mirror of
https://github.com/SickGear/SickGear.git
synced 2024-12-18 08:43:37 +00:00
342 lines
10 KiB
Python
342 lines
10 KiB
Python
# coding: utf-8
|
||
"""
|
||
|
||
webencodings
|
||
~~~~~~~~~~~~
|
||
|
||
This is a Python implementation of the `WHATWG Encoding standard
|
||
<http://encoding.spec.whatwg.org/>`. See README for details.
|
||
|
||
:copyright: Copyright 2012 by Simon Sapin
|
||
:license: BSD, see LICENSE for details.
|
||
|
||
"""
|
||
|
||
from __future__ import unicode_literals
|
||
|
||
import codecs
|
||
|
||
from .labels import LABELS
|
||
|
||
|
||
VERSION = '0.5.1'
|
||
|
||
|
||
# Some names in Encoding are not valid Python aliases. Remap these.
|
||
PYTHON_NAMES = {
|
||
'iso-8859-8-i': 'iso-8859-8',
|
||
'x-mac-cyrillic': 'mac-cyrillic',
|
||
'macintosh': 'mac-roman',
|
||
'windows-874': 'cp874'}
|
||
|
||
CACHE = {}
|
||
|
||
|
||
def ascii_lower(string):
|
||
r"""Transform (only) ASCII letters to lower case: A-Z is mapped to a-z.
|
||
|
||
:param string: An Unicode string.
|
||
:returns: A new Unicode string.
|
||
|
||
This is used for `ASCII case-insensitive
|
||
<http://encoding.spec.whatwg.org/#ascii-case-insensitive>`_
|
||
matching of encoding labels.
|
||
The same matching is also used, among other things,
|
||
for `CSS keywords <http://dev.w3.org/csswg/css-values/#keywords>`_.
|
||
|
||
This is different from the :meth:`~py:str.lower` method of Unicode strings
|
||
which also affect non-ASCII characters,
|
||
sometimes mapping them into the ASCII range:
|
||
|
||
>>> keyword = u'Bac\N{KELVIN SIGN}ground'
|
||
>>> assert keyword.lower() == u'background'
|
||
>>> assert ascii_lower(keyword) != keyword.lower()
|
||
>>> assert ascii_lower(keyword) == u'bac\N{KELVIN SIGN}ground'
|
||
|
||
"""
|
||
# This turns out to be faster than unicode.translate()
|
||
return string.encode('utf8').lower().decode('utf8')
|
||
|
||
|
||
def lookup(label):
|
||
"""
|
||
Look for an encoding by its label.
|
||
This is the spec’s `get an encoding
|
||
<http://encoding.spec.whatwg.org/#concept-encoding-get>`_ algorithm.
|
||
Supported labels are listed there.
|
||
|
||
:param label: A string.
|
||
:returns:
|
||
An :class:`Encoding` object, or :obj:`None` for an unknown label.
|
||
|
||
"""
|
||
# Only strip ASCII whitespace: U+0009, U+000A, U+000C, U+000D, and U+0020.
|
||
label = ascii_lower(label.strip('\t\n\f\r '))
|
||
name = LABELS.get(label)
|
||
if name is None:
|
||
return None
|
||
encoding = CACHE.get(name)
|
||
if encoding is None:
|
||
if name == 'x-user-defined':
|
||
from .x_user_defined import codec_info
|
||
else:
|
||
python_name = PYTHON_NAMES.get(name, name)
|
||
# Any python_name value that gets to here should be valid.
|
||
codec_info = codecs.lookup(python_name)
|
||
encoding = Encoding(name, codec_info)
|
||
CACHE[name] = encoding
|
||
return encoding
|
||
|
||
|
||
def _get_encoding(encoding_or_label):
|
||
"""
|
||
Accept either an encoding object or label.
|
||
|
||
:param encoding: An :class:`Encoding` object or a label string.
|
||
:returns: An :class:`Encoding` object.
|
||
:raises: :exc:`~exceptions.LookupError` for an unknown label.
|
||
|
||
"""
|
||
if hasattr(encoding_or_label, 'codec_info'):
|
||
return encoding_or_label
|
||
|
||
encoding = lookup(encoding_or_label)
|
||
if encoding is None:
|
||
raise LookupError('Unknown encoding label: %r' % encoding_or_label)
|
||
return encoding
|
||
|
||
|
||
class Encoding(object):
|
||
"""Reresents a character encoding such as UTF-8,
|
||
that can be used for decoding or encoding.
|
||
|
||
.. attribute:: name
|
||
|
||
Canonical name of the encoding
|
||
|
||
.. attribute:: codec_info
|
||
|
||
The actual implementation of the encoding,
|
||
a stdlib :class:`~codecs.CodecInfo` object.
|
||
See :func:`codecs.register`.
|
||
|
||
"""
|
||
def __init__(self, name, codec_info):
|
||
self.name = name
|
||
self.codec_info = codec_info
|
||
|
||
def __repr__(self):
|
||
return '<Encoding %s>' % self.name
|
||
|
||
|
||
#: The UTF-8 encoding. Should be used for new content and formats.
|
||
UTF8 = lookup('utf-8')
|
||
|
||
_UTF16LE = lookup('utf-16le')
|
||
_UTF16BE = lookup('utf-16be')
|
||
|
||
|
||
def decode(input, fallback_encoding, errors='replace'):
|
||
"""
|
||
Decode a single string.
|
||
|
||
:param input: A byte string
|
||
:param fallback_encoding:
|
||
An :class:`Encoding` object or a label string.
|
||
The encoding to use if :obj:`input` does note have a BOM.
|
||
:param errors: Type of error handling. See :func:`codecs.register`.
|
||
:raises: :exc:`~exceptions.LookupError` for an unknown encoding label.
|
||
:return:
|
||
A ``(output, encoding)`` tuple of an Unicode string
|
||
and an :obj:`Encoding`.
|
||
|
||
"""
|
||
# Fail early if `encoding` is an invalid label.
|
||
fallback_encoding = _get_encoding(fallback_encoding)
|
||
bom_encoding, input = _detect_bom(input)
|
||
encoding = bom_encoding or fallback_encoding
|
||
return encoding.codec_info.decode(input, errors)[0], encoding
|
||
|
||
|
||
def _detect_bom(input):
|
||
"""Return (bom_encoding, input), with any BOM removed from the input."""
|
||
if input.startswith(b'\xFF\xFE'):
|
||
return _UTF16LE, input[2:]
|
||
if input.startswith(b'\xFE\xFF'):
|
||
return _UTF16BE, input[2:]
|
||
if input.startswith(b'\xEF\xBB\xBF'):
|
||
return UTF8, input[3:]
|
||
return None, input
|
||
|
||
|
||
def encode(input, encoding=UTF8, errors='strict'):
|
||
"""
|
||
Encode a single string.
|
||
|
||
:param input: An Unicode string.
|
||
:param encoding: An :class:`Encoding` object or a label string.
|
||
:param errors: Type of error handling. See :func:`codecs.register`.
|
||
:raises: :exc:`~exceptions.LookupError` for an unknown encoding label.
|
||
:return: A byte string.
|
||
|
||
"""
|
||
return _get_encoding(encoding).codec_info.encode(input, errors)[0]
|
||
|
||
|
||
def iter_decode(input, fallback_encoding, errors='replace'):
|
||
"""
|
||
"Pull"-based decoder.
|
||
|
||
:param input:
|
||
An iterable of byte strings.
|
||
|
||
The input is first consumed just enough to determine the encoding
|
||
based on the precense of a BOM,
|
||
then consumed on demand when the return value is.
|
||
:param fallback_encoding:
|
||
An :class:`Encoding` object or a label string.
|
||
The encoding to use if :obj:`input` does note have a BOM.
|
||
:param errors: Type of error handling. See :func:`codecs.register`.
|
||
:raises: :exc:`~exceptions.LookupError` for an unknown encoding label.
|
||
:returns:
|
||
An ``(output, encoding)`` tuple.
|
||
:obj:`output` is an iterable of Unicode strings,
|
||
:obj:`encoding` is the :obj:`Encoding` that is being used.
|
||
|
||
"""
|
||
|
||
decoder = IncrementalDecoder(fallback_encoding, errors)
|
||
generator = _iter_decode_generator(input, decoder)
|
||
encoding = next(generator)
|
||
return generator, encoding
|
||
|
||
|
||
def _iter_decode_generator(input, decoder):
|
||
"""Return a generator that first yields the :obj:`Encoding`,
|
||
then yields output chukns as Unicode strings.
|
||
|
||
"""
|
||
decode = decoder.decode
|
||
input = iter(input)
|
||
for chunck in input:
|
||
output = decode(chunck)
|
||
if output:
|
||
assert decoder.encoding is not None
|
||
yield decoder.encoding
|
||
yield output
|
||
break
|
||
else:
|
||
# Input exhausted without determining the encoding
|
||
output = decode(b'', final=True)
|
||
assert decoder.encoding is not None
|
||
yield decoder.encoding
|
||
if output:
|
||
yield output
|
||
return
|
||
|
||
for chunck in input:
|
||
output = decode(chunck)
|
||
if output:
|
||
yield output
|
||
output = decode(b'', final=True)
|
||
if output:
|
||
yield output
|
||
|
||
|
||
def iter_encode(input, encoding=UTF8, errors='strict'):
|
||
"""
|
||
“Pull”-based encoder.
|
||
|
||
:param input: An iterable of Unicode strings.
|
||
:param encoding: An :class:`Encoding` object or a label string.
|
||
:param errors: Type of error handling. See :func:`codecs.register`.
|
||
:raises: :exc:`~exceptions.LookupError` for an unknown encoding label.
|
||
:returns: An iterable of byte strings.
|
||
|
||
"""
|
||
# Fail early if `encoding` is an invalid label.
|
||
encode = IncrementalEncoder(encoding, errors).encode
|
||
return _iter_encode_generator(input, encode)
|
||
|
||
|
||
def _iter_encode_generator(input, encode):
|
||
for chunck in input:
|
||
output = encode(chunck)
|
||
if output:
|
||
yield output
|
||
output = encode('', final=True)
|
||
if output:
|
||
yield output
|
||
|
||
|
||
class IncrementalDecoder(object):
|
||
"""
|
||
“Push”-based decoder.
|
||
|
||
:param fallback_encoding:
|
||
An :class:`Encoding` object or a label string.
|
||
The encoding to use if :obj:`input` does note have a BOM.
|
||
:param errors: Type of error handling. See :func:`codecs.register`.
|
||
:raises: :exc:`~exceptions.LookupError` for an unknown encoding label.
|
||
|
||
"""
|
||
def __init__(self, fallback_encoding, errors='replace'):
|
||
# Fail early if `encoding` is an invalid label.
|
||
self._fallback_encoding = _get_encoding(fallback_encoding)
|
||
self._errors = errors
|
||
self._buffer = b''
|
||
self._decoder = None
|
||
#: The actual :class:`Encoding` that is being used,
|
||
#: or :obj:`None` if that is not determined yet.
|
||
#: (Ie. if there is not enough input yet to determine
|
||
#: if there is a BOM.)
|
||
self.encoding = None # Not known yet.
|
||
|
||
def decode(self, input, final=False):
|
||
"""Decode one chunk of the input.
|
||
|
||
:param input: A byte string.
|
||
:param final:
|
||
Indicate that no more input is available.
|
||
Must be :obj:`True` if this is the last call.
|
||
:returns: An Unicode string.
|
||
|
||
"""
|
||
decoder = self._decoder
|
||
if decoder is not None:
|
||
return decoder(input, final)
|
||
|
||
input = self._buffer + input
|
||
encoding, input = _detect_bom(input)
|
||
if encoding is None:
|
||
if len(input) < 3 and not final: # Not enough data yet.
|
||
self._buffer = input
|
||
return ''
|
||
else: # No BOM
|
||
encoding = self._fallback_encoding
|
||
decoder = encoding.codec_info.incrementaldecoder(self._errors).decode
|
||
self._decoder = decoder
|
||
self.encoding = encoding
|
||
return decoder(input, final)
|
||
|
||
|
||
class IncrementalEncoder(object):
|
||
"""
|
||
“Push”-based encoder.
|
||
|
||
:param encoding: An :class:`Encoding` object or a label string.
|
||
:param errors: Type of error handling. See :func:`codecs.register`.
|
||
:raises: :exc:`~exceptions.LookupError` for an unknown encoding label.
|
||
|
||
.. method:: encode(input, final=False)
|
||
|
||
:param input: An Unicode string.
|
||
:param final:
|
||
Indicate that no more input is available.
|
||
Must be :obj:`True` if this is the last call.
|
||
:returns: A byte string.
|
||
|
||
"""
|
||
def __init__(self, encoding=UTF8, errors='strict'):
|
||
encoding = _get_encoding(encoding)
|
||
self.encode = encoding.codec_info.incrementalencoder(errors).encode
|