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       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                 :            :  * Decision manager, which manages all decision strategies owned by
      11                 :            :  * theory solvers within TheoryEngine.
      12                 :            :  */
      13                 :            : 
      14                 :            : #include "cvc5_private.h"
      15                 :            : 
      16                 :            : #ifndef CVC5__THEORY__DECISION_MANAGER__H
      17                 :            : #define CVC5__THEORY__DECISION_MANAGER__H
      18                 :            : 
      19                 :            : #include <map>
      20                 :            : 
      21                 :            : #include "context/cdlist.h"
      22                 :            : #include "theory/decision_strategy.h"
      23                 :            : 
      24                 :            : namespace cvc5::internal {
      25                 :            : namespace theory {
      26                 :            : 
      27                 :            : /** DecisionManager
      28                 :            :  *
      29                 :            :  * This class manages all "decision strategies" for theory solvers in
      30                 :            :  * TheoryEngine. A decision strategy is a callback in the SAT solver for
      31                 :            :  * imposing its next decision. This is useful, for instance, in
      32                 :            :  * branch-and-bound algorithms where we require that the first decision
      33                 :            :  * is a bound on some quantity. For instance, finite model finding may impose
      34                 :            :  * a bound on the cardinality of an uninterpreted sort as the first decision.
      35                 :            :  *
      36                 :            :  * This class maintains a user-context-dependent set of pointers to
      37                 :            :  * DecisionStrategy objects, which implement indivdual decision strategies.
      38                 :            :  *
      39                 :            :  * Decision strategies may be registered to this class via registerStrategy
      40                 :            :  * at any time during solving. They are cleared via a call to reset during
      41                 :            :  * TheoryEngine's postSolve method.
      42                 :            :  *
      43                 :            :  * Decision strategies have a fixed order, which is managed by the enumeration
      44                 :            :  * type StrategyId, where strategies with smaller id have higher precedence
      45                 :            :  * in our global decision strategy.
      46                 :            :  */
      47                 :            : class DecisionManager
      48                 :            : {
      49                 :            :   typedef context::CDList<DecisionStrategy*> DecisionStrategyList;
      50                 :            : 
      51                 :            :  public:
      52                 :            :   enum StrategyId
      53                 :            :   {
      54                 :            :     // The order of the global decision strategy used by the TheoryEngine
      55                 :            :     // for getNextDecision.
      56                 :            : 
      57                 :            :     //----- assume-feasibile strategies
      58                 :            :     //  These are required to go first for the sake of model-soundness. In
      59                 :            :     //  other words, if these strategies did not go first, we might answer
      60                 :            :     //  "sat" for problems that are unsat.
      61                 :            :     STRAT_QUANT_CEGQI_FEASIBLE,
      62                 :            :     STRAT_QUANT_SYGUS_FEASIBLE,
      63                 :            :     // placeholder for last model-sound required strategy
      64                 :            :     STRAT_LAST_M_SOUND,
      65                 :            : 
      66                 :            :     //----- finite model finding strategies
      67                 :            :     //  We require these go here for the sake of finite-model completeness. In
      68                 :            :     //  other words, if these strategies did not go before other decisions, we
      69                 :            :     //  might be non-terminating instead of answering "sat" with a solution
      70                 :            :     //  within a given a bound.
      71                 :            :     STRAT_ORACLE_ARG_VALUE,
      72                 :            :     STRAT_UF_COMBINED_CARD,
      73                 :            :     STRAT_UF_CARD,
      74                 :            :     STRAT_DT_SYGUS_ENUM_ACTIVE,
      75                 :            :     STRAT_DT_SYGUS_ENUM_SIZE,
      76                 :            :     STRAT_STRINGS_SUM_LENGTHS,
      77                 :            :     STRAT_QUANT_BOUND_INT_SIZE,
      78                 :            :     STRAT_QUANT_CEGIS_UNIF_NUM_ENUMS,
      79                 :            :     STRAT_SEP_NEG_GUARD,
      80                 :            :     // placeholder for last finite-model-complete required strategy
      81                 :            :     STRAT_LAST_FM_COMPLETE,
      82                 :            : 
      83                 :            :     //----- decision strategies that are optimizations
      84                 :            :     STRAT_ARRAYS,
      85                 :            : 
      86                 :            :     STRAT_LAST
      87                 :            :   };
      88                 :            :   /** The scope of a strategy, used in registerStrategy below */
      89                 :            :   enum StrategyScope
      90                 :            :   {
      91                 :            :     // The strategy is user-context dependent, that is, it is cleared when
      92                 :            :     // the user context is popped.
      93                 :            :     STRAT_SCOPE_USER_CTX_DEPENDENT,
      94                 :            :     // The strategy is local to a check-sat call, that is, it is cleared on
      95                 :            :     // a call to presolve.
      96                 :            :     STRAT_SCOPE_LOCAL_SOLVE,
      97                 :            :     // The strategy is context-independent.
      98                 :            :     STRAT_SCOPE_CTX_INDEPENDENT,
      99                 :            :   };
     100                 :            :   DecisionManager(context::Context* userContext);
     101                 :      28839 :   ~DecisionManager() {}
     102                 :            :   /** presolve
     103                 :            :    *
     104                 :            :    * This clears all decision strategies that are registered to this manager
     105                 :            :    * that no longer exist in the current user context.
     106                 :            :    * We require that each satisfiability check beyond the first calls this
     107                 :            :    * function exactly once. It is called during TheoryEngine::presolve.
     108                 :            :    */
     109                 :            :   void presolve();
     110                 :            :   /**
     111                 :            :    * Registers the strategy ds with this manager. The id specifies when the
     112                 :            :    * strategy should be run. The argument sscope indicates the scope of the
     113                 :            :    * strategy, i.e. how long it persists.
     114                 :            :    *
     115                 :            :    * Typically, strategies that are user-context-dependent are those that are
     116                 :            :    * in response to an assertion (e.g. a strategy that decides that a sygus
     117                 :            :    * conjecture is feasible). An example of a strategy that is context
     118                 :            :    * independent is the combined cardinality decision strategy for finite model
     119                 :            :    * finding for UF, which is not specific to any formula/type.
     120                 :            :    */
     121                 :            :   void registerStrategy(StrategyId id,
     122                 :            :                         DecisionStrategy* ds,
     123                 :            :                         StrategyScope sscope = STRAT_SCOPE_USER_CTX_DEPENDENT);
     124                 :            :   /** Get the next decision request
     125                 :            :    *
     126                 :            :    * If this method returns a non-null node n, then n is a literal corresponding
     127                 :            :    * to the next decision that the SAT solver should take. If this method
     128                 :            :    * returns null, then no decisions are required by a decision strategy
     129                 :            :    * registered to this class. In the latter case, the SAT solver will choose
     130                 :            :    * a decision based on its given heuristic.
     131                 :            :    */
     132                 :            :   Node getNextDecisionRequest();
     133                 :            : 
     134                 :            :  private:
     135                 :            :   /** Map containing all strategies registered to this manager */
     136                 :            :   std::map<StrategyId, std::vector<DecisionStrategy*> > d_reg_strategy;
     137                 :            :   /** Set of decision strategies in this user context */
     138                 :            :   DecisionStrategyList d_strategyCacheC;
     139                 :            :   /** Set of decision strategies that are context independent */
     140                 :            :   std::unordered_set<DecisionStrategy*> d_strategyCache;
     141                 :            : };
     142                 :            : 
     143                 :            : }  // namespace theory
     144                 :            : }  // namespace cvc5::internal
     145                 :            : 
     146                 :            : #endif /* CVC5__THEORY__DECISION_MANAGER__H */