""" codecs -- Python Codec Registry, API and helpers.


Written by Marc-Andre Lemburg (mal@lemburg.com).

(c) Copyright CNRI, All Rights Reserved. NO WARRANTY.

"""

import builtins
import sys

### Registry and builtin stateless codec functions

try:
 from _codecs import *
except ImportError as why:
 raise SystemError('Failed to load the builtin codecs: %s' % why)

__all__ = ["register", "lookup", "open", "EncodedFile", "BOM", "BOM_BE",
 "BOM_LE", "BOM32_BE", "BOM32_LE", "BOM64_BE", "BOM64_LE",
 "BOM_UTF8", "BOM_UTF16", "BOM_UTF16_LE", "BOM_UTF16_BE",
 "BOM_UTF32", "BOM_UTF32_LE", "BOM_UTF32_BE",
 "CodecInfo", "Codec", "IncrementalEncoder", "IncrementalDecoder",
 "StreamReader", "StreamWriter",
 "StreamReaderWriter", "StreamRecoder",
 "getencoder", "getdecoder", "getincrementalencoder",
 "getincrementaldecoder", "getreader", "getwriter",
 "encode", "decode", "iterencode", "iterdecode",
 "strict_errors", "ignore_errors", "replace_errors",
 "xmlcharrefreplace_errors",
 "backslashreplace_errors", "namereplace_errors",
 "register_error", "lookup_error"]

### Constants

#
# Byte Order Mark (BOM = ZERO WIDTH NO-BREAK SPACE = U+FEFF)
# and its possible byte string values
# for UTF8/UTF16/UTF32 output and little/big endian machines
#

# UTF-8
BOM_UTF8 = b'\xef\xbb\xbf'

# UTF-16, little endian
BOM_LE = BOM_UTF16_LE = b'\xff\xfe'

# UTF-16, big endian
BOM_BE = BOM_UTF16_BE = b'\xfe\xff'

# UTF-32, little endian
BOM_UTF32_LE = b'\xff\xfe\x00\x00'

# UTF-32, big endian
BOM_UTF32_BE = b'\x00\x00\xfe\xff'

if sys.byteorder == 'little':

 # UTF-16, native endianness
 BOM = BOM_UTF16 = BOM_UTF16_LE

 # UTF-32, native endianness
 BOM_UTF32 = BOM_UTF32_LE

else:

 # UTF-16, native endianness
 BOM = BOM_UTF16 = BOM_UTF16_BE

 # UTF-32, native endianness
 BOM_UTF32 = BOM_UTF32_BE

# Old broken names (don't use in new code)
BOM32_LE = BOM_UTF16_LE
BOM32_BE = BOM_UTF16_BE
BOM64_LE = BOM_UTF32_LE
BOM64_BE = BOM_UTF32_BE


### Codec base classes (defining the API)

class CodecInfo(tuple):
 """Codec details when looking up the codec registry"""

 # Private API to allow Python 3.4 to blacklist the known non-Unicode
 # codecs in the standard library. A more general mechanism to
 # reliably distinguish test encodings from other codecs will hopefully
 # be defined for Python 3.5
 #
 # See http://bugs.python.org/issue19619
 _is_text_encoding = True # Assume codecs are text encodings by default

 def __new__(cls, encode, decode, streamreader=None, streamwriter=None,
 incrementalencoder=None, incrementaldecoder=None, name=None,
 *, _is_text_encoding=None):
 self = tuple.__new__(cls, (encode, decode, streamreader, streamwriter))
 self.name = name
 self.encode = encode
 self.decode = decode
 self.incrementalencoder = incrementalencoder
 self.incrementaldecoder = incrementaldecoder
 self.streamwriter = streamwriter
 self.streamreader = streamreader
 if _is_text_encoding is not None:
 self._is_text_encoding = _is_text_encoding
 return self

 def __repr__(self):
 return "<%s.%s object for encoding %s at %#x>" % \
 (self.__class__.__module__, self.__class__.__qualname__,
 self.name, id(self))

class Codec:

 """ Defines the interface for stateless encoders/decoders.

 The .encode()/.decode() methods may use different error
 handling schemes by providing the errors argument. These
 string values are predefined:

 'strict' - raise a ValueError error (or a subclass)
 'ignore' - ignore the character and continue with the next
 'replace' - replace with a suitable replacement character;
 Python will use the official U+FFFD REPLACEMENT
 CHARACTER for the builtin Unicode codecs on
 decoding and '?' on encoding.
 'surrogateescape' - replace with private code points U+DCnn.
 'xmlcharrefreplace' - Replace with the appropriate XML
 character reference (only for encoding).
 'backslashreplace' - Replace with backslashed escape sequences.
 'namereplace' - Replace with \\N{...} escape sequences
 (only for encoding).

 The set of allowed values can be extended via register_error.

 """
 def encode(self, input, errors='strict'):

 """ Encodes the object input and returns a tuple (output
 object, length consumed).

 errors defines the error handling to apply. It defaults to
 'strict' handling.

 The method may not store state in the Codec instance. Use
 StreamWriter for codecs which have to keep state in order to
 make encoding efficient.

 The encoder must be able to handle zero length input and
 return an empty object of the output object type in this
 situation.

 """
 raise NotImplementedError

 def decode(self, input, errors='strict'):

 """ Decodes the object input and returns a tuple (output
 object, length consumed).

 input must be an object which provides the bf_getreadbuf
 buffer slot. Python strings, buffer objects and memory
 mapped files are examples of objects providing this slot.

 errors defines the error handling to apply. It defaults to
 'strict' handling.

 The method may not store state in the Codec instance. Use
 StreamReader for codecs which have to keep state in order to
 make decoding efficient.

 The decoder must be able to handle zero length input and
 return an empty object of the output object type in this
 situation.

 """
 raise NotImplementedError

class IncrementalEncoder(object):
 """
 An IncrementalEncoder encodes an input in multiple steps. The input can
 be passed piece by piece to the encode() method. The IncrementalEncoder
 remembers the state of the encoding process between calls to encode().
 """
 def __init__(self, errors='strict'):
 """
 Creates an IncrementalEncoder instance.

 The IncrementalEncoder may use different error handling schemes by
 providing the errors keyword argument. See the module docstring
 for a list of possible values.
 """
 self.errors = errors
 self.buffer = ""

 def encode(self, input, final=False):
 """
 Encodes input and returns the resulting object.
 """
 raise NotImplementedError

 def reset(self):
 """
 Resets the encoder to the initial state.
 """

 def getstate(self):
 """
 Return the current state of the encoder.
 """
 return 0

 def setstate(self, state):
 """
 Set the current state of the encoder. state must have been
 returned by getstate().
 """

class BufferedIncrementalEncoder(IncrementalEncoder):
 """
 This subclass of IncrementalEncoder can be used as the baseclass for an
 incremental encoder if the encoder must keep some of the output in a
 buffer between calls to encode().
 """
 def __init__(self, errors='strict'):
 IncrementalEncoder.__init__(self, errors)
 # unencoded input that is kept between calls to encode()
 self.buffer = ""

 def _buffer_encode(self, input, errors, final):
 # Overwrite this method in subclasses: It must encode input
 # and return an (output, length consumed) tuple
 raise NotImplementedError

 def encode(self, input, final=False):
 # encode input (taking the buffer into account)
 data = self.buffer + input
 (result, consumed) = self._buffer_encode(data, self.errors, final)
 # keep unencoded input until the next call
 self.buffer = data[consumed:]
 return result

 def reset(self):
 IncrementalEncoder.reset(self)
 self.buffer = ""

 def getstate(self):
 return self.buffer or 0

 def setstate(self, state):
 self.buffer = state or ""

class IncrementalDecoder(object):
 """
 An IncrementalDecoder decodes an input in multiple steps. The input can
 be passed piece by piece to the decode() method. The IncrementalDecoder
 remembers the state of the decoding process between calls to decode().
 """
 def __init__(self, errors='strict'):
 """
 Create an IncrementalDecoder instance.

 The IncrementalDecoder may use different error handling schemes by
 providing the errors keyword argument. See the module docstring
 for a list of possible values.
 """
 self.errors = errors

 def decode(self, input, final=False):
 """
 Decode input and returns the resulting object.
 """
 raise NotImplementedError

 def reset(self):
 """
 Reset the decoder to the initial state.
 """

 def getstate(self):
 """
 Return the current state of the decoder.

 This must be a (buffered_input, additional_state_info) tuple.
 buffered_input must be a bytes object containing bytes that
 were passed to decode() that have not yet been converted.
 additional_state_info must be a non-negative integer
 representing the state of the decoder WITHOUT yet having
 processed the contents of buffered_input. In the initial state
 and after reset(), getstate() must return (b"", 0).
 """
 return (b"", 0)

 def setstate(self, state):
 """
 Set the current state of the decoder.

 state must have been returned by getstate(). The effect of
 setstate((b"", 0)) must be equivalent to reset().
 """

class BufferedIncrementalDecoder(IncrementalDecoder):
 """
 This subclass of IncrementalDecoder can be used as the baseclass for an
 incremental decoder if the decoder must be able to handle incomplete
 byte sequences.
 """
 def __init__(self, errors='strict'):
 IncrementalDecoder.__init__(self, errors)
 # undecoded input that is kept between calls to decode()
 self.buffer = b""

 def _buffer_decode(self, input, errors, final):
 # Overwrite this method in subclasses: It must decode input
 # and return an (output, length consumed) tuple
 raise NotImplementedError

 def decode(self, input, final=False):
 # decode input (taking the buffer into account)
 data = self.buffer + input
 (result, consumed) = self._buffer_decode(data, self.errors, final)
 # keep undecoded input until the next call
 self.buffer = data[consumed:]
 return result

 def reset(self):
 IncrementalDecoder.reset(self)
 self.buffer = b""

 def getstate(self):
 # additional state info is always 0
 return (self.buffer, 0)

 def setstate(self, state):
 # ignore additional state info
 self.buffer = state[0]

#
# The StreamWriter and StreamReader class provide generic working
# interfaces which can be used to implement new encoding submodules
# very easily. See encodings/utf_8.py for an example on how this is
# done.
#

class StreamWriter(Codec):

 def __init__(self, stream, errors='strict'):

 """ Creates a StreamWriter instance.

 stream must be a file-like object open for writing.

 The StreamWriter may use different error handling
 schemes by providing the errors keyword argument. These
 parameters are predefined:

 'strict' - raise a ValueError (or a subclass)
 'ignore' - ignore the character and continue with the next
 'replace'- replace with a suitable replacement character
 'xmlcharrefreplace' - Replace with the appropriate XML
 character reference.
 'backslashreplace' - Replace with backslashed escape
 sequences.
 'namereplace' - Replace with \\N{...} escape sequences.

 The set of allowed parameter values can be extended via
 register_error.
 """
 self.stream = stream
 self.errors = errors

 def write(self, object):

 """ Writes the object's contents encoded to self.stream.
 """
 data, consumed = self.encode(object, self.errors)
 self.stream.write(data)

 def writelines(self, list):

 """ Writes the concatenated list of strings to the stream
 using .write().
 """
 self.write(''.join(list))

 def reset(self):

 """ Flushes and resets the codec buffers used for keeping state.

 Calling this method should ensure that the data on the
 output is put into a clean state, that allows appending
 of new fresh data without having to rescan the whole
 stream to recover state.

 """
 pass

 def seek(self, offset, whence=0):
 self.stream.seek(offset, whence)
 if whence == 0 and offset == 0:
 self.reset()

 def __getattr__(self, name,
 getattr=getattr):

 """ Inherit all other methods from the underlying stream.
 """
 return getattr(self.stream, name)

 def __enter__(self):
 return self

 def __exit__(self, type, value, tb):
 self.stream.close()

###

class StreamReader(Codec):

 charbuffertype = str

 def __init__(self, stream, errors='strict'):

 """ Creates a StreamReader instance.

 stream must be a file-like object open for reading.

 The StreamReader may use different error handling
 schemes by providing the errors keyword argument. These
 parameters are predefined:

 'strict' - raise a ValueError (or a subclass)
 'ignore' - ignore the character and continue with the next
 'replace'- replace with a suitable replacement character
 'backslashreplace' - Replace with backslashed escape sequences;

 The set of allowed parameter values can be extended via
 register_error.
 """
 self.stream = stream
 self.errors = errors
 self.bytebuffer = b""
 self._empty_charbuffer = self.charbuffertype()
 self.charbuffer = self._empty_charbuffer
 self.linebuffer = None

 def decode(self, input, errors='strict'):
 raise NotImplementedError

 def read(self, size=-1, chars=-1, firstline=False):

 """ Decodes data from the stream self.stream and returns the
 resulting object.

 chars indicates the number of decoded code points or bytes to
 return. read() will never return more data than requested,
 but it might return less, if there is not enough available.

 size indicates the approximate maximum number of decoded
 bytes or code points to read for decoding. The decoder
 can modify this setting as appropriate. The default value
 -1 indicates to read and decode as much as possible. size
 is intended to prevent having to decode huge files in one
 step.

 If firstline is true, and a UnicodeDecodeError happens
 after the first line terminator in the input only the first line
 will be returned, the rest of the input will be kept until the
 next call to read().

 The method should use a greedy read strategy, meaning that
 it should read as much data as is allowed within the
 definition of the encoding and the given size, e.g. if
 optional encoding endings or state markers are available
 on the stream, these should be read too.
 """
 # If we have lines cached, first merge them back into characters
 if self.linebuffer:
 self.charbuffer = self._empty_charbuffer.join(self.linebuffer)
 self.linebuffer = None

 if chars < 0:
 # For compatibility with other read() methods that take a
 # single argument
 chars = size

 # read until we get the required number of characters (if available)
 while True:
 # can the request be satisfied from the character buffer?
 if chars >= 0:
 if len(self.charbuffer) >= chars:
 break
 # we need more data
 if size < 0:
 newdata = self.stream.read()
 else:
 newdata = self.stream.read(size)
 # decode bytes (those remaining from the last call included)
 data = self.bytebuffer + newdata
 if not data:
 break
 try:
 newchars, decodedbytes = self.decode(data, self.errors)
 except UnicodeDecodeError as exc:
 if firstline:
 newchars, decodedbytes = \
 self.decode(data[:exc.start], self.errors)
 lines = newchars.splitlines(keepends=True)
 if len(lines)<=1:
 raise
 else:
 raise
 # keep undecoded bytes until the next call
 self.bytebuffer = data[decodedbytes:]
 # put new characters in the character buffer
 self.charbuffer += newchars
 # there was no data available
 if not newdata:
 break
 if chars < 0:
 # Return everything we've got
 result = self.charbuffer
 self.charbuffer = self._empty_charbuffer
 else:
 # Return the first chars characters
 result = self.charbuffer[:chars]
 self.charbuffer = self.charbuffer[chars:]
 return result

 def readline(self, size=None, keepends=True):

 """ Read one line from the input stream and return the
 decoded data.

 size, if given, is passed as size argument to the
 read() method.

 """
 # If we have lines cached from an earlier read, return
 # them unconditionally
 if self.linebuffer:
 line = self.linebuffer[0]
 del self.linebuffer[0]
 if len(self.linebuffer) == 1:
 # revert to charbuffer mode; we might need more data
 # next time
 self.charbuffer = self.linebuffer[0]
 self.linebuffer = None
 if not keepends:
 line = line.splitlines(keepends=False)[0]
 return line

 readsize = size or 72
 line = self._empty_charbuffer
 # If size is given, we call read() only once
 while True:
 data = self.read(readsize, firstline=True)
 if data:
 # If we're at a "\r" read one extra character (which might
 # be a "\n") to get a proper line ending. If the stream is
 # temporarily exhausted we return the wrong line ending.
 if (isinstance(data, str) and data.endswith("\r")) or \
 (isinstance(data, bytes) and data.endswith(b"\r")):
 data += self.read(size=1, chars=1)

 line += data
 lines = line.splitlines(keepends=True)
 if lines:
 if len(lines) > 1:
 # More than one line result; the first line is a full line
 # to return
 line = lines[0]
 del lines[0]
 if len(lines) > 1:
 # cache the remaining lines
 lines[-1] += self.charbuffer
 self.linebuffer = lines
 self.charbuffer = None
 else:
 # only one remaining line, put it back into charbuffer
 self.charbuffer = lines[0] + self.charbuffer
 if not keepends:
 line = line.splitlines(keepends=False)[0]
 break
 line0withend = lines[0]
 line0withoutend = lines[0].splitlines(keepends=False)[0]
 if line0withend != line0withoutend: # We really have a line end
 # Put the rest back together and keep it until the next call
 self.charbuffer = self._empty_charbuffer.join(lines[1:]) + \
 self.charbuffer
 if keepends:
 line = line0withend
 else:
 line = line0withoutend
 break
 # we didn't get anything or this was our only try
 if not data or size is not None:
 if line and not keepends:
 line = line.splitlines(keepends=False)[0]
 break
 if readsize < 8000:
 readsize *= 2
 return line

 def readlines(self, sizehint=None, keepends=True):

 """ Read all lines available on the input stream
 and return them as a list.

 Line breaks are implemented using the codec's decoder
 method and are included in the list entries.

 sizehint, if given, is ignored since there is no efficient
 way to finding the true end-of-line.

 """
 data = self.read()
 return data.splitlines(keepends)

 def reset(self):

 """ Resets the codec buffers used for keeping state.

 Note that no stream repositioning should take place.
 This method is primarily intended to be able to recover
 from decoding errors.

 """
 self.bytebuffer = b""
 self.charbuffer = self._empty_charbuffer
 self.linebuffer = None

 def seek(self, offset, whence=0):
 """ Set the input stream's current position.

 Resets the codec buffers used for keeping state.
 """
 self.stream.seek(offset, whence)
 self.reset()

 def __next__(self):

 """ Return the next decoded line from the input stream."""
 line = self.readline()
 if line:
 return line
 raise StopIteration

 def __iter__(self):
 return self

 def __getattr__(self, name,
 getattr=getattr):

 """ Inherit all other methods from the underlying stream.
 """
 return getattr(self.stream, name)

 def __enter__(self):
 return self

 def __exit__(self, type, value, tb):
 self.stream.close()

###

class StreamReaderWriter:

 """ StreamReaderWriter instances allow wrapping streams which
 work in both read and write modes.

 The design is such that one can use the factory functions
 returned by the codec.lookup() function to construct the
 instance.

 """
 # Optional attributes set by the file wrappers below
 encoding = 'unknown'

 def __init__(self, stream, Reader, Writer, errors='strict'):

 """ Creates a StreamReaderWriter instance.

 stream must be a Stream-like object.

 Reader, Writer must be factory functions or classes
 providing the StreamReader, StreamWriter interface resp.

 Error handling is done in the same way as defined for the
 StreamWriter/Readers.

 """
 self.stream = stream
 self.reader = Reader(stream, errors)
 self.writer = Writer(stream, errors)
 self.errors = errors

 def read(self, size=-1):

 return self.reader.read(size)

 def readline(self, size=None):

 return self.reader.readline(size)

 def readlines(self, sizehint=None):

 return self.reader.readlines(sizehint)

 def __next__(self):

 """ Return the next decoded line from the input stream."""
 return next(self.reader)

 def __iter__(self):
 return self

 def write(self, data):

 return self.writer.write(data)

 def writelines(self, list):

 return self.writer.writelines(list)

 def reset(self):

 self.reader.reset()
 self.writer.reset()

 def seek(self, offset, whence=0):
 self.stream.seek(offset, whence)
 self.reader.reset()
 if whence == 0 and offset == 0:
 self.writer.reset()

 def __getattr__(self, name,
 getattr=getattr):

 """ Inherit all other methods from the underlying stream.
 """
 return getattr(self.stream, name)

 # these are needed to make "with StreamReaderWriter(...)" work properly

 def __enter__(self):
 return self

 def __exit__(self, type, value, tb):
 self.stream.close()

###

class StreamRecoder:

 """ StreamRecoder instances translate data from one encoding to another.

 They use the complete set of APIs returned by the
 codecs.lookup() function to implement their task.

 Data written to the StreamRecoder is first decoded into an
 intermediate format (depending on the "decode" codec) and then
 written to the underlying stream using an instance of the provided
 Writer class.

 In the other direction, data is read from the underlying stream using
 a Reader instance and then encoded and returned to the caller.

 """
 # Optional attributes set by the file wrappers below
 data_encoding = 'unknown'
 file_encoding = 'unknown'

 def __init__(self, stream, encode, decode, Reader, Writer,
 errors='strict'):

 """ Creates a StreamRecoder instance which implements a two-way
 conversion: encode and decode work on the frontend (the
 data visible to .read() and .write()) while Reader and Writer
 work on the backend (the data in stream).

 You can use these objects to do transparent
 transcodings from e.g. latin-1 to utf-8 and back.

 stream must be a file-like object.

 encode and decode must adhere to the Codec interface; Reader and
 Writer must be factory functions or classes providing the
 StreamReader and StreamWriter interfaces resp.

 Error handling is done in the same way as defined for the
 StreamWriter/Readers.

 """
 self.stream = stream
 self.encode = encode
 self.decode = decode
 self.reader = Reader(stream, errors)
 self.writer = Writer(stream, errors)
 self.errors = errors

 def read(self, size=-1):

 data = self.reader.read(size)
 data, bytesencoded = self.encode(data, self.errors)
 return data

 def readline(self, size=None):

 if size is None:
 data = self.reader.readline()
 else:
 data = self.reader.readline(size)
 data, bytesencoded = self.encode(data, self.errors)
 return data

 def readlines(self, sizehint=None):

 data = self.reader.read()
 data, bytesencoded = self.encode(data, self.errors)
 return data.splitlines(keepends=True)

 def __next__(self):

 """ Return the next decoded line from the input stream."""
 data = next(self.reader)
 data, bytesencoded = self.encode(data, self.errors)
 return data

 def __iter__(self):
 return self

 def write(self, data):

 data, bytesdecoded = self.decode(data, self.errors)
 return self.writer.write(data)

 def writelines(self, list):

 data = b''.join(list)
 data, bytesdecoded = self.decode(data, self.errors)
 return self.writer.write(data)

 def reset(self):

 self.reader.reset()
 self.writer.reset()

 def seek(self, offset, whence=0):
 # Seeks must be propagated to both the readers and writers
 # as they might need to reset their internal buffers.
 self.reader.seek(offset, whence)
 self.writer.seek(offset, whence)

 def __getattr__(self, name,
 getattr=getattr):

 """ Inherit all other methods from the underlying stream.
 """
 return getattr(self.stream, name)

 def __enter__(self):
 return self

 def __exit__(self, type, value, tb):
 self.stream.close()

### Shortcuts

def open(filename, mode='r', encoding=None, errors='strict', buffering=-1):

 """ Open an encoded file using the given mode and return
 a wrapped version providing transparent encoding/decoding.

 Note: The wrapped version will only accept the object format
 defined by the codecs, i.e. Unicode objects for most builtin
 codecs. Output is also codec dependent and will usually be
 Unicode as well.

 Underlying encoded files are always opened in binary mode.
 The default file mode is 'r', meaning to open the file in read mode.

 encoding specifies the encoding which is to be used for the
 file.

 errors may be given to define the error handling. It defaults
 to 'strict' which causes ValueErrors to be raised in case an
 encoding error occurs.

 buffering has the same meaning as for the builtin open() API.
 It defaults to -1 which means that the default buffer size will
 be used.

 The returned wrapped file object provides an extra attribute
 .encoding which allows querying the used encoding. This
 attribute is only available if an encoding was specified as
 parameter.

 """
 if encoding is not None and \
 'b' not in mode:
 # Force opening of the file in binary mode
 mode = mode + 'b'
 file = builtins.open(filename, mode, buffering)
 if encoding is None:
 return file

 try:
 info = lookup(encoding)
 srw = StreamReaderWriter(file, info.streamreader, info.streamwriter, errors)
 # Add attributes to simplify introspection
 srw.encoding = encoding
 return srw
 except:
 file.close()
 raise

def EncodedFile(file, data_encoding, file_encoding=None, errors='strict'):

 """ Return a wrapped version of file which provides transparent
 encoding translation.

 Data written to the wrapped file is decoded according
 to the given data_encoding and then encoded to the underlying
 file using file_encoding. The intermediate data type
 will usually be Unicode but depends on the specified codecs.

 Bytes read from the file are decoded using file_encoding and then
 passed back to the caller encoded using data_encoding.

 If file_encoding is not given, it defaults to data_encoding.

 errors may be given to define the error handling. It defaults
 to 'strict' which causes ValueErrors to be raised in case an
 encoding error occurs.

 The returned wrapped file object provides two extra attributes
 .data_encoding and .file_encoding which reflect the given
 parameters of the same name. The attributes can be used for
 introspection by Python programs.

 """
 if file_encoding is None:
 file_encoding = data_encoding
 data_info = lookup(data_encoding)
 file_info = lookup(file_encoding)
 sr = StreamRecoder(file, data_info.encode, data_info.decode,
 file_info.streamreader, file_info.streamwriter, errors)
 # Add attributes to simplify introspection
 sr.data_encoding = data_encoding
 sr.file_encoding = file_encoding
 return sr

### Helpers for codec lookup

def getencoder(encoding):

 """ Lookup up the codec for the given encoding and return
 its encoder function.

 Raises a LookupError in case the encoding cannot be found.

 """
 return lookup(encoding).encode

def getdecoder(encoding):

 """ Lookup up the codec for the given encoding and return
 its decoder function.

 Raises a LookupError in case the encoding cannot be found.

 """
 return lookup(encoding).decode

def getincrementalencoder(encoding):

 """ Lookup up the codec for the given encoding and return
 its IncrementalEncoder class or factory function.

 Raises a LookupError in case the encoding cannot be found
 or the codecs doesn't provide an incremental encoder.

 """
 encoder = lookup(encoding).incrementalencoder
 if encoder is None:
 raise LookupError(encoding)
 return encoder

def getincrementaldecoder(encoding):

 """ Lookup up the codec for the given encoding and return
 its IncrementalDecoder class or factory function.

 Raises a LookupError in case the encoding cannot be found
 or the codecs doesn't provide an incremental decoder.

 """
 decoder = lookup(encoding).incrementaldecoder
 if decoder is None:
 raise LookupError(encoding)
 return decoder

def getreader(encoding):

 """ Lookup up the codec for the given encoding and return
 its StreamReader class or factory function.

 Raises a LookupError in case the encoding cannot be found.

 """
 return lookup(encoding).streamreader

def getwriter(encoding):

 """ Lookup up the codec for the given encoding and return
 its StreamWriter class or factory function.

 Raises a LookupError in case the encoding cannot be found.

 """
 return lookup(encoding).streamwriter

def iterencode(iterator, encoding, errors='strict', **kwargs):
 """
 Encoding iterator.

 Encodes the input strings from the iterator using an IncrementalEncoder.

 errors and kwargs are passed through to the IncrementalEncoder
 constructor.
 """
 encoder = getincrementalencoder(encoding)(errors, **kwargs)
 for input in iterator:
 output = encoder.encode(input)
 if output:
 yield output
 output = encoder.encode("", True)
 if output:
 yield output

def iterdecode(iterator, encoding, errors='strict', **kwargs):
 """
 Decoding iterator.

 Decodes the input strings from the iterator using an IncrementalDecoder.

 errors and kwargs are passed through to the IncrementalDecoder
 constructor.
 """
 decoder = getincrementaldecoder(encoding)(errors, **kwargs)
 for input in iterator:
 output = decoder.decode(input)
 if output:
 yield output
 output = decoder.decode(b"", True)
 if output:
 yield output

### Helpers for charmap-based codecs

def make_identity_dict(rng):

 """ make_identity_dict(rng) -> dict

 Return a dictionary where elements of the rng sequence are
 mapped to themselves.

 """
 return {i:i for i in rng}

def make_encoding_map(decoding_map):

 """ Creates an encoding map from a decoding map.

 If a target mapping in the decoding map occurs multiple
 times, then that target is mapped to None (undefined mapping),
 causing an exception when encountered by the charmap codec
 during translation.

 One example where this happens is cp875.py which decodes
 multiple character to \\u001a.

 """
 m = {}
 for k,v in decoding_map.items():
 if not v in m:
 m[v] = k
 else:
 m[v] = None
 return m

### error handlers

try:
 strict_errors = lookup_error("strict")
 ignore_errors = lookup_error("ignore")
 replace_errors = lookup_error("replace")
 xmlcharrefreplace_errors = lookup_error("xmlcharrefreplace")
 backslashreplace_errors = lookup_error("backslashreplace")
 namereplace_errors = lookup_error("namereplace")
except LookupError:
 # In --disable-unicode builds, these error handler are missing
 strict_errors = None
 ignore_errors = None
 replace_errors = None
 xmlcharrefreplace_errors = None
 backslashreplace_errors = None
 namereplace_errors = None

# Tell modulefinder that using codecs probably needs the encodings
# package
_false = 0
if _false:
 import encodings

### Tests

if __name__ == '__main__':

 # Make stdout translate Latin-1 output into UTF-8 output
 sys.stdout = EncodedFile(sys.stdout, 'latin-1', 'utf-8')

 # Have stdin translate Latin-1 input into UTF-8 input
 sys.stdin = EncodedFile(sys.stdin, 'utf-8', 'latin-1')