collate/_locale.py

   1 """Locale utility routines."""
   2
   3 import sys
   4
   5 try:
   6     import locale
   7 except ImportError:
   8     locale = None
   9
  10 try:
  11     import codecs
  12 except ImportError:
  13     codecs = None
  14
  15 __all__ = ["localelist"]
  16
  17 def localelist(*locales):
  18     """Normalize and return a list of locales, with appended defaults.
  19
  20     e.g. on a system with en_US as the default locale,
  21
  22     localelist('en_GB.utf8', 'de_DE') =>
  23         ['en_GB', 'en', 'de_DE', 'de', 'en_US', 'C']
  24
  25     """
  26
  27     locales = list(locales)
  28
  29     if locale is not None:
  30         # Set the locale if it hasn't already been set, but don't fail
  31         # if we can't set it for some reason.
  32         if locale.getlocale(locale.LC_COLLATE)[0] is None:
  33             try:
  34                 locale.setlocale(locale.LC_COLLATE, '')
  35             except locale.Error:
  36                 pass
  37
  38         # Throw in the user's specified collation locale, the current locale,
  39         # the default locale, and POSIX, for free.
  40         locales.append(locale.getlocale(locale.LC_COLLATE)[0])
  41         locales.append(locale.getlocale()[0])
  42         locales.append(locale.getdefaultlocale()[0])
  43     locales.append("C")
  44
  45     # Don't put the same locale in the return list more than twice.
  46     added = set()
  47     retlist = []
  48
  49     for code in locales:
  50         if not code:
  51             continue
  52         if locale is not None:
  53             code = locale.normalize(code)
  54         # Strip off encoding if present.
  55         code = code.split(".")[0]
  56         if code.lower() not in added:
  57             retlist.append(code)
  58             added.add(code.lower())
  59         # Strip off territory if present.
  60         code = code.split("_")[0]
  61         if code.lower() not in added:
  62             retlist.append(code)
  63             added.add(code.lower())
  64
  65     return retlist
  66
  67 def encoding(preferred=None):
  68     """Try to find an optimal encoding.
  69
  70     Arguments:
  71     preferred - use this encoding if possible
  72
  73     Otherwise, the locale encoding or the Python system encoding are
  74     used.
  75     """
  76     # can't use any codecs, use the system one (ascii).
  77     if codecs is None:
  78         return sys.getdefaultencoding()
  79
  80     # if preferred is a valid codec, use it.
  81     if preferred is not None:
  82         try:
  83             return codecs.lookup(preferred).name
  84         except (LookupError, AttributeError):
  85             pass
  86
  87     # preferred is bad and can't get it from locale.
  88     if locale is None:
  89         return sys.getdefaultencoding()
  90
  91     # try to get it from the locale, if not there, set it and try again.
  92     fromlocale = locale.getlocale(locale.LC_COLLATE)[1]
  93     if fromlocale is not None:
  94         return fromlocale
  95     try:
  96         locale.setlocale(locale.LC_COLLATE, '')[1]
  97     except locale.Error:
  98         pass
  99     else:
 100         fromlocale = locale.getlocale(locale.LC_COLLATE)
 101         if fromlocale is not None:
 102             return fromlocale
 103
 104     # okay, LC_COLLATE isn't set, maybe the generic locale is.
 105     fromlocale = locale.getlocale()[1]
 106     if fromlocale is not None:
 107         return fromlocale
 108
 109     # but we won't reset the generic locale if it isn't, that'd be
 110     # rude.
 111
 112     # if the locale can't even give us a simple encoding, go back
 113     # to the system one, and give up.
 114     return locale.getpreferredencoding() or sys.getdefaultencoding()
 115
 116 def getpair(locale_, encoding_):
 117     if "." in locale_:
 118         if encoding_ is None:
 119             locale_, encoding_ = locale_.rsplit(".", 1)
 120         else:
 121             locale_ = locale_.rsplit(".")[0]
 122     return locale_, encoding(encoding_)
 123