/******************************************************************************

 * Top contributors (to current version):

 *   Andrew Reynolds, Mathias Preiner, Abdalrhman Mohamed

 *

 * 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.

 * ****************************************************************************

 *

 * candidate_rewrite_database

 */

#include "cvc5_private.h"

#ifndef CVC5__THEORY__QUANTIFIERS__CANDIDATE_REWRITE_DATABASE_H

#define CVC5__THEORY__QUANTIFIERS__CANDIDATE_REWRITE_DATABASE_H

#include <vector>

#include "theory/quantifiers/candidate_rewrite_filter.h"

#include "theory/quantifiers/expr_miner.h"

#include "theory/quantifiers/sygus_sampler.h"

namespace cvc5 {

namespace theory {

namespace quantifiers {

/** CandidateRewriteDatabase

 *

 * This maintains the necessary data structures for generating a database

 * of candidate rewrite rules (see Noetzli et al "Syntax-Guided Rewrite Rule

 * Enumeration for SMT Solvers" SAT 2019). The primary responsibilities

 * of this class are to perform the "equivalence checking" and "congruence

 * and matching filtering" in Figure 1. The equivalence checking is done

 * through a combination of the sygus sampler object owned by this class

 * and the calls made to copies of the SmtEngine in ::addTerm. The rewrite

 * rule filtering (based on congruence, matching, variable ordering) is also

 * managed by the sygus sampler object.

 */

class CandidateRewriteDatabase : public ExprMiner

{

 public:

  /**

   * Constructor

   * @param doCheck Whether to check rewrite rules using subsolvers.

   * @param rewAccel Whether to construct symmetry breaking lemmas based on

   * discovered rewrites (see option sygusRewSynthAccel()).

   * @param silent Whether to silence the output of rewrites discovered by this

   * class.

   * @param filterPairs Whether to filter rewrite pairs using filtering

   * techniques from the SAT 2019 paper above.

   */

  CandidateRewriteDatabase(bool doCheck,

                           bool rewAccel = false,

                           bool silent = false,

                           bool filterPairs = true);

  /**  Initialize this class */

  void initialize(const std::vector<Node>& var, SygusSampler* ss) override;

  /**  Initialize this class

   *

   * Serves the same purpose as the above function, but we will be using

   * sygus to enumerate terms and generate samples.

   *

   * tds : pointer to sygus term database. We use the extended rewriter of this

   * database when computing candidate rewrites,

   * f : a term of some SyGuS datatype type whose values we will be

   * testing under the free variables in the grammar of f. This is the

   * "candidate variable" CegConjecture::d_candidates.

   */

  void initializeSygus(const std::vector<Node>& vars,

                       TermDbSygus* tds,

                       Node f,

                       SygusSampler* ss);

  /** add term

   *

   * Notifies this class that the solution sol was enumerated. This may

   * cause a candidate-rewrite to be printed on the output stream out.

   *

   * @param sol The term to add to this class.

   * @param rec If true, then we also recursively add all subterms of sol

   * to this class as well.

   * @param out The stream to output rewrite rules on.

   * @param rew_print Set to true if this class printed a rewrite involving sol.

   * @return A previous term eq_sol added to this class, such that sol is

   * equivalent to eq_sol based on the criteria used by this class.

   */

  Node addTerm(Node sol, bool rec, std::ostream& out, bool& rew_print);

  Node addTerm(Node sol, bool rec, std::ostream& out);

  /**

   * Same as above, returns true if the return value of addTerm was equal to

   * sol, in other words, sol was a new unique term. This assumes false for

   * the argument rec.

   */

  bool addTerm(Node sol, std::ostream& out) override;

  /** sets whether this class should output candidate rewrites it finds */

  void setSilent(bool flag);

  /** set the (extended) rewriter used by this class */

  void setExtendedRewriter(ExtendedRewriter* er);

 private:

  /** (required) pointer to the sygus term database of d_qe */

  TermDbSygus* d_tds;

  /** an extended rewriter object */

  ExtendedRewriter* d_ext_rewrite;

  /** the function-to-synthesize we are testing (if sygus) */

  Node d_candidate;

  /** whether we are checking equivalence using subsolver */

  bool d_doCheck;

  /**

   * If true, we use acceleration for symmetry breaking rewrites (see option

   * sygusRewSynthAccel()).

   */

  bool d_rewAccel;

  /** if true, we silence the output of candidate rewrites */

  bool d_silent;

  /** if true, we filter pairs of terms to check equivalence */

  bool d_filterPairs;

  /** whether we are using sygus */

  bool d_using_sygus;

  /** candidate rewrite filter */

  CandidateRewriteFilter d_crewrite_filter;

  /** the cache for results of addTerm */

  std::unordered_map<Node, Node> d_add_term_cache;

};

}  // namespace quantifiers

}  // namespace theory

}  // namespace cvc5

#endif /* CVC5__THEORY__QUANTIFIERS__CANDIDATE_REWRITE_DATABASE_H */