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