108 lines
4.5 KiB
Python
108 lines
4.5 KiB
Python
# Protocol Buffers - Google's data interchange format
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# Copyright 2008 Google Inc. All rights reserved.
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# https://developers.google.com/protocol-buffers/
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above
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# copyright notice, this list of conditions and the following disclaimer
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# in the documentation and/or other materials provided with the
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# distribution.
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# * Neither the name of Google Inc. nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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"""Encoding related utilities."""
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import re
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import six
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# Lookup table for utf8
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_cescape_utf8_to_str = [chr(i) for i in range(0, 256)]
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_cescape_utf8_to_str[9] = r'\t' # optional escape
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_cescape_utf8_to_str[10] = r'\n' # optional escape
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_cescape_utf8_to_str[13] = r'\r' # optional escape
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_cescape_utf8_to_str[39] = r"\'" # optional escape
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_cescape_utf8_to_str[34] = r'\"' # necessary escape
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_cescape_utf8_to_str[92] = r'\\' # necessary escape
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# Lookup table for non-utf8, with necessary escapes at (o >= 127 or o < 32)
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_cescape_byte_to_str = ([r'\%03o' % i for i in range(0, 32)] +
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[chr(i) for i in range(32, 127)] +
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[r'\%03o' % i for i in range(127, 256)])
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_cescape_byte_to_str[9] = r'\t' # optional escape
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_cescape_byte_to_str[10] = r'\n' # optional escape
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_cescape_byte_to_str[13] = r'\r' # optional escape
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_cescape_byte_to_str[39] = r"\'" # optional escape
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_cescape_byte_to_str[34] = r'\"' # necessary escape
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_cescape_byte_to_str[92] = r'\\' # necessary escape
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def CEscape(text, as_utf8):
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"""Escape a bytes string for use in an ascii protocol buffer.
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text.encode('string_escape') does not seem to satisfy our needs as it
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encodes unprintable characters using two-digit hex escapes whereas our
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C++ unescaping function allows hex escapes to be any length. So,
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"\0011".encode('string_escape') ends up being "\\x011", which will be
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decoded in C++ as a single-character string with char code 0x11.
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Args:
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text: A byte string to be escaped
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as_utf8: Specifies if result should be returned in UTF-8 encoding
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Returns:
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Escaped string
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"""
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# PY3 hack: make Ord work for str and bytes:
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# //platforms/networking/data uses unicode here, hence basestring.
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Ord = ord if isinstance(text, six.string_types) else lambda x: x
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if as_utf8:
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return ''.join(_cescape_utf8_to_str[Ord(c)] for c in text)
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return ''.join(_cescape_byte_to_str[Ord(c)] for c in text)
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_CUNESCAPE_HEX = re.compile(r'(\\+)x([0-9a-fA-F])(?![0-9a-fA-F])')
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_cescape_highbit_to_str = ([chr(i) for i in range(0, 127)] +
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[r'\%03o' % i for i in range(127, 256)])
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def CUnescape(text):
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"""Unescape a text string with C-style escape sequences to UTF-8 bytes."""
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def ReplaceHex(m):
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# Only replace the match if the number of leading back slashes is odd. i.e.
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# the slash itself is not escaped.
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if len(m.group(1)) & 1:
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return m.group(1) + 'x0' + m.group(2)
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return m.group(0)
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# This is required because the 'string_escape' encoding doesn't
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# allow single-digit hex escapes (like '\xf').
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result = _CUNESCAPE_HEX.sub(ReplaceHex, text)
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if str is bytes: # PY2
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return result.decode('string_escape')
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result = ''.join(_cescape_highbit_to_str[ord(c)] for c in result)
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return (result.encode('ascii') # Make it bytes to allow decode.
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.decode('unicode_escape')
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# Make it bytes again to return the proper type.
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.encode('raw_unicode_escape'))
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