aeidon/finder.py¶
Source code for module aeidon.finder from file aeidon/finder.py.
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 | # -*- coding: utf-8 -*-
# Copyright (C) 2005 Osmo Salomaa
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""String and regular expression finder and replacer."""
import re
__all__ = ("Finder",)
class Finder:
"""
String and regular expression finder and replacer.
:ivar ignore_case: ``True`` to ignore case when finding matches
:ivar match: Regular expression object for the latest match of pattern
:ivar match_span: Tuple of start and end position for match
:ivar pattern: String or regular expression object to find
:ivar pos: Current offset from the beginning of the text
:ivar replacement: Plain- or regular expression replacement string
:ivar text: Target text to find matches of pattern in
"""
def __init__(self):
"""Initialize a :class:`Finder` instance."""
self.ignore_case = False
self.match = None
self.match_span = None
self.pattern = None
self.pos = None
self.replacement = None
self.text = None
def next(self):
"""
Find the next match of pattern.
Raise :exc:`StopIteration` if no next match found.
Return tuple of match start, end position.
"""
if self.pos is None:
# Start new search from beginning.
self.pos = 0
if isinstance(self.pattern, str):
text = self.text
pattern = self.pattern
if self.ignore_case:
text = text.lower()
pattern = pattern.lower()
try:
index = text.index(pattern, self.pos)
except ValueError:
raise StopIteration
self.match_span = (index, index + len(pattern))
else: # Regular expression
match = self.pattern.search(self.text, self.pos)
if match is None:
raise StopIteration
# Avoid getting stuck with zero-length regular expressions.
if match.span() == self.match_span == (self.pos, self.pos):
if self.pos == len(self.text):
raise StopIteration
self.pos += 1
return self.next()
self.match = match
self.match_span = match.span()
self.pos = self.match_span[1]
return self.match_span
def previous(self):
"""
Find the previous match of pattern.
Raise :exc:`StopIteration` if no previous match found.
Return tuple of match start, end position.
"""
if self.pos is None:
# Start new search from end.
self.pos = len(self.text)
if isinstance(self.pattern, str):
text = self.text
pattern = self.pattern
if self.ignore_case:
text = text.lower()
pattern = pattern.lower()
try:
index = text.rindex(pattern, 0, self.pos)
except ValueError:
raise StopIteration
self.match_span = (index, index + len(pattern))
else: # Regular expression
iterator = self.pattern.finditer(self.text)
match = None
while True:
try:
candidate = next(iterator)
if candidate.end() > self.pos:
raise StopIteration
except StopIteration:
break
match = candidate
if match is None:
raise StopIteration
# Avoid getting stuck with zero-length regular expressions.
if match.span() == self.match_span == (self.pos, self.pos):
if self.pos == 0:
raise StopIteration
self.pos -= 1
return self.previous()
self.match = match
self.match_span = match.span()
self.pos = self.match_span[0]
return self.match_span
def replace(self, next=True):
"""
Replace the current match of pattern.
`next` should be ``True`` to finish at end of match, ``False`` for
beginning. Raise :exc:`re.error` if bad replacement.
"""
a, z = self.match_span
orig_length = len(self.text)
replacement = self.replacement
if not isinstance(self.pattern, str):
replacement = self.match.expand(self.replacement)
self.text = self.text[:a] + replacement + self.text[z:]
shift = len(self.text) - orig_length
self.pos = ((z + shift) if next else a)
# Adapt match span to new text length to avoid
# getting stuck with zero-length regular expressions.
if next and (self.match_span[0] == self.match_span[1]):
self.match_span = (self.pos, self.pos)
def replace_all(self):
"""
Replace all occurences of pattern.
Raise :exc:`re.error` if bad replacement.
Return the amount of substitutions made.
"""
self.pos = 0
self.match = None
self.match_span = None
count = 0
while True:
try:
self.next()
except StopIteration:
self.pos = len(self.text)
self.match_span = None
break
self.replace()
count += 1
return count
def set_regex(self, pattern, flags=re.DOTALL|re.MULTILINE):
"""
Set and use regular expression as pattern.
The default value for `flags` is ``DOTALL`` and ``MULTILINE``.
``IGNORECASE`` is automatically added to flags if :attr:`ignore_case`
is ``True``.
Raise :exc:`re.error` if bad pattern.
"""
if self.ignore_case:
flags = flags | re.IGNORECASE
self.pattern = re.compile(pattern, flags)
def set_text(self, text):
"""Set the target text to search in and reset position."""
self.text = text
self.match = None
self.match_span = None
self.pos = None
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