1 /********************* */
2 /*! \file output_channel.h
4 ** Top contributors (to current version):
5 ** Morgan Deters, Andrew Reynolds, Tim King
6 ** This file is part of the CVC4 project.
7 ** Copyright (c) 2009-2020 by the authors listed in the file AUTHORS
8 ** in the top-level source directory and their institutional affiliations.
9 ** All rights reserved. See the file COPYING in the top-level source
10 ** directory for licensing information.\endverbatim
12 ** \brief The theory output channel interface
14 ** The theory output channel interface.
17 #include "cvc4_private.h"
19 #ifndef CVC4__THEORY__OUTPUT_CHANNEL_H
20 #define CVC4__THEORY__OUTPUT_CHANNEL_H
24 #include "expr/proof_node.h"
25 #include "smt/logic_exception.h"
26 #include "theory/interrupted.h"
27 #include "theory/trust_node.h"
28 #include "util/resource_manager.h"
33 /** Properties of lemmas */
34 enum class LemmaProperty
: uint32_t
38 // whether the lemma is removable
40 // whether the lemma needs preprocessing
42 // whether the processing of the lemma should send atoms to the caller
44 // whether the lemma is part of the justification for answering "sat"
47 /** Define operator lhs | rhs */
48 LemmaProperty
operator|(LemmaProperty lhs
, LemmaProperty rhs
);
49 /** Define operator lhs |= rhs */
50 LemmaProperty
& operator|=(LemmaProperty
& lhs
, LemmaProperty rhs
);
51 /** Define operator lhs & rhs */
52 LemmaProperty
operator&(LemmaProperty lhs
, LemmaProperty rhs
);
53 /** Define operator lhs &= rhs */
54 LemmaProperty
& operator&=(LemmaProperty
& lhs
, LemmaProperty rhs
);
55 /** is the removable bit set on p? */
56 bool isLemmaPropertyRemovable(LemmaProperty p
);
57 /** is the preprocess bit set on p? */
58 bool isLemmaPropertyPreprocess(LemmaProperty p
);
59 /** is the send atoms bit set on p? */
60 bool isLemmaPropertySendAtoms(LemmaProperty p
);
61 /** is the needs justify bit set on p? */
62 bool isLemmaPropertyNeedsJustify(LemmaProperty p
);
65 * Writes an lemma property name to a stream.
67 * @param out The stream to write to
68 * @param p The lemma property to write to the stream
71 std::ostream
& operator<<(std::ostream
& out
, LemmaProperty p
);
76 * A LemmaStatus, returned from OutputChannel::lemma(), provides information
77 * about the lemma added. In particular, it contains the T-rewritten lemma
78 * for inspection and the user-level at which the lemma will reside.
82 LemmaStatus(TNode rewrittenLemma
, unsigned level
);
84 /** Get the T-rewritten form of the lemma. */
85 TNode
getRewrittenLemma() const;
87 * Get the user-level at which the lemma resides. After this user level
88 * is popped, the lemma is un-asserted from the SAT layer. This level
89 * will be 0 if the lemma didn't reach the SAT layer at all.
91 unsigned getLevel() const;
94 Node d_rewrittenLemma
;
96 }; /* class LemmaStatus */
99 * Generic "theory output channel" interface.
101 * All methods can throw unrecoverable CVC4::Exception's unless otherwise
104 class OutputChannel
{
106 /** Construct an OutputChannel. */
110 * Destructs an OutputChannel. This implementation does nothing,
111 * but we need a virtual destructor for safety in case subclasses
114 virtual ~OutputChannel() {}
116 OutputChannel(const OutputChannel
&) = delete;
117 OutputChannel
& operator=(const OutputChannel
&) = delete;
120 * With safePoint(), the theory signals that it is at a safe point
121 * and can be interrupted.
123 * @throws Interrupted if the theory can be safely interrupted.
125 virtual void safePoint(ResourceManager::Resource r
) {}
128 * Indicate a theory conflict has arisen.
130 * @param n - a conflict at the current decision level. This should
131 * be an AND-kinded node of literals that are TRUE in the current
132 * assignment and are in conflict (i.e., at least one must be
133 * assigned false), or else a literal by itself (in the case of a
134 * unit conflict) which is assigned TRUE (and T-conflicting) in the
135 * current assignment.
137 virtual void conflict(TNode n
) = 0;
140 * Propagate a theory literal.
142 * @param n - a theory consequence at the current decision level
143 * @return false if an immediate conflict was encountered
145 virtual bool propagate(TNode n
) = 0;
148 * Tell the core that a valid theory lemma at decision level 0 has
149 * been detected. (This requests a split.)
151 * @param n - a theory lemma valid at decision level 0
152 * @param p The properties of the lemma
153 * @return the "status" of the lemma, including user level at which
154 * the lemma resides; the lemma will be removed when this user level pops
156 virtual LemmaStatus
lemma(TNode n
, LemmaProperty p
= LemmaProperty::NONE
) = 0;
159 * Request a split on a new theory atom. This is equivalent to
160 * calling lemma({OR n (NOT n)}).
162 * @param n - a theory atom; must be of Boolean type
164 LemmaStatus
split(TNode n
);
166 virtual LemmaStatus
splitLemma(TNode n
, bool removable
= false) = 0;
169 * If a decision is made on n, it must be in the phase specified.
170 * Note that this is enforced *globally*, i.e., it is completely
171 * context-INdependent. If you ever requirePhase() on a literal,
172 * it is phase-locked forever and ever. If it is to ever have the
173 * other phase as its assignment, it will be because it has been
174 * propagated that way (or it's a unit, at decision level 0).
176 * @param n - a theory atom with a SAT literal assigned; must have
177 * been pre-registered
178 * @param phase - the phase to decide on n
180 virtual void requirePhase(TNode n
, bool phase
) = 0;
183 * Notification from a theory that it realizes it is incomplete at
184 * this context level. If SAT is later determined by the
185 * TheoryEngine, it should actually return an UNKNOWN result.
187 virtual void setIncomplete() = 0;
190 * "Spend" a "resource." The meaning is specific to the context in
191 * which the theory is operating, and may even be ignored. The
192 * intended meaning is that if the user has set a limit on the "units
193 * of resource" that can be expended in a search, and that limit is
194 * exceeded, then the search is terminated. Note that the check for
195 * termination occurs in the main search loop, so while theories
196 * should call OutputChannel::spendResource() during particularly
197 * long-running operations, they cannot rely on resource() to break
198 * out of infinite or intractable computations.
200 virtual void spendResource(ResourceManager::Resource r
) {}
203 * Handle user attribute.
204 * Associates theory t with the attribute attr. Theory t will be
205 * notified whenever an attribute of name attr is set on a node.
206 * This can happen through, for example, the SMT-LIBv2 language.
208 virtual void handleUserAttribute(const char* attr
, Theory
* t
) {}
210 /** Demands that the search restart from sat search level 0.
211 * Using this leads to non-termination issues.
212 * It is appropriate for prototyping for theories.
214 virtual void demandRestart() {}
216 //---------------------------- new proof
218 * Let pconf be the pair (Node conf, ProofGenerator * pfg). This method
219 * sends conf on the output channel of this class whose proof can be generated
220 * by the generator pfg. Apart from pfg, the interface for this method is
221 * the same as OutputChannel.
223 virtual void trustedConflict(TrustNode pconf
);
225 * Let plem be the pair (Node lem, ProofGenerator * pfg).
226 * Send lem on the output channel of this class whose proof can be generated
227 * by the generator pfg. Apart from pfg, the interface for this method is
228 * the same as OutputChannel.
230 virtual LemmaStatus
trustedLemma(TrustNode lem
,
231 LemmaProperty p
= LemmaProperty::NONE
);
232 //---------------------------- end new proof
233 }; /* class OutputChannel */
235 } // namespace theory
238 #endif /* CVC4__THEORY__OUTPUT_CHANNEL_H */