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/******************************************************************************
* Top contributors (to current version):
* Andrew Reynolds, Mathias Preiner
*
* This file is part of the cvc5 project.
*
* Copyright (c) 2009-2021 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.
* ****************************************************************************
*
* Techniques for eliminating regular expressions.
*/
#include "cvc5_private.h"
#ifndef CVC5__THEORY__STRINGS__REGEXP_ELIM_H
#define CVC5__THEORY__STRINGS__REGEXP_ELIM_H
#include "expr/node.h"
#include "theory/eager_proof_generator.h"
#include "theory/trust_node.h"
namespace cvc5 {
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:
/**
* @param isAgg Whether aggressive eliminations are enabled
* @param pnm The proof node manager to use (for proofs)
* @param c The context to use (for proofs)
*/
RegExpElimination(bool isAgg = false,
ProofNodeManager* pnm = nullptr,
context::Context* c = nullptr);
/** 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.
*
* @param atom The node to eliminate
* @param isAgg Whether we apply aggressive elimination techniques
* @return The node with regular expressions eliminated, or null if atom
* was unchanged.
*/
static Node eliminate(Node atom, bool isAgg);
/**
* Return the trust node corresponding to rewriting n based on eliminate
* above.
*/
TrustNode eliminateTrusted(Node atom);
private:
/** 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.
*/
static Node returnElim(Node atom, Node atomElim, const char* id);
/** elimination for regular expression concatenation */
static Node eliminateConcat(Node atom, bool isAgg);
/** elimination for regular expression star */
static Node eliminateStar(Node atom, bool isAgg);
/** Are proofs enabled? */
bool isProofEnabled() const;
/** Are aggressive eliminations enabled? */
bool d_isAggressive;
/** Pointer to the proof node manager */
ProofNodeManager* d_pnm;
/** An eager proof generator for storing proofs in eliminate trusted above */
std::unique_ptr<EagerProofGenerator> d_epg;
}; /* class RegExpElimination */
} // namespace strings
} // namespace theory
} // namespace cvc5
#endif /* CVC5__THEORY__STRINGS__REGEXP_ELIM_H */
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