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| 1 # Protocol Buffers - Google's data interchange format |
| 2 # Copyright 2008 Google Inc. All rights reserved. |
| 3 # http://code.google.com/p/protobuf/ |
| 4 # |
| 5 # Redistribution and use in source and binary forms, with or without |
| 6 # modification, are permitted provided that the following conditions are |
| 7 # met: |
| 8 # |
| 9 # * Redistributions of source code must retain the above copyright |
| 10 # notice, this list of conditions and the following disclaimer. |
| 11 # * Redistributions in binary form must reproduce the above |
| 12 # copyright notice, this list of conditions and the following disclaimer |
| 13 # in the documentation and/or other materials provided with the |
| 14 # distribution. |
| 15 # * Neither the name of Google Inc. nor the names of its |
| 16 # contributors may be used to endorse or promote products derived from |
| 17 # this software without specific prior written permission. |
| 18 # |
| 19 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 20 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 21 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 22 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 23 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 24 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 25 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 26 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 27 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 28 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 29 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 30 |
| 31 #PY25 compatible for GAE. |
| 32 # |
| 33 """Encoding related utilities.""" |
| 34 |
| 35 import re |
| 36 import sys ##PY25 |
| 37 |
| 38 # Lookup table for utf8 |
| 39 _cescape_utf8_to_str = [chr(i) for i in xrange(0, 256)] |
| 40 _cescape_utf8_to_str[9] = r'\t' # optional escape |
| 41 _cescape_utf8_to_str[10] = r'\n' # optional escape |
| 42 _cescape_utf8_to_str[13] = r'\r' # optional escape |
| 43 _cescape_utf8_to_str[39] = r"\'" # optional escape |
| 44 |
| 45 _cescape_utf8_to_str[34] = r'\"' # necessary escape |
| 46 _cescape_utf8_to_str[92] = r'\\' # necessary escape |
| 47 |
| 48 # Lookup table for non-utf8, with necessary escapes at (o >= 127 or o < 32) |
| 49 _cescape_byte_to_str = ([r'\%03o' % i for i in xrange(0, 32)] + |
| 50 [chr(i) for i in xrange(32, 127)] + |
| 51 [r'\%03o' % i for i in xrange(127, 256)]) |
| 52 _cescape_byte_to_str[9] = r'\t' # optional escape |
| 53 _cescape_byte_to_str[10] = r'\n' # optional escape |
| 54 _cescape_byte_to_str[13] = r'\r' # optional escape |
| 55 _cescape_byte_to_str[39] = r"\'" # optional escape |
| 56 |
| 57 _cescape_byte_to_str[34] = r'\"' # necessary escape |
| 58 _cescape_byte_to_str[92] = r'\\' # necessary escape |
| 59 |
| 60 |
| 61 def CEscape(text, as_utf8): |
| 62 """Escape a bytes string for use in an ascii protocol buffer. |
| 63 |
| 64 text.encode('string_escape') does not seem to satisfy our needs as it |
| 65 encodes unprintable characters using two-digit hex escapes whereas our |
| 66 C++ unescaping function allows hex escapes to be any length. So, |
| 67 "\0011".encode('string_escape') ends up being "\\x011", which will be |
| 68 decoded in C++ as a single-character string with char code 0x11. |
| 69 |
| 70 Args: |
| 71 text: A byte string to be escaped |
| 72 as_utf8: Specifies if result should be returned in UTF-8 encoding |
| 73 Returns: |
| 74 Escaped string |
| 75 """ |
| 76 # PY3 hack: make Ord work for str and bytes: |
| 77 # //platforms/networking/data uses unicode here, hence basestring. |
| 78 Ord = ord if isinstance(text, basestring) else lambda x: x |
| 79 if as_utf8: |
| 80 return ''.join(_cescape_utf8_to_str[Ord(c)] for c in text) |
| 81 return ''.join(_cescape_byte_to_str[Ord(c)] for c in text) |
| 82 |
| 83 |
| 84 _CUNESCAPE_HEX = re.compile(r'(\\+)x([0-9a-fA-F])(?![0-9a-fA-F])') |
| 85 _cescape_highbit_to_str = ([chr(i) for i in range(0, 127)] + |
| 86 [r'\%03o' % i for i in range(127, 256)]) |
| 87 |
| 88 |
| 89 def CUnescape(text): |
| 90 """Unescape a text string with C-style escape sequences to UTF-8 bytes.""" |
| 91 |
| 92 def ReplaceHex(m): |
| 93 # Only replace the match if the number of leading back slashes is odd. i.e. |
| 94 # the slash itself is not escaped. |
| 95 if len(m.group(1)) & 1: |
| 96 return m.group(1) + 'x0' + m.group(2) |
| 97 return m.group(0) |
| 98 |
| 99 # This is required because the 'string_escape' encoding doesn't |
| 100 # allow single-digit hex escapes (like '\xf'). |
| 101 result = _CUNESCAPE_HEX.sub(ReplaceHex, text) |
| 102 |
| 103 if sys.version_info[0] < 3: ##PY25 |
| 104 ##!PY25 if str is bytes: # PY2 |
| 105 return result.decode('string_escape') |
| 106 result = ''.join(_cescape_highbit_to_str[ord(c)] for c in result) |
| 107 return (result.encode('ascii') # Make it bytes to allow decode. |
| 108 .decode('unicode_escape') |
| 109 # Make it bytes again to return the proper type. |
| 110 .encode('raw_unicode_escape')) |
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