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/********************* */
/*! \file strings_fmf.cpp
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds
** This file is part of the CVC4 project.
** Copyright (c) 2009-2019 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 a finite model finding decision strategy for
** strings.
**/
#include "theory/strings/strings_fmf.h"
using namespace std;
using namespace CVC4::context;
using namespace CVC4::kind;
namespace CVC4 {
namespace theory {
namespace strings {
StringsFmf::StringsFmf(context::Context* c,
context::UserContext* u,
Valuation valuation,
SkolemCache& skc)
: d_sslds(nullptr),
d_satContext(c),
d_userContext(u),
d_valuation(valuation),
d_skCache(skc),
d_inputVars(u)
{
}
StringsFmf::~StringsFmf() {}
void StringsFmf::preRegisterTerm(TNode n)
{
if (!n.getType().isString())
{
return;
}
Kind k = n.getKind();
// Our decision strategy will minimize the length of this term if it is a
// variable but not an internally generated Skolem, or a term that does
// not belong to this theory.
if (n.isVar() ? !d_skCache.isSkolem(n) : kindToTheoryId(k) != THEORY_STRINGS)
{
d_inputVars.insert(n);
Trace("strings-dstrat-reg") << "input variable: " << n << std::endl;
}
}
void StringsFmf::presolve()
{
d_sslds.reset(new StringSumLengthDecisionStrategy(
d_satContext, d_userContext, d_valuation));
Trace("strings-dstrat-reg")
<< "presolve: register decision strategy." << std::endl;
std::vector<Node> inputVars;
for (NodeSet::const_iterator itr = d_inputVars.begin();
itr != d_inputVars.end();
++itr)
{
inputVars.push_back(*itr);
}
d_sslds->initialize(inputVars);
}
DecisionStrategy* StringsFmf::getDecisionStrategy() const
{
return d_sslds.get();
}
StringsFmf::StringSumLengthDecisionStrategy::StringSumLengthDecisionStrategy(
context::Context* c, context::UserContext* u, Valuation valuation)
: DecisionStrategyFmf(c, valuation), d_inputVarLsum(u)
{
}
bool StringsFmf::StringSumLengthDecisionStrategy::isInitialized()
{
return !d_inputVarLsum.get().isNull();
}
void StringsFmf::StringSumLengthDecisionStrategy::initialize(
const std::vector<Node>& vars)
{
if (d_inputVarLsum.get().isNull() && !vars.empty())
{
NodeManager* nm = NodeManager::currentNM();
std::vector<Node> sum;
for (const Node& v : vars)
{
sum.push_back(nm->mkNode(STRING_LENGTH, v));
}
Node sumn = sum.size() == 1 ? sum[0] : nm->mkNode(PLUS, sum);
d_inputVarLsum.set(sumn);
}
}
Node StringsFmf::StringSumLengthDecisionStrategy::mkLiteral(unsigned i)
{
if (d_inputVarLsum.get().isNull())
{
return Node::null();
}
NodeManager* nm = NodeManager::currentNM();
Node lit = nm->mkNode(LEQ, d_inputVarLsum.get(), nm->mkConst(Rational(i)));
Trace("strings-fmf") << "StringsFMF::mkLiteral: " << lit << std::endl;
return lit;
}
std::string StringsFmf::StringSumLengthDecisionStrategy::identify() const
{
return std::string("string_sum_len");
}
} // namespace strings
} // namespace theory
} // namespace CVC4
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