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