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/********************* */
/*! \file decision_strategy.cpp
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds
** 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 Implementation of base classes for decision strategies used by theory
** solvers for use in the DecisionManager of TheoryEngine.
**/
#include "theory/decision_strategy.h"
#include "theory/rewriter.h"
using namespace CVC4::kind;
namespace CVC4 {
namespace theory {
DecisionStrategyFmf::DecisionStrategyFmf(context::Context* satContext,
Valuation valuation)
: d_valuation(valuation),
d_has_curr_literal(false, satContext),
d_curr_literal(0, satContext)
{
}
void DecisionStrategyFmf::initialize() { d_literals.clear(); }
Node DecisionStrategyFmf::getNextDecisionRequest()
{
Trace("dec-strategy-debug")
<< "Get next decision request " << identify() << "..." << std::endl;
if (d_has_curr_literal.get())
{
Trace("dec-strategy-debug") << "...already has decision" << std::endl;
return Node::null();
}
bool success;
unsigned curr_lit = d_curr_literal.get();
do
{
success = true;
// get the current literal
Node lit = getLiteral(curr_lit);
Trace("dec-strategy-debug")
<< "...check literal #" << curr_lit << " : " << lit << std::endl;
// if out of literals, we are done in the current SAT context
if (!lit.isNull())
{
bool value;
if (!d_valuation.hasSatValue(lit, value))
{
Trace("dec-strategy-debug") << "...not assigned, return." << std::endl;
// if it has not been decided, return it
return lit;
}
else if (!value)
{
Trace("dec-strategy-debug")
<< "...assigned false, increment." << std::endl;
// asserted false, the current literal is incremented
curr_lit = d_curr_literal.get() + 1;
d_curr_literal.set(curr_lit);
// repeat
success = false;
}
else
{
Trace("dec-strategy-debug") << "...already assigned true." << std::endl;
}
}
else
{
Trace("dec-strategy-debug") << "...exhausted literals." << std::endl;
}
} while (!success);
// the current literal has been decided with the right polarity, we are done
d_has_curr_literal = true;
return Node::null();
}
bool DecisionStrategyFmf::getAssertedLiteralIndex(unsigned& i) const
{
if (d_has_curr_literal.get())
{
i = d_curr_literal.get();
return true;
}
return false;
}
Node DecisionStrategyFmf::getAssertedLiteral()
{
if (d_has_curr_literal.get())
{
Assert(d_curr_literal.get() < d_literals.size());
return getLiteral(d_curr_literal.get());
}
return Node::null();
}
Node DecisionStrategyFmf::getLiteral(unsigned n)
{
// allocate until the index is valid
while (n >= d_literals.size())
{
Node lit = mkLiteral(d_literals.size());
if (!lit.isNull())
{
lit = Rewriter::rewrite(lit);
}
d_literals.push_back(lit);
}
Node ret = d_literals[n];
if (!ret.isNull())
{
// always ensure it is in the CNF stream
ret = d_valuation.ensureLiteral(ret);
}
return ret;
}
DecisionStrategySingleton::DecisionStrategySingleton(
const char* name,
Node lit,
context::Context* satContext,
Valuation valuation)
: DecisionStrategyFmf(satContext, valuation), d_name(name), d_literal(lit)
{
}
Node DecisionStrategySingleton::mkLiteral(unsigned n)
{
if (n == 0)
{
return d_literal;
}
return Node::null();
}
Node DecisionStrategySingleton::getSingleLiteral() { return d_literal; }
} // namespace theory
} // namespace CVC4
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