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/****************************************************************************** |
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* Top contributors (to current version): |
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* Andrew Reynolds, Mudathir Mohamed, Gereon Kremer |
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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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* Inference information utility. |
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*/ |
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#include "cvc5_private.h" |
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#ifndef CVC5__THEORY__STRINGS__INFER_INFO_H |
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#define CVC5__THEORY__STRINGS__INFER_INFO_H |
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#include <map> |
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#include <vector> |
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#include "expr/node.h" |
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#include "theory/inference_id.h" |
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#include "theory/theory_inference.h" |
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#include "util/safe_print.h" |
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namespace cvc5 { |
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namespace theory { |
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namespace strings { |
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/** |
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* Length status, used for indicating the length constraints for Skolems |
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* introduced by the theory of strings. |
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*/ |
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enum LengthStatus |
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{ |
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// The length of the Skolem should not be constrained. This should be |
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// used for Skolems whose length is already implied. |
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LENGTH_IGNORE, |
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// The length of the Skolem is not specified, and should be split on. |
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LENGTH_SPLIT, |
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// The length of the Skolem is exactly one. |
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LENGTH_ONE, |
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// The length of the Skolem is greater than or equal to one. |
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LENGTH_GEQ_ONE |
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}; |
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class InferenceManager; |
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/** |
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* An inference. This is a class to track an unprocessed call to either |
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* send a fact, lemma, or conflict that is waiting to be asserted to the |
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* equality engine or sent on the output channel. |
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* |
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* For the sake of proofs, the premises in InferInfo have a particular |
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* ordering for many of the core strings rules, which is expected by |
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* InferProofCons for constructing proofs of F_CONST, F_UNIFY, N_CONST, etc. |
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* which apply to a pair of string terms t and s. At a high level, the ordering |
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* expected in d_ant is: |
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* (1) (multiple) literals that explain why t and s have the same prefix/suffix, |
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* (2) t = s, |
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* (3) (optionally) a length constraint. |
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* For example, say we have: |
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* { x ++ y ++ v1 = z ++ w ++ v2, x = z ++ u, u = "", len(y) = len(w) } |
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* We can conclude y = w by the N_UNIFY rule from the left side. The premise |
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* has the following form: |
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* - (prefix up to y/w equal) x = z ++ u, u = "", |
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* - (main equality) x ++ y ++ v1 = z ++ w ++ v2, |
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* - (length constraint) len(y) = len(w). |
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*/ |
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class InferInfo : public TheoryInference |
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{ |
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public: |
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InferInfo(InferenceId id); |
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~InferInfo() {} |
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/** Process lemma */ |
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TrustNode processLemma(LemmaProperty& p) override; |
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/** Process internal fact */ |
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Node processFact(std::vector<Node>& exp, ProofGenerator*& pg) override; |
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/** Pointer to the class used for processing this info */ |
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InferenceManager* d_sim; |
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/** Whether it is the reverse form of the above id */ |
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bool d_idRev; |
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/** The conclusion */ |
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Node d_conc; |
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/** |
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* The premise(s) of the inference, interpreted conjunctively. These are |
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* literals that currently hold in the equality engine. |
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*/ |
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std::vector<Node> d_premises; |
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/** |
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* The "new literal" premise(s) of the inference, interpreted |
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* conjunctively. These are literals that were needed to show the conclusion |
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* but do not currently hold in the equality engine. These should be a subset |
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* of d_ant. In other words, premises that are not explained are stored |
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* in *both* d_ant and d_noExplain. |
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*/ |
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std::vector<Node> d_noExplain; |
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/** |
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* A list of new skolems introduced as a result of this inference. They |
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* are mapped to by a length status, indicating the length constraint that |
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* can be assumed for them. |
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*/ |
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std::map<LengthStatus, std::vector<Node> > d_skolems; |
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/** Is this infer info trivial? True if d_conc is true. */ |
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bool isTrivial() const; |
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/** |
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* Does this infer info correspond to a conflict? True if d_conc is false |
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* and it has no new premises (d_noExplain). |
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*/ |
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bool isConflict() const; |
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/** |
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* Does this infer info correspond to a "fact". A fact is an inference whose |
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* conclusion should be added as an equality or predicate to the equality |
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* engine with no new external premises (d_noExplain). |
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*/ |
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bool isFact() const; |
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/** Get premises */ |
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Node getPremises() const; |
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}; |
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/** |
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* Writes an inference info to a stream. |
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* |
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* @param out The stream to write to |
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* @param ii The inference info to write to the stream |
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* @return The stream |
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*/ |
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std::ostream& operator<<(std::ostream& out, const InferInfo& ii); |
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} // namespace strings |
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} // namespace theory |
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} // namespace cvc5 |
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#endif /* CVC5__THEORY__STRINGS__INFER_INFO_H */ |