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+/*********************                                                        */
+/*! \file fun_def_evaluator.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2019 by the authors listed in the file AUTHORS
+ ** in the top-level source directory) and their institutional affiliations.
+ ** All rights reserved.  See the file COPYING in the top-level source
+ ** directory for licensing information.\endverbatim
+ **
+ ** \brief Techniques for evaluating terms with recursively defined functions.
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef CVC4__QUANTIFIERS_FUN_DEF_EVALUATOR_H
+#define CVC4__QUANTIFIERS_FUN_DEF_EVALUATOR_H
+
+#include <map>
+#include <vector>
+#include "expr/node.h"
+
+namespace CVC4 {
+namespace theory {
+namespace quantifiers {
+
+/**
+ * Techniques for evaluating recursively defined functions.
+ */
+class FunDefEvaluator
+{
+ public:
+  FunDefEvaluator();
+  ~FunDefEvaluator() {}
+  /**
+   * Assert definition of a (recursive) function definition given by quantified
+   * formula q.
+   */
+  void assertDefinition(Node q);
+  /**
+   * Simplify node based on the (recursive) function definitions known by this
+   * class. If n cannot be simplified to a constant, then this method returns
+   * null.
+   */
+  Node evaluate(Node n) const;
+  /**
+   * Has a call to assertDefinition been made? If this returns false, then
+   * the evaluate method is the same as calling the rewriter, and returning
+   * false if the result is non-constant.
+   */
+  bool hasDefinitions() const;
+
+ private:
+  /** information cached per function definition */
+  class FunDefInfo
+  {
+   public:
+    /** the body */
+    Node d_body;
+    /** the formal argument list */
+    std::vector<Node> d_args;
+  };
+  /** maps functions to the above information */
+  std::map<Node, FunDefInfo> d_funDefMap;
+};
+
+}  // namespace quantifiers
+}  // namespace theory
+}  // namespace CVC4
+
+#endif