""" 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 return a CodecInfo object with encoder, decoder, incrementalencoder, incrementaldecoder, streamwriter and streamreader attributes 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 import sys from . import aliases _cache = {} _unknown = '--unknown--' _import_tail = ['*'] _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 isinstance(encoding, bytes): encoding = str(encoding, "ascii") chars = [] punct = False for c in encoding: if c.isalnum() or c == '.': if punct and chars: chars.append('_') chars.append(c) punct = False else: punct = True return ''.join(chars) 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: # Import is absolute to prevent the possibly malicious import of a # module with side-effects that is not in the 'encodings' package. mod = __import__('encodings.' + modname, fromlist=_import_tail, level=0) except ImportError: # ImportError may occur because 'encodings.(modname)' does not exist, # or because it imports a name that does not exist (see mbcs and oem) 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 alias not in _aliases: _aliases[alias] = modname # Return the registry entry return entry # Register the search_function in the Python codec registry codecs.register(search_function) if sys.platform == 'win32': def _alias_mbcs(encoding): try: import _winapi ansi_code_page = "cp%s" % _winapi.GetACP() if encoding == ansi_code_page: import encodings.mbcs return encodings.mbcs.getregentry() except ImportError: # Imports may fail while we are shutting down pass codecs.register(_alias_mbcs)