/usr/share/pyshared/hachoir_regex/parser.py is in python-hachoir-regex 1.0.5-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 | """
Parse string to create Regex object.
TODO:
- Support \: \001, \x00, \0, \ \[, \(, \{, etc.
- Support Python extensions: (?:...), (?P<name>...), etc.
- Support \<, \>, \s, \S, \w, \W, \Z <=> $, \d, \D, \A <=> ^, \b, \B, [[:space:]], etc.
"""
from hachoir_regex import (RegexString, RegexEmpty, RegexRepeat,
RegexDot, RegexWord, RegexStart, RegexEnd,
RegexRange, RegexRangeItem, RegexRangeCharacter)
import re
REGEX_COMMAND_CHARACTERS = '.^$[](){}|+?*\\'
def parseRange(text, start):
r"""
>>> parseRange('[a]b', 1)
(<RegexRange '[a]'>, 3)
>>> parseRange('[a-z]b', 1)
(<RegexRange '[a-z]'>, 5)
>>> parseRange('[^a-z-]b', 1)
(<RegexRange '[^a-z-]'>, 7)
>>> parseRange('[^]-]b', 1)
(<RegexRange '[^]-]'>, 5)
>>> parseRange(r'[\]abc]', 1)
(<RegexRange '[]a-c]'>, 7)
>>> parseRange(r'[a\-x]', 1)
(<RegexRange '[ax-]'>, 6)
"""
index = start
char_range = []
exclude = False
if text[index] == '^':
exclude = True
index += 1
if text[index] == ']':
char_range.append(RegexRangeCharacter(']'))
index += 1
while index < len(text) and text[index] != ']':
if index+1 < len(text) \
and text[index] == '\\':
char_range.append(RegexRangeCharacter(text[index+1]))
index += 2
elif index+1 < len(text) \
and text[index] == '-' and text[index+1] == ']':
break
elif index+3 < len(text) \
and text[index+1] == '-' \
and text[index+2] != ']':
char_range.append(RegexRangeItem(ord(text[index]), ord(text[index+2])))
index += 3
else:
char_range.append(RegexRangeCharacter(text[index]))
index += 1
if index < len(text) and text[index] == '-':
char_range.append(RegexRangeCharacter('-'))
index += 1
if index == len(text) or text[index] != ']':
raise SyntaxError('Invalid range: %s' % text[start-1:index])
return RegexRange(char_range, exclude), index+1
def parseOr(text, start):
"""
>>> parseOr('(a)', 1)
(<RegexString 'a'>, 3)
>>> parseOr('(a|c)', 1)
(<RegexRange '[ac]'>, 5)
>>> parseOr(' (a|[bc]|d)', 2)
(<RegexRange '[a-d]'>, 11)
"""
index = start
# (?:...): Skip Python prefix '?:'
if text[index:index+2] == '?:':
index += 2
if text[index] == '?':
raise NotImplementedError("Doesn't support Python extension (?...)")
regex = None
while True:
new_regex, index = _parse(text, index, "|)")
if regex:
regex = regex | new_regex
else:
regex = new_regex
if len(text) <= index:
raise SyntaxError('Missing closing parenthesis')
if text[index] == ')':
break
index += 1
index += 1
if regex is None:
regex = RegexEmpty()
return regex, index
REPEAT_REGEX = re.compile("([0-9]+)(,[0-9]*)?}")
def parseRepeat(text, start):
"""
>>> parseRepeat('a{0,1}b', 2)
(0, 1, 6)
>>> parseRepeat('a{12}', 2)
(12, 12, 5)
"""
match = REPEAT_REGEX.match(text, start)
if not match:
raise SyntaxError('Unable to parse repetition '+text[start:])
rmin = int(match.group(1))
if match.group(2):
text = match.group(2)[1:]
if text:
rmax = int(text)
else:
rmax = None
else:
rmax = rmin
return (rmin, rmax, match.end(0))
CHAR_TO_FUNC = {'[': parseRange, '(': parseOr}
CHAR_TO_CLASS = {'.': RegexDot, '^': RegexStart, '$': RegexEnd}
CHAR_TO_REPEAT = {'*': (0, None), '?': (0, 1), '+': (1, None)}
def _parse(text, start=0, until=None):
if len(text) == start:
return RegexEmpty(), 0
index = start
regex = RegexEmpty()
last = None
done = False
while index < len(text):
char = text[index]
if until and char in until:
done = True
break
if char in REGEX_COMMAND_CHARACTERS:
if char in CHAR_TO_FUNC:
new_regex, index = CHAR_TO_FUNC[char] (text, index+1)
elif char in CHAR_TO_CLASS:
new_regex = CHAR_TO_CLASS[char]()
index += 1
elif char == '{':
rmin, rmax, index = parseRepeat(text, index+1)
new_regex = RegexRepeat(last, rmin, rmax)
last = None
elif char in CHAR_TO_REPEAT:
rmin, rmax = CHAR_TO_REPEAT[char]
if last is None:
raise SyntaxError('Repetition character (%s) without previous expression' % text[index])
new_regex = RegexRepeat(last, rmin, rmax)
last = None
index += 1
elif char == "\\":
index += 1
if index == len(text):
raise SyntaxError("Antislash (\\) without escaped character")
char = text[index]
if char == 'b':
new_regex = RegexWord()
else:
if not(char in REGEX_COMMAND_CHARACTERS or char in " '"):
raise SyntaxError("Operator '\\%s' is not supported" % char)
new_regex = RegexString(char)
index += 1
else:
raise NotImplementedError("Operator '%s' is not supported" % char)
if last:
regex = regex + last
last = new_regex
else:
subtext = text[index]
index += 1
if last:
regex = regex + last
last = RegexString(subtext)
if last:
regex = regex + last
return regex, index
def parse(text):
r"""
>>> parse('')
<RegexEmpty ''>
>>> parse('abc')
<RegexString 'abc'>
>>> parse("chats?")
<RegexAnd 'chats?'>
>>> parse('[bc]d')
<RegexAnd '[bc]d'>
>>> parse("\\.")
<RegexString '\.'>
"""
regex, index = _parse(text)
assert index == len(text)
return regex
if __name__ == "__main__":
import doctest
doctest.testmod()
|