name : text_encoding.py # 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 import six # Lookup table for utf8 _cescape_utf8_to_str = [chr(i) for i in range(0, 256)] _cescape_utf8_to_str[9] = r'\t' # optional escape _cescape_utf8_to_str[10] = r'\n' # optional escape _cescape_utf8_to_str[13] = r'\r' # optional escape _cescape_utf8_to_str[39] = r"\'" # optional escape _cescape_utf8_to_str[34] = r'\"' # necessary escape _cescape_utf8_to_str[92] = r'\\' # necessary escape # 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)]) _cescape_byte_to_str[9] = r'\t' # optional escape _cescape_byte_to_str[10] = r'\n' # optional escape _cescape_byte_to_str[13] = r'\r' # optional escape _cescape_byte_to_str[39] = r"\'" # optional escape _cescape_byte_to_str[34] = r'\"' # necessary escape _cescape_byte_to_str[92] = r'\\' # necessary escape def CEscape(text, as_utf8): """Escape a bytes string for use in an ascii protocol buffer. text.encode('string_escape') does not seem to satisfy our needs as it 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. Args: text: A byte string to be escaped as_utf8: Specifies if result should be returned in UTF-8 encoding Returns: Escaped string """ # PY3 hack: make Ord work for str and bytes: # //platforms/networking/data uses unicode here, hence basestring. Ord = ord if isinstance(text, six.string_types) else lambda x: x if as_utf8: return ''.join(_cescape_utf8_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])') _cescape_highbit_to_str = ([chr(i) for i in range(0, 127)] + [r'\%03o' % i for i in range(127, 256)]) def CUnescape(text): """Unescape a text string with C-style escape sequences to UTF-8 bytes.""" 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) if str is bytes: # PY2 return result.decode('string_escape') result = ''.join(_cescape_highbit_to_str[ord(c)] for c in result) return (result.encode('ascii') # Make it bytes to allow decode. .decode('unicode_escape') # Make it bytes again to return the proper type. .encode('raw_unicode_escape'))