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/********************* */
/*! \file real_to_int.cpp
** \verbatim
** Top contributors (to current version):
** Haniel Barbosa, Andrew Reynolds, Tim King
** This file is part of the CVC4 project.
** Copyright (c) 2009-2021 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 The RealToInt preprocessing pass
**
** Converts real operations into integer operations
**/
#include "preprocessing/passes/real_to_int.h"
#include <string>
#include "preprocessing/assertion_pipeline.h"
#include "preprocessing/preprocessing_pass_context.h"
#include "theory/arith/arith_msum.h"
#include "theory/rewriter.h"
#include "theory/theory_model.h"
namespace CVC4 {
namespace preprocessing {
namespace passes {
using namespace std;
using namespace CVC4::theory;
Node RealToInt::realToIntInternal(TNode n, NodeMap& cache, std::vector<Node>& var_eq)
{
Trace("real-as-int-debug") << "Convert : " << n << std::endl;
NodeMap::iterator find = cache.find(n);
if (find != cache.end())
{
return (*find).second;
}
else
{
NodeManager* nm = NodeManager::currentNM();
Node ret = n;
if (n.getNumChildren() > 0)
{
if ((n.getKind() == kind::EQUAL && n[0].getType().isReal())
|| n.getKind() == kind::GEQ || n.getKind() == kind::LT
|| n.getKind() == kind::GT || n.getKind() == kind::LEQ)
{
ret = Rewriter::rewrite(n);
Trace("real-as-int-debug") << "Now looking at : " << ret << std::endl;
if (!ret.isConst())
{
Node ret_lit = ret.getKind() == kind::NOT ? ret[0] : ret;
bool ret_pol = ret.getKind() != kind::NOT;
std::map<Node, Node> msum;
if (ArithMSum::getMonomialSumLit(ret_lit, msum))
{
// get common coefficient
std::vector<Node> coeffs;
for (std::map<Node, Node>::iterator itm = msum.begin();
itm != msum.end();
++itm)
{
Node v = itm->first;
Node c = itm->second;
if (!c.isNull())
{
Assert(c.isConst());
coeffs.push_back(NodeManager::currentNM()->mkConst(
Rational(c.getConst<Rational>().getDenominator())));
}
}
Node cc =
coeffs.empty()
? Node::null()
: (coeffs.size() == 1
? coeffs[0]
: Rewriter::rewrite(NodeManager::currentNM()->mkNode(
kind::MULT, coeffs)));
std::vector<Node> sum;
for (std::map<Node, Node>::iterator itm = msum.begin();
itm != msum.end();
++itm)
{
Node v = itm->first;
Node c = itm->second;
Node s;
if (c.isNull())
{
c = cc.isNull() ? NodeManager::currentNM()->mkConst(Rational(1))
: cc;
}
else
{
if (!cc.isNull())
{
c = Rewriter::rewrite(
NodeManager::currentNM()->mkNode(kind::MULT, c, cc));
}
}
Assert(c.getType().isInteger());
if (v.isNull())
{
sum.push_back(c);
}
else
{
Node vv = realToIntInternal(v, cache, var_eq);
if (vv.getType().isInteger())
{
sum.push_back(
NodeManager::currentNM()->mkNode(kind::MULT, c, vv));
}
else
{
throw TypeCheckingExceptionPrivate(
v,
std::string("Cannot translate to Int: ") + v.toString());
}
}
}
Node sumt =
sum.empty()
? NodeManager::currentNM()->mkConst(Rational(0))
: (sum.size() == 1
? sum[0]
: NodeManager::currentNM()->mkNode(kind::PLUS, sum));
ret = NodeManager::currentNM()->mkNode(
ret_lit.getKind(),
sumt,
NodeManager::currentNM()->mkConst(Rational(0)));
if (!ret_pol)
{
ret = ret.negate();
}
Trace("real-as-int") << "Convert : " << std::endl;
Trace("real-as-int") << " " << n << std::endl;
Trace("real-as-int") << " " << ret << std::endl;
}
}
}
else
{
bool childChanged = false;
std::vector<Node> children;
for (unsigned i = 0; i < n.getNumChildren(); i++)
{
Node nc = realToIntInternal(n[i], cache, var_eq);
childChanged = childChanged || nc != n[i];
children.push_back(nc);
}
if (childChanged)
{
if (n.getMetaKind() == kind::metakind::PARAMETERIZED)
{
children.insert(children.begin(), n.getOperator());
}
ret = NodeManager::currentNM()->mkNode(n.getKind(), children);
}
}
}
else
{
TypeNode tn = n.getType();
if (tn.isReal() && !tn.isInteger())
{
if (n.getKind() == kind::BOUND_VARIABLE)
{
// cannot change the type of quantified variables, since this leads
// to incompleteness.
throw TypeCheckingExceptionPrivate(
n,
std::string("Cannot translate bound variable to Int: ")
+ n.toString());
}
else if (n.isVar())
{
ret = nm->mkSkolem("__realToIntInternal_var",
nm->integerType(),
"Variable introduced in realToIntInternal pass");
var_eq.push_back(n.eqNode(ret));
// ensure that the original variable is defined to be the returned
// one, which is important for models and for incremental solving.
std::vector<Node> args;
d_preprocContext->getSmt()->defineFunction(n, args, ret);
}
}
}
cache[n] = ret;
return ret;
}
}
RealToInt::RealToInt(PreprocessingPassContext* preprocContext)
: PreprocessingPass(preprocContext, "real-to-int"){};
PreprocessingPassResult RealToInt::applyInternal(
AssertionPipeline* assertionsToPreprocess)
{
unordered_map<Node, Node, NodeHashFunction> cache;
std::vector<Node> var_eq;
for (unsigned i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
{
assertionsToPreprocess->replace(
i, realToIntInternal((*assertionsToPreprocess)[i], cache, var_eq));
}
return PreprocessingPassResult::NO_CONFLICT;
}
} // namespace passes
} // namespace preprocessing
} // namespace CVC4
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