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