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"""
This is Victor Stinner's pure-Python implementation of PEP 383: the "surrogateescape" error
handler of Python 3.
Source: misc/python/surrogateescape.py in https://bitbucket.org/haypo/misc
"""
# This code is released under the Python license and the BSD 2-clause license
import codecs
import sys
from future import utils
FS_ERRORS = 'surrogateescape'
# # -- Python 2/3 compatibility -------------------------------------
# FS_ERRORS = 'my_surrogateescape'
def u(text):
if utils.PY3:
return text
else:
return text.decode('unicode_escape')
def b(data):
if utils.PY3:
return data.encode('latin1')
else:
return data
if utils.PY3:
_unichr = chr
bytes_chr = lambda code: bytes((code,))
else:
_unichr = unichr
bytes_chr = chr
def surrogateescape_handler(exc):
"""
Pure Python implementation of the PEP 383: the "surrogateescape" error
handler of Python 3. Undecodable bytes will be replaced by a Unicode
character U+DCxx on decoding, and these are translated into the
original bytes on encoding.
"""
mystring = exc.object[exc.start:exc.end]
try:
if isinstance(exc, UnicodeDecodeError):
# mystring is a byte-string in this case
decoded = replace_surrogate_decode(mystring)
elif isinstance(exc, UnicodeEncodeError):
# In the case of u'\udcc3'.encode('ascii',
# 'this_surrogateescape_handler'), both Python 2.x and 3.x raise an
# exception anyway after this function is called, even though I think
# it's doing what it should. It seems that the strict encoder is called
# to encode the unicode string that this function returns ...
decoded = replace_surrogate_encode(mystring)
else:
raise exc
except NotASurrogateError:
raise exc
return (decoded, exc.end)
class NotASurrogateError(Exception):
pass
def replace_surrogate_encode(mystring):
"""
Returns a (unicode) string, not the more logical bytes, because the codecs
register_error functionality expects this.
"""
decoded = []
for ch in mystring:
# if utils.PY3:
# code = ch
# else:
code = ord(ch)
# The following magic comes from Py3.3's Python/codecs.c file:
if not 0xD800 <= code <= 0xDCFF:
# Not a surrogate. Fail with the original exception.
raise NotASurrogateError
# mybytes = [0xe0 | (code >> 12),
# 0x80 | ((code >> 6) & 0x3f),
# 0x80 | (code & 0x3f)]
# Is this a good idea?
if 0xDC00 <= code <= 0xDC7F:
decoded.append(_unichr(code - 0xDC00))
elif code <= 0xDCFF:
decoded.append(_unichr(code - 0xDC00))
else:
raise NotASurrogateError
return str().join(decoded)
def replace_surrogate_decode(mybytes):
"""
Returns a (unicode) string
"""
decoded = []
for ch in mybytes:
# We may be parsing newbytes (in which case ch is an int) or a native
# str on Py2
if isinstance(ch, int):
code = ch
else:
code = ord(ch)
if 0x80 <= code <= 0xFF:
decoded.append(_unichr(0xDC00 + code))
elif code <= 0x7F:
decoded.append(_unichr(code))
else:
# # It may be a bad byte
# # Try swallowing it.
# continue
# print("RAISE!")
raise NotASurrogateError
return str().join(decoded)
def encodefilename(fn):
if FS_ENCODING == 'ascii':
# ASCII encoder of Python 2 expects that the error handler returns a
# Unicode string encodable to ASCII, whereas our surrogateescape error
# handler has to return bytes in 0x80-0xFF range.
encoded = []
for index, ch in enumerate(fn):
code = ord(ch)
if code < 128:
ch = bytes_chr(code)
elif 0xDC80 <= code <= 0xDCFF:
ch = bytes_chr(code - 0xDC00)
else:
raise UnicodeEncodeError(FS_ENCODING,
fn, index, index+1,
'ordinal not in range(128)')
encoded.append(ch)
return bytes().join(encoded)
elif FS_ENCODING == 'utf-8':
# UTF-8 encoder of Python 2 encodes surrogates, so U+DC80-U+DCFF
# doesn't go through our error handler
encoded = []
for index, ch in enumerate(fn):
code = ord(ch)
if 0xD800 <= code <= 0xDFFF:
if 0xDC80 <= code <= 0xDCFF:
ch = bytes_chr(code - 0xDC00)
encoded.append(ch)
else:
raise UnicodeEncodeError(
FS_ENCODING,
fn, index, index+1, 'surrogates not allowed')
else:
ch_utf8 = ch.encode('utf-8')
encoded.append(ch_utf8)
return bytes().join(encoded)
else:
return fn.encode(FS_ENCODING, FS_ERRORS)
def decodefilename(fn):
return fn.decode(FS_ENCODING, FS_ERRORS)
FS_ENCODING = 'ascii'; fn = b('[abc\xff]'); encoded = u('[abc\udcff]')
# FS_ENCODING = 'cp932'; fn = b('[abc\x81\x00]'); encoded = u('[abc\udc81\x00]')
# FS_ENCODING = 'UTF-8'; fn = b('[abc\xff]'); encoded = u('[abc\udcff]')
# normalize the filesystem encoding name.
# For example, we expect "utf-8", not "UTF8".
FS_ENCODING = codecs.lookup(FS_ENCODING).name
def register_surrogateescape():
"""
Registers the surrogateescape error handler on Python 2 (only)
"""
if utils.PY3:
return
try:
codecs.lookup_error(FS_ERRORS)
except LookupError:
codecs.register_error(FS_ERRORS, surrogateescape_handler)
if __name__ == '__main__':
pass
# # Tests:
# register_surrogateescape()
# b = decodefilename(fn)
# assert b == encoded, "%r != %r" % (b, encoded)
# c = encodefilename(b)
# assert c == fn, '%r != %r' % (c, fn)
# # print("ok")