""" 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 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): | |
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.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 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 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 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: | |
if 'U' in mode: | |
# No automatic conversion of '\n' is done on reading and writing | |
mode = mode.strip().replace('U', '') | |
if mode[:1] not in set('rwa'): | |
mode = 'r' + mode | |
if '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') |