136 lines
3.9 KiB
Python
136 lines
3.9 KiB
Python
# Copyright 2014 Matt Chaput. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY MATT CHAPUT ``AS IS'' AND ANY EXPRESS OR
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# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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# EVENT SHALL MATT CHAPUT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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# OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and documentation are
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# those of the authors and should not be interpreted as representing official
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# policies, either expressed or implied, of Matt Chaput.
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import re
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from whoosh.automata.fsa import ANY, EPSILON, NFA
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# Operator precedence
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CHOICE = ("|", )
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ops = ()
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def parse(pattern):
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stack = []
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ops = []
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class RegexBuilder(object):
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def __init__(self):
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self.statenum = 1
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def new_state(self):
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self.statenum += 1
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return self.statenum
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def epsilon(self):
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s = self.new_state()
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e = self.new_state()
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nfa = NFA(s)
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nfa.add_transition(s, EPSILON, e)
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nfa.add_final_state(e)
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return nfa
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def char(self, label):
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s = self.new_state()
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e = self.new_state()
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nfa = NFA(s)
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nfa.add_transition(s, label, e)
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nfa.add_final_state(e)
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return nfa
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def charset(self, chars):
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s = self.new_state()
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e = self.new_state()
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nfa = NFA(s)
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for char in chars:
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nfa.add_transition(s, char, e)
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nfa.add_final_state(e)
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return e
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def dot(self):
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s = self.new_state()
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e = self.new_state()
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nfa = NFA(s)
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nfa.add_transition(s, ANY, e)
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nfa.add_final_state(e)
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return nfa
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def choice(self, n1, n2):
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s = self.new_state()
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s1 = self.new_state()
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s2 = self.new_state()
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e1 = self.new_state()
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e2 = self.new_state()
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e = self.new_state()
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nfa = NFA(s)
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nfa.add_transition(s, EPSILON, s1)
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nfa.add_transition(s, EPSILON, s2)
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nfa.insert(s1, n1, e1)
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nfa.insert(s2, n2, e2)
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nfa.add_transition(e1, EPSILON, e)
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nfa.add_transition(e2, EPSILON, e)
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nfa.add_final_state(e)
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return nfa
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def concat(self, n1, n2):
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s = self.new_state()
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m = self.new_state()
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e = self.new_state()
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nfa = NFA(s)
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nfa.insert(s, n1, m)
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nfa.insert(m, n2, e)
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nfa.add_final_state(e)
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return nfa
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def star(self, n):
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s = self.new_state()
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m1 = self.new_state()
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m2 = self.new_state()
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e = self.new_state()
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nfa = NFA(s)
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nfa.add_transition(s, EPSILON, m1)
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nfa.add_transition(s, EPSILON, e)
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nfa.insert(m1, n, m2)
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nfa.add_transition(m2, EPSILON, m1)
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nfa.add_transition(m2, EPSILON, e)
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nfa.add_final_state(e)
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return nfa
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def plus(self, n):
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return self.concat(n, self.star(n))
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def question(self, n):
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return self.choice(n, self.epsilon())
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