src/theory/theory_rewriter.h

   1 /*********************                                                        */
   2 /*! \file theory_rewriter.h
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Andres Noetzli, Morgan Deters, Andrew Reynolds
   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 The TheoryRewriter class
  13  **
  14  ** The TheoryRewriter class is the interface that theory rewriters implement.
  15  **/
  16
  17 #include "cvc4_private.h"
  18
  19 #ifndef CVC4__THEORY__THEORY_REWRITER_H
  20 #define CVC4__THEORY__THEORY_REWRITER_H
  21
  22 #include "expr/node.h"
  23
  24 namespace CVC4 {
  25 namespace theory {
  26
  27 class Rewriter;
  28
  29 /**
  30  * Theory rewriters signal whether more rewriting is needed (or not)
  31  * by using a member of this enumeration.  See RewriteResponse, below.
  32  */
  33 enum RewriteStatus
  34 {
  35   /** The node is fully rewritten (no more rewrites apply) */
  36   REWRITE_DONE,
  37   /** The node may be rewritten further */
  38   REWRITE_AGAIN,
  39   /** Subnodes of the node may be rewritten further */
  40   REWRITE_AGAIN_FULL
  41 }; /* enum RewriteStatus */
  42
  43 /**
  44  * Instances of this class serve as response codes from
  45  * TheoryRewriter::preRewrite() and TheoryRewriter::postRewrite(). The response
  46  * consists of the rewritten node as well as a status that indicates whether
  47  * more rewriting is needed or not.
  48  */
  49 struct RewriteResponse
  50 {
  51   const RewriteStatus d_status;
  52   const Node d_node;
  53   RewriteResponse(RewriteStatus status, Node n) : d_status(status), d_node(n) {}
  54 }; /* struct RewriteResponse */
  55
  56 /**
  57  * The interface that a theory rewriter has to implement.
  58  *
  59  * Note: A theory rewriter is expected to handle all kinds of a theory, even
  60  * the ones that are removed by `Theory::expandDefinition()` since it may be
  61  * called on terms before the definitions have been expanded.
  62  */
  63 class TheoryRewriter
  64 {
  65  public:
  66   virtual ~TheoryRewriter() = default;
  67
  68   /**
  69    * Registers the rewrites of a given theory with the rewriter.
  70    *
  71    * @param rewriter The rewriter to register the rewrites with.
  72    */
  73   virtual void registerRewrites(Rewriter* rewriter) {}
  74
  75   /**
  76    * Performs a pre-rewrite step.
  77    *
  78    * @param node The node to rewrite
  79    */
  80   virtual RewriteResponse postRewrite(TNode node) = 0;
  81
  82   /**
  83    * Performs a post-rewrite step.
  84    *
  85    * @param node The node to rewrite
  86    */
  87   virtual RewriteResponse preRewrite(TNode node) = 0;
  88 };
  89
  90 }  // namespace theory
  91 }  // namespace CVC4
  92
  93 #endif /* CVC4__THEORY__THEORY_REWRITER_H */