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





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



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



"""#"



import __builtin__, sys



### Registry and builtin stateless codec functions



try:

    from _codecs import *

except ImportError, 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",

           "strict_errors", "ignore_errors", "replace_errors",

           "xmlcharrefreplace_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 = '\xef\xbb\xbf'



# UTF-16, little endian

BOM_LE = BOM_UTF16_LE = '\xff\xfe'



# UTF-16, big endian

BOM_BE = BOM_UTF16_BE = '\xfe\xff'



# UTF-32, little endian

BOM_UTF32_LE = '\xff\xfe\x00\x00'



# UTF-32, big endian

BOM_UTF32_BE = '\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):



    def __new__(cls, encode, decode, streamreader=None, streamwriter=None,

        incrementalencoder=None, incrementaldecoder=None, name=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

        return self



    def __repr__(self):

        return "<%s.%s object for encoding %s at 0x%x>" % (self.__class__.__module__, self.__class__.__name__, 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.

         'xmlcharrefreplace' - Replace with the appropriate XML

                               character reference (only for encoding).

         'backslashreplace'  - Replace with backslashed 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

            StreamCodec for codecs which have to keep state in order to

            make encoding/decoding 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

            StreamCodec for codecs which have to keep state in order to

            make encoding/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)

        self.buffer = "" # unencoded input that is kept between calls to encode()



    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'):

        """

        Creates a 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):

        """

        Decodes input and returns the resulting object.

        """

        raise NotImplementedError



    def reset(self):

        """

        Resets 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)

        self.buffer = "" # undecoded input that is kept between calls to decode()



    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 = ""



    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

            (binary) data.



            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 (only for encoding).



            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 __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):



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



        """ Creates a StreamReader instance.



            stream must be a file-like object open for reading

            (binary) data.



            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;



            The set of allowed parameter values can be extended via

            register_error.

        """

        self.stream = stream

        self.errors = errors

        self.bytebuffer = ""

        # For str->str decoding this will stay a str

        # For str->unicode decoding the first read will promote it to unicode

        self.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 characters to read from the

            stream. read() will never return more than chars

            characters, but it might return less, if there are not enough

            characters available.



            size indicates the approximate maximum number of bytes to

            read from the stream for decoding purposes. 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 = "".join(self.linebuffer)

            self.linebuffer = None



        # read until we get the required number of characters (if available)

        while True:

            # can the request can be satisfied from the character buffer?

            if chars < 0:

                if size < 0:

                    if self.charbuffer:

                        break

                elif len(self.charbuffer) >= size:

                    break

            else:

                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

            try:

                newchars, decodedbytes = self.decode(data, self.errors)

            except UnicodeDecodeError, exc:

                if firstline:

                    newchars, decodedbytes = self.decode(data[:exc.start], self.errors)

                    lines = newchars.splitlines(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 = ""

        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(False)[0]

            return line



        readsize = size or 72

        line = ""

        # 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 data.endswith("\r"):

                    data += self.read(size=1, chars=1)



            line += data

            lines = line.splitlines(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(False)[0]

                    break

                line0withend = lines[0]

                line0withoutend = lines[0].splitlines(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 = "".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(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 list of lines.



            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 = ""

        self.charbuffer = u""

        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.reset()

        self.stream.seek(offset, whence)



    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 self.reader.next()



    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 __getattr__(self, name,

                    getattr=getattr):



        """ Inherit all other methods from the underlying stream.

        """

        return getattr(self.stream, name)



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



    def __enter__(self):

        return self



    def __exit__(self, type, value, tb):

        self.stream.close()



###



class StreamRecoder:



    """ StreamRecoder instances provide a frontend - backend

        view of encoding data.



        They use the complete set of APIs returned by the

        codecs.lookup() function to implement their task.



        Data written to the stream is first decoded into an

        intermediate format (which is dependent on the given codec

        combination) and then written to the stream using an instance

        of the provided Writer class.



        In the other direction, data is read from the stream using a

        Reader instance and then return encoded data 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

            input to .read() and output of .write()) while

            Reader and Writer work on the backend (reading and

            writing to the stream).



            You can use these objects to do transparent direct

            recodings from e.g. latin-1 to utf-8 and back.



            stream must be a file-like object.



            encode, decode must adhere to the Codec interface, Reader,

            Writer must be factory functions or classes providing the

            StreamReader, StreamWriter interface resp.



            encode and decode are needed for the frontend translation,

            Reader and Writer for the backend translation. Unicode is

            used as intermediate encoding.



            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(1)



    def next(self):



        """ Return the next decoded line from the input stream."""

        data = self.reader.next()

        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 = ''.join(list)

        data, bytesdecoded = self.decode(data, self.errors)

        return self.writer.write(data)



    def reset(self):



        self.reader.reset()

        self.writer.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()



### Shortcuts



def open(filename, mode='rb', 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.



        Files are always opened in binary mode, even if no binary mode

        was specified. This is done to avoid data loss due to encodings

        using 8-bit values. The default file mode is 'rb' meaning to

        open the file in binary 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 line buffered.



        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 = __builtin__.open(filename, mode, buffering)

    if encoding is None:

        return file

    info = lookup(encoding)

    srw = StreamReaderWriter(file, info.streamreader, info.streamwriter, errors)

    # Add attributes to simplify introspection

    srw.encoding = encoding

    return srw



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



    """ Return a wrapped version of file which provides transparent

        encoding translation.



        Strings written to the wrapped file are interpreted according

        to the given data_encoding and then written to the original

        file as string using file_encoding. The intermediate encoding

        will usually be Unicode but depends on the specified codecs.



        Strings are read from the file using file_encoding and then

        passed back to the caller as string 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 a 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 a 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("", 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.



    """

    res = {}

    for i in rng:

        res[i]=i

    return res



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")

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



# 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')

