(_current_domain, context, 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
