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/********************* */
/*! \file tableau.h
** \verbatim
** Original author: taking
** Major contributors: mdeters
** Minor contributors (to current version): dejan
** 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 "expr/node.h"
#include "expr/attribute.h"
#include "theory/arith/arith_utilities.h"
#include "theory/arith/arith_activity.h"
#include "theory/arith/basic.h"
#include "theory/arith/normal_form.h"
#include <ext/hash_map>
#include <map>
#include <set>
#ifndef __CVC4__THEORY__ARITH__TABLEAU_H
#define __CVC4__THEORY__ARITH__TABLEAU_H
namespace CVC4 {
namespace theory {
namespace arith {
class Row {
ArithVar d_x_i;
typedef std::map<ArithVar, Rational, std::greater<ArithVar> > CoefficientTable;
CoefficientTable d_coeffs;
public:
typedef CoefficientTable::iterator iterator;
/**
* Construct a row equal to:
* basic = \sum_{x_i} c_i * x_i
*/
Row(ArithVar basic,
const std::vector< Rational >& coefficients,
const std::vector< ArithVar >& variables);
iterator begin(){
return d_coeffs.begin();
}
iterator end(){
return d_coeffs.end();
}
ArithVar basicVar(){
return d_x_i;
}
bool has(ArithVar x_j){
CoefficientTable::iterator x_jPos = d_coeffs.find(x_j);
return x_jPos != d_coeffs.end();
}
const Rational& lookup(ArithVar x_j){
CoefficientTable::iterator x_jPos = d_coeffs.find(x_j);
Assert(x_jPos != d_coeffs.end());
return (*x_jPos).second;
}
void pivot(ArithVar x_j);
void subsitute(Row& row_s);
void printRow();
};
class ArithVarSet {
private:
typedef std::list<ArithVar> VarList;
public:
typedef VarList::const_iterator iterator;
private:
VarList d_list;
std::vector< VarList::iterator > d_posVector;
public:
ArithVarSet() : d_list(), d_posVector() {}
iterator begin() const{ return d_list.begin(); }
iterator end() const{ return d_list.end(); }
void insert(ArithVar av){
Assert(inRange(av) );
Assert(!inSet(av) );
d_posVector[av] = d_list.insert(d_list.end(), av);
}
void erase(ArithVar var){
Assert( inRange(var) );
Assert( inSet(var) );
d_list.erase(d_posVector[var]);
d_posVector[var] = d_list.end();
}
void increaseSize(){
d_posVector.push_back(d_list.end());
}
bool inSet(ArithVar v) const{
Assert(inRange(v) );
return d_posVector[v] != d_list.end();
}
private:
bool inRange(ArithVar v) const{
return v < d_posVector.size();
}
};
class Tableau {
private:
typedef std::vector< Row* > RowsTable;
ArithVarSet d_activeBasicVars;
RowsTable d_rowsTable;
ActivityMonitor& d_activityMonitor;
IsBasicManager& d_basicManager;
public:
/**
* Constructs an empty tableau.
*/
Tableau(ActivityMonitor &am, IsBasicManager& bm) :
d_activeBasicVars(),
d_rowsTable(),
d_activityMonitor(am),
d_basicManager(bm)
{}
void increaseSize(){
d_activeBasicVars.increaseSize();
d_rowsTable.push_back(NULL);
}
ArithVarSet::iterator begin(){
return d_activeBasicVars.begin();
}
ArithVarSet::iterator end(){
return d_activeBasicVars.end();
}
Row* lookup(ArithVar var){
Assert(isActiveBasicVariable(var));
return d_rowsTable[var];
}
private:
Row* lookupEjected(ArithVar var){
Assert(isEjected(var));
return d_rowsTable[var];
}
public:
void addRow(ArithVar basicVar, const std::vector<Rational>& coeffs, const std::vector<ArithVar>& variables);
/**
* preconditions:
* x_r is basic,
* x_s is non-basic, and
* a_rs != 0.
*/
void pivot(ArithVar x_r, ArithVar x_s);
void printTableau();
bool isEjected(ArithVar var){
return d_basicManager.isBasic(var) && !isActiveBasicVariable(var);
}
void ejectBasic(ArithVar basic){
Assert(d_basicManager.isBasic(basic));
Assert(isActiveBasicVariable(basic));
d_activeBasicVars.erase(basic);
}
void reinjectBasic(ArithVar basic){
Assert(d_basicManager.isBasic(basic));
Assert(isEjected(basic));
Row* row = lookupEjected(basic);
d_activeBasicVars.insert(basic);
updateRow(row);
}
private:
inline bool isActiveBasicVariable(ArithVar var){
return d_activeBasicVars.inSet(var);
}
void updateRow(Row* row);
};
}; /* namespace arith */
}; /* namespace theory */
}; /* namespace CVC4 */
#endif /* __CVC4__THEORY__ARITH__TABLEAU_H */
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