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/********************* */
/*! \file substitutions.h
** \verbatim
** Top contributors (to current version):
** Morgan Deters, Dejan Jovanovic, Clark Barrett
** This file is part of the CVC4 project.
** Copyright (c) 2009-2020 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 A substitution mapping for theory simplification
**
** A substitution mapping for theory simplification.
**/
#include "cvc4_private.h"
#ifndef CVC4__THEORY__SUBSTITUTIONS_H
#define CVC4__THEORY__SUBSTITUTIONS_H
//#include <algorithm>
#include <utility>
#include <vector>
#include <unordered_map>
#include "expr/node.h"
#include "context/context.h"
#include "context/cdo.h"
#include "context/cdhashmap.h"
#include "util/hash.h"
namespace CVC4 {
namespace theory {
/**
* The type for the Substitutions mapping output by
* Theory::simplify(), TheoryEngine::simplify(), and
* Valuation::simplify(). This is in its own header to
* avoid circular dependences between those three.
*
* This map is context-dependent.
*/
class SubstitutionMap {
public:
typedef context::CDHashMap<Node, Node, NodeHashFunction> NodeMap;
typedef NodeMap::iterator iterator;
typedef NodeMap::const_iterator const_iterator;
private:
typedef std::unordered_map<Node, Node, NodeHashFunction> NodeCache;
/** The variables, in order of addition */
NodeMap d_substitutions;
/** Cache of the already performed substitutions */
NodeCache d_substitutionCache;
/** Whether or not to substitute under quantifiers */
bool d_substituteUnderQuantifiers;
/** Has the cache been invalidated? */
bool d_cacheInvalidated;
/** Whether to keep substitutions in solved form */
bool d_solvedForm;
/** Internal method that performs substitution */
Node internalSubstitute(TNode t, NodeCache& cache);
/** Helper class to invalidate cache on user pop */
class CacheInvalidator : public context::ContextNotifyObj {
bool& d_cacheInvalidated;
protected:
void contextNotifyPop() override { d_cacheInvalidated = true; }
public:
CacheInvalidator(context::Context* context, bool& cacheInvalidated) :
context::ContextNotifyObj(context),
d_cacheInvalidated(cacheInvalidated) {
}
};/* class SubstitutionMap::CacheInvalidator */
/**
* This object is notified on user pop and marks the SubstitutionMap's
* cache as invalidated.
*/
CacheInvalidator d_cacheInvalidator;
public:
SubstitutionMap(context::Context* context, bool substituteUnderQuantifiers = true, bool solvedForm = false) :
d_substitutions(context),
d_substitutionCache(),
d_substituteUnderQuantifiers(substituteUnderQuantifiers),
d_cacheInvalidated(false),
d_solvedForm(solvedForm),
d_cacheInvalidator(context, d_cacheInvalidated)
{
}
/**
* Adds a substitution from x to t.
*/
void addSubstitution(TNode x, TNode t, bool invalidateCache = true);
/**
* Merge subMap into current set of substitutions
*/
void addSubstitutions(SubstitutionMap& subMap, bool invalidateCache = true);
/**
* Returns true iff x is in the substitution map
*/
bool hasSubstitution(TNode x) const {
return d_substitutions.find(x) != d_substitutions.end();
}
/**
* Returns the substitution mapping that was given for x via
* addSubstitution(). Note that the returned value might itself
* be in the map; for the actual substitution that would be
* performed for x, use .apply(x). This getSubstitution() function
* is mainly intended for constructing assertions about what has
* already been put in the map.
*/
TNode getSubstitution(TNode x) const {
AssertArgument(hasSubstitution(x), x, "element not in this substitution map");
return (*d_substitutions.find(x)).second;
}
/**
* Apply the substitutions to the node.
*/
Node apply(TNode t);
/**
* Apply the substitutions to the node.
*/
Node apply(TNode t) const {
return const_cast<SubstitutionMap*>(this)->apply(t);
}
iterator begin() {
return d_substitutions.begin();
}
iterator end() {
return d_substitutions.end();
}
const_iterator begin() const {
return d_substitutions.begin();
}
const_iterator end() const {
return d_substitutions.end();
}
bool empty() const {
return d_substitutions.empty();
}
// NOTE [MGD]: removed clear() and swap() from the interface
// when this data structure became context-dependent
// because they weren't used---and it's not clear how they
// should best interact with cache invalidation on context
// pops.
// Simplify right-hand sides of current map using the given substitutions
void simplifyRHS(const SubstitutionMap& subMap);
// Simplify right-hand sides of current map with lhs -> rhs
void simplifyRHS(TNode lhs, TNode rhs);
bool isSolvedForm() const { return d_solvedForm; }
/**
* Print to the output stream
*/
void print(std::ostream& out) const;
void debugPrint() const;
};/* class SubstitutionMap */
inline std::ostream& operator << (std::ostream& out, const SubstitutionMap& subst) {
subst.print(out);
return out;
}
}/* CVC4::theory namespace */
std::ostream& operator<<(std::ostream& out, const theory::SubstitutionMap::iterator& i);
}/* CVC4 namespace */
#endif /* CVC4__THEORY__SUBSTITUTIONS_H */
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