cpython/Lib/gettext.py at 3.15 · python/cpython · GitHub

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"""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.

import operator

import os

import sys

__all__ = ['NullTranslations', 'GNUTranslations', 'Catalog',

'bindtextdomain', 'find', 'translation', 'install',

'textdomain', 'dgettext', 'dngettext', 'gettext',

'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 = None

def _tokenize(plural):

global _token_pattern

if _token_pattern is None:

import re

_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)

for mo in _token_pattern.finditer(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 = frozendict({op: i for i, ops in enumerate(_binary_ops, 1)

for op in ops})

_c2py_ops = frozendict({'||': '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)

# Unary '!' binds tighter than binary operators in C, unlike 'not'.

if result.startswith('not '):

result = '(%s)' % result

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:

round(n)

except TypeError:

raise TypeError('Plural value must be an integer, got %s' %

(n.__class__.__name__,)) from None

return _as_int2(n)

def _as_int2(n):

try:

return operator.index(n)

except TypeError:

pass

import warnings

frame = sys._getframe(1)

stacklevel = 2

while frame.f_back is not None and frame.f_globals.get('__name__') == __name__:

stacklevel += 1

frame = frame.f_back

warnings.warn('Plural value must be an integer, got %s' %

(n.__class__.__name__,),

DeprecationWarning,

stacklevel)

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, '__name__': __name__}

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

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)

n = _as_int2(n)

if n == 1:

return msgid1

else:

return msgid2

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)

n = _as_int2(n)

if n == 1:

return msgid1

else:

return msgid2

def info(self):

return self._info

def charset(self):

return self._charset

def install(self, names=None):

import builtins

builtins.__dict__['_'] = self.gettext

if names is not None:

allowed = {'gettext', 'ngettext', 'npgettext', 'pgettext'}

for name in allowed & set(names):

builtins.__dict__[name] = getattr(self, name)

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

def gettext(self, message):

missing = object()

tmsg = self._catalog.get(message, missing)

if tmsg is missing:

tmsg = self._catalog.get((message, self.plural(1)), missing)

if tmsg is not missing:

return tmsg

if self._fallback:

return self._fallback.gettext(message)

return message

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:

tmsg = self._catalog.get((ctxt_msg_id, self.plural(1)), missing)

if tmsg is not missing:

return tmsg

if self._fallback:

return self._fallback.pgettext(context, message)

return message

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

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 = {}

def translation(domain, localedir=None, languages=None,

class_=None, fallback=False):

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 result is None:

result = t

else:

result.add_fallback(t)

return result

def install(domain, localedir=None, *, names=None):

t = translation(domain, localedir, fallback=True)

t.install(names)

# 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 OSError:

return message

return t.gettext(message)

def dngettext(domain, msgid1, msgid2, n):

try:

t = translation(domain, _localedirs.get(domain, None))

except OSError:

n = _as_int2(n)

if n == 1:

return msgid1

else:

return msgid2

return t.ngettext(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:

n = _as_int2(n)

if n == 1:

return msgid1

else:

return msgid2

return t.npgettext(context, msgid1, msgid2, n)

def gettext(message):

return dgettext(_current_domain, message)

def ngettext(msgid1, msgid2, n):

return dngettext(_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

cpython/Lib/gettext.py at 3.15 · python/cpython · GitHub

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