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493 lines
16 KiB
493 lines
16 KiB
"""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 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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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._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 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 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 install(self, unicode=False): |
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import __builtin__ |
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__builtin__.__dict__['_'] = unicode and self.ugettext or self.gettext |
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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 msg.find('\x00') >= 0: |
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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._charset: |
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return tmsg.encode(self._charset) |
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return tmsg |
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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._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 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): |
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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. |
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# All other instance data is shared with the cached object. |
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t = copy.copy(t) |
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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): |
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translation(domain, localedir, fallback=True).install(unicode) |
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# a mapping b/w domains and locale directories |
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_localedirs = {} |
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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 dgettext(domain, message): |
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try: |
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t = translation(domain, _localedirs.get(domain, None)) |
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except IOError: |
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return message |
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return t.gettext(message) |
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def dngettext(domain, msgid1, msgid2, n): |
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try: |
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t = translation(domain, _localedirs.get(domain, None)) |
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except IOError: |
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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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return t.ngettext(msgid1, msgid2, n) |
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def gettext(message): |
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return dgettext(_current_domain, message) |
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def ngettext(msgid1, msgid2, n): |
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return dngettext(_current_domain, msgid1, msgid2, n) |
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# dcgettext() has been deemed unnecessary and is not implemented. |
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# James Henstridge's Catalog constructor from GNOME gettext. Documented usage |
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# was: |
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# |
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# import gettext |
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# cat = gettext.Catalog(PACKAGE, localedir=LOCALEDIR) |
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# _ = cat.gettext |
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# print _('Hello World') |
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# The resulting catalog object currently don't support access through a |
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# dictionary API, which was supported (but apparently unused) in GNOME |
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# gettext. |
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Catalog = translation
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