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# sectracker.regexpcase -- Python module for regexp-based dispatching
# Copyright (C) 2009, 2010 Florian Weimer <fw@deneb.enyo.de>
#
# 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 2 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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
import re
class RegexpCase(object):
def __init__(self, rules, prefix=None, suffix=None, default=None):
offset = 0
probes = []
maycall = default is None or callable(default)
# We use a single regular expression and use special probe
# captures to figure out which one has actually matched.
# Hopefully, the regular expression engine will make this run
# fast.
for (regexp, action) in rules:
compiled = re.compile(regexp)
probes.append((offset, offset + 1, offset + compiled.groups + 1,
action))
offset += compiled.groups + 1
if action is not None:
maycall = maycall and callable(action)
self.probes = tuple(probes)
self.maycall = maycall
if not self.probes:
raise ValueError("empty rule list")
if prefix is None:
prefix = "^(?:("
else:
if re.compile(prefix).groups > 0:
raise ValueError("prefix must not contain captures")
prefix = "^(?:" + prefix + ")(?:("
if suffix is None:
suffix = "))$"
else:
if re.compile(suffix).groups > 0:
raise ValueError("suffix must not contain captures")
suffix = "))(?:" + suffix + ")$"
self.regexp = re.compile(
prefix + ')|('.join(regexp for (regexp, action) in rules)
+ suffix)
self.default = default
def match(self, key):
match = self.regexp.match(key)
if match is None:
return (None, self.default)
groups = match.groups()
for (probe, i, j, action) in self.probes:
if groups[probe] is not None:
return (groups[i:j], action)
raise AssertionError("pattern and offset list incongruent")
def __getitem__(self, key):
return self.match(key)[1]
def __call__(self, key, *args):
if not self.maycall:
raise TypeError("not all actions are callable")
(groups, action) = self.match(key)
if action is None:
return None
if groups is None:
groups = key
return action(groups, *args)
def rule(regexp):
"""Add a regular expression to the function, for the rule list"""
return lambda f: (regexp, f)
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