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