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/********************* */
/*! \file regexp_elim.h
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds
** This file is part of the CVC4 project.
** Copyright (c) 2009-2019 by the authors listed in the file AUTHORS
** in the top-level source directory) and their institutional affiliations.
** All rights reserved. See the file COPYING in the top-level source
** directory for licensing information.\endverbatim
**
** \brief Techniques for eliminating regular expressions
**
**/
#include "cvc4_private.h"
#ifndef CVC4__THEORY__STRINGS__REGEXP_ELIM_H
#define CVC4__THEORY__STRINGS__REGEXP_ELIM_H
#include "expr/node.h"
namespace CVC4 {
namespace theory {
namespace strings {
/** Regular expression membership elimination
*
* This class implements techniques for reducing regular expression memberships
* to bounded integer quantifiers + extended function constraints.
*
* It is used by TheoryStrings during ppRewrite.
*/
class RegExpElimination
{
public:
RegExpElimination();
/** eliminate membership
*
* This method takes as input a regular expression membership atom of the
* form (str.in.re x R). If this method returns a non-null node ret, then ret
* is equivalent to atom.
*/
Node eliminate(Node atom);
private:
/** common terms */
Node d_zero;
Node d_one;
Node d_neg_one;
/** return elimination
*
* This method is called when atom is rewritten to atomElim, and returns
* atomElim. id is an identifier indicating the reason for the elimination.
*/
Node returnElim(Node atom, Node atomElim, const char* id);
/** elimination for regular expression concatenation */
Node eliminateConcat(Node atom);
/** elimination for regular expression star */
Node eliminateStar(Node atom);
}; /* class RegExpElimination */
} // namespace strings
} // namespace theory
} // namespace CVC4
#endif /* CVC4__THEORY__STRINGS__REGEXP_ELIM_H */
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