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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 lazy proof utility. |
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*/ |
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#include "proof/lazy_proof.h" |
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#include "proof/proof_ensure_closed.h" |
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#include "proof/proof_node.h" |
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#include "proof/proof_node_manager.h" |
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using namespace cvc5::kind; |
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namespace cvc5 { |
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LazyCDProof::LazyCDProof(ProofNodeManager* pnm, |
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ProofGenerator* dpg, |
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context::Context* c, |
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const std::string& name) |
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: CDProof(pnm, c, name), d_gens(c ? c : &d_context), d_defaultGen(dpg) |
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{ |
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} |
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LazyCDProof::~LazyCDProof() {} |
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std::shared_ptr<ProofNode> LazyCDProof::getProofFor(Node fact) |
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{ |
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Trace("lazy-cdproof") << "LazyCDProof::mkLazyProof " << fact << std::endl; |
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// make the proof, which should always be non-null, since we construct an |
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// assumption in the worst case. |
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std::shared_ptr<ProofNode> opf = CDProof::getProofFor(fact); |
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Assert(opf != nullptr); |
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if (!hasGenerators()) |
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{ |
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Trace("lazy-cdproof") << "...no generators, finished" << std::endl; |
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// optimization: no generators, we are done |
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return opf; |
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} |
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// otherwise, we traverse the proof opf and fill in the ASSUME leafs that |
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// have generators |
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std::unordered_set<ProofNode*> visited; |
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std::unordered_set<ProofNode*>::iterator it; |
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std::vector<ProofNode*> visit; |
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ProofNode* cur; |
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visit.push_back(opf.get()); |
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do |
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{ |
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cur = visit.back(); |
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visit.pop_back(); |
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it = visited.find(cur); |
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if (it == visited.end()) |
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{ |
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visited.insert(cur); |
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Node cfact = cur->getResult(); |
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if (getProof(cfact).get() != cur) |
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{ |
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// We don't own this proof, skip it. This is to ensure that this method |
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// is idempotent, since it may be the case that a previous call to |
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// getProofFor connected a proof from a proof generator as a child of |
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// a ProofNode in the range of the map in CDProof. Thus, this ensures |
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// we don't touch such proofs. |
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Trace("lazy-cdproof") << "...skip unowned proof" << std::endl; |
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} |
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else if (cur->getRule() == PfRule::ASSUME) |
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{ |
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bool isSym = false; |
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ProofGenerator* pg = getGeneratorFor(cfact, isSym); |
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if (pg != nullptr) |
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{ |
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Trace("lazy-cdproof") |
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<< "LazyCDProof: Call generator " << pg->identify() |
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<< " for assumption " << cfact << std::endl; |
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Node cfactGen = isSym ? CDProof::getSymmFact(cfact) : cfact; |
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Assert(!cfactGen.isNull()); |
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// Do not use the addProofTo interface, instead use the update node |
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// interface, since this ensures that we don't take ownership for |
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// the current proof. Instead, it is only linked, and ignored on |
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// future calls to getProofFor due to the check above. |
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std::shared_ptr<ProofNode> pgc = pg->getProofFor(cfactGen); |
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// If the proof was null, then the update is not performed. This is |
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// not considered an error, since this behavior is equivalent to |
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// if pg had provided the proof (ASSUME cfactGen). Ensuring the |
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// proper behavior wrt closed proofs should be done outside this |
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// method. |
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if (pgc != nullptr) |
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{ |
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Trace("lazy-cdproof-gen") |
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<< "LazyCDProof: stored proof: " << *pgc.get() << std::endl; |
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if (isSym) |
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{ |
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if (pgc->getRule() == PfRule::SYMM) |
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{ |
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d_manager->updateNode(cur, pgc->getChildren()[0].get()); |
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} |
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else |
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{ |
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d_manager->updateNode(cur, PfRule::SYMM, {pgc}, {}); |
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} |
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} |
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else |
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{ |
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d_manager->updateNode(cur, pgc.get()); |
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} |
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Trace("lazy-cdproof") << "LazyCDProof: Successfully added fact for " |
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<< cfactGen << std::endl; |
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} |
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} |
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else |
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{ |
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Trace("lazy-cdproof") << "LazyCDProof: " << identify() |
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<< " : No generator for " << cfact << std::endl; |
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} |
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// Notice that we do not traverse the proofs that have been generated |
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// lazily by the proof generators here. In other words, we assume that |
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// the proofs from provided proof generators are final and need |
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// no further modification by this class. |
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} |
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else |
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{ |
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const std::vector<std::shared_ptr<ProofNode>>& cc = cur->getChildren(); |
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for (const std::shared_ptr<ProofNode>& cp : cc) |
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{ |
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visit.push_back(cp.get()); |
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} |
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} |
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} |
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} while (!visit.empty()); |
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// we have now updated the ASSUME leafs of opf, return it |
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Trace("lazy-cdproof") << "...finished" << std::endl; |
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Assert(opf->getResult() == fact); |
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return opf; |
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} |
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void LazyCDProof::addLazyStep(Node expected, |
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ProofGenerator* pg, |
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PfRule idNull, |
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bool isClosed, |
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const char* ctx, |
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bool forceOverwrite) |
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{ |
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if (pg == nullptr) |
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{ |
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// null generator, should have given a proof rule |
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if (idNull == PfRule::ASSUME) |
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{ |
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Unreachable() << "LazyCDProof::addLazyStep: " << identify() |
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<< ": failed to provide proof generator for " << expected; |
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return; |
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} |
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Trace("lazy-cdproof") << "LazyCDProof::addLazyStep: " << expected |
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<< " set (trusted) step " << idNull << "\n"; |
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addStep(expected, idNull, {}, {expected}); |
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return; |
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} |
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Trace("lazy-cdproof") << "LazyCDProof::addLazyStep: " << expected |
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<< " set to generator " << pg->identify() << "\n"; |
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if (!forceOverwrite) |
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{ |
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NodeProofGeneratorMap::const_iterator it = d_gens.find(expected); |
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if (it != d_gens.end()) |
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{ |
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// don't overwrite something that is already there |
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return; |
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} |
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} |
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// just store now |
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d_gens.insert(expected, pg); |
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// debug checking |
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if (isClosed) |
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{ |
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Trace("lazy-cdproof-debug") << "Checking closed..." << std::endl; |
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pfgEnsureClosed(expected, pg, "lazy-cdproof-debug", ctx); |
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} |
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} |
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ProofGenerator* LazyCDProof::getGeneratorFor(Node fact, bool& isSym) |
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{ |
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isSym = false; |
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NodeProofGeneratorMap::const_iterator it = d_gens.find(fact); |
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if (it != d_gens.end()) |
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{ |
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return (*it).second; |
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} |
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Node factSym = CDProof::getSymmFact(fact); |
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// could be symmetry |
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if (factSym.isNull()) |
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{ |
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// can't be symmetry, return the default generator |
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return d_defaultGen; |
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} |
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it = d_gens.find(factSym); |
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if (it != d_gens.end()) |
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{ |
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isSym = true; |
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return (*it).second; |
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} |
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// return the default generator |
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return d_defaultGen; |
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} |
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bool LazyCDProof::hasGenerators() const |
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{ |
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return !d_gens.empty() || d_defaultGen != nullptr; |
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} |
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bool LazyCDProof::hasGenerator(Node fact) const |
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{ |
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if (d_defaultGen != nullptr) |
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return true; |
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} |
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NodeProofGeneratorMap::const_iterator it = d_gens.find(fact); |
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if (it != d_gens.end()) |
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{ |
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return true; |
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} |
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// maybe there is a symmetric fact? |
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Node factSym = CDProof::getSymmFact(fact); |
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if (!factSym.isNull()) |
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{ |
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it = d_gens.find(factSym); |
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} |
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return it != d_gens.end(); |
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} |
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} // namespace cvc5 |