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/********************* */
/*! \file partial_model.h
** \verbatim
** Original author: taking
** Major contributors: none
** Minor contributors (to current version): mdeters
** This file is part of the CVC4 prototype.
** Copyright (c) 2009, 2010 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 [[ Add one-line brief description here ]]
**
** [[ Add lengthier description here ]]
** \todo document this file
**/
#include "context/context.h"
#include "context/cdmap.h"
#include "theory/arith/delta_rational.h"
#include "expr/attribute.h"
#include "expr/node.h"
#include <deque>
#ifndef __CVC4__THEORY__ARITH__PARTIAL_MODEL_H
#define __CVC4__THEORY__ARITH__PARTIAL_MODEL_H
namespace CVC4 {
namespace theory {
namespace arith {
namespace partial_model {
struct DeltaRationalCleanupStrategy{
static void cleanup(DeltaRational* dq){
Debug("arithgc") << "cleaning up " << dq << "\n";
if(dq != NULL){
delete dq;
}
}
};
struct AssignmentAttrID {};
typedef expr::Attribute<AssignmentAttrID,
DeltaRational*,
DeltaRationalCleanupStrategy> Assignment;
struct SafeAssignmentAttrID {};
typedef expr::Attribute<SafeAssignmentAttrID,
DeltaRational*,
DeltaRationalCleanupStrategy> SafeAssignment;
/**
* This defines a context dependent delta rational map.
* This is used to keep track of the current lower and upper bounds on
* each variable. This information is conext dependent.
*/
typedef context::CDMap<TNode, DeltaRational, TNodeHashFunction> CDDRationalMap;
/* Side disucssion for why new tables are introduced instead of using the
* attribute framework.
* It comes down to that the obvious ways to use the current attribute
* framework do not provide a terribly satisfying answer.
* - Suppose the type of the attribute is CD and maps to type DeltaRational.
* Well it can't map to a DeltaRational, and it thus it will be a
* DeltaRational*
* However being context dependent means givening up cleanup functions.
* So this leaks memory.
* - Suppose the type of the attribute is CD and the type mapped to
* was a Node wrapping a CONST_DELTA_RATIONAL.
* This was rejected for inefficiency, and uglyness.
* Inefficiency: Every lookup and comparison will require going through the
* massaging in between a node and the constant being wrapped. Every update
* requires going through the additional expense of creating at least 1 node.
* The Uglyness: If this was chosen it would also suggest using comparisons
* against DeltaRationals for the tracking the constraints for conflict
* analysis. This seems to invite misuse and introducing Nodes that should
* probably not escape arith.
* - Suppose that the of the attribute was not CD and mapped to a
* CDO<DeltaRational*> or similarly a ContextObj that wraps a DeltaRational*.
* This is currently rejected just because this is difficult to get right,
* and maintain. However with enough effort this the best solution is
* probably of this form.
*/
/**
* This is the literal that was asserted in the current context to the theory
* that asserted the tightest lower bound on a variable.
* For example: for a variable x this could be the constraint
* (>= x 4) or (not (<= x 50))
* Note the strong correspondence between this and LowerBoundMap.
* This is used during conflict analysis.
*/
struct LowerConstraintAttrID {};
typedef expr::CDAttribute<LowerConstraintAttrID,TNode> LowerConstraint;
/**
* See the documentation for LowerConstraint.
*/
struct UpperConstraintAttrID {};
typedef expr::CDAttribute<UpperConstraintAttrID,TNode> UpperConstraint;
struct TheoryArithPropagatedID {};
typedef expr::CDAttribute<TheoryArithPropagatedID, bool> TheoryArithPropagated;
struct HasHadABoundID {};
typedef expr::Attribute<HasHadABoundID, bool> HasHadABound;
}; /*namespace partial_model*/
class ArithPartialModel {
private:
partial_model::CDDRationalMap d_LowerBoundMap;
partial_model::CDDRationalMap d_UpperBoundMap;
/**
* List contains all of the variables that have an unsafe assignment.
*/
typedef std::vector<TNode> HistoryList;
HistoryList d_history;
public:
ArithPartialModel(context::Context* c):
d_LowerBoundMap(c),
d_UpperBoundMap(c),
d_history()
{ }
void setLowerConstraint(TNode x, TNode constraint);
void setUpperConstraint(TNode x, TNode constraint);
TNode getLowerConstraint(TNode x);
TNode getUpperConstraint(TNode x);
/* Initializes a variable to a safe value.*/
void initialize(TNode x, const DeltaRational& r);
/* Gets the last assignment to a variable that is known to be conistent. */
DeltaRational getSafeAssignment(TNode x) const;
/* Reverts all variable assignments to their safe values. */
void revertAssignmentChanges();
/* Commits all variables assignments as safe.*/
void commitAssignmentChanges();
void setUpperBound(TNode x, const DeltaRational& r);
void setLowerBound(TNode x, const DeltaRational& r);
/* Sets an unsafe variable assignment */
void setAssignment(TNode x, const DeltaRational& r);
void setAssignment(TNode x, const DeltaRational& safe, const DeltaRational& r);
/** Must know that the bound exists before calling this! */
DeltaRational getUpperBound(TNode x) const;
DeltaRational getLowerBound(TNode x) const;
const DeltaRational& getAssignment(TNode x) const;
/**
* x <= l
* ? c < l
*/
bool belowLowerBound(TNode x, const DeltaRational& c, bool strict);
/**
* x <= u
* ? c < u
*/
bool aboveUpperBound(TNode x, const DeltaRational& c, bool strict);
bool strictlyBelowUpperBound(TNode x);
bool strictlyAboveLowerBound(TNode x);
bool assignmentIsConsistent(TNode x);
void printModel(TNode x);
bool hasBounds(TNode x);
bool hasEverHadABound(TNode var){
return var.getAttribute(partial_model::HasHadABound());
}
private:
/**
* This function implements the mostly identical:
* revertAssignmentChanges() and commitAssignmentChanges().
*/
void clearSafeAssignments(bool revert);
};
}; /* namesapce arith */
}; /* namespace theory */
}; /* namespace CVC4 */
#endif /* __CVC4__THEORY__ARITH__PARTIAL_MODEL_H */
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