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07bcf05fcf
plural form selections in the gettext module. The expression parser now supports exact syntax supported by GNU gettext.
608 lines
20 KiB
Python
608 lines
20 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, io, 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.base_prefix, 'share', 'locale')
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# Expression parsing for plural form selection.
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#
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# The gettext library supports a small subset of C syntax. The only
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# incompatible difference is that integer literals starting with zero are
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# decimal.
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#
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# https://www.gnu.org/software/gettext/manual/gettext.html#Plural-forms
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# http://git.savannah.gnu.org/cgit/gettext.git/tree/gettext-runtime/intl/plural.y
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_token_pattern = re.compile(r"""
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(?P<WHITESPACES>[ \t]+) | # spaces and horizontal tabs
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(?P<NUMBER>[0-9]+\b) | # decimal integer
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(?P<NAME>n\b) | # only n is allowed
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(?P<PARENTHESIS>[()]) |
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(?P<OPERATOR>[-*/%+?:]|[><!]=?|==|&&|\|\|) | # !, *, /, %, +, -, <, >,
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# <=, >=, ==, !=, &&, ||,
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# ? :
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# unary and bitwise ops
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# not allowed
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(?P<INVALID>\w+|.) # invalid token
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""", re.VERBOSE|re.DOTALL)
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def _tokenize(plural):
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for mo in re.finditer(_token_pattern, plural):
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kind = mo.lastgroup
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if kind == 'WHITESPACES':
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continue
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value = mo.group(kind)
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if kind == 'INVALID':
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raise ValueError('invalid token in plural form: %s' % value)
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yield value
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yield ''
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def _error(value):
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if value:
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return ValueError('unexpected token in plural form: %s' % value)
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else:
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return ValueError('unexpected end of plural form')
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_binary_ops = (
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('||',),
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('&&',),
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('==', '!='),
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('<', '>', '<=', '>='),
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('+', '-'),
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('*', '/', '%'),
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)
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_binary_ops = {op: i for i, ops in enumerate(_binary_ops, 1) for op in ops}
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_c2py_ops = {'||': 'or', '&&': 'and', '/': '//'}
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def _parse(tokens, priority=-1):
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result = ''
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nexttok = next(tokens)
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while nexttok == '!':
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result += 'not '
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nexttok = next(tokens)
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if nexttok == '(':
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sub, nexttok = _parse(tokens)
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result = '%s(%s)' % (result, sub)
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if nexttok != ')':
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raise ValueError('unbalanced parenthesis in plural form')
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elif nexttok == 'n':
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result = '%s%s' % (result, nexttok)
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else:
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try:
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value = int(nexttok, 10)
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except ValueError:
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raise _error(nexttok) from None
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result = '%s%d' % (result, value)
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nexttok = next(tokens)
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j = 100
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while nexttok in _binary_ops:
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i = _binary_ops[nexttok]
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if i < priority:
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break
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# Break chained comparisons
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if i in (3, 4) and j in (3, 4): # '==', '!=', '<', '>', '<=', '>='
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result = '(%s)' % result
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# Replace some C operators by their Python equivalents
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op = _c2py_ops.get(nexttok, nexttok)
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right, nexttok = _parse(tokens, i + 1)
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result = '%s %s %s' % (result, op, right)
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j = i
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if j == priority == 4: # '<', '>', '<=', '>='
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result = '(%s)' % result
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if nexttok == '?' and priority <= 0:
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if_true, nexttok = _parse(tokens, 0)
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if nexttok != ':':
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raise _error(nexttok)
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if_false, nexttok = _parse(tokens)
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result = '%s if %s else %s' % (if_true, result, if_false)
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if priority == 0:
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result = '(%s)' % result
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return result, nexttok
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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 function that implements an equivalent expression.
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"""
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if len(plural) > 1000:
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raise ValueError('plural form expression is too long')
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try:
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result, nexttok = _parse(_tokenize(plural))
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if nexttok:
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raise _error(nexttok)
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depth = 0
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for c in result:
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if c == '(':
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depth += 1
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if depth > 20:
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# Python compiler limit is about 90.
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# The most complex example has 2.
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raise ValueError('plural form expression is too complex')
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elif c == ')':
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depth -= 1
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ns = {}
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exec('''if True:
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def func(n):
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if not isinstance(n, int):
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raise ValueError('Plural value must be an integer.')
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return int(%s)
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''' % result, ns)
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return ns['func']
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except RuntimeError:
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# Recursion error can be raised in _parse() or exec().
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raise ValueError('plural form expression is too complex')
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def _expand_lang(loc):
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loc = locale.normalize(loc)
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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 = loc.find('@')
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if pos >= 0:
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modifier = loc[pos:]
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loc = loc[:pos]
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mask |= COMPONENT_MODIFIER
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else:
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modifier = ''
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pos = loc.find('.')
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if pos >= 0:
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codeset = loc[pos:]
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loc = loc[:pos]
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mask |= COMPONENT_CODESET
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else:
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codeset = ''
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pos = loc.find('_')
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if pos >= 0:
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territory = loc[pos:]
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loc = loc[:pos]
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mask |= COMPONENT_TERRITORY
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else:
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territory = ''
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language = loc
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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 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, names=None):
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import builtins
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builtins.__dict__['_'] = self.gettext
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if hasattr(names, "__contains__"):
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if "gettext" in names:
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builtins.__dict__['gettext'] = builtins.__dict__['_']
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if "ngettext" in names:
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builtins.__dict__['ngettext'] = self.ngettext
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if "lgettext" in names:
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builtins.__dict__['lgettext'] = self.lgettext
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if "lngettext" in names:
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builtins.__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 = 0x950412de
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BE_MAGIC = 0xde120495
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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 range(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 b_item in tmsg.split('\n'.encode("ascii")):
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item = b_item.decode().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 applications
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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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charset = self._charset or 'ascii'
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if b'\x00' in msg:
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# Plural forms
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msgid1, msgid2 = msg.split(b'\x00')
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tmsg = tmsg.split(b'\x00')
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msgid1 = str(msgid1, charset)
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for i, x in enumerate(tmsg):
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catalog[(msgid1, i)] = str(x, charset)
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else:
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catalog[str(msg, charset)] = str(tmsg, charset)
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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 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 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 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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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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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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tmsg = msgid1
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else:
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tmsg = 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=False):
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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=True)
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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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# 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 = (class_, os.path.abspath(mofile))
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t = _translations.get(key)
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if t is None:
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with open(mofile, 'rb') as fp:
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t = _translations.setdefault(key, class_(fp))
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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, codeset=None, names=None):
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t = translation(domain, localedir, fallback=True, codeset=codeset)
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t.install(names)
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# a mapping b/w domains and locale directories
|
|
_localedirs = {}
|
|
# a mapping b/w domains and codesets
|
|
_localecodesets = {}
|
|
# current global domain, `messages' used for compatibility w/ GNU gettext
|
|
_current_domain = 'messages'
|
|
|
|
|
|
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 bind_textdomain_codeset(domain, codeset=None):
|
|
global _localecodesets
|
|
if codeset is not None:
|
|
_localecodesets[domain] = codeset
|
|
return _localecodesets.get(domain)
|
|
|
|
|
|
def dgettext(domain, message):
|
|
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
|