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| # Protocol Buffers - Google's data interchange format | |
| # Copyright 2008 Google Inc. All rights reserved. | |
| # https://developers.google.com/protocol-buffers/ | |
| # | |
| # Redistribution and use in source and binary forms, with or without | |
| # modification, are permitted provided that the following conditions are | |
| # met: | |
| # | |
| # * Redistributions of source code must retain the above copyright | |
| # notice, this list of conditions and the following disclaimer. | |
| # * Redistributions in binary form must reproduce the above | |
| # copyright notice, this list of conditions and the following disclaimer | |
| # in the documentation and/or other materials provided with the | |
| # distribution. | |
| # * Neither the name of Google Inc. nor the names of its | |
| # contributors may be used to endorse or promote products derived from | |
| # this software without specific prior written permission. | |
| # | |
| # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| """Encoding related utilities.""" | |
| import re | |
| _cescape_chr_to_symbol_map = {} | |
| _cescape_chr_to_symbol_map[9] = r'\t' # optional escape | |
| _cescape_chr_to_symbol_map[10] = r'\n' # optional escape | |
| _cescape_chr_to_symbol_map[13] = r'\r' # optional escape | |
| _cescape_chr_to_symbol_map[34] = r'\"' # necessary escape | |
| _cescape_chr_to_symbol_map[39] = r"\'" # optional escape | |
| _cescape_chr_to_symbol_map[92] = r'\\' # necessary escape | |
| # Lookup table for unicode | |
| _cescape_unicode_to_str = [chr(i) for i in range(0, 256)] | |
| for byte, string in _cescape_chr_to_symbol_map.items(): | |
| _cescape_unicode_to_str[byte] = string | |
| # Lookup table for non-utf8, with necessary escapes at (o >= 127 or o < 32) | |
| _cescape_byte_to_str = ([r'\%03o' % i for i in range(0, 32)] + | |
| [chr(i) for i in range(32, 127)] + | |
| [r'\%03o' % i for i in range(127, 256)]) | |
| for byte, string in _cescape_chr_to_symbol_map.items(): | |
| _cescape_byte_to_str[byte] = string | |
| del byte, string | |
| def CEscape(text, as_utf8): | |
| # type: (...) -> str | |
| """Escape a bytes string for use in an text protocol buffer. | |
| Args: | |
| text: A byte string to be escaped. | |
| as_utf8: Specifies if result may contain non-ASCII characters. | |
| In Python 3 this allows unescaped non-ASCII Unicode characters. | |
| In Python 2 the return value will be valid UTF-8 rather than only ASCII. | |
| Returns: | |
| Escaped string (str). | |
| """ | |
| # Python's text.encode() 'string_escape' or 'unicode_escape' codecs do not | |
| # satisfy our needs; they encodes unprintable characters using two-digit hex | |
| # escapes whereas our C++ unescaping function allows hex escapes to be any | |
| # length. So, "\0011".encode('string_escape') ends up being "\\x011", which | |
| # will be decoded in C++ as a single-character string with char code 0x11. | |
| text_is_unicode = isinstance(text, str) | |
| if as_utf8 and text_is_unicode: | |
| # We're already unicode, no processing beyond control char escapes. | |
| return text.translate(_cescape_chr_to_symbol_map) | |
| ord_ = ord if text_is_unicode else lambda x: x # bytes iterate as ints. | |
| if as_utf8: | |
| return ''.join(_cescape_unicode_to_str[ord_(c)] for c in text) | |
| return ''.join(_cescape_byte_to_str[ord_(c)] for c in text) | |
| _CUNESCAPE_HEX = re.compile(r'(\\+)x([0-9a-fA-F])(?![0-9a-fA-F])') | |
| def CUnescape(text): | |
| # type: (str) -> bytes | |
| """Unescape a text string with C-style escape sequences to UTF-8 bytes. | |
| Args: | |
| text: The data to parse in a str. | |
| Returns: | |
| A byte string. | |
| """ | |
| def ReplaceHex(m): | |
| # Only replace the match if the number of leading back slashes is odd. i.e. | |
| # the slash itself is not escaped. | |
| if len(m.group(1)) & 1: | |
| return m.group(1) + 'x0' + m.group(2) | |
| return m.group(0) | |
| # This is required because the 'string_escape' encoding doesn't | |
| # allow single-digit hex escapes (like '\xf'). | |
| result = _CUNESCAPE_HEX.sub(ReplaceHex, text) | |
| return (result.encode('utf-8') # Make it bytes to allow decode. | |
| .decode('unicode_escape') | |
| # Make it bytes again to return the proper type. | |
| .encode('raw_unicode_escape')) | |