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/****************************************************************************** |
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* Top contributors (to current version): |
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* Andrew Reynolds, Tianyi Liang, 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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* Implementation of a finite model finding decision strategy for strings. |
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*/ |
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#include "theory/strings/strings_fmf.h" |
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#include "util/rational.h" |
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using namespace std; |
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using namespace cvc5::context; |
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using namespace cvc5::kind; |
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namespace cvc5 { |
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namespace theory { |
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namespace strings { |
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StringsFmf::StringsFmf(Env& env, Valuation valuation, TermRegistry& tr) |
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: EnvObj(env), d_sslds(nullptr), d_valuation(valuation), d_termReg(tr) |
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{ |
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} |
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StringsFmf::~StringsFmf() {} |
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void StringsFmf::presolve() |
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{ |
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d_sslds.reset(new StringSumLengthDecisionStrategy(d_env, d_valuation)); |
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Trace("strings-dstrat-reg") |
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<< "presolve: register decision strategy." << std::endl; |
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const NodeSet& ivars = d_termReg.getInputVars(); |
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std::vector<Node> inputVars; |
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for (NodeSet::const_iterator itr = ivars.begin(); itr != ivars.end(); ++itr) |
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{ |
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inputVars.push_back(*itr); |
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} |
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d_sslds->initialize(inputVars); |
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} |
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DecisionStrategy* StringsFmf::getDecisionStrategy() const |
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{ |
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return d_sslds.get(); |
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} |
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StringsFmf::StringSumLengthDecisionStrategy::StringSumLengthDecisionStrategy( |
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Env& env, Valuation valuation) |
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: DecisionStrategyFmf(env, valuation), d_inputVarLsum(userContext()) |
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{ |
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} |
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bool StringsFmf::StringSumLengthDecisionStrategy::isInitialized() |
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{ |
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return !d_inputVarLsum.get().isNull(); |
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} |
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void StringsFmf::StringSumLengthDecisionStrategy::initialize( |
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const std::vector<Node>& vars) |
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{ |
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if (d_inputVarLsum.get().isNull() && !vars.empty()) |
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{ |
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NodeManager* nm = NodeManager::currentNM(); |
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std::vector<Node> sum; |
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for (const Node& v : vars) |
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{ |
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sum.push_back(nm->mkNode(STRING_LENGTH, v)); |
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} |
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Node sumn = sum.size() == 1 ? sum[0] : nm->mkNode(PLUS, sum); |
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d_inputVarLsum.set(sumn); |
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} |
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} |
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Node StringsFmf::StringSumLengthDecisionStrategy::mkLiteral(unsigned i) |
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{ |
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if (d_inputVarLsum.get().isNull()) |
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{ |
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return Node::null(); |
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} |
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NodeManager* nm = NodeManager::currentNM(); |
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Node lit = nm->mkNode(LEQ, d_inputVarLsum.get(), nm->mkConst(Rational(i))); |
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Trace("strings-fmf") << "StringsFMF::mkLiteral: " << lit << std::endl; |
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return lit; |
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} |
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std::string StringsFmf::StringSumLengthDecisionStrategy::identify() const |
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{ |
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return std::string("string_sum_len"); |
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} |
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} // namespace strings |
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} // namespace theory |
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} // namespace cvc5 |