Branch data     Line data    Source code

       1                 :            : /******************************************************************************
       2                 :            :  * This file is part of the cvc5 project.
       3                 :            :  *
       4                 :            :  * Copyright (c) 2009-2026 by the authors listed in the file AUTHORS
       5                 :            :  * in the top-level source directory and their institutional affiliations.
       6                 :            :  * All rights reserved.  See the file COPYING in the top-level source
       7                 :            :  * directory for licensing information.
       8                 :            :  * ****************************************************************************
       9                 :            :  *
      10                 :            :  * SAT Solver.
      11                 :            :  */
      12                 :            : 
      13                 :            : #include "cvc5_private.h"
      14                 :            : 
      15                 :            : #ifndef CVC5__PROP__SAT_SOLVER_H
      16                 :            : #define CVC5__PROP__SAT_SOLVER_H
      17                 :            : 
      18                 :            : #include "proof/clause_id.h"
      19                 :            : #include "prop/prop_proof_manager.h"
      20                 :            : #include "prop/sat_solver_types.h"
      21                 :            : 
      22                 :            : namespace cvc5::internal {
      23                 :            : namespace prop {
      24                 :            : 
      25                 :            : class SatSolverFactory;
      26                 :            : class SatProofManager;
      27                 :            : class TheoryProxy;
      28                 :            : 
      29                 :            : class SatSolver
      30                 :            : {
      31                 :            :   friend class SatSolverFactory;
      32                 :            : 
      33                 :            :  public:
      34                 :            :   /** Virtual destructor */
      35                 :      48699 :   virtual ~SatSolver() = default;
      36                 :            : 
      37                 :            :   /**
      38                 :            :    * Add clause to SAT solver.
      39                 :            :    * @param clause    The clause to add.
      40                 :            :    * @param removable True to indicate that this clause is not irredundant.
      41                 :            :    */
      42                 :            :   virtual ClauseId addClause(const SatClause& clause, bool removable) = 0;
      43                 :            : 
      44                 :            :   /**
      45                 :            :    * Create a new boolean variable in the solver.
      46                 :            :    * @param isTheoryAtom is this a theory atom that needs to be asserted to
      47                 :            :    * theory
      48                 :            :    * @param canErase whether the sat solver can safely eliminate this variable
      49                 :            :    */
      50                 :            :   virtual SatVariable newVar(bool isTheoryAtom, bool canErase) = 0;
      51                 :            : 
      52                 :            :   /**
      53                 :            :    * Create a new (or return an existing) boolean variable representing the
      54                 :            :    * constant `true`.
      55                 :            :    * @return The variable representing true.
      56                 :            :    */
      57                 :            :   virtual SatVariable trueVar() = 0;
      58                 :            : 
      59                 :            :   /**
      60                 :            :    * Create a new (or return an existing) boolean variable representing the
      61                 :            :    * constant false.
      62                 :            :    * @return The variable representing false.
      63                 :            :    */
      64                 :            :   virtual SatVariable falseVar() = 0;
      65                 :            : 
      66                 :            :   /** Check the satisfiability of the added clauses */
      67                 :            :   virtual SatValue solve() = 0;
      68                 :            : 
      69                 :            :   /** Check the satisfiability of the added clauses */
      70                 :            :   virtual SatValue solve(long unsigned int&) = 0;
      71                 :            : 
      72                 :            :   /** Check satisfiability under assumptions */
      73                 :            :   virtual SatValue solve(const std::vector<SatLiteral>& assumptions) = 0;
      74                 :            : 
      75                 :            :   /**
      76                 :            :    * Tell SAT solver to only do propagation on next solve().
      77                 :            :    *
      78                 :            :    * @return true if feature is supported, otherwise false.
      79                 :            :    */
      80                 :          0 :   virtual bool setPropagateOnly() { return false; }
      81                 :            : 
      82                 :            :   /** Interrupt the solver */
      83                 :            :   virtual void interrupt() = 0;
      84                 :            : 
      85                 :            :   /** Call value() during the search.*/
      86                 :            :   virtual SatValue value(SatLiteral l) = 0;
      87                 :            : 
      88                 :            :   /** Call modelValue() when the search is done.*/
      89                 :            :   virtual SatValue modelValue(SatLiteral l) = 0;
      90                 :            : 
      91                 :            :   /** Check if the solver is in an inconsistent state */
      92                 :            :   virtual bool ok() const = 0;
      93                 :            : 
      94                 :            :   /**
      95                 :            :    * Get list of unsatisfiable assumptions.
      96                 :            :    *
      97                 :            :    * The returned assumptions are a subset of the assumptions provided to
      98                 :            :    * the solve method.
      99                 :            :    * Can only be called if satisfiability check under assumptions was used and
     100                 :            :    * if it returned SAT_VALUE_FALSE.
     101                 :            :    */
     102                 :            :   virtual void getUnsatAssumptions(
     103                 :            :       std::vector<SatLiteral>& unsat_assumptions) = 0;
     104                 :            : 
     105                 :            :  private:
     106                 :            :   /** Is called by the SatSolverFactory right after construction. */
     107                 :            :   virtual void initialize() = 0;
     108                 :            : };
     109                 :            : 
     110                 :            : class CDCLTSatSolver : public SatSolver
     111                 :            : {
     112                 :            :   friend class SatSolverFactory;
     113                 :            : 
     114                 :            :  public:
     115                 :            :   /** Virtual destructor */
     116                 :      48678 :   ~CDCLTSatSolver() override = default;
     117                 :            : 
     118                 :            :   virtual void attachProofManager(PropPfManager* ppm) = 0;
     119                 :            : 
     120                 :            :   /** Get the current assertion level */
     121                 :            :   virtual uint32_t getAssertionLevel() const = 0;
     122                 :            : 
     123                 :            :   virtual void push() = 0;
     124                 :            : 
     125                 :            :   virtual void pop() = 0;
     126                 :            : 
     127                 :            :   /**
     128                 :            :    * Reset the decisions in the DPLL(T) SAT solver at the current assertion
     129                 :            :    * level.
     130                 :            :    */
     131                 :            :   virtual void resetTrail() = 0;
     132                 :            : 
     133                 :            :   /**
     134                 :            :    * Configure the preferred phase for a decision literal.
     135                 :            :    *
     136                 :            :    * @note This phase is always enforced when the SAT solver decides to make a
     137                 :            :    *       decision on this variable on its own. If a decision is injected into
     138                 :            :    *       the SAT solver via TheoryProxy::getNextDecisionRequest(), the
     139                 :            :    *       preferred phase will only be considered if the decision was derived
     140                 :            :    *       by the decision engine. It will be ignored if the decision was
     141                 :            :    *       derived from a theory (the phase enforced by the theory overrides
     142                 :            :    *       the preferred phase).
     143                 :            :    *
     144                 :            :    * @param lit The literal.
     145                 :            :    */
     146                 :            :   virtual void preferPhase(SatLiteral lit) = 0;
     147                 :            : 
     148                 :            :   virtual bool isDecision(SatVariable decn) const = 0;
     149                 :            : 
     150                 :            :   /**
     151                 :            :    * Return whether variable has a fixed assignment.
     152                 :            :    */
     153                 :            :   virtual bool isFixed(SatVariable var) const = 0;
     154                 :            : 
     155                 :            :   /**
     156                 :            :    * Return the current list of decisions made by the SAT solver.
     157                 :            :    */
     158                 :            :   virtual std::vector<SatLiteral> getDecisions() const = 0;
     159                 :            : 
     160                 :            :   /**
     161                 :            :    * Return the order heap of the SAT solver, which is a priority queueue
     162                 :            :    * of literals ordered with respect to variable activity.
     163                 :            :    */
     164                 :            :   virtual std::vector<Node> getOrderHeap() const = 0;
     165                 :            : 
     166                 :            :   /**
     167                 :            :    * Get proof, which is used if option prop-proof-mode is PROOF.
     168                 :            :    * @return a complete proof computed by this SAT solver.
     169                 :            :    */
     170                 :            :   virtual std::shared_ptr<ProofNode> getProof() = 0;
     171                 :            : 
     172                 :            :  private:
     173                 :            :   /**
     174                 :            :    * Regular initialization to generate a solver that does not have
     175                 :            :    * CDCLT features. To be called by SatSolverFactory.
     176                 :            :    */
     177                 :            :   void initialize() override = 0;
     178                 :            : 
     179                 :            :   /**
     180                 :            :    * Used instead of initialize() to initializes the solver to act as
     181                 :            :    * CDCLT solver. To be called by SatSolverFactory.
     182                 :            :    */
     183                 :            :   virtual void initialize(TheoryProxy* theoryProxy) = 0;
     184                 :            : 
     185                 :            : }; /* class CDCLTSatSolver */
     186                 :            : 
     187                 :            : }  // namespace prop
     188                 :            : }  // namespace cvc5::internal
     189                 :            : 
     190                 :            : #endif /* CVC5__PROP__SAT_SOLVER_H */