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/****************************************************************************** |
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* Top contributors (to current version): |
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* Haniel Barbosa, Andrew Reynolds, Aina Niemetz |
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* |
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* This file is part of the cvc5 project. |
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* |
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* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS |
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* in the top-level source directory and their institutional affiliations. |
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* All rights reserved. See the file COPYING in the top-level source |
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* directory for licensing information. |
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* **************************************************************************** |
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* |
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* The RealToInt preprocessing pass. |
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* |
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* Converts real operations into integer operations. |
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*/ |
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#include "preprocessing/passes/real_to_int.h" |
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#include <string> |
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#include "expr/skolem_manager.h" |
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#include "preprocessing/assertion_pipeline.h" |
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#include "preprocessing/preprocessing_pass_context.h" |
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#include "theory/arith/arith_msum.h" |
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#include "theory/rewriter.h" |
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#include "theory/theory_model.h" |
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#include "util/rational.h" |
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using namespace cvc5::theory; |
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namespace cvc5 { |
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namespace preprocessing { |
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namespace passes { |
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RealToInt::RealToInt(PreprocessingPassContext* preprocContext) |
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: PreprocessingPass(preprocContext, "real-to-int"), |
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d_cache(preprocContext->getUserContext()) |
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{ |
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} |
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Node RealToInt::realToIntInternal(TNode n, NodeMap& cache, std::vector<Node>& var_eq) |
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{ |
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Trace("real-as-int-debug") << "Convert : " << n << std::endl; |
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NodeMap::iterator find = cache.find(n); |
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if (find != cache.end()) |
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{ |
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return (*find).second; |
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} |
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else |
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{ |
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NodeManager* nm = NodeManager::currentNM(); |
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SkolemManager* sm = nm->getSkolemManager(); |
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Node ret = n; |
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if (n.getNumChildren() > 0) |
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{ |
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if ((n.getKind() == kind::EQUAL && n[0].getType().isReal()) |
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|| n.getKind() == kind::GEQ || n.getKind() == kind::LT |
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|| n.getKind() == kind::GT || n.getKind() == kind::LEQ) |
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{ |
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ret = Rewriter::rewrite(n); |
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Trace("real-as-int-debug") << "Now looking at : " << ret << std::endl; |
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if (!ret.isConst()) |
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{ |
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Node ret_lit = ret.getKind() == kind::NOT ? ret[0] : ret; |
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bool ret_pol = ret.getKind() != kind::NOT; |
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std::map<Node, Node> msum; |
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if (ArithMSum::getMonomialSumLit(ret_lit, msum)) |
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{ |
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// get common coefficient |
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std::vector<Node> coeffs; |
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for (std::map<Node, Node>::iterator itm = msum.begin(); |
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itm != msum.end(); |
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++itm) |
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{ |
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Node v = itm->first; |
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Node c = itm->second; |
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if (!c.isNull()) |
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{ |
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Assert(c.isConst()); |
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coeffs.push_back(NodeManager::currentNM()->mkConst( |
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Rational(c.getConst<Rational>().getDenominator()))); |
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} |
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} |
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Node cc = |
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coeffs.empty() |
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? Node::null() |
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: (coeffs.size() == 1 |
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? coeffs[0] |
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: Rewriter::rewrite(NodeManager::currentNM()->mkNode( |
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kind::MULT, coeffs))); |
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std::vector<Node> sum; |
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for (std::map<Node, Node>::iterator itm = msum.begin(); |
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itm != msum.end(); |
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++itm) |
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{ |
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Node v = itm->first; |
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Node c = itm->second; |
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Node s; |
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if (c.isNull()) |
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{ |
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c = cc.isNull() ? NodeManager::currentNM()->mkConst(Rational(1)) |
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: cc; |
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} |
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else |
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{ |
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if (!cc.isNull()) |
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{ |
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c = Rewriter::rewrite( |
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NodeManager::currentNM()->mkNode(kind::MULT, c, cc)); |
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} |
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} |
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Assert(c.getType().isInteger()); |
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if (v.isNull()) |
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{ |
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sum.push_back(c); |
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} |
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else |
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{ |
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Node vv = realToIntInternal(v, cache, var_eq); |
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if (vv.getType().isInteger()) |
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{ |
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sum.push_back( |
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NodeManager::currentNM()->mkNode(kind::MULT, c, vv)); |
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} |
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else |
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{ |
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throw TypeCheckingExceptionPrivate( |
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v, |
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std::string("Cannot translate to Int: ") + v.toString()); |
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} |
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} |
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} |
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Node sumt = |
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sum.empty() |
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? NodeManager::currentNM()->mkConst(Rational(0)) |
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: (sum.size() == 1 |
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? sum[0] |
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: NodeManager::currentNM()->mkNode(kind::PLUS, sum)); |
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ret = NodeManager::currentNM()->mkNode( |
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ret_lit.getKind(), |
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sumt, |
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NodeManager::currentNM()->mkConst(Rational(0))); |
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if (!ret_pol) |
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{ |
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ret = ret.negate(); |
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} |
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Trace("real-as-int") << "Convert : " << std::endl; |
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Trace("real-as-int") << " " << n << std::endl; |
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Trace("real-as-int") << " " << ret << std::endl; |
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} |
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} |
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} |
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else |
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{ |
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bool childChanged = false; |
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std::vector<Node> children; |
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for (unsigned i = 0; i < n.getNumChildren(); i++) |
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{ |
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Node nc = realToIntInternal(n[i], cache, var_eq); |
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childChanged = childChanged || nc != n[i]; |
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children.push_back(nc); |
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} |
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if (childChanged) |
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{ |
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if (n.getMetaKind() == kind::metakind::PARAMETERIZED) |
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{ |
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children.insert(children.begin(), n.getOperator()); |
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} |
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ret = NodeManager::currentNM()->mkNode(n.getKind(), children); |
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} |
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} |
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} |
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else |
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{ |
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TypeNode tn = n.getType(); |
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if (tn.isReal() && !tn.isInteger()) |
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{ |
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if (n.getKind() == kind::BOUND_VARIABLE) |
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{ |
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// cannot change the type of quantified variables, since this leads |
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// to incompleteness. |
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throw TypeCheckingExceptionPrivate( |
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n, |
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std::string("Cannot translate bound variable to Int: ") |
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+ n.toString()); |
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} |
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else if (n.isVar()) |
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{ |
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Node toIntN = nm->mkNode(kind::TO_INTEGER, n); |
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ret = sm->mkPurifySkolem(toIntN, "__realToIntInternal_var"); |
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var_eq.push_back(n.eqNode(ret)); |
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// add the substitution to the preprocessing context, which ensures |
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// the model for n is correct, as well as substituting it in the input |
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// assertions when necessary. |
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d_preprocContext->addSubstitution(n, ret); |
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} |
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} |
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} |
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cache[n] = ret; |
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return ret; |
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} |
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} |
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PreprocessingPassResult RealToInt::applyInternal( |
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AssertionPipeline* assertionsToPreprocess) |
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{ |
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std::vector<Node> var_eq; |
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for (unsigned i = 0, size = assertionsToPreprocess->size(); i < size; ++i) |
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{ |
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assertionsToPreprocess->replace( |
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i, realToIntInternal((*assertionsToPreprocess)[i], d_cache, var_eq)); |
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} |
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return PreprocessingPassResult::NO_CONFLICT; |
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} |
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} // namespace passes |
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} // namespace preprocessing |
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} // namespace cvc5 |