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