src/theory/valuation.h

   1 /*********************                                                        */
   2 /*! \file valuation.h
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Morgan Deters, Andrew Reynolds, Dejan Jovanovic
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2020 by the authors listed in the file AUTHORS
   8  ** in the top-level source directory and their institutional affiliations.
   9  ** All rights reserved.  See the file COPYING in the top-level source
  10  ** directory for licensing information.\endverbatim
  11  **
  12  ** \brief A "valuation" proxy for TheoryEngine
  13  **
  14  ** A "valuation" proxy for TheoryEngine.  This class breaks the dependence
  15  ** of theories' getValue() implementations on TheoryEngine.  getValue()
  16  ** takes a Valuation, which delegates to TheoryEngine.
  17  **/
  18
  19 #include "cvc4_private.h"
  20
  21 #ifndef CVC4__THEORY__VALUATION_H
  22 #define CVC4__THEORY__VALUATION_H
  23
  24 #include "expr/node.h"
  25 #include "options/theory_options.h"
  26
  27 namespace CVC4 {
  28
  29 class TheoryEngine;
  30
  31 namespace theory {
  32
  33 class TheoryModel;
  34
  35 /**
  36  * The status of an equality in the current context.
  37  */
  38 enum EqualityStatus {
  39   /** The equality is known to be true and has been propagated */
  40   EQUALITY_TRUE_AND_PROPAGATED,
  41   /** The equality is known to be false and has been propagated */
  42   EQUALITY_FALSE_AND_PROPAGATED,
  43   /** The equality is known to be true */
  44   EQUALITY_TRUE,
  45   /** The equality is known to be false */
  46   EQUALITY_FALSE,
  47   /** The equality is not known, but is true in the current model */
  48   EQUALITY_TRUE_IN_MODEL,
  49   /** The equality is not known, but is false in the current model */
  50   EQUALITY_FALSE_IN_MODEL,
  51   /** The equality is completely unknown */
  52   EQUALITY_UNKNOWN
  53 };/* enum EqualityStatus */
  54
  55 std::ostream& operator<<(std::ostream& os, EqualityStatus s);
  56
  57 /**
  58  * Returns true if the two statuses are compatible, i.e. both TRUE
  59  * or both FALSE (regardless of inmodel/propagation).
  60  */
  61 bool equalityStatusCompatible(EqualityStatus s1, EqualityStatus s2);
  62
  63 class Valuation {
  64   TheoryEngine* d_engine;
  65 public:
  66   Valuation(TheoryEngine* engine) :
  67     d_engine(engine) {
  68   }
  69
  70   /**
  71    * Return true if n has an associated SAT literal
  72    */
  73   bool isSatLiteral(TNode n) const;
  74
  75   /**
  76    * Get the current SAT assignment to the node n.
  77    *
  78    * This is only permitted if n is a theory atom that has an associated
  79    * SAT literal (or its negation).
  80    *
  81    * @return Node::null() if no current assignment; otherwise true or false.
  82    */
  83   Node getSatValue(TNode n) const;
  84
  85   /**
  86    * Returns true if the node has a current SAT assignment. If yes, the
  87    * argument "value" is set to its value.
  88    *
  89    * This is only permitted if n is a theory atom that has an associated
  90    * SAT literal.
  91    *
  92    * @return true if the literal has a current assignment, and returns the
  93    * value in the "value" argument; otherwise false and the "value"
  94    * argument is unmodified.
  95    */
  96   bool hasSatValue(TNode n, bool& value) const;
  97
  98   /**
  99    * Returns the equality status of the two terms, from the theory that owns the domain type.
 100    * The types of a and b must be the same.
 101    */
 102   EqualityStatus getEqualityStatus(TNode a, TNode b);
 103
 104   /**
 105    * Returns the model value of the shared term (or null if not available).
 106    */
 107   Node getModelValue(TNode var);
 108
 109   /**
 110    * Returns pointer to model. This model is only valid during last call effort
 111    * check.
 112    */
 113   TheoryModel* getModel();
 114
 115   //-------------------------------------- static configuration of the model
 116   /**
 117    * Set that k is an unevaluated kind in the TheoryModel, if it exists.
 118    * See TheoryModel::setUnevaluatedKind for details.
 119    */
 120   void setUnevaluatedKind(Kind k);
 121   /**
 122    * Set that k is an unevaluated kind in the TheoryModel, if it exists.
 123    * See TheoryModel::setSemiEvaluatedKind for details.
 124    */
 125   void setSemiEvaluatedKind(Kind k);
 126   /**
 127    * Set that k is an irrelevant kind in the TheoryModel, if it exists.
 128    * See TheoryModel::setIrrelevantKind for details.
 129    */
 130   void setIrrelevantKind(Kind k);
 131   //-------------------------------------- end static configuration of the model
 132
 133   /**
 134    * Ensure that the given node will have a designated SAT literal
 135    * that is definitionally equal to it.  The result of this function
 136    * is a Node that can be queried via getSatValue().
 137    *
 138    * @return the actual node that's been "literalized," which may
 139    * differ from the input due to theory-rewriting and preprocessing,
 140    * as well as CNF conversion
 141    */
 142   Node ensureLiteral(TNode n) CVC4_WARN_UNUSED_RESULT;
 143
 144   /**
 145    * Returns whether the given lit (which must be a SAT literal) is a decision
 146    * literal or not.  Throws an exception if lit is not a SAT literal.  "lit" may
 147    * be in either phase; that is, if "lit" is a SAT literal, this function returns
 148    * true both for lit and the negation of lit.
 149    */
 150   bool isDecision(Node lit) const;
 151
 152   /**
 153    * Get the assertion level of the SAT solver.
 154    */
 155   unsigned getAssertionLevel() const;
 156
 157   /**
 158    * Request an entailment check according to the given theoryOfMode.
 159    * See theory.h for documentation on entailmentCheck().
 160    */
 161   std::pair<bool, Node> entailmentCheck(options::TheoryOfMode mode, TNode lit);
 162
 163   /** need check ? */
 164   bool needCheck() const;
 165
 166   /**
 167    * Is the literal lit (possibly) critical for satisfying the input formula in
 168    * the current context? This call is applicable only during collectModelInfo
 169    * or during LAST_CALL effort.
 170    */
 171   bool isRelevant(Node lit) const;
 172 };/* class Valuation */
 173
 174 }/* CVC4::theory namespace */
 175 }/* CVC4 namespace */
 176
 177 #endif /* CVC4__THEORY__VALUATION_H */