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/********************* */
/*! \file substitutions.h
** \verbatim
** Original author: mdeters
** Major contributors: dejan
** Minor contributors (to current version): none
** This file is part of the CVC4 prototype.
** Copyright (c) 2009, 2010, 2011 The Analysis of Computer Systems Group (ACSys)
** Courant Institute of Mathematical Sciences
** New York University
** 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 <utility>
#include <vector>
#include <algorithm>
#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::hash_map<Node, Node, NodeHashFunction> NodeCache;
/** The context within which this SubstitutionMap was constructed. */
context::Context* d_context;
/** The variables, in order of addition */
NodeMap d_substitutions;
/** Cache of the already performed substitutions */
NodeCache d_substitutionCache;
/** Has the cache been invalidated? */
bool d_cacheInvalidated;
/** Internal method that performs substitution */
Node internalSubstitute(TNode t, NodeCache& substitutionCache);
/** Helper class to invalidate cache on user pop */
class CacheInvalidator : public context::ContextNotifyObj {
bool& d_cacheInvalidated;
protected:
void contextNotifyPop() {
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) :
d_context(context),
d_substitutions(context),
d_substitutionCache(),
d_cacheInvalidated(false),
d_cacheInvalidator(context, d_cacheInvalidated) {
}
/**
* Adds a substitution from x to t. Typically you also want to apply this
* substitution to the existing set (backSub), but you do not need to
* apply the existing set to the new substitution (forwardSub). However,
* the method allows you to do either. Probably you should not do both,
* as it will be very difficult to maintain the invariant that no
* left-hand side appears on any right-hand side.
*/
void addSubstitution(TNode x, TNode t,
bool invalidateCache = true,
bool backSub = true,
bool forwardSub = false);
/**
* Returns true iff x is in the substitution map
*/
bool hasSubstitution(TNode x)
{ return d_substitutions.find(x) != d_substitutions.end(); }
/**
* 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();
}
// 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.
/**
* Print to the output stream
*/
void print(std::ostream& out) const;
};
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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