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       1                 :            : /******************************************************************************
       2                 :            :  * Top contributors (to current version):
       3                 :            :  *   Andrew Reynolds, Yoni Zohar
       4                 :            :  *
       5                 :            :  * This file is part of the cvc5 project.
       6                 :            :  *
       7                 :            :  * Copyright (c) 2009-2024 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.
      11                 :            :  * ****************************************************************************
      12                 :            :  *
      13                 :            :  * Utility for detecting quantifier macro definitions.
      14                 :            :  */
      15                 :            : 
      16                 :            : #include "cvc5_private.h"
      17                 :            : 
      18                 :            : #ifndef CVC5__THEORY__QUANTIFIERS__QUANTIFIERS_MACROS_H
      19                 :            : #define CVC5__THEORY__QUANTIFIERS__QUANTIFIERS_MACROS_H
      20                 :            : 
      21                 :            : #include <map>
      22                 :            : #include <vector>
      23                 :            : 
      24                 :            : #include "expr/node.h"
      25                 :            : #include "smt/env_obj.h"
      26                 :            : 
      27                 :            : namespace cvc5::internal {
      28                 :            : namespace theory {
      29                 :            : namespace quantifiers {
      30                 :            : 
      31                 :            : class QuantifiersRegistry;
      32                 :            : 
      33                 :            : /**
      34                 :            :  * A utility for inferring macros from quantified formulas. This can be seen as
      35                 :            :  * a method for putting quantified formulas in solved form, e.g.
      36                 :            :  *   forall x. P(x) ---> P = (lambda x. true)
      37                 :            :  */
      38                 :            : class QuantifiersMacros : protected EnvObj
      39                 :            : {
      40                 :            :  public:
      41                 :            :   QuantifiersMacros(Env& env, QuantifiersRegistry& qr);
      42                 :         90 :   ~QuantifiersMacros() {}
      43                 :            :   /**
      44                 :            :    * Called on quantified formulas lit of the form
      45                 :            :    *   forall x1 ... xn. n = ndef
      46                 :            :    * where n is of the form U(x1...xn). Returns an equality of the form
      47                 :            :    *   U = lambda x1 ... xn. ndef
      48                 :            :    * if this is a legal macro definition for U, and the null node otherwise.
      49                 :            :    *
      50                 :            :    * @param lit The body of the quantified formula
      51                 :            :    * @param reqGround Whether we require the macro definition to be ground,
      52                 :            :    * i.e. does not contain quantified formulas as subterms.
      53                 :            :    * @return If a macro can be inferred, an equality of the form
      54                 :            :    * (op = lambda x1 ... xn. def)), or the null node otherwise.
      55                 :            :    */
      56                 :            :   Node solve(Node lit, bool reqGround = false);
      57                 :            : 
      58                 :            :  private:
      59                 :            :   /**
      60                 :            :    * Return true n is an APPLY_UF with pairwise unique BOUND_VARIABLE as
      61                 :            :    * children.
      62                 :            :    */
      63                 :            :   bool isBoundVarApplyUf(Node n);
      64                 :            :   /**
      65                 :            :    * Returns true if n contains op, or if n contains a quantified formula
      66                 :            :    * as a subterm and reqGround is true.
      67                 :            :    */
      68                 :            :   bool containsBadOp(Node n, Node op, bool reqGround);
      69                 :            :   /**
      70                 :            :    * Return true if n preserves trigger variables in quantified formula q, that
      71                 :            :    * is, triggers can be inferred containing all variables in q in term n.
      72                 :            :    */
      73                 :            :   bool preservesTriggerVariables(Node q, Node n);
      74                 :            :   /**
      75                 :            :    * From n, get a list of possible subterms of n that could be the head of a
      76                 :            :    * macro definition.
      77                 :            :    */
      78                 :            :   void getMacroCandidates(Node n,
      79                 :            :                           std::vector<Node>& candidates,
      80                 :            :                           std::map<Node, bool>& visited);
      81                 :            :   /**
      82                 :            :    * Solve n in literal lit, return n' such that n = n' is equivalent to lit
      83                 :            :    * if possible, or null otherwise.
      84                 :            :    */
      85                 :            :   Node solveInEquality(Node n, Node lit);
      86                 :            :   /**
      87                 :            :    * Called when we have inferred a quantified formula is of the form
      88                 :            :    *   forall x1 ... xn. n = ndef
      89                 :            :    * where n is of the form U(x1...xn).
      90                 :            :    */
      91                 :            :   Node solveEq(Node n, Node ndef);
      92                 :            :   /**
      93                 :            :    * Returns the macro fdef, which originated from lit. This method is for
      94                 :            :    * debugging.
      95                 :            :    */
      96                 :            :   Node returnMacro(Node fdef, Node lit) const;
      97                 :            :   /** Reference to the quantifiers registry */
      98                 :            :   QuantifiersRegistry& d_qreg;
      99                 :            : };
     100                 :            : 
     101                 :            : }  // namespace quantifiers
     102                 :            : }  // namespace theory
     103                 :            : }  // namespace cvc5::internal
     104                 :            : 
     105                 :            : #endif /*CVC5__THEORY__QUANTIFIERS__QUANTIFIER_MACROS_H */