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 RemoveTermFormulas;
 105
 106 /**
 107  * This is essentially an abstraction for a collection of theories.  A
 108  * TheoryEngine provides services to a PropEngine, making various
 109  * T-solvers look like a single unit to the propositional part of
 110  * CVC4.
 111  */
 112 class TheoryEngine {
 113
 114   /** Shared terms database can use the internals notify the theories */
 115   friend class SharedTermsDatabase;
 116   friend class theory::quantifiers::TermDb;
 117
 118   /** Associated PropEngine engine */
 119   prop::PropEngine* d_propEngine;
 120
 121   /** Our context */
 122   context::Context* d_context;
 123
 124   /** Our user context */
 125   context::UserContext* d_userContext;
 126
 127   /**
 128    * A table of from theory IDs to theory pointers. Never use this table
 129    * directly, use theoryOf() instead.
 130    */
 131   theory::Theory* d_theoryTable[theory::THEORY_LAST];
 132
 133   /**
 134    * A collection of theories that are "active" for the current run.
 135    * This set is provided by the user (as a logic string, say, in SMT-LIBv2
 136    * format input), or else by default it's all-inclusive.  This is important
 137    * because we can optimize for single-theory runs (no sharing), can reduce
 138    * the cost of walking the DAG on registration, etc.
 139    */
 140   const LogicInfo& d_logicInfo;
 141
 142   /**
 143    * The database of shared terms.
 144    */
 145   SharedTermsDatabase d_sharedTerms;
 146
 147   /**
 148    * Master equality engine, to share with theories.
 149    */
 150   theory::eq::EqualityEngine* d_masterEqualityEngine;
 151
 152   /** notify class for master equality engine */
 153   class NotifyClass : public theory::eq::EqualityEngineNotify {
 154     TheoryEngine& d_te;
 155   public:
 156     NotifyClass(TheoryEngine& te): d_te(te) {}
 157     bool eqNotifyTriggerEquality(TNode equality, bool value) override
 158     {
 159       return true;
 160     }
 161     bool eqNotifyTriggerPredicate(TNode predicate, bool value) override
 162     {
 163       return true;
 164     }
 165     bool eqNotifyTriggerTermEquality(theory::TheoryId tag,
 166                                      TNode t1,
 167                                      TNode t2,
 168                                      bool value) override
 169     {
 170       return true;
 171     }
 172     void eqNotifyConstantTermMerge(TNode t1, TNode t2) override {}
 173     void eqNotifyNewClass(TNode t) override { d_te.eqNotifyNewClass(t); }
 174     void eqNotifyPreMerge(TNode t1, TNode t2) override
 175     {
 176     }
 177     void eqNotifyPostMerge(TNode t1, TNode t2) override
 178     {
 179     }
 180     void eqNotifyDisequal(TNode t1, TNode t2, TNode reason) override
 181     {
 182     }
 183   };/* class TheoryEngine::NotifyClass */
 184   NotifyClass d_masterEENotify;
 185
 186   /**
 187    * notification methods
 188    */
 189   void eqNotifyNewClass(TNode t);
 190   void eqNotifyPreMerge(TNode t1, TNode t2);
 191   void eqNotifyPostMerge(TNode t1, TNode t2);
 192   void eqNotifyDisequal(TNode t1, TNode t2, TNode reason);
 193
 194   /**
 195    * The quantifiers engine
 196    */
 197   theory::QuantifiersEngine* d_quantEngine;
 198   /**
 199    * The decision manager
 200    */
 201   std::unique_ptr<theory::DecisionManager> d_decManager;
 202
 203   /**
 204    * Default model object
 205    */
 206   theory::TheoryModel* d_curr_model;
 207   bool d_aloc_curr_model;
 208   /**
 209    * Model builder object
 210    */
 211   theory::TheoryEngineModelBuilder* d_curr_model_builder;
 212   bool d_aloc_curr_model_builder;
 213   /** are we in eager model building mode? (see setEagerModelBuilding). */
 214   bool d_eager_model_building;
 215
 216   typedef std::unordered_map<Node, Node, NodeHashFunction> NodeMap;
 217   typedef std::unordered_map<TNode, Node, TNodeHashFunction> TNodeMap;
 218
 219   /**
 220   * Cache for theory-preprocessing of assertions
 221    */
 222   NodeMap d_ppCache;
 223
 224   /**
 225    * Used for "missed-t-propagations" dumping mode only.  A set of all
 226    * theory-propagable literals.
 227    */
 228   context::CDList<TNode> d_possiblePropagations;
 229
 230   /**
 231    * Used for "missed-t-propagations" dumping mode only.  A
 232    * context-dependent set of those theory-propagable literals that
 233    * have been propagated.
 234    */
 235   context::CDHashSet<Node, NodeHashFunction> d_hasPropagated;
 236
 237
 238   /**
 239    * Statistics for a particular theory.
 240    */
 241   class Statistics {
 242
 243     static std::string mkName(std::string prefix,
 244                               theory::TheoryId theory,
 245                               std::string suffix) {
 246       std::stringstream ss;
 247       ss << prefix << theory << suffix;
 248       return ss.str();
 249     }
 250
 251    public:
 252     IntStat conflicts, propagations, lemmas, requirePhase, restartDemands;
 253
 254     Statistics(theory::TheoryId theory);
 255     ~Statistics();
 256   };/* class TheoryEngine::Statistics */
 257
 258   /**
 259    * An output channel for Theory that passes messages
 260    * back to a TheoryEngine.
 261    */
 262   class EngineOutputChannel : public theory::OutputChannel {
 263     friend class TheoryEngine;
 264
 265     /**
 266      * The theory engine we're communicating with.
 267      */
 268     TheoryEngine* d_engine;
 269
 270     /**
 271      * The statistics of the theory interractions.
 272      */
 273     Statistics d_statistics;
 274
 275     /** The theory owning this channel. */
 276     theory::TheoryId d_theory;
 277
 278    public:
 279     EngineOutputChannel(TheoryEngine* engine, theory::TheoryId theory)
 280         : d_engine(engine), d_statistics(theory), d_theory(theory) {}
 281
 282     void safePoint(ResourceManager::Resource r) override
 283     {
 284       spendResource(r);
 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(ResourceManager::Resource r) override
 326     {
 327       d_engine->spendResource(r);
 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  public:
 469   /** Constructs a theory engine */
 470   TheoryEngine(context::Context* context,
 471                context::UserContext* userContext,
 472                RemoveTermFormulas& iteRemover,
 473                const LogicInfo& logic);
 474
 475   /** Destroys a theory engine */
 476   ~TheoryEngine();
 477
 478   void interrupt();
 479
 480   /** "Spend" a resource during a search or preprocessing.*/
 481   void spendResource(ResourceManager::Resource r);
 482
 483   /**
 484    * Adds a theory. Only one theory per TheoryId can be present, so if
 485    * there is another theory it will be deleted.
 486    */
 487   template <class TheoryClass>
 488   inline void addTheory(theory::TheoryId theoryId)
 489   {
 490     Assert(d_theoryTable[theoryId] == NULL && d_theoryOut[theoryId] == NULL);
 491     d_theoryOut[theoryId] = new EngineOutputChannel(this, theoryId);
 492     d_theoryTable[theoryId] = new TheoryClass(d_context,
 493                                               d_userContext,
 494                                               *d_theoryOut[theoryId],
 495                                               theory::Valuation(this),
 496                                               d_logicInfo);
 497     theory::Rewriter::registerTheoryRewriter(
 498         theoryId, d_theoryTable[theoryId]->getTheoryRewriter());
 499   }
 500
 501   void setPropEngine(prop::PropEngine* propEngine)
 502   {
 503     d_propEngine = propEngine;
 504   }
 505
 506   /** Called when all initialization of options/logic is done */
 507   void finishInit();
 508
 509   /**
 510    * Get a pointer to the underlying propositional engine.
 511    */
 512   inline prop::PropEngine* getPropEngine() const {
 513     return d_propEngine;
 514   }
 515
 516   /**
 517    * Get a pointer to the underlying sat context.
 518    */
 519   inline context::Context* getSatContext() const {
 520     return d_context;
 521   }
 522
 523   /**
 524    * Get a pointer to the underlying user context.
 525    */
 526   inline context::Context* getUserContext() const {
 527     return d_userContext;
 528   }
 529
 530   /**
 531    * Get a pointer to the underlying quantifiers engine.
 532    */
 533   theory::QuantifiersEngine* getQuantifiersEngine() const {
 534     return d_quantEngine;
 535   }
 536   /**
 537    * Get a pointer to the underlying decision manager.
 538    */
 539   theory::DecisionManager* getDecisionManager() const
 540   {
 541     return d_decManager.get();
 542   }
 543
 544  private:
 545   /**
 546    * Helper for preprocess
 547    */
 548   Node ppTheoryRewrite(TNode term);
 549
 550   /**
 551    * Queue of nodes for pre-registration.
 552    */
 553   std::queue<TNode> d_preregisterQueue;
 554
 555   /**
 556    * Boolean flag denoting we are in pre-registration.
 557    */
 558   bool d_inPreregister;
 559
 560   /**
 561    * Did the theories get any new facts since the last time we called
 562    * check()
 563    */
 564   context::CDO<bool> d_factsAsserted;
 565
 566   /**
 567    * Map from equality atoms to theories that would like to be notified about them.
 568    */
 569
 570
 571   /**
 572    * Assert the formula to the given theory.
 573    * @param assertion the assertion to send (not necesserily normalized)
 574    * @param original the assertion as it was sent in from the propagating theory
 575    * @param toTheoryId the theory to assert to
 576    * @param fromTheoryId the theory that sent it
 577    */
 578   void assertToTheory(TNode assertion, TNode originalAssertion, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 579
 580   /**
 581    * Marks a theory propagation from a theory to a theory where a
 582    * theory could be the THEORY_SAT_SOLVER for literals coming from
 583    * or being propagated to the SAT solver. If the receiving theory
 584    * already recieved the literal, the method returns false, otherwise
 585    * it returns true.
 586    *
 587    * @param assertion the normalized assertion being sent
 588    * @param originalAssertion the actual assertion that was sent
 589    * @param toTheoryId the theory that is on the receiving end
 590    * @param fromTheoryId the theory that sent the assertino
 591    * @return true if a new assertion, false if theory already got it
 592    */
 593   bool markPropagation(TNode assertion, TNode originalAssertions, theory::TheoryId toTheoryId, theory::TheoryId fromTheoryId);
 594
 595   /**
 596    * Computes the explanation by travarsing the propagation graph and
 597    * asking relevant theories to explain the propagations. Initially
 598    * the explanation vector should contain only the element (node, theory)
 599    * where the node is the one to be explained, and the theory is the
 600    * theory that sent the literal. The lemmaProofRecipe will contain a list
 601    * of the explanation steps required to produce the original node.
 602    */
 603   void getExplanation(std::vector<NodeTheoryPair>& explanationVector, LemmaProofRecipe* lemmaProofRecipe);
 604
 605 public:
 606
 607   /**
 608    * Signal the start of a new round of assertion preprocessing
 609    */
 610   void preprocessStart();
 611
 612   /**
 613    * Runs theory specific preprocessing on the non-Boolean parts of
 614    * the formula.  This is only called on input assertions, after ITEs
 615    * have been removed.
 616    */
 617   Node preprocess(TNode node);
 618
 619   /** Notify (preprocessed) assertions. */
 620   void notifyPreprocessedAssertions(const std::vector<Node>& assertions);
 621
 622   /** Return whether or not we are incomplete (in the current context). */
 623   inline bool isIncomplete() const { return d_incomplete; }
 624
 625   /**
 626    * Returns true if we need another round of checking.  If this
 627    * returns true, check(FULL_EFFORT) _must_ be called by the
 628    * propositional layer before reporting SAT.
 629    *
 630    * This is especially necessary for incomplete theories that lazily
 631    * output some lemmas on FULL_EFFORT check (e.g. quantifier reasoning
 632    * outputing quantifier instantiations).  In such a case, a lemma can
 633    * be asserted that is simplified away (perhaps it's already true).
 634    * However, we must maintain the invariant that, if a theory uses the
 635    * OutputChannel, it implicitly requests that another check(FULL_EFFORT)
 636    * be performed before exit, even if no new facts are on its fact queue,
 637    * as it might decide to further instantiate some lemmas, precluding
 638    * a SAT response.
 639    */
 640   inline bool needCheck() const {
 641     return d_outputChannelUsed || d_lemmasAdded;
 642   }
 643
 644   /**
 645    * This is called at shutdown time by the SmtEngine, just before
 646    * destruction.  It is important because there are destruction
 647    * ordering issues between PropEngine and Theory.
 648    */
 649   void shutdown();
 650
 651   /**
 652    * Solve the given literal with a theory that owns it.
 653    */
 654   theory::Theory::PPAssertStatus solve(TNode literal,
 655                                     theory::SubstitutionMap& substitutionOut);
 656
 657   /**
 658    * Preregister a Theory atom with the responsible theory (or
 659    * theories).
 660    */
 661   void preRegister(TNode preprocessed);
 662
 663   /**
 664    * Assert the formula to the appropriate theory.
 665    * @param node the assertion
 666    */
 667   void assertFact(TNode node);
 668
 669   /**
 670    * Check all (currently-active) theories for conflicts.
 671    * @param effort the effort level to use
 672    */
 673   void check(theory::Theory::Effort effort);
 674
 675   /**
 676    * Run the combination framework.
 677    */
 678   void combineTheories();
 679
 680   /**
 681    * Calls ppStaticLearn() on all theories, accumulating their
 682    * combined contributions in the "learned" builder.
 683    */
 684   void ppStaticLearn(TNode in, NodeBuilder<>& learned);
 685
 686   /**
 687    * Calls presolve() on all theories and returns true
 688    * if one of the theories discovers a conflict.
 689    */
 690   bool presolve();
 691
 692    /**
 693    * Calls postsolve() on all theories.
 694    */
 695   void postsolve();
 696
 697   /**
 698    * Calls notifyRestart() on all active theories.
 699    */
 700   void notifyRestart();
 701
 702   void getPropagatedLiterals(std::vector<TNode>& literals) {
 703     for (; d_propagatedLiteralsIndex < d_propagatedLiterals.size(); d_propagatedLiteralsIndex = d_propagatedLiteralsIndex + 1) {
 704       Debug("getPropagatedLiterals") << "TheoryEngine::getPropagatedLiterals: propagating: " << d_propagatedLiterals[d_propagatedLiteralsIndex] << std::endl;
 705       literals.push_back(d_propagatedLiterals[d_propagatedLiteralsIndex]);
 706     }
 707   }
 708
 709   /**
 710    * Returns the next decision request, or null if none exist. The next
 711    * decision request is a literal that this theory engine prefers the SAT
 712    * solver to make as its next decision. Decision requests are managed by
 713    * the decision manager d_decManager.
 714    */
 715   Node getNextDecisionRequest();
 716
 717   bool properConflict(TNode conflict) const;
 718   bool properPropagation(TNode lit) const;
 719   bool properExplanation(TNode node, TNode expl) const;
 720
 721   /**
 722    * Returns an explanation of the node propagated to the SAT solver.
 723    */
 724   Node getExplanation(TNode node);
 725
 726   /**
 727    * Returns an explanation of the node propagated to the SAT solver and the theory
 728    * that propagated it.
 729    */
 730   Node getExplanationAndRecipe(TNode node, LemmaProofRecipe* proofRecipe);
 731
 732   /**
 733    * collect model info
 734    */
 735   bool collectModelInfo(theory::TheoryModel* m);
 736   /** post process model */
 737   void postProcessModel( theory::TheoryModel* m );
 738
 739   /**
 740    * Get the pointer to the model object used by this theory engine.
 741    */
 742   theory::TheoryModel* getModel();
 743   /**
 744    * Get the current model for the current set of assertions. This method
 745    * should only be called immediately after a satisfiable or unknown
 746    * response to a check-sat call, and only if produceModels is true.
 747    *
 748    * If the model is not already built, this will cause this theory engine
 749    * to build the model.
 750    *
 751    * If the model is not available (for instance, if the last call to check-sat
 752    * was interrupted), then this returns the null pointer.
 753    */
 754   theory::TheoryModel* getBuiltModel();
 755   /** set eager model building
 756    *
 757    * If this method is called, then this TheoryEngine will henceforth build
 758    * its model immediately after every satisfiability check that results
 759    * in a satisfiable or unknown result. The motivation for this mode is to
 760    * accomodate API users that get the model object from the TheoryEngine,
 761    * where we want to ensure that this model is always valid.
 762    * TODO (#2648): revisit this.
 763    */
 764   void setEagerModelBuilding() { d_eager_model_building = true; }
 765
 766   /** get synth solutions
 767    *
 768    * This method returns true if there is a synthesis solution available. This
 769    * is the case if the last call to check satisfiability originated in a
 770    * check-synth call, and the synthesis solver successfully found a solution
 771    * for all active synthesis conjectures.
 772    *
 773    * This method adds entries to sol_map that map functions-to-synthesize with
 774    * their solutions, for all active conjectures. This should be called
 775    * immediately after the solver answers unsat for sygus input.
 776    *
 777    * For details on what is added to sol_map, see
 778    * SynthConjecture::getSynthSolutions.
 779    */
 780   bool getSynthSolutions(std::map<Node, std::map<Node, Node> >& sol_map);
 781
 782   /**
 783    * Get the model builder
 784    */
 785   theory::TheoryEngineModelBuilder* getModelBuilder() { return d_curr_model_builder; }
 786
 787   /**
 788    * Get the theory associated to a given Node.
 789    *
 790    * @returns the theory, or NULL if the TNode is
 791    * of built-in type.
 792    */
 793   inline theory::Theory* theoryOf(TNode node) const {
 794     return d_theoryTable[theory::Theory::theoryOf(node)];
 795   }
 796
 797   /**
 798    * Get the theory associated to a the given theory id.
 799    *
 800    * @returns the theory
 801    */
 802   inline theory::Theory* theoryOf(theory::TheoryId theoryId) const {
 803     Assert(theoryId < theory::THEORY_LAST);
 804     return d_theoryTable[theoryId];
 805   }
 806
 807   inline bool isTheoryEnabled(theory::TheoryId theoryId) const {
 808     return d_logicInfo.isTheoryEnabled(theoryId);
 809   }
 810   /** get the logic info used by this theory engine */
 811   const LogicInfo& getLogicInfo() const;
 812   /**
 813    * Returns the equality status of the two terms, from the theory
 814    * that owns the domain type.  The types of a and b must be the same.
 815    */
 816   theory::EqualityStatus getEqualityStatus(TNode a, TNode b);
 817
 818   /**
 819    * Returns the value that a theory that owns the type of var currently
 820    * has (or null if none);
 821    */
 822   Node getModelValue(TNode var);
 823
 824   /**
 825    * Takes a literal and returns an equivalent literal that is guaranteed to be a SAT literal
 826    */
 827   Node ensureLiteral(TNode n);
 828
 829   /**
 830    * Print all instantiations made by the quantifiers module.
 831    */
 832   void printInstantiations( std::ostream& out );
 833
 834   /**
 835    * Print solution for synthesis conjectures found by ce_guided_instantiation module
 836    */
 837   void printSynthSolution( std::ostream& out );
 838
 839   /**
 840    * Get list of quantified formulas that were instantiated
 841    */
 842   void getInstantiatedQuantifiedFormulas( std::vector< Node >& qs );
 843
 844   /**
 845    * Get instantiation methods
 846    *   first inputs forall x.q[x] and returns ( q[a], ..., q[z] )
 847    *   second inputs forall x.q[x] and returns ( a, ..., z )
 848    *   third and fourth return mappings e.g. forall x.q1[x] -> ( q1[a]...q1[z] ) , ... , forall x.qn[x] -> ( qn[a]...qn[z] )
 849    */
 850   void getInstantiations( Node q, std::vector< Node >& insts );
 851   void getInstantiationTermVectors( Node q, std::vector< std::vector< Node > >& tvecs );
 852   void getInstantiations( std::map< Node, std::vector< Node > >& insts );
 853   void getInstantiationTermVectors( std::map< Node, std::vector< std::vector< Node > > >& insts );
 854
 855   /**
 856    * Get instantiated conjunction, returns q[t1] ^ ... ^ q[tn] where t1...tn are current set of instantiations for q.
 857    *   Can be used for quantifier elimination when satisfiable and q[t1] ^ ... ^ q[tn] |= q
 858    */
 859   Node getInstantiatedConjunction( Node q );
 860
 861   /**
 862    * Forwards an entailment check according to the given theoryOfMode.
 863    * See theory.h for documentation on entailmentCheck().
 864    */
 865   std::pair<bool, Node> entailmentCheck(
 866       options::TheoryOfMode mode,
 867       TNode lit,
 868       const theory::EntailmentCheckParameters* params = NULL,
 869       theory::EntailmentCheckSideEffects* out = NULL);
 870
 871  private:
 872   /** Default visitor for pre-registration */
 873   PreRegisterVisitor d_preRegistrationVisitor;
 874
 875   /** Visitor for collecting shared terms */
 876   SharedTermsVisitor d_sharedTermsVisitor;
 877
 878   /** Dump the assertions to the dump */
 879   void dumpAssertions(const char* tag);
 880
 881   /** For preprocessing pass lifting bit-vectors of size 1 to booleans */
 882 public:
 883   void staticInitializeBVOptions(const std::vector<Node>& assertions);
 884
 885   Node ppSimpITE(TNode assertion);
 886   /** Returns false if an assertion simplified to false. */
 887   bool donePPSimpITE(std::vector<Node>& assertions);
 888
 889   SharedTermsDatabase* getSharedTermsDatabase() { return &d_sharedTerms; }
 890
 891   theory::eq::EqualityEngine* getMasterEqualityEngine() { return d_masterEqualityEngine; }
 892
 893   RemoveTermFormulas* getTermFormulaRemover() { return &d_tform_remover; }
 894
 895   SortInference* getSortInference() { return &d_sortInfer; }
 896
 897   /** Prints the assertions to the debug stream */
 898   void printAssertions(const char* tag);
 899
 900 private:
 901
 902   std::map< std::string, std::vector< theory::Theory* > > d_attr_handle;
 903
 904  public:
 905   /** Set user attribute.
 906    *
 907    * This function is called when an attribute is set by a user.  In SMT-LIBv2
 908    * this is done via the syntax (! n :attr)
 909    */
 910   void setUserAttribute(const std::string& attr,
 911                         Node n,
 912                         const std::vector<Node>& node_values,
 913                         const std::string& str_value);
 914
 915   /** Handle user attribute.
 916    *
 917    * Associates theory t with the attribute attr.  Theory t will be
 918    * notified whenever an attribute of name attr is set.
 919    */
 920   void handleUserAttribute(const char* attr, theory::Theory* t);
 921
 922   /**
 923    * Check that the theory assertions are satisfied in the model.
 924    * This function is called from the smt engine's checkModel routine.
 925    */
 926   void checkTheoryAssertionsWithModel(bool hardFailure);
 927
 928  private:
 929   IntStat d_arithSubstitutionsAdded;
 930
 931 };/* class TheoryEngine */
 932
 933 }/* CVC4 namespace */
 934
 935 #endif /* CVC4__THEORY_ENGINE_H */