src/theory/theory_engine.h

   1 /*********************                                                        */
   2 /*! \file theory_engine.h
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Dejan Jovanovic, Morgan Deters, Andrew Reynolds
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2019 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
  11  **
  12  ** \brief The theory engine
  13  **
  14  ** The theory engine.
  15  **/
  16
  17 #include "cvc4_private.h"
  18
  19 #ifndef CVC4__THEORY_ENGINE_H
  20 #define CVC4__THEORY_ENGINE_H
  21
  22 #include <deque>
  23 #include <memory>
  24 #include <set>
  25 #include <unordered_map>
  26 #include <utility>
  27 #include <vector>
  28
  29 #include "base/check.h"
  30 #include "context/cdhashset.h"
  31 #include "expr/node.h"
  32 #include "options/options.h"
  33 #include "options/smt_options.h"
  34 #include "options/theory_options.h"
  35 #include "prop/prop_engine.h"
  36 #include "smt/command.h"
  37 #include "smt_util/lemma_channels.h"
  38 #include "theory/atom_requests.h"
  39 #include "theory/decision_manager.h"
  40 #include "theory/interrupted.h"
  41 #include "theory/rewriter.h"
  42 #include "theory/shared_terms_database.h"
  43 #include "theory/sort_inference.h"
  44 #include "theory/substitutions.h"
  45 #include "theory/term_registration_visitor.h"
  46 #include "theory/theory.h"
  47 #include "theory/uf/equality_engine.h"
  48 #include "theory/valuation.h"
  49 #include "util/hash.h"
  50 #include "util/statistics_registry.h"
  51 #include "util/unsafe_interrupt_exception.h"
  52
  53 namespace CVC4 {
  54
  55 class ResourceManager;
  56 class LemmaProofRecipe;
  57
  58 /**
  59  * A pair of a theory and a node. This is used to mark the flow of
  60  * propagations between theories.
  61  */
  62 struct NodeTheoryPair {
  63   Node node;
  64   theory::TheoryId theory;
  65   size_t timestamp;
  66   NodeTheoryPair(TNode node, theory::TheoryId theory, size_t timestamp = 0)
  67   : node(node), theory(theory), timestamp(timestamp) {}
  68   NodeTheoryPair() : theory(theory::THEORY_LAST), timestamp() {}
  69   // Comparison doesn't take into account the timestamp
  70   bool operator == (const NodeTheoryPair& pair) const {
  71     return node == pair.node && theory == pair.theory;
  72   }
  73 };/* struct NodeTheoryPair */
  74
  75 struct NodeTheoryPairHashFunction {
  76   NodeHashFunction hashFunction;
  77   // Hash doesn't take into account the timestamp
  78   size_t operator()(const NodeTheoryPair& pair) const {
  79     uint64_t hash = fnv1a::fnv1a_64(NodeHashFunction()(pair.node));
  80     return static_cast<size_t>(fnv1a::fnv1a_64(pair.theory, hash));
  81   }
  82 };/* struct NodeTheoryPairHashFunction */
  83
  84
  85 /* Forward declarations */
  86 namespace theory {
  87   class TheoryModel;
  88   class TheoryEngineModelBuilder;
  89
  90   namespace eq {
  91     class EqualityEngine;
  92   }/* CVC4::theory::eq namespace */
  93
  94   namespace quantifiers {
  95     class TermDb;
  96   }
  97
  98   class EntailmentCheckParameters;
  99   class EntailmentCheckSideEffects;
 100 }/* CVC4::theory namespace */
 101
 102 class DecisionEngine;
 103 class RemoveTermFormulas;
 104
 105 /**
 106  * This is essentially an abstraction for a collection of theories.  A
 107  * TheoryEngine provides services to a PropEngine, making various
 108  * T-solvers look like a single unit to the propositional part of
 109  * CVC4.
 110  */
 111 class TheoryEngine {
 112
 113   /** Shared terms database can use the internals notify the theories */
 114   friend class SharedTermsDatabase;
 115   friend class theory::quantifiers::TermDb;
 116
 117   /** Associated PropEngine engine */
 118   prop::PropEngine* d_propEngine;
 119
 120   /** Access to decision engine */
 121   DecisionEngine* d_decisionEngine;
 122
 123   /** Our context */
 124   context::Context* d_context;
 125
 126   /** Our user context */
 127   context::UserContext* d_userContext;
 128
 129   /**
 130    * A table of from theory IDs to theory pointers. Never use this table
 131    * directly, use theoryOf() instead.
 132    */
 133   theory::Theory* d_theoryTable[theory::THEORY_LAST];
 134
 135   /**
 136    * A collection of theories that are "active" for the current run.
 137    * This set is provided by the user (as a logic string, say, in SMT-LIBv2
 138    * format input), or else by default it's all-inclusive.  This is important
 139    * because we can optimize for single-theory runs (no sharing), can reduce
 140    * the cost of walking the DAG on registration, etc.
 141    */
 142   const LogicInfo& d_logicInfo;
 143
 144   /**
 145    * The database of shared terms.
 146    */
 147   SharedTermsDatabase d_sharedTerms;
 148
 149   /**
 150    * Master equality engine, to share with theories.
 151    */
 152   theory::eq::EqualityEngine* d_masterEqualityEngine;
 153
 154   /** notify class for master equality engine */
 155   class NotifyClass : public theory::eq::EqualityEngineNotify {
 156     TheoryEngine& d_te;
 157   public:
 158     NotifyClass(TheoryEngine& te): d_te(te) {}
 159     bool eqNotifyTriggerEquality(TNode equality, bool value) override
 160     {
 161       return true;
 162     }
 163     bool eqNotifyTriggerPredicate(TNode predicate, bool value) override
 164     {
 165       return true;
 166     }
 167     bool eqNotifyTriggerTermEquality(theory::TheoryId tag,
 168                                      TNode t1,
 169                                      TNode t2,
 170                                      bool value) override
 171     {
 172       return true;
 173     }
 174     void eqNotifyConstantTermMerge(TNode t1, TNode t2) override {}
 175     void eqNotifyNewClass(TNode t) override { d_te.eqNotifyNewClass(t); }
 176     void eqNotifyPreMerge(TNode t1, TNode t2) override
 177     {
 178     }
 179     void eqNotifyPostMerge(TNode t1, TNode t2) override
 180     {
 181     }
 182     void eqNotifyDisequal(TNode t1, TNode t2, TNode reason) override
 183     {
 184     }
 185   };/* class TheoryEngine::NotifyClass */
 186   NotifyClass d_masterEENotify;
 187
 188   /**
 189    * notification methods
 190    */
 191   void eqNotifyNewClass(TNode t);
 192   void eqNotifyPreMerge(TNode t1, TNode t2);
 193   void eqNotifyPostMerge(TNode t1, TNode t2);
 194   void eqNotifyDisequal(TNode t1, TNode t2, TNode reason);
 195
 196   /**
 197    * The quantifiers engine
 198    */
 199   theory::QuantifiersEngine* d_quantEngine;
 200   /**
 201    * The decision manager
 202    */
 203   std::unique_ptr<theory::DecisionManager> d_decManager;
 204
 205   /**
 206    * Default model object
 207    */
 208   theory::TheoryModel* d_curr_model;
 209   bool d_aloc_curr_model;
 210   /**
 211    * Model builder object
 212    */
 213   theory::TheoryEngineModelBuilder* d_curr_model_builder;
 214   bool d_aloc_curr_model_builder;
 215   /** are we in eager model building mode? (see setEagerModelBuilding). */
 216   bool d_eager_model_building;
 217
 218   typedef std::unordered_map<Node, Node, NodeHashFunction> NodeMap;
 219   typedef std::unordered_map<TNode, Node, TNodeHashFunction> TNodeMap;
 220
 221   /**
 222   * Cache for theory-preprocessing of assertions
 223    */
 224   NodeMap d_ppCache;
 225
 226   /**
 227    * Used for "missed-t-propagations" dumping mode only.  A set of all
 228    * theory-propagable literals.
 229    */
 230   context::CDList<TNode> d_possiblePropagations;
 231
 232   /**
 233    * Used for "missed-t-propagations" dumping mode only.  A
 234    * context-dependent set of those theory-propagable literals that
 235    * have been propagated.
 236    */
 237   context::CDHashSet<Node, NodeHashFunction> d_hasPropagated;
 238
 239
 240   /**
 241    * Statistics for a particular theory.
 242    */
 243   class Statistics {
 244
 245     static std::string mkName(std::string prefix,
 246                               theory::TheoryId theory,
 247                               std::string suffix) {
 248       std::stringstream ss;
 249       ss << prefix << theory << suffix;
 250       return ss.str();
 251     }
 252
 253    public:
 254     IntStat conflicts, propagations, lemmas, requirePhase, restartDemands;
 255
 256     Statistics(theory::TheoryId theory);
 257     ~Statistics();
 258   };/* class TheoryEngine::Statistics */
 259
 260   /**
 261    * An output channel for Theory that passes messages
 262    * back to a TheoryEngine.
 263    */
 264   class EngineOutputChannel : public theory::OutputChannel {
 265     friend class TheoryEngine;
 266
 267     /**
 268      * The theory engine we're communicating with.
 269      */
 270     TheoryEngine* d_engine;
 271
 272     /**
 273      * The statistics of the theory interractions.
 274      */
 275     Statistics d_statistics;
 276
 277     /** The theory owning this channel. */
 278     theory::TheoryId d_theory;
 279
 280    public:
 281     EngineOutputChannel(TheoryEngine* engine, theory::TheoryId theory)
 282         : d_engine(engine), d_statistics(theory), d_theory(theory) {}
 283
 284     void safePoint(uint64_t amount) override {
 285       spendResource(amount);
 286       if (d_engine->d_interrupted) {
 287         throw theory::Interrupted();
 288       }
 289     }
 290
 291     void conflict(TNode conflictNode,
 292                   std::unique_ptr<Proof> pf = nullptr) override;
 293     bool propagate(TNode literal) override;
 294
 295     theory::LemmaStatus lemma(TNode lemma, ProofRule rule,
 296                               bool removable = false, bool preprocess = false,
 297                               bool sendAtoms = false) override;
 298
 299     theory::LemmaStatus splitLemma(TNode lemma,
 300                                    bool removable = false) override;
 301
 302     void demandRestart() override {
 303       NodeManager* curr = NodeManager::currentNM();
 304       Node restartVar = curr->mkSkolem(
 305           "restartVar", curr->booleanType(),
 306           "A boolean variable asserted to be true to force a restart");
 307       Trace("theory::restart")
 308           << "EngineOutputChannel<" << d_theory << ">::restart(" << restartVar
 309           << ")" << std::endl;
 310       ++d_statistics.restartDemands;
 311       lemma(restartVar, RULE_INVALID, true);
 312     }
 313
 314     void requirePhase(TNode n, bool phase) override {
 315       Debug("theory") << "EngineOutputChannel::requirePhase(" << n << ", "
 316                       << phase << ")" << std::endl;
 317       ++d_statistics.requirePhase;
 318       d_engine->d_propEngine->requirePhase(n, phase);
 319     }
 320
 321     void setIncomplete() override {
 322       Trace("theory") << "TheoryEngine::setIncomplete()" << std::endl;
 323       d_engine->setIncomplete(d_theory);
 324     }
 325
 326     void spendResource(unsigned amount) override {
 327       d_engine->spendResource(amount);
 328     }
 329
 330     void handleUserAttribute(const char* attr, theory::Theory* t) override {
 331       d_engine->handleUserAttribute(attr, t);
 332     }
 333
 334    private:
 335     /**
 336      * A helper function for registering lemma recipes with the proof engine
 337      */
 338     void registerLemmaRecipe(Node lemma, Node originalLemma, bool preprocess,
 339                              theory::TheoryId theoryId);
 340   }; /* class TheoryEngine::EngineOutputChannel */
 341
 342   /**
 343    * Output channels for individual theories.
 344    */
 345   EngineOutputChannel* d_theoryOut[theory::THEORY_LAST];
 346
 347   /**
 348    * Are we in conflict.
 349    */
 350   context::CDO<bool> d_inConflict;
 351
 352   /**
 353    * Are we in "SAT mode"? In this state, the user can query for the model.
 354    * This corresponds to the state in Figure 4.1, page 52 of the SMT-LIB
 355    * standard, version 2.6.
 356    */
 357   bool d_inSatMode;
 358
 359   /**
 360    * Called by the theories to notify of a conflict.
 361    */
 362   void conflict(TNode conflict, theory::TheoryId theoryId);
 363
 364   /**
 365    * Debugging flag to ensure that shutdown() is called before the
 366    * destructor.
 367    */
 368   bool d_hasShutDown;
 369
 370   /**
 371    * True if a theory has notified us of incompleteness (at this
 372    * context level or below).
 373    */
 374   context::CDO<bool> d_incomplete;
 375
 376   /**
 377    * Called by the theories to notify that the current branch is incomplete.
 378    */
 379   void setIncomplete(theory::TheoryId theory) {
 380     d_incomplete = true;
 381   }
 382
 383
 384   /**
 385    * Mapping of propagations from recievers to senders.
 386    */
 387   typedef context::CDHashMap<NodeTheoryPair, NodeTheoryPair, NodeTheoryPairHashFunction> PropagationMap;
 388   PropagationMap d_propagationMap;
 389
 390   /**
 391    * Timestamp of propagations
 392    */
 393   context::CDO<size_t> d_propagationMapTimestamp;
 394
 395   /**
 396    * Literals that are propagated by the theory. Note that these are TNodes.
 397    * The theory can only propagate nodes that have an assigned literal in the
 398    * SAT solver and are hence referenced in the SAT solver.
 399    */
 400   context::CDList<TNode> d_propagatedLiterals;
 401
 402   /**
 403    * The index of the next literal to be propagated by a theory.
 404    */
 405   context::CDO<unsigned> d_propagatedLiteralsIndex;
 406
 407   /**
 408    * Called by the output channel to propagate literals and facts
 409    * @return false if immediate conflict
 410    */
 411   bool propagate(TNode literal, theory::TheoryId theory);
 412
 413   /**
 414    * Internal method to call the propagation routines and collect the
 415    * propagated literals.
 416    */
 417   void propagate(theory::Theory::Effort effort);
 418
 419   /**
 420    * A variable to mark if we added any lemmas.
 421    */
 422   bool d_lemmasAdded;
 423
 424   /**
 425    * A variable to mark if the OutputChannel was "used" by any theory
 426    * since the start of the last check.  If it has been, we require
 427    * a FULL_EFFORT check before exiting and reporting SAT.
 428    *
 429    * See the documentation for the needCheck() function, below.
 430    */
 431   bool d_outputChannelUsed;
 432
 433   /** Atom requests from lemmas */
 434   AtomRequests d_atomRequests;
 435
 436   /**
 437    * Adds a new lemma, returning its status.
 438    * @param node the lemma
 439    * @param negated should the lemma be asserted negated
 440    * @param removable can the lemma be remove (restrictions apply)
 441    * @param needAtoms if not THEORY_LAST, then
 442    */
 443   theory::LemmaStatus lemma(TNode node,
 444                             ProofRule rule,
 445                             bool negated,
 446                             bool removable,
 447                             bool preprocess,
 448                             theory::TheoryId atomsTo);
 449
 450   /** Enusre that the given atoms are send to the given theory */
 451   void ensureLemmaAtoms(const std::vector<TNode>& atoms, theory::TheoryId theory);
 452
 453   RemoveTermFormulas& d_tform_remover;
 454
 455   /** sort inference module */
 456   SortInference d_sortInfer;
 457
 458   /** Time spent in theory combination */
 459   TimerStat d_combineTheoriesTime;
 460
 461   Node d_true;
 462   Node d_false;
 463
 464   /** Whether we were just interrupted (or not) */
 465   bool d_interrupted;
 466   ResourceManager* d_resourceManager;
 467
 468   /** Container for lemma input and output channels. */
 469   LemmaChannels* d_channels;
 470
 471 public:
 472
 473   /** Constructs a theory engine */
 474   TheoryEngine(context::Context* context, context::UserContext* userContext,
 475                RemoveTermFormulas& iteRemover, const LogicInfo& logic,
 476                LemmaChannels* channels);
 477
 478   /** Destroys a theory engine */
 479   ~TheoryEngine();
 480
 481   void interrupt();
 482
 483   /** "Spend" a resource during a search or preprocessing.*/
 484   void spendResource(unsigned amount);
 485
 486   /**
 487    * Adds a theory. Only one theory per TheoryId can be present, so if
 488    * there is another theory it will be deleted.
 489    */
 490   template <class TheoryClass>
 491   inline void addTheory(theory::TheoryId theoryId) {
 492     Assert(d_theoryTable[theoryId] == NULL && d_theoryOut[theoryId] == NULL);
 493     d_theoryOut[theoryId] = new EngineOutputChannel(this, theoryId);
 494     d_theoryTable[theoryId] =
 495         new TheoryClass(d_context, d_userContext, *d_theoryOut[theoryId],
 496                         theory::Valuation(this), d_logicInfo);
 497   }
 498
 499   inline void setPropEngine(prop::PropEngine* propEngine) {
 500     Assert(d_propEngine == NULL);
 501     d_propEngine = propEngine;
 502   }
 503
 504   inline void setDecisionEngine(DecisionEngine* decisionEngine) {
 505     Assert(d_decisionEngine == NULL);
 506     d_decisionEngine = decisionEngine;
 507   }
 508
 509   /** Called when all initialization of options/logic is done */
 510   void finishInit();
 511
 512   /**
 513    * Get a pointer to the underlying propositional engine.
 514    */
 515   inline prop::PropEngine* getPropEngine() const {
 516     return d_propEngine;
 517   }
 518
 519   /**
 520    * Get a pointer to the underlying sat context.
 521    */
 522   inline context::Context* getSatContext() const {
 523     return d_context;
 524   }
 525
 526   /**
 527    * Get a pointer to the underlying user context.
 528    */
 529   inline context::Context* getUserContext() const {
 530     return d_userContext;
 531   }
 532
 533   /**
 534    * Get a pointer to the underlying quantifiers engine.
 535    */
 536   theory::QuantifiersEngine* getQuantifiersEngine() const {
 537     return d_quantEngine;
 538   }
 539   /**
 540    * Get a pointer to the underlying decision manager.
 541    */
 542   theory::DecisionManager* getDecisionManager() const
 543   {
 544     return d_decManager.get();
 545   }
 546
 547  private:
 548   /**
 549    * Helper for preprocess
 550    */
 551   Node ppTheoryRewrite(TNode term);
 552
 553   /**
 554    * Queue of nodes for pre-registration.
 555    */
 556   std::queue<TNode> d_preregisterQueue;
 557
 558   /**
 559    * Boolean flag denoting we are in pre-registration.
 560    */
 561   bool d_inPreregister;
 562
 563   /**
 564    * Did the theories get any new facts since the last time we called
 565    * check()
 566    */
 567   context::CDO<bool> d_factsAsserted;
 568
 569   /**
 570    * Map from equality atoms to theories that would like to be notified about them.
 571    */
 572
 573
 574   /**
 575    * Assert the formula to the given theory.
 576    * @param assertion the assertion to send (not necesserily normalized)
 577    * @param original the assertion as it was sent in from the propagating theory
 578    * @param toTheoryId the theory to assert to
 579    * @param fromTheoryId the theory that sent it
 580    */
 581   void assertToTheory(TNode assertion, TNode originalAssertion, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 582
 583   /**
 584    * Marks a theory propagation from a theory to a theory where a
 585    * theory could be the THEORY_SAT_SOLVER for literals coming from
 586    * or being propagated to the SAT solver. If the receiving theory
 587    * already recieved the literal, the method returns false, otherwise
 588    * it returns true.
 589    *
 590    * @param assertion the normalized assertion being sent
 591    * @param originalAssertion the actual assertion that was sent
 592    * @param toTheoryId the theory that is on the receiving end
 593    * @param fromTheoryId the theory that sent the assertino
 594    * @return true if a new assertion, false if theory already got it
 595    */
 596   bool markPropagation(TNode assertion, TNode originalAssertions, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 597
 598   /**
 599    * Computes the explanation by travarsing the propagation graph and
 600    * asking relevant theories to explain the propagations. Initially
 601    * the explanation vector should contain only the element (node, theory)
 602    * where the node is the one to be explained, and the theory is the
 603    * theory that sent the literal. The lemmaProofRecipe will contain a list
 604    * of the explanation steps required to produce the original node.
 605    */
 606   void getExplanation(std::vector<NodeTheoryPair>& explanationVector, LemmaProofRecipe* lemmaProofRecipe);
 607
 608 public:
 609
 610   /**
 611    * Signal the start of a new round of assertion preprocessing
 612    */
 613   void preprocessStart();
 614
 615   /**
 616    * Runs theory specific preprocessing on the non-Boolean parts of
 617    * the formula.  This is only called on input assertions, after ITEs
 618    * have been removed.
 619    */
 620   Node preprocess(TNode node);
 621
 622   /** Notify (preprocessed) assertions. */
 623   void notifyPreprocessedAssertions(const std::vector<Node>& assertions);
 624
 625   /** Return whether or not we are incomplete (in the current context). */
 626   inline bool isIncomplete() const { return d_incomplete; }
 627
 628   /**
 629    * Returns true if we need another round of checking.  If this
 630    * returns true, check(FULL_EFFORT) _must_ be called by the
 631    * propositional layer before reporting SAT.
 632    *
 633    * This is especially necessary for incomplete theories that lazily
 634    * output some lemmas on FULL_EFFORT check (e.g. quantifier reasoning
 635    * outputing quantifier instantiations).  In such a case, a lemma can
 636    * be asserted that is simplified away (perhaps it's already true).
 637    * However, we must maintain the invariant that, if a theory uses the
 638    * OutputChannel, it implicitly requests that another check(FULL_EFFORT)
 639    * be performed before exit, even if no new facts are on its fact queue,
 640    * as it might decide to further instantiate some lemmas, precluding
 641    * a SAT response.
 642    */
 643   inline bool needCheck() const {
 644     return d_outputChannelUsed || d_lemmasAdded;
 645   }
 646
 647   /**
 648    * This is called at shutdown time by the SmtEngine, just before
 649    * destruction.  It is important because there are destruction
 650    * ordering issues between PropEngine and Theory.
 651    */
 652   void shutdown();
 653
 654   /**
 655    * Solve the given literal with a theory that owns it.
 656    */
 657   theory::Theory::PPAssertStatus solve(TNode literal,
 658                                     theory::SubstitutionMap& substitutionOut);
 659
 660   /**
 661    * Preregister a Theory atom with the responsible theory (or
 662    * theories).
 663    */
 664   void preRegister(TNode preprocessed);
 665
 666   /**
 667    * Assert the formula to the appropriate theory.
 668    * @param node the assertion
 669    */
 670   void assertFact(TNode node);
 671
 672   /**
 673    * Check all (currently-active) theories for conflicts.
 674    * @param effort the effort level to use
 675    */
 676   void check(theory::Theory::Effort effort);
 677
 678   /**
 679    * Run the combination framework.
 680    */
 681   void combineTheories();
 682
 683   /**
 684    * Calls ppStaticLearn() on all theories, accumulating their
 685    * combined contributions in the "learned" builder.
 686    */
 687   void ppStaticLearn(TNode in, NodeBuilder<>& learned);
 688
 689   /**
 690    * Calls presolve() on all theories and returns true
 691    * if one of the theories discovers a conflict.
 692    */
 693   bool presolve();
 694
 695    /**
 696    * Calls postsolve() on all theories.
 697    */
 698   void postsolve();
 699
 700   /**
 701    * Calls notifyRestart() on all active theories.
 702    */
 703   void notifyRestart();
 704
 705   void getPropagatedLiterals(std::vector<TNode>& literals) {
 706     for (; d_propagatedLiteralsIndex < d_propagatedLiterals.size(); d_propagatedLiteralsIndex = d_propagatedLiteralsIndex + 1) {
 707       Debug("getPropagatedLiterals") << "TheoryEngine::getPropagatedLiterals: propagating: " << d_propagatedLiterals[d_propagatedLiteralsIndex] << std::endl;
 708       literals.push_back(d_propagatedLiterals[d_propagatedLiteralsIndex]);
 709     }
 710   }
 711
 712   /**
 713    * Returns the next decision request, or null if none exist. The next
 714    * decision request is a literal that this theory engine prefers the SAT
 715    * solver to make as its next decision. Decision requests are managed by
 716    * the decision manager d_decManager.
 717    */
 718   Node getNextDecisionRequest();
 719
 720   bool properConflict(TNode conflict) const;
 721   bool properPropagation(TNode lit) const;
 722   bool properExplanation(TNode node, TNode expl) const;
 723
 724   /**
 725    * Returns an explanation of the node propagated to the SAT solver.
 726    */
 727   Node getExplanation(TNode node);
 728
 729   /**
 730    * Returns an explanation of the node propagated to the SAT solver and the theory
 731    * that propagated it.
 732    */
 733   Node getExplanationAndRecipe(TNode node, LemmaProofRecipe* proofRecipe);
 734
 735   /**
 736    * collect model info
 737    */
 738   bool collectModelInfo(theory::TheoryModel* m);
 739   /** post process model */
 740   void postProcessModel( theory::TheoryModel* m );
 741
 742   /**
 743    * Get the pointer to the model object used by this theory engine.
 744    */
 745   theory::TheoryModel* getModel();
 746   /**
 747    * Get the current model for the current set of assertions. This method
 748    * should only be called immediately after a satisfiable or unknown
 749    * response to a check-sat call, and only if produceModels is true.
 750    *
 751    * If the model is not already built, this will cause this theory engine
 752    * to build the model.
 753    *
 754    * If the model is not available (for instance, if the last call to check-sat
 755    * was interrupted), then this returns the null pointer.
 756    */
 757   theory::TheoryModel* getBuiltModel();
 758   /** set eager model building
 759    *
 760    * If this method is called, then this TheoryEngine will henceforth build
 761    * its model immediately after every satisfiability check that results
 762    * in a satisfiable or unknown result. The motivation for this mode is to
 763    * accomodate API users that get the model object from the TheoryEngine,
 764    * where we want to ensure that this model is always valid.
 765    * TODO (#2648): revisit this.
 766    */
 767   void setEagerModelBuilding() { d_eager_model_building = true; }
 768
 769   /** get synth solutions
 770    *
 771    * This method returns true if there is a synthesis solution available. This
 772    * is the case if the last call to check satisfiability originated in a
 773    * check-synth call, and the synthesis solver successfully found a solution
 774    * for all active synthesis conjectures.
 775    *
 776    * This method adds entries to sol_map that map functions-to-synthesize with
 777    * their solutions, for all active conjectures. This should be called
 778    * immediately after the solver answers unsat for sygus input.
 779    *
 780    * For details on what is added to sol_map, see
 781    * SynthConjecture::getSynthSolutions.
 782    */
 783   bool getSynthSolutions(std::map<Node, std::map<Node, Node> >& sol_map);
 784
 785   /**
 786    * Get the model builder
 787    */
 788   theory::TheoryEngineModelBuilder* getModelBuilder() { return d_curr_model_builder; }
 789
 790   /**
 791    * Get the theory associated to a given Node.
 792    *
 793    * @returns the theory, or NULL if the TNode is
 794    * of built-in type.
 795    */
 796   inline theory::Theory* theoryOf(TNode node) const {
 797     return d_theoryTable[theory::Theory::theoryOf(node)];
 798   }
 799
 800   /**
 801    * Get the theory associated to a the given theory id.
 802    *
 803    * @returns the theory
 804    */
 805   inline theory::Theory* theoryOf(theory::TheoryId theoryId) const {
 806     Assert(theoryId < theory::THEORY_LAST);
 807     return d_theoryTable[theoryId];
 808   }
 809
 810   inline bool isTheoryEnabled(theory::TheoryId theoryId) const {
 811     return d_logicInfo.isTheoryEnabled(theoryId);
 812   }
 813   /** get the logic info used by this theory engine */
 814   const LogicInfo& getLogicInfo() const;
 815   /**
 816    * Returns the equality status of the two terms, from the theory
 817    * that owns the domain type.  The types of a and b must be the same.
 818    */
 819   theory::EqualityStatus getEqualityStatus(TNode a, TNode b);
 820
 821   /**
 822    * Returns the value that a theory that owns the type of var currently
 823    * has (or null if none);
 824    */
 825   Node getModelValue(TNode var);
 826
 827   /**
 828    * Takes a literal and returns an equivalent literal that is guaranteed to be a SAT literal
 829    */
 830   Node ensureLiteral(TNode n);
 831
 832   /**
 833    * Print all instantiations made by the quantifiers module.
 834    */
 835   void printInstantiations( std::ostream& out );
 836
 837   /**
 838    * Print solution for synthesis conjectures found by ce_guided_instantiation module
 839    */
 840   void printSynthSolution( std::ostream& out );
 841
 842   /**
 843    * Get list of quantified formulas that were instantiated
 844    */
 845   void getInstantiatedQuantifiedFormulas( std::vector< Node >& qs );
 846
 847   /**
 848    * Get instantiation methods
 849    *   first inputs forall x.q[x] and returns ( q[a], ..., q[z] )
 850    *   second inputs forall x.q[x] and returns ( a, ..., z )
 851    *   third and fourth return mappings e.g. forall x.q1[x] -> ( q1[a]...q1[z] ) , ... , forall x.qn[x] -> ( qn[a]...qn[z] )
 852    */
 853   void getInstantiations( Node q, std::vector< Node >& insts );
 854   void getInstantiationTermVectors( Node q, std::vector< std::vector< Node > >& tvecs );
 855   void getInstantiations( std::map< Node, std::vector< Node > >& insts );
 856   void getInstantiationTermVectors( std::map< Node, std::vector< std::vector< Node > > >& insts );
 857
 858   /**
 859    * Get instantiated conjunction, returns q[t1] ^ ... ^ q[tn] where t1...tn are current set of instantiations for q.
 860    *   Can be used for quantifier elimination when satisfiable and q[t1] ^ ... ^ q[tn] |= q
 861    */
 862   Node getInstantiatedConjunction( Node q );
 863
 864   /**
 865    * Forwards an entailment check according to the given theoryOfMode.
 866    * See theory.h for documentation on entailmentCheck().
 867    */
 868   std::pair<bool, Node> entailmentCheck(
 869       options::TheoryOfMode mode,
 870       TNode lit,
 871       const theory::EntailmentCheckParameters* params = NULL,
 872       theory::EntailmentCheckSideEffects* out = NULL);
 873
 874  private:
 875   /** Default visitor for pre-registration */
 876   PreRegisterVisitor d_preRegistrationVisitor;
 877
 878   /** Visitor for collecting shared terms */
 879   SharedTermsVisitor d_sharedTermsVisitor;
 880
 881   /** Dump the assertions to the dump */
 882   void dumpAssertions(const char* tag);
 883
 884   /** For preprocessing pass lifting bit-vectors of size 1 to booleans */
 885 public:
 886   void staticInitializeBVOptions(const std::vector<Node>& assertions);
 887
 888   Node ppSimpITE(TNode assertion);
 889   /** Returns false if an assertion simplified to false. */
 890   bool donePPSimpITE(std::vector<Node>& assertions);
 891
 892   SharedTermsDatabase* getSharedTermsDatabase() { return &d_sharedTerms; }
 893
 894   theory::eq::EqualityEngine* getMasterEqualityEngine() { return d_masterEqualityEngine; }
 895
 896   RemoveTermFormulas* getTermFormulaRemover() { return &d_tform_remover; }
 897
 898   SortInference* getSortInference() { return &d_sortInfer; }
 899
 900   /** Prints the assertions to the debug stream */
 901   void printAssertions(const char* tag);
 902
 903   /** Theory alternative is in use. */
 904   bool useTheoryAlternative(const std::string& name);
 905
 906   /** Enables using a theory alternative by name. */
 907   void enableTheoryAlternative(const std::string& name);
 908
 909 private:
 910   std::set< std::string > d_theoryAlternatives;
 911
 912   std::map< std::string, std::vector< theory::Theory* > > d_attr_handle;
 913
 914  public:
 915   /** Set user attribute.
 916    *
 917    * This function is called when an attribute is set by a user.  In SMT-LIBv2
 918    * this is done via the syntax (! n :attr)
 919    */
 920   void setUserAttribute(const std::string& attr,
 921                         Node n,
 922                         const std::vector<Node>& node_values,
 923                         const std::string& str_value);
 924
 925   /** Handle user attribute.
 926    *
 927    * Associates theory t with the attribute attr.  Theory t will be
 928    * notified whenever an attribute of name attr is set.
 929    */
 930   void handleUserAttribute(const char* attr, theory::Theory* t);
 931
 932   /**
 933    * Check that the theory assertions are satisfied in the model.
 934    * This function is called from the smt engine's checkModel routine.
 935    */
 936   void checkTheoryAssertionsWithModel(bool hardFailure);
 937
 938  private:
 939   IntStat d_arithSubstitutionsAdded;
 940
 941 };/* class TheoryEngine */
 942
 943 }/* CVC4 namespace */
 944
 945 #endif /* CVC4__THEORY_ENGINE_H */