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/****************************************************************************** |
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* Top contributors (to current version): |
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* 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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* Implementation of base classes for decision strategies used by theory |
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* solvers for use in the DecisionManager of TheoryEngine. |
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*/ |
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#include "theory/decision_strategy.h" |
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#include "theory/rewriter.h" |
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using namespace cvc5::kind; |
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namespace cvc5 { |
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namespace theory { |
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DecisionStrategyFmf::DecisionStrategyFmf(Env& env, Valuation valuation) |
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: DecisionStrategy(env), |
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d_valuation(valuation), |
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d_has_curr_literal(false, context()), |
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d_curr_literal(0, context()) |
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{ |
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} |
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void DecisionStrategyFmf::initialize() { d_literals.clear(); } |
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Node DecisionStrategyFmf::getNextDecisionRequest() |
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{ |
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Trace("dec-strategy-debug") |
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<< "Get next decision request " << identify() << "..." << std::endl; |
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if (d_has_curr_literal.get()) |
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{ |
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Trace("dec-strategy-debug") << "...already has decision" << std::endl; |
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return Node::null(); |
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} |
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bool success; |
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unsigned curr_lit = d_curr_literal.get(); |
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do |
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{ |
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success = true; |
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// get the current literal |
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Node lit = getLiteral(curr_lit); |
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Trace("dec-strategy-debug") |
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<< "...check literal #" << curr_lit << " : " << lit << std::endl; |
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// if out of literals, we are done in the current SAT context |
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if (!lit.isNull()) |
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{ |
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bool value; |
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if (!d_valuation.hasSatValue(lit, value)) |
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{ |
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Trace("dec-strategy-debug") << "...not assigned, return." << std::endl; |
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// if it has not been decided, return it |
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return lit; |
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} |
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else if (!value) |
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{ |
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Trace("dec-strategy-debug") |
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<< "...assigned false, increment." << std::endl; |
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// asserted false, the current literal is incremented |
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curr_lit = d_curr_literal.get() + 1; |
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d_curr_literal.set(curr_lit); |
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// repeat |
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success = false; |
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} |
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else |
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{ |
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Trace("dec-strategy-debug") << "...already assigned true." << std::endl; |
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} |
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} |
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else |
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{ |
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Trace("dec-strategy-debug") << "...exhausted literals." << std::endl; |
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} |
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} while (!success); |
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// the current literal has been decided with the right polarity, we are done |
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d_has_curr_literal = true; |
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return Node::null(); |
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} |
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bool DecisionStrategyFmf::getAssertedLiteralIndex(unsigned& i) const |
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{ |
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if (d_has_curr_literal.get()) |
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{ |
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i = d_curr_literal.get(); |
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return true; |
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} |
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return false; |
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} |
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Node DecisionStrategyFmf::getAssertedLiteral() |
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{ |
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if (d_has_curr_literal.get()) |
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{ |
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Assert(d_curr_literal.get() < d_literals.size()); |
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return getLiteral(d_curr_literal.get()); |
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} |
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return Node::null(); |
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} |
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Node DecisionStrategyFmf::getLiteral(unsigned n) |
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{ |
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// allocate until the index is valid |
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while (n >= d_literals.size()) |
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{ |
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Node lit = mkLiteral(d_literals.size()); |
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if (!lit.isNull()) |
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{ |
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lit = Rewriter::rewrite(lit); |
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} |
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d_literals.push_back(lit); |
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} |
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Node ret = d_literals[n]; |
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if (!ret.isNull()) |
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{ |
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// always ensure it is in the CNF stream |
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ret = d_valuation.ensureLiteral(ret); |
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} |
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return ret; |
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} |
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DecisionStrategySingleton::DecisionStrategySingleton(Env& env, |
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const char* name, |
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Node lit, |
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Valuation valuation) |
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: DecisionStrategyFmf(env, valuation), d_name(name), d_literal(lit) |
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{ |
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} |
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Node DecisionStrategySingleton::mkLiteral(unsigned n) |
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{ |
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if (n == 0) |
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{ |
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return d_literal; |
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} |
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return Node::null(); |
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} |
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Node DecisionStrategySingleton::getSingleLiteral() { return d_literal; } |
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} // namespace theory |
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} // namespace cvc5 |