bazarr/libs/ftfy/bad_codecs/__init__.py

94 lines
3.1 KiB
Python

r"""
The `ftfy.bad_codecs` module gives Python the ability to decode some common,
flawed encodings.
Python does not want you to be sloppy with your text. Its encoders and decoders
("codecs") follow the relevant standards whenever possible, which means that
when you get text that *doesn't* follow those standards, you'll probably fail
to decode it. Or you might succeed at decoding it for implementation-specific
reasons, which is perhaps worse.
There are some encodings out there that Python wishes didn't exist, which are
widely used outside of Python:
- "utf-8-variants", a family of not-quite-UTF-8 encodings, including the
ever-popular CESU-8 and "Java modified UTF-8".
- "Sloppy" versions of character map encodings, where bytes that don't map to
anything will instead map to the Unicode character with the same number.
Simply importing this module, or in fact any part of the `ftfy` package, will
make these new "bad codecs" available to Python through the standard Codecs
API. You never have to actually call any functions inside `ftfy.bad_codecs`.
However, if you want to call something because your code checker insists on it,
you can call ``ftfy.bad_codecs.ok()``.
A quick example of decoding text that's encoded in CESU-8:
>>> import ftfy.bad_codecs
>>> print(b'\xed\xa0\xbd\xed\xb8\x8d'.decode('utf-8-variants'))
😍
"""
from encodings import normalize_encoding
import codecs
from typing import Dict
_CACHE: Dict[str, codecs.CodecInfo] = {}
# Define some aliases for 'utf-8-variants'. All hyphens get turned into
# underscores, because of `normalize_encoding`.
UTF8_VAR_NAMES = (
'utf_8_variants', 'utf8_variants',
'utf_8_variant', 'utf8_variant',
'utf_8_var', 'utf8_var',
'cesu_8', 'cesu8',
'java_utf_8', 'java_utf8'
)
def search_function(encoding):
"""
Register our "bad codecs" with Python's codecs API. This involves adding
a search function that takes in an encoding name, and returns a codec
for that encoding if it knows one, or None if it doesn't.
The encodings this will match are:
- Encodings of the form 'sloppy-windows-NNNN' or 'sloppy-iso-8859-N',
where the non-sloppy version is an encoding that leaves some bytes
unmapped to characters.
- The 'utf-8-variants' encoding, which has the several aliases seen
above.
"""
if encoding in _CACHE:
return _CACHE[encoding]
norm_encoding = normalize_encoding(encoding)
codec = None
if norm_encoding in UTF8_VAR_NAMES:
from ftfy.bad_codecs.utf8_variants import CODEC_INFO
codec = CODEC_INFO
elif norm_encoding.startswith('sloppy_'):
from ftfy.bad_codecs.sloppy import CODECS
codec = CODECS.get(norm_encoding)
if codec is not None:
_CACHE[encoding] = codec
return codec
def ok():
"""
A feel-good function that gives you something to call after importing
this package.
Why is this here? Pyflakes. Pyflakes gets upset when you import a module
and appear not to use it. It doesn't know that you're using it when
you use the ``unicode.encode`` and ``bytes.decode`` methods with certain
encodings.
"""
codecs.register(search_function)