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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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