""" Standard "encodings" Package     Standard Python encoding modules are stored in this package    directory.     Codec modules must have names corresponding to normalized encoding    names as defined in the normalize_encoding() function below, e.g.    'utf-8' must be implemented by the module 'utf_8.py'.     Each codec module must export the following interface:     * getregentry() -> codecs.CodecInfo object    The getregentry() API must a CodecInfo object with encoder, decoder,    incrementalencoder, incrementaldecoder, streamwriter and streamreader    atttributes which adhere to the Python Codec Interface Standard.     In addition, a module may optionally also define the following    APIs which are then used by the package's codec search function:     * getaliases() -> sequence of encoding name strings to use as aliases     Alias names returned by getaliases() must be normalized encoding    names as defined by normalize_encoding(). Written by Marc-Andre Lemburg (mal@lemburg.com). (c) Copyright CNRI, All Rights Reserved. NO WARRANTY. """#" import codecs, typesfrom encodings import aliases _cache = {}_unknown = '--unknown--'_import_tail = ['*']_norm_encoding_map = ('                                              . '                      '0123456789       ABCDEFGHIJKLMNOPQRSTUVWXYZ     '                      ' abcdefghijklmnopqrstuvwxyz                     '                      '                                                '                      '                                                '                      '                ')_aliases = aliases.aliases class CodecRegistryError(LookupError, SystemError):    pass def normalize_encoding(encoding):     """ Normalize an encoding name.         Normalization works as follows: all non-alphanumeric        characters except the dot used for Python package names are        collapsed and replaced with a single underscore, e.g. '  -;#'        becomes '_'. Leading and trailing underscores are removed.         Note that encoding names should be ASCII only; if they do use        non-ASCII characters, these must be Latin-1 compatible.     """    # Make sure we have an 8-bit string, because .translate() works    # differently for Unicode strings.    if type(encoding) is types.UnicodeType:        # Note that .encode('latin-1') does *not* use the codec        # registry, so this call doesn't recurse. (See unicodeobject.c        # PyUnicode_AsEncodedString() for details)        encoding = encoding.encode('latin-1')    return '_'.join(encoding.translate(_norm_encoding_map).split()) def search_function(encoding):     # Cache lookup    entry = _cache.get(encoding, _unknown)    if entry is not _unknown:        return entry     # Import the module:    #    # First try to find an alias for the normalized encoding    # name and lookup the module using the aliased name, then try to    # lookup the module using the standard import scheme, i.e. first    # try in the encodings package, then at top-level.    #    norm_encoding = normalize_encoding(encoding)    aliased_encoding = _aliases.get(norm_encoding) or \                       _aliases.get(norm_encoding.replace('.', '_'))    if aliased_encoding is not None:        modnames = [aliased_encoding,                    norm_encoding]    else:        modnames = [norm_encoding]    for modname in modnames:        if not modname or '.' in modname:            continue        try:            mod = __import__('encodings.' + modname,                             globals(), locals(), _import_tail)        except ImportError:            pass        else:            break    else:        mod = None     try:        getregentry = mod.getregentry    except AttributeError:        # Not a codec module        mod = None     if mod is None:        # Cache misses        _cache[encoding] = None        return None     # Now ask the module for the registry entry    entry = getregentry()    if not isinstance(entry, codecs.CodecInfo):        if not 4 <= len(entry) <= 7:            raise CodecRegistryError,\                 'module "%s" (%s) failed to register' % \                  (mod.__name__, mod.__file__)        if not callable(entry[0]) or \           not callable(entry[1]) or \           (entry[2] is not None and not callable(entry[2])) or \           (entry[3] is not None and not callable(entry[3])) or \           (len(entry) > 4 and entry[4] is not None and not callable(entry[4])) or \           (len(entry) > 5 and entry[5] is not None and not callable(entry[5])):            raise CodecRegistryError,\                'incompatible codecs in module "%s" (%s)' % \                (mod.__name__, mod.__file__)        if len(entry)<7 or entry[6] is None:            entry += (None,)*(6-len(entry)) + (mod.__name__.split(".", 1)[1],)        entry = codecs.CodecInfo(*entry)     # Cache the codec registry entry    _cache[encoding] = entry     # Register its aliases (without overwriting previously registered    # aliases)    try:        codecaliases = mod.getaliases()    except AttributeError:        pass    else:        for alias in codecaliases:            if not _aliases.has_key(alias):                _aliases[alias] = modname     # Return the registry entry    return entry # Register the search_function in the Python codec registrycodecs.register(search_function)