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/********************* */
/*! \file theory_preprocessor.h
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds
** This file is part of the CVC4 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.\endverbatim
**
** \brief The theory preprocessor.
**/
#include "cvc4_private.h"
#ifndef CVC4__THEORY__THEORY_PREPROCESSOR_H
#define CVC4__THEORY__THEORY_PREPROCESSOR_H
#include <unordered_map>
#include "context/cdhashmap.h"
#include "context/context.h"
#include "expr/lazy_proof.h"
#include "expr/node.h"
#include "expr/tconv_seq_proof_generator.h"
#include "expr/term_conversion_proof_generator.h"
#include "smt/term_formula_removal.h"
#include "theory/skolem_lemma.h"
#include "theory/trust_node.h"
namespace CVC4 {
class LogicInfo;
class TheoryEngine;
class RemoveTermFormulas;
namespace theory {
/**
* The preprocessor used in TheoryEngine.
*
* A summary of the steps taken by the method preprocess:
*
* [1]
* apply rewriter
* [2]
* TRAVERSE(
* prerewrite:
* if theory atom {
* TRAVERSE(
* prerewrite:
* // nothing
* postrewrite:
* apply rewriter
* apply ppRewrite
* if changed
* apply rewriter
* REPEAT traversal
* )
* apply term formula removal
* apply rewriter
* }
* postrewrite: // for Boolean connectives
* apply rewriter
* )
*
* Note that the rewriter must be applied beforehand, since the rewriter may
* rewrite a theory atom into a formula, e.g. quantifiers miniscoping. This
* impacts what the inner traversal is applied to.
*/
class TheoryPreprocessor
{
typedef context::CDHashMap<Node, Node, NodeHashFunction> NodeMap;
public:
/** Constructs a theory preprocessor */
TheoryPreprocessor(TheoryEngine& engine,
context::UserContext* userContext,
ProofNodeManager* pnm = nullptr);
/** Destroys a theory preprocessor */
~TheoryPreprocessor();
/**
* Preprocesses the given assertion node. It returns a TrustNode of kind
* TrustNodeKind::REWRITE indicating the preprocessed form of node. It stores
* additional lemmas in newLemmas, which are trust nodes of kind
* TrustNodeKind::LEMMA. These correspond to e.g. lemmas corresponding to ITE
* removal. For each lemma in newLemmas, we add the corresponding skolem that
* the lemma defines.
*
* @param node The assertion to preprocess,
* @param newLemmas The lemmas to add to the set of assertions,
* @param newSkolems The skolems that newLemmas correspond to,
* @return The (REWRITE) trust node corresponding to rewritten node via
* preprocessing.
*/
TrustNode preprocess(TNode node,
std::vector<TrustNode>& newLemmas,
std::vector<Node>& newSkolems);
/**
* Same as above, but transforms the proof of node into a proof of the
* preprocessed node and returns the LEMMA trust node.
*
* @param node The assertion to preprocess,
* @param newLemmas The lemmas to add to the set of assertions,
* @param newSkolems The skolems that newLemmas correspond to,
* @return The (LEMMA) trust node corresponding to the proof of the rewritten
* form of the proven field of node.
*/
TrustNode preprocessLemma(TrustNode node,
std::vector<TrustNode>& newLemmas,
std::vector<Node>& newSkolems);
/** Get the term formula removal utility */
RemoveTermFormulas& getRemoveTermFormulas();
private:
/**
* Runs theory specific preprocessing (Theory::ppRewrite) on the non-Boolean
* parts of the node.
*/
TrustNode theoryPreprocess(TNode node,
std::vector<TrustNode>& newLemmas,
std::vector<Node>& newSkolems);
/**
* Internal helper for preprocess, which also optionally preprocesses the
* new lemmas generated until a fixed point is reached based on argument
* procLemmas.
*/
TrustNode preprocessInternal(TNode node,
std::vector<TrustNode>& newLemmas,
std::vector<Node>& newSkolems,
bool procLemmas);
/**
* Internal helper for preprocessLemma, which also optionally preprocesses the
* new lemmas generated until a fixed point is reached based on argument
* procLemmas.
*/
TrustNode preprocessLemmaInternal(TrustNode node,
std::vector<TrustNode>& newLemmas,
std::vector<Node>& newSkolems,
bool procLemmas);
/** Reference to owning theory engine */
TheoryEngine& d_engine;
/** Logic info of theory engine */
const LogicInfo& d_logicInfo;
/**
* Cache for theory-preprocessing of theory atoms. The domain of this map
* are terms that appear within theory atoms given to this class.
*/
NodeMap d_ppCache;
/**
* Cache for theory-preprocessing + term formula removal of the Boolean
* structure of assertions. The domain of this map are the Boolean
* connectives and theory atoms given to this class.
*/
NodeMap d_rtfCache;
/** The term formula remover */
RemoveTermFormulas d_tfr;
/** The term context, which computes hash values for term contexts. */
InQuantTermContext d_iqtc;
/**
* A term conversion proof generator storing preprocessing and rewriting
* steps, which is done until fixed point in the inner traversal of this
* class for theory atoms in step [2] above.
*/
std::unique_ptr<TConvProofGenerator> d_tpg;
/**
* A term conversion proof generator storing large steps from d_tpg (results
* of its fixed point) and term formula removal steps for the outer traversal
* of this class for theory atoms in step [2] above.
*/
std::unique_ptr<TConvProofGenerator> d_tpgRtf;
/**
* A term conversion proof generator storing rewriting steps, which is used
* for top-level rewriting before the preprocessing pass, step [1] above.
*/
std::unique_ptr<TConvProofGenerator> d_tpgRew;
/**
* A term conversion sequence generator, which applies rewriting,
* (theory-preprocessing + rewriting + term formula removal), rewriting again
* in sequence, given by d_tpgRew and d_tpgRtf.
*/
std::unique_ptr<TConvSeqProofGenerator> d_tspg;
/** A lazy proof, for additional lemmas. */
std::unique_ptr<LazyCDProof> d_lp;
/**
* Helper for theoryPreprocess, which traverses the provided term and
* applies ppRewrite and rewriting until fixed point on term using
* the method preprocessWithProof helper below.
*/
Node ppTheoryRewrite(TNode term, std::vector<SkolemLemma>& lems);
/**
* Rewrite with proof, which stores a REWRITE step in pg if necessary
* and returns the rewritten form of term.
*
* @param term The term to rewrite
* @param pg The proof generator to register to
* @param isPre whether the rewrite is a pre-rewrite.
*/
Node rewriteWithProof(Node term, TConvProofGenerator* pg, bool isPre);
/**
* Preprocess with proof, which calls the appropriate ppRewrite method,
* stores the corresponding rewrite step in d_tpg if necessary and returns
* the preprocessed and rewritten form of term. It should be the case that
* term is already in rewritten form.
*/
Node preprocessWithProof(Node term, std::vector<SkolemLemma>& lems);
/**
* Register rewrite trn based on trust node into term conversion generator
* pg, which uses THEORY_PREPROCESS as a step if no proof generator is
* provided in trn.
*
* @param trn The REWRITE trust node
* @param pg The proof generator to register to
* @param isPre whether the rewrite is a pre-rewrite.
*/
void registerTrustedRewrite(TrustNode trn,
TConvProofGenerator* pg,
bool isPre);
/** Proofs enabled */
bool isProofEnabled() const;
};
} // namespace theory
} // namespace CVC4
#endif /* CVC4__THEORY__THEORY_PREPROCESSOR_H */
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