src/theory/valuation.h

   1 /*********************                                                        */
   2 /*! \file valuation.h
   3  ** \verbatim
   4  ** Original author: Morgan Deters
   5  ** Major contributors: Dejan Jovanovic
   6  ** Minor contributors (to current version): Tim King, Clark Barrett, Andrew Reynolds
   7  ** This file is part of the CVC4 project.
   8  ** Copyright (c) 2009-2014  New York University and The University of Iowa
   9  ** See the file COPYING in the top-level source directory for licensing
  10  ** 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 "theory/theoryof_mode.h"
  26
  27 namespace CVC4 {
  28
  29 class TheoryEngine;
  30
  31 namespace theory {
  32
  33 class EntailmentCheckParameters;
  34 class EntailmentCheckSideEffects;
  35
  36 /**
  37  * The status of an equality in the current context.
  38  */
  39 enum EqualityStatus {
  40   /** The equality is known to be true and has been propagated */
  41   EQUALITY_TRUE_AND_PROPAGATED,
  42   /** The equality is known to be false and has been propagated */
  43   EQUALITY_FALSE_AND_PROPAGATED,
  44   /** The equality is known to be true */
  45   EQUALITY_TRUE,
  46   /** The equality is known to be false */
  47   EQUALITY_FALSE,
  48   /** The equality is not known, but is true in the current model */
  49   EQUALITY_TRUE_IN_MODEL,
  50   /** The equality is not known, but is false in the current model */
  51   EQUALITY_FALSE_IN_MODEL,
  52   /** The equality is completely unknown */
  53   EQUALITY_UNKNOWN
  54 };/* enum EqualityStatus */
  55
  56 /**
  57  * Returns true if the two statuses are compatible, i.e. both TRUE
  58  * or both FALSE (regardless of inmodel/propagation).
  59  */
  60 bool equalityStatusCompatible(EqualityStatus s1, EqualityStatus s2);
  61
  62 class Valuation {
  63   TheoryEngine* d_engine;
  64 public:
  65   Valuation(TheoryEngine* engine) :
  66     d_engine(engine) {
  67   }
  68
  69   /**
  70    * Return true if n has an associated SAT literal
  71    */
  72   bool isSatLiteral(TNode n) const;
  73
  74   /**
  75    * Get the current SAT assignment to the node n.
  76    *
  77    * This is only permitted if n is a theory atom that has an associated
  78    * SAT literal (or its negation).
  79    *
  80    * @return Node::null() if no current assignment; otherwise true or false.
  81    */
  82   Node getSatValue(TNode n) const;
  83
  84   /**
  85    * Returns true if the node has a current SAT assignment. If yes, the
  86    * argument "value" is set to its value.
  87    *
  88    * This is only permitted if n is a theory atom that has an associated
  89    * SAT literal.
  90    *
  91    * @return true if the literal has a current assignment, and returns the
  92    * value in the "value" argument; otherwise false and the "value"
  93    * argument is unmodified.
  94    */
  95   bool hasSatValue(TNode n, bool& value) const;
  96
  97   /**
  98    * Returns the equality status of the two terms, from the theory that owns the domain type.
  99    * The types of a and b must be the same.
 100    */
 101   EqualityStatus getEqualityStatus(TNode a, TNode b);
 102
 103   /**
 104    * Returns the model value of the shared term (or null if not available).
 105    */
 106   Node getModelValue(TNode var);
 107
 108   /**
 109    * Ensure that the given node will have a designated SAT literal
 110    * that is definitionally equal to it.  The result of this function
 111    * is a Node that can be queried via getSatValue().
 112    *
 113    * @return the actual node that's been "literalized," which may
 114    * differ from the input due to theory-rewriting and preprocessing,
 115    * as well as CNF conversion
 116    */
 117   Node ensureLiteral(TNode n) CVC4_WARN_UNUSED_RESULT;
 118
 119   /**
 120    * Returns whether the given lit (which must be a SAT literal) is a decision
 121    * literal or not.  Throws an exception if lit is not a SAT literal.  "lit" may
 122    * be in either phase; that is, if "lit" is a SAT literal, this function returns
 123    * true both for lit and the negation of lit.
 124    */
 125   bool isDecision(Node lit) const;
 126
 127   /**
 128    * Get the assertion level of the SAT solver.
 129    */
 130   unsigned getAssertionLevel() const;
 131
 132   /**
 133    * Request an entailment check according to the given theoryOfMode.
 134    * See theory.h for documentation on entailmentCheck().
 135    */
 136   std::pair<bool, Node> entailmentCheck(theory::TheoryOfMode mode, TNode lit, const theory::EntailmentCheckParameters* params = NULL, theory::EntailmentCheckSideEffects* out = NULL);
 137
 138   /** need check ? */
 139   bool needCheck() const;
 140
 141 };/* class Valuation */
 142
 143 }/* CVC4::theory namespace */
 144 }/* CVC4 namespace */
 145
 146 #endif /* __CVC4__THEORY__VALUATION_H */