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 "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/resource_manager.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 d_node;
  64   theory::TheoryId d_theory;
  65   size_t d_timestamp;
  66   NodeTheoryPair(TNode n, theory::TheoryId t, size_t ts = 0)
  67       : d_node(n), d_theory(t), d_timestamp(ts)
  68   {
  69   }
  70   NodeTheoryPair() : d_theory(theory::THEORY_LAST), d_timestamp() {}
  71   // Comparison doesn't take into account the timestamp
  72   bool operator == (const NodeTheoryPair& pair) const {
  73     return d_node == pair.d_node && d_theory == pair.d_theory;
  74   }
  75 };/* struct NodeTheoryPair */
  76
  77 struct NodeTheoryPairHashFunction {
  78   NodeHashFunction hashFunction;
  79   // Hash doesn't take into account the timestamp
  80   size_t operator()(const NodeTheoryPair& pair) const {
  81     uint64_t hash = fnv1a::fnv1a_64(NodeHashFunction()(pair.d_node));
  82     return static_cast<size_t>(fnv1a::fnv1a_64(pair.d_theory, hash));
  83   }
  84 };/* struct NodeTheoryPairHashFunction */
  85
  86
  87 /* Forward declarations */
  88 namespace theory {
  89   class TheoryModel;
  90   class TheoryEngineModelBuilder;
  91
  92   namespace eq {
  93     class EqualityEngine;
  94   }/* CVC4::theory::eq namespace */
  95
  96   namespace quantifiers {
  97     class TermDb;
  98   }
  99
 100   class EntailmentCheckParameters;
 101   class EntailmentCheckSideEffects;
 102 }/* CVC4::theory namespace */
 103
 104 class DecisionEngine;
 105 class RemoveTermFormulas;
 106
 107 /**
 108  * This is essentially an abstraction for a collection of theories.  A
 109  * TheoryEngine provides services to a PropEngine, making various
 110  * T-solvers look like a single unit to the propositional part of
 111  * CVC4.
 112  */
 113 class TheoryEngine {
 114
 115   /** Shared terms database can use the internals notify the theories */
 116   friend class SharedTermsDatabase;
 117   friend class theory::quantifiers::TermDb;
 118
 119   /** Associated PropEngine engine */
 120   prop::PropEngine* d_propEngine;
 121
 122   /** Access to decision engine */
 123   DecisionEngine* d_decisionEngine;
 124
 125   /** Our context */
 126   context::Context* d_context;
 127
 128   /** Our user context */
 129   context::UserContext* d_userContext;
 130
 131   /**
 132    * A table of from theory IDs to theory pointers. Never use this table
 133    * directly, use theoryOf() instead.
 134    */
 135   theory::Theory* d_theoryTable[theory::THEORY_LAST];
 136
 137   /**
 138    * A collection of theories that are "active" for the current run.
 139    * This set is provided by the user (as a logic string, say, in SMT-LIBv2
 140    * format input), or else by default it's all-inclusive.  This is important
 141    * because we can optimize for single-theory runs (no sharing), can reduce
 142    * the cost of walking the DAG on registration, etc.
 143    */
 144   const LogicInfo& d_logicInfo;
 145
 146   /**
 147    * The database of shared terms.
 148    */
 149   SharedTermsDatabase d_sharedTerms;
 150
 151   /**
 152    * Master equality engine, to share with theories.
 153    */
 154   theory::eq::EqualityEngine* d_masterEqualityEngine;
 155
 156   /** notify class for master equality engine */
 157   class NotifyClass : public theory::eq::EqualityEngineNotify {
 158     TheoryEngine& d_te;
 159   public:
 160     NotifyClass(TheoryEngine& te): d_te(te) {}
 161     bool eqNotifyTriggerEquality(TNode equality, bool value) override
 162     {
 163       return true;
 164     }
 165     bool eqNotifyTriggerPredicate(TNode predicate, bool value) override
 166     {
 167       return true;
 168     }
 169     bool eqNotifyTriggerTermEquality(theory::TheoryId tag,
 170                                      TNode t1,
 171                                      TNode t2,
 172                                      bool value) override
 173     {
 174       return true;
 175     }
 176     void eqNotifyConstantTermMerge(TNode t1, TNode t2) override {}
 177     void eqNotifyNewClass(TNode t) override { d_te.eqNotifyNewClass(t); }
 178     void eqNotifyPreMerge(TNode t1, TNode t2) override
 179     {
 180     }
 181     void eqNotifyPostMerge(TNode t1, TNode t2) override
 182     {
 183     }
 184     void eqNotifyDisequal(TNode t1, TNode t2, TNode reason) override
 185     {
 186     }
 187   };/* class TheoryEngine::NotifyClass */
 188   NotifyClass d_masterEENotify;
 189
 190   /**
 191    * notification methods
 192    */
 193   void eqNotifyNewClass(TNode t);
 194   void eqNotifyPreMerge(TNode t1, TNode t2);
 195   void eqNotifyPostMerge(TNode t1, TNode t2);
 196   void eqNotifyDisequal(TNode t1, TNode t2, TNode reason);
 197
 198   /**
 199    * The quantifiers engine
 200    */
 201   theory::QuantifiersEngine* d_quantEngine;
 202   /**
 203    * The decision manager
 204    */
 205   std::unique_ptr<theory::DecisionManager> d_decManager;
 206
 207   /**
 208    * Default model object
 209    */
 210   theory::TheoryModel* d_curr_model;
 211   bool d_aloc_curr_model;
 212   /**
 213    * Model builder object
 214    */
 215   theory::TheoryEngineModelBuilder* d_curr_model_builder;
 216   bool d_aloc_curr_model_builder;
 217   /** are we in eager model building mode? (see setEagerModelBuilding). */
 218   bool d_eager_model_building;
 219
 220   typedef std::unordered_map<Node, Node, NodeHashFunction> NodeMap;
 221   typedef std::unordered_map<TNode, Node, TNodeHashFunction> TNodeMap;
 222
 223   /**
 224   * Cache for theory-preprocessing of assertions
 225    */
 226   NodeMap d_ppCache;
 227
 228   /**
 229    * Used for "missed-t-propagations" dumping mode only.  A set of all
 230    * theory-propagable literals.
 231    */
 232   context::CDList<TNode> d_possiblePropagations;
 233
 234   /**
 235    * Used for "missed-t-propagations" dumping mode only.  A
 236    * context-dependent set of those theory-propagable literals that
 237    * have been propagated.
 238    */
 239   context::CDHashSet<Node, NodeHashFunction> d_hasPropagated;
 240
 241
 242   /**
 243    * Statistics for a particular theory.
 244    */
 245   class Statistics {
 246
 247     static std::string mkName(std::string prefix,
 248                               theory::TheoryId theory,
 249                               std::string suffix) {
 250       std::stringstream ss;
 251       ss << prefix << theory << suffix;
 252       return ss.str();
 253     }
 254
 255    public:
 256     IntStat conflicts, propagations, lemmas, requirePhase, restartDemands;
 257
 258     Statistics(theory::TheoryId theory);
 259     ~Statistics();
 260   };/* class TheoryEngine::Statistics */
 261
 262   /**
 263    * An output channel for Theory that passes messages
 264    * back to a TheoryEngine.
 265    */
 266   class EngineOutputChannel : public theory::OutputChannel {
 267     friend class TheoryEngine;
 268
 269     /**
 270      * The theory engine we're communicating with.
 271      */
 272     TheoryEngine* d_engine;
 273
 274     /**
 275      * The statistics of the theory interractions.
 276      */
 277     Statistics d_statistics;
 278
 279     /** The theory owning this channel. */
 280     theory::TheoryId d_theory;
 281
 282    public:
 283     EngineOutputChannel(TheoryEngine* engine, theory::TheoryId theory)
 284         : d_engine(engine), d_statistics(theory), d_theory(theory) {}
 285
 286     void safePoint(ResourceManager::Resource r) override
 287     {
 288       spendResource(r);
 289       if (d_engine->d_interrupted) {
 290         throw theory::Interrupted();
 291       }
 292     }
 293
 294     void conflict(TNode conflictNode,
 295                   std::unique_ptr<Proof> pf = nullptr) override;
 296     bool propagate(TNode literal) override;
 297
 298     theory::LemmaStatus lemma(TNode lemma, ProofRule rule,
 299                               bool removable = false, bool preprocess = false,
 300                               bool sendAtoms = false) override;
 301
 302     theory::LemmaStatus splitLemma(TNode lemma,
 303                                    bool removable = false) override;
 304
 305     void demandRestart() override {
 306       NodeManager* curr = NodeManager::currentNM();
 307       Node restartVar = curr->mkSkolem(
 308           "restartVar", curr->booleanType(),
 309           "A boolean variable asserted to be true to force a restart");
 310       Trace("theory::restart")
 311           << "EngineOutputChannel<" << d_theory << ">::restart(" << restartVar
 312           << ")" << std::endl;
 313       ++d_statistics.restartDemands;
 314       lemma(restartVar, RULE_INVALID, true);
 315     }
 316
 317     void requirePhase(TNode n, bool phase) override {
 318       Debug("theory") << "EngineOutputChannel::requirePhase(" << n << ", "
 319                       << phase << ")" << std::endl;
 320       ++d_statistics.requirePhase;
 321       d_engine->d_propEngine->requirePhase(n, phase);
 322     }
 323
 324     void setIncomplete() override {
 325       Trace("theory") << "TheoryEngine::setIncomplete()" << std::endl;
 326       d_engine->setIncomplete(d_theory);
 327     }
 328
 329     void spendResource(ResourceManager::Resource r) override
 330     {
 331       d_engine->spendResource(r);
 332     }
 333
 334     void handleUserAttribute(const char* attr, theory::Theory* t) override {
 335       d_engine->handleUserAttribute(attr, t);
 336     }
 337
 338    private:
 339     /**
 340      * A helper function for registering lemma recipes with the proof engine
 341      */
 342     void registerLemmaRecipe(Node lemma, Node originalLemma, bool preprocess,
 343                              theory::TheoryId theoryId);
 344   }; /* class TheoryEngine::EngineOutputChannel */
 345
 346   /**
 347    * Output channels for individual theories.
 348    */
 349   EngineOutputChannel* d_theoryOut[theory::THEORY_LAST];
 350
 351   /**
 352    * Are we in conflict.
 353    */
 354   context::CDO<bool> d_inConflict;
 355
 356   /**
 357    * Are we in "SAT mode"? In this state, the user can query for the model.
 358    * This corresponds to the state in Figure 4.1, page 52 of the SMT-LIB
 359    * standard, version 2.6.
 360    */
 361   bool d_inSatMode;
 362
 363   /**
 364    * Called by the theories to notify of a conflict.
 365    */
 366   void conflict(TNode conflict, theory::TheoryId theoryId);
 367
 368   /**
 369    * Debugging flag to ensure that shutdown() is called before the
 370    * destructor.
 371    */
 372   bool d_hasShutDown;
 373
 374   /**
 375    * True if a theory has notified us of incompleteness (at this
 376    * context level or below).
 377    */
 378   context::CDO<bool> d_incomplete;
 379
 380   /**
 381    * Called by the theories to notify that the current branch is incomplete.
 382    */
 383   void setIncomplete(theory::TheoryId theory) {
 384     d_incomplete = true;
 385   }
 386
 387
 388   /**
 389    * Mapping of propagations from recievers to senders.
 390    */
 391   typedef context::CDHashMap<NodeTheoryPair, NodeTheoryPair, NodeTheoryPairHashFunction> PropagationMap;
 392   PropagationMap d_propagationMap;
 393
 394   /**
 395    * Timestamp of propagations
 396    */
 397   context::CDO<size_t> d_propagationMapTimestamp;
 398
 399   /**
 400    * Literals that are propagated by the theory. Note that these are TNodes.
 401    * The theory can only propagate nodes that have an assigned literal in the
 402    * SAT solver and are hence referenced in the SAT solver.
 403    */
 404   context::CDList<TNode> d_propagatedLiterals;
 405
 406   /**
 407    * The index of the next literal to be propagated by a theory.
 408    */
 409   context::CDO<unsigned> d_propagatedLiteralsIndex;
 410
 411   /**
 412    * Called by the output channel to propagate literals and facts
 413    * @return false if immediate conflict
 414    */
 415   bool propagate(TNode literal, theory::TheoryId theory);
 416
 417   /**
 418    * Internal method to call the propagation routines and collect the
 419    * propagated literals.
 420    */
 421   void propagate(theory::Theory::Effort effort);
 422
 423   /**
 424    * A variable to mark if we added any lemmas.
 425    */
 426   bool d_lemmasAdded;
 427
 428   /**
 429    * A variable to mark if the OutputChannel was "used" by any theory
 430    * since the start of the last check.  If it has been, we require
 431    * a FULL_EFFORT check before exiting and reporting SAT.
 432    *
 433    * See the documentation for the needCheck() function, below.
 434    */
 435   bool d_outputChannelUsed;
 436
 437   /** Atom requests from lemmas */
 438   AtomRequests d_atomRequests;
 439
 440   /**
 441    * Adds a new lemma, returning its status.
 442    * @param node the lemma
 443    * @param negated should the lemma be asserted negated
 444    * @param removable can the lemma be remove (restrictions apply)
 445    * @param needAtoms if not THEORY_LAST, then
 446    */
 447   theory::LemmaStatus lemma(TNode node,
 448                             ProofRule rule,
 449                             bool negated,
 450                             bool removable,
 451                             bool preprocess,
 452                             theory::TheoryId atomsTo);
 453
 454   /** Enusre that the given atoms are send to the given theory */
 455   void ensureLemmaAtoms(const std::vector<TNode>& atoms, theory::TheoryId theory);
 456
 457   RemoveTermFormulas& d_tform_remover;
 458
 459   /** sort inference module */
 460   SortInference d_sortInfer;
 461
 462   /** Time spent in theory combination */
 463   TimerStat d_combineTheoriesTime;
 464
 465   Node d_true;
 466   Node d_false;
 467
 468   /** Whether we were just interrupted (or not) */
 469   bool d_interrupted;
 470   ResourceManager* d_resourceManager;
 471
 472  public:
 473   /** Constructs a theory engine */
 474   TheoryEngine(context::Context* context,
 475                context::UserContext* userContext,
 476                RemoveTermFormulas& iteRemover,
 477                const LogicInfo& logic);
 478
 479   /** Destroys a theory engine */
 480   ~TheoryEngine();
 481
 482   void interrupt();
 483
 484   /** "Spend" a resource during a search or preprocessing.*/
 485   void spendResource(ResourceManager::Resource r);
 486
 487   /**
 488    * Adds a theory. Only one theory per TheoryId can be present, so if
 489    * there is another theory it will be deleted.
 490    */
 491   template <class TheoryClass>
 492   inline void addTheory(theory::TheoryId theoryId)
 493   {
 494     Assert(d_theoryTable[theoryId] == NULL && d_theoryOut[theoryId] == NULL);
 495     d_theoryOut[theoryId] = new EngineOutputChannel(this, theoryId);
 496     d_theoryTable[theoryId] = new TheoryClass(d_context,
 497                                               d_userContext,
 498                                               *d_theoryOut[theoryId],
 499                                               theory::Valuation(this),
 500                                               d_logicInfo);
 501   }
 502
 503   inline void setPropEngine(prop::PropEngine* propEngine) {
 504     Assert(d_propEngine == NULL);
 505     d_propEngine = propEngine;
 506   }
 507
 508   inline void setDecisionEngine(DecisionEngine* decisionEngine) {
 509     Assert(d_decisionEngine == NULL);
 510     d_decisionEngine = decisionEngine;
 511   }
 512
 513   /** Called when all initialization of options/logic is done */
 514   void finishInit();
 515
 516   /**
 517    * Get a pointer to the underlying propositional engine.
 518    */
 519   inline prop::PropEngine* getPropEngine() const {
 520     return d_propEngine;
 521   }
 522
 523   /**
 524    * Get a pointer to the underlying sat context.
 525    */
 526   inline context::Context* getSatContext() const {
 527     return d_context;
 528   }
 529
 530   /**
 531    * Get a pointer to the underlying user context.
 532    */
 533   inline context::Context* getUserContext() const {
 534     return d_userContext;
 535   }
 536
 537   /**
 538    * Get a pointer to the underlying quantifiers engine.
 539    */
 540   theory::QuantifiersEngine* getQuantifiersEngine() const {
 541     return d_quantEngine;
 542   }
 543   /**
 544    * Get a pointer to the underlying decision manager.
 545    */
 546   theory::DecisionManager* getDecisionManager() const
 547   {
 548     return d_decManager.get();
 549   }
 550
 551  private:
 552   /**
 553    * Helper for preprocess
 554    */
 555   Node ppTheoryRewrite(TNode term);
 556
 557   /**
 558    * Queue of nodes for pre-registration.
 559    */
 560   std::queue<TNode> d_preregisterQueue;
 561
 562   /**
 563    * Boolean flag denoting we are in pre-registration.
 564    */
 565   bool d_inPreregister;
 566
 567   /**
 568    * Did the theories get any new facts since the last time we called
 569    * check()
 570    */
 571   context::CDO<bool> d_factsAsserted;
 572
 573   /**
 574    * Map from equality atoms to theories that would like to be notified about them.
 575    */
 576
 577
 578   /**
 579    * Assert the formula to the given theory.
 580    * @param assertion the assertion to send (not necesserily normalized)
 581    * @param original the assertion as it was sent in from the propagating theory
 582    * @param toTheoryId the theory to assert to
 583    * @param fromTheoryId the theory that sent it
 584    */
 585   void assertToTheory(TNode assertion, TNode originalAssertion, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 586
 587   /**
 588    * Marks a theory propagation from a theory to a theory where a
 589    * theory could be the THEORY_SAT_SOLVER for literals coming from
 590    * or being propagated to the SAT solver. If the receiving theory
 591    * already recieved the literal, the method returns false, otherwise
 592    * it returns true.
 593    *
 594    * @param assertion the normalized assertion being sent
 595    * @param originalAssertion the actual assertion that was sent
 596    * @param toTheoryId the theory that is on the receiving end
 597    * @param fromTheoryId the theory that sent the assertino
 598    * @return true if a new assertion, false if theory already got it
 599    */
 600   bool markPropagation(TNode assertion, TNode originalAssertions, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 601
 602   /**
 603    * Computes the explanation by travarsing the propagation graph and
 604    * asking relevant theories to explain the propagations. Initially
 605    * the explanation vector should contain only the element (node, theory)
 606    * where the node is the one to be explained, and the theory is the
 607    * theory that sent the literal. The lemmaProofRecipe will contain a list
 608    * of the explanation steps required to produce the original node.
 609    */
 610   void getExplanation(std::vector<NodeTheoryPair>& explanationVector, LemmaProofRecipe* lemmaProofRecipe);
 611
 612 public:
 613
 614   /**
 615    * Signal the start of a new round of assertion preprocessing
 616    */
 617   void preprocessStart();
 618
 619   /**
 620    * Runs theory specific preprocessing on the non-Boolean parts of
 621    * the formula.  This is only called on input assertions, after ITEs
 622    * have been removed.
 623    */
 624   Node preprocess(TNode node);
 625
 626   /** Notify (preprocessed) assertions. */
 627   void notifyPreprocessedAssertions(const std::vector<Node>& assertions);
 628
 629   /** Return whether or not we are incomplete (in the current context). */
 630   inline bool isIncomplete() const { return d_incomplete; }
 631
 632   /**
 633    * Returns true if we need another round of checking.  If this
 634    * returns true, check(FULL_EFFORT) _must_ be called by the
 635    * propositional layer before reporting SAT.
 636    *
 637    * This is especially necessary for incomplete theories that lazily
 638    * output some lemmas on FULL_EFFORT check (e.g. quantifier reasoning
 639    * outputing quantifier instantiations).  In such a case, a lemma can
 640    * be asserted that is simplified away (perhaps it's already true).
 641    * However, we must maintain the invariant that, if a theory uses the
 642    * OutputChannel, it implicitly requests that another check(FULL_EFFORT)
 643    * be performed before exit, even if no new facts are on its fact queue,
 644    * as it might decide to further instantiate some lemmas, precluding
 645    * a SAT response.
 646    */
 647   inline bool needCheck() const {
 648     return d_outputChannelUsed || d_lemmasAdded;
 649   }
 650
 651   /**
 652    * This is called at shutdown time by the SmtEngine, just before
 653    * destruction.  It is important because there are destruction
 654    * ordering issues between PropEngine and Theory.
 655    */
 656   void shutdown();
 657
 658   /**
 659    * Solve the given literal with a theory that owns it.
 660    */
 661   theory::Theory::PPAssertStatus solve(TNode literal,
 662                                     theory::SubstitutionMap& substitutionOut);
 663
 664   /**
 665    * Preregister a Theory atom with the responsible theory (or
 666    * theories).
 667    */
 668   void preRegister(TNode preprocessed);
 669
 670   /**
 671    * Assert the formula to the appropriate theory.
 672    * @param node the assertion
 673    */
 674   void assertFact(TNode node);
 675
 676   /**
 677    * Check all (currently-active) theories for conflicts.
 678    * @param effort the effort level to use
 679    */
 680   void check(theory::Theory::Effort effort);
 681
 682   /**
 683    * Run the combination framework.
 684    */
 685   void combineTheories();
 686
 687   /**
 688    * Calls ppStaticLearn() on all theories, accumulating their
 689    * combined contributions in the "learned" builder.
 690    */
 691   void ppStaticLearn(TNode in, NodeBuilder<>& learned);
 692
 693   /**
 694    * Calls presolve() on all theories and returns true
 695    * if one of the theories discovers a conflict.
 696    */
 697   bool presolve();
 698
 699    /**
 700    * Calls postsolve() on all theories.
 701    */
 702   void postsolve();
 703
 704   /**
 705    * Calls notifyRestart() on all active theories.
 706    */
 707   void notifyRestart();
 708
 709   void getPropagatedLiterals(std::vector<TNode>& literals) {
 710     for (; d_propagatedLiteralsIndex < d_propagatedLiterals.size(); d_propagatedLiteralsIndex = d_propagatedLiteralsIndex + 1) {
 711       Debug("getPropagatedLiterals") << "TheoryEngine::getPropagatedLiterals: propagating: " << d_propagatedLiterals[d_propagatedLiteralsIndex] << std::endl;
 712       literals.push_back(d_propagatedLiterals[d_propagatedLiteralsIndex]);
 713     }
 714   }
 715
 716   /**
 717    * Returns the next decision request, or null if none exist. The next
 718    * decision request is a literal that this theory engine prefers the SAT
 719    * solver to make as its next decision. Decision requests are managed by
 720    * the decision manager d_decManager.
 721    */
 722   Node getNextDecisionRequest();
 723
 724   bool properConflict(TNode conflict) const;
 725   bool properPropagation(TNode lit) const;
 726   bool properExplanation(TNode node, TNode expl) const;
 727
 728   /**
 729    * Returns an explanation of the node propagated to the SAT solver.
 730    */
 731   Node getExplanation(TNode node);
 732
 733   /**
 734    * Returns an explanation of the node propagated to the SAT solver and the theory
 735    * that propagated it.
 736    */
 737   Node getExplanationAndRecipe(TNode node, LemmaProofRecipe* proofRecipe);
 738
 739   /**
 740    * collect model info
 741    */
 742   bool collectModelInfo(theory::TheoryModel* m);
 743   /** post process model */
 744   void postProcessModel( theory::TheoryModel* m );
 745
 746   /**
 747    * Get the pointer to the model object used by this theory engine.
 748    */
 749   theory::TheoryModel* getModel();
 750   /**
 751    * Get the current model for the current set of assertions. This method
 752    * should only be called immediately after a satisfiable or unknown
 753    * response to a check-sat call, and only if produceModels is true.
 754    *
 755    * If the model is not already built, this will cause this theory engine
 756    * to build the model.
 757    *
 758    * If the model is not available (for instance, if the last call to check-sat
 759    * was interrupted), then this returns the null pointer.
 760    */
 761   theory::TheoryModel* getBuiltModel();
 762   /** set eager model building
 763    *
 764    * If this method is called, then this TheoryEngine will henceforth build
 765    * its model immediately after every satisfiability check that results
 766    * in a satisfiable or unknown result. The motivation for this mode is to
 767    * accomodate API users that get the model object from the TheoryEngine,
 768    * where we want to ensure that this model is always valid.
 769    * TODO (#2648): revisit this.
 770    */
 771   void setEagerModelBuilding() { d_eager_model_building = true; }
 772
 773   /** get synth solutions
 774    *
 775    * This method returns true if there is a synthesis solution available. This
 776    * is the case if the last call to check satisfiability originated in a
 777    * check-synth call, and the synthesis solver successfully found a solution
 778    * for all active synthesis conjectures.
 779    *
 780    * This method adds entries to sol_map that map functions-to-synthesize with
 781    * their solutions, for all active conjectures. This should be called
 782    * immediately after the solver answers unsat for sygus input.
 783    *
 784    * For details on what is added to sol_map, see
 785    * SynthConjecture::getSynthSolutions.
 786    */
 787   bool getSynthSolutions(std::map<Node, std::map<Node, Node> >& sol_map);
 788
 789   /**
 790    * Get the model builder
 791    */
 792   theory::TheoryEngineModelBuilder* getModelBuilder() { return d_curr_model_builder; }
 793
 794   /**
 795    * Get the theory associated to a given Node.
 796    *
 797    * @returns the theory, or NULL if the TNode is
 798    * of built-in type.
 799    */
 800   inline theory::Theory* theoryOf(TNode node) const {
 801     return d_theoryTable[theory::Theory::theoryOf(node)];
 802   }
 803
 804   /**
 805    * Get the theory associated to a the given theory id.
 806    *
 807    * @returns the theory
 808    */
 809   inline theory::Theory* theoryOf(theory::TheoryId theoryId) const {
 810     Assert(theoryId < theory::THEORY_LAST);
 811     return d_theoryTable[theoryId];
 812   }
 813
 814   inline bool isTheoryEnabled(theory::TheoryId theoryId) const {
 815     return d_logicInfo.isTheoryEnabled(theoryId);
 816   }
 817   /** get the logic info used by this theory engine */
 818   const LogicInfo& getLogicInfo() const;
 819   /**
 820    * Returns the equality status of the two terms, from the theory
 821    * that owns the domain type.  The types of a and b must be the same.
 822    */
 823   theory::EqualityStatus getEqualityStatus(TNode a, TNode b);
 824
 825   /**
 826    * Returns the value that a theory that owns the type of var currently
 827    * has (or null if none);
 828    */
 829   Node getModelValue(TNode var);
 830
 831   /**
 832    * Takes a literal and returns an equivalent literal that is guaranteed to be a SAT literal
 833    */
 834   Node ensureLiteral(TNode n);
 835
 836   /**
 837    * Print all instantiations made by the quantifiers module.
 838    */
 839   void printInstantiations( std::ostream& out );
 840
 841   /**
 842    * Print solution for synthesis conjectures found by ce_guided_instantiation module
 843    */
 844   void printSynthSolution( std::ostream& out );
 845
 846   /**
 847    * Get list of quantified formulas that were instantiated
 848    */
 849   void getInstantiatedQuantifiedFormulas( std::vector< Node >& qs );
 850
 851   /**
 852    * Get instantiation methods
 853    *   first inputs forall x.q[x] and returns ( q[a], ..., q[z] )
 854    *   second inputs forall x.q[x] and returns ( a, ..., z )
 855    *   third and fourth return mappings e.g. forall x.q1[x] -> ( q1[a]...q1[z] ) , ... , forall x.qn[x] -> ( qn[a]...qn[z] )
 856    */
 857   void getInstantiations( Node q, std::vector< Node >& insts );
 858   void getInstantiationTermVectors( Node q, std::vector< std::vector< Node > >& tvecs );
 859   void getInstantiations( std::map< Node, std::vector< Node > >& insts );
 860   void getInstantiationTermVectors( std::map< Node, std::vector< std::vector< Node > > >& insts );
 861
 862   /**
 863    * Get instantiated conjunction, returns q[t1] ^ ... ^ q[tn] where t1...tn are current set of instantiations for q.
 864    *   Can be used for quantifier elimination when satisfiable and q[t1] ^ ... ^ q[tn] |= q
 865    */
 866   Node getInstantiatedConjunction( Node q );
 867
 868   /**
 869    * Forwards an entailment check according to the given theoryOfMode.
 870    * See theory.h for documentation on entailmentCheck().
 871    */
 872   std::pair<bool, Node> entailmentCheck(
 873       options::TheoryOfMode mode,
 874       TNode lit,
 875       const theory::EntailmentCheckParameters* params = NULL,
 876       theory::EntailmentCheckSideEffects* out = NULL);
 877
 878  private:
 879   /** Default visitor for pre-registration */
 880   PreRegisterVisitor d_preRegistrationVisitor;
 881
 882   /** Visitor for collecting shared terms */
 883   SharedTermsVisitor d_sharedTermsVisitor;
 884
 885   /** Dump the assertions to the dump */
 886   void dumpAssertions(const char* tag);
 887
 888   /** For preprocessing pass lifting bit-vectors of size 1 to booleans */
 889 public:
 890   void staticInitializeBVOptions(const std::vector<Node>& assertions);
 891
 892   Node ppSimpITE(TNode assertion);
 893   /** Returns false if an assertion simplified to false. */
 894   bool donePPSimpITE(std::vector<Node>& assertions);
 895
 896   SharedTermsDatabase* getSharedTermsDatabase() { return &d_sharedTerms; }
 897
 898   theory::eq::EqualityEngine* getMasterEqualityEngine() { return d_masterEqualityEngine; }
 899
 900   RemoveTermFormulas* getTermFormulaRemover() { return &d_tform_remover; }
 901
 902   SortInference* getSortInference() { return &d_sortInfer; }
 903
 904   /** Prints the assertions to the debug stream */
 905   void printAssertions(const char* tag);
 906
 907   /** Theory alternative is in use. */
 908   bool useTheoryAlternative(const std::string& name);
 909
 910   /** Enables using a theory alternative by name. */
 911   void enableTheoryAlternative(const std::string& name);
 912
 913 private:
 914   std::set< std::string > d_theoryAlternatives;
 915
 916   std::map< std::string, std::vector< theory::Theory* > > d_attr_handle;
 917
 918  public:
 919   /** Set user attribute.
 920    *
 921    * This function is called when an attribute is set by a user.  In SMT-LIBv2
 922    * this is done via the syntax (! n :attr)
 923    */
 924   void setUserAttribute(const std::string& attr,
 925                         Node n,
 926                         const std::vector<Node>& node_values,
 927                         const std::string& str_value);
 928
 929   /** Handle user attribute.
 930    *
 931    * Associates theory t with the attribute attr.  Theory t will be
 932    * notified whenever an attribute of name attr is set.
 933    */
 934   void handleUserAttribute(const char* attr, theory::Theory* t);
 935
 936   /**
 937    * Check that the theory assertions are satisfied in the model.
 938    * This function is called from the smt engine's checkModel routine.
 939    */
 940   void checkTheoryAssertionsWithModel(bool hardFailure);
 941
 942  private:
 943   IntStat d_arithSubstitutionsAdded;
 944
 945 };/* class TheoryEngine */
 946
 947 }/* CVC4 namespace */
 948
 949 #endif /* CVC4__THEORY_ENGINE_H */