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/********************* */
/*! \file theory_strings_preprocess.h
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds, Tianyi Liang
** 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 Strings Preprocess
**
** Strings Preprocess.
**/
#include "cvc4_private.h"
#ifndef CVC4__THEORY__STRINGS__PREPROCESS_H
#define CVC4__THEORY__STRINGS__PREPROCESS_H
#include <vector>
#include "context/cdhashmap.h"
#include "theory/rewriter.h"
#include "theory/strings/skolem_cache.h"
#include "theory/theory.h"
#include "util/hash.h"
namespace CVC4 {
namespace theory {
namespace strings {
/** Strings preprocessor
*
* This class is responsible for extended function reductions. It is used as
* a preprocessor when --no-strings-lazy-pp is enabled. By default, it is
* used for reducing extended functions on-demand during the "extended function
* reductions" inference schema of TheoryStrings.
*/
class StringsPreprocess {
public:
StringsPreprocess(SkolemCache *sc, context::UserContext *u);
~StringsPreprocess();
/**
* Returns a node t' such that
* (exists k) new_nodes => t = t'
* is valid, where k are the free skolems introduced when constructing
* new_nodes.
*/
Node simplify(Node t, std::vector<Node> &new_nodes);
/**
* Applies simplifyRec on t until a fixed point is reached, and returns
* the resulting term t', which is such that
* (exists k) new_nodes => t = t'
* is valid, where k are the free skolems introduced when constructing
* new_nodes.
*/
Node processAssertion(Node t, std::vector<Node> &new_nodes);
/**
* Replaces all formulas t in vec_node with an equivalent formula t' that
* contains no free instances of extended functions (that is, extended
* functions may only appear beneath quantifiers). This applies simplifyRec
* on each assertion in vec_node until a fixed point is reached.
*/
void processAssertions(std::vector<Node> &vec_node);
private:
/** commonly used constants */
Node d_zero;
Node d_one;
Node d_neg_one;
Node d_empty_str;
/** pointer to the skolem cache used by this class */
SkolemCache *d_sc;
/**
* Applies simplify to all top-level extended function subterms of t. New
* assertions created in this reduction are added to new_nodes. The argument
* visited stores a cache of previous results.
*/
Node simplifyRec(Node t,
std::vector<Node> &new_nodes,
std::map<Node, Node> &visited);
};
}/* CVC4::theory::strings namespace */
}/* CVC4::theory namespace */
}/* CVC4 namespace */
#endif /* CVC4__THEORY__STRINGS__PREPROCESS_H */
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