src/theory/theory.cpp

   1 /*********************                                                        */
   2 /*! \file theory.cpp
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Andrew Reynolds, Tim King, Mathias Preiner
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2020 by the authors listed in the file AUTHORS
   8  ** in the top-level source directory and their institutional affiliations.
   9  ** All rights reserved.  See the file COPYING in the top-level source
  10  ** directory for licensing information.\endverbatim
  11  **
  12  ** \brief Base for theory interface.
  13  **
  14  ** Base for theory interface.
  15  **/
  16
  17 #include "theory/theory.h"
  18
  19 #include <iostream>
  20 #include <sstream>
  21 #include <string>
  22 #include <vector>
  23
  24 #include "base/check.h"
  25 #include "expr/node_algorithm.h"
  26 #include "options/smt_options.h"
  27 #include "options/theory_options.h"
  28 #include "smt/smt_statistics_registry.h"
  29 #include "theory/ext_theory.h"
  30 #include "theory/quantifiers_engine.h"
  31 #include "theory/substitutions.h"
  32 #include "theory/theory_rewriter.h"
  33
  34 using namespace std;
  35
  36 namespace CVC4 {
  37 namespace theory {
  38
  39 /** Default value for the uninterpreted sorts is the UF theory */
  40 TheoryId Theory::s_uninterpretedSortOwner = THEORY_UF;
  41
  42 std::ostream& operator<<(std::ostream& os, Theory::Effort level){
  43   switch(level){
  44   case Theory::EFFORT_STANDARD:
  45     os << "EFFORT_STANDARD"; break;
  46   case Theory::EFFORT_FULL:
  47     os << "EFFORT_FULL"; break;
  48   case Theory::EFFORT_LAST_CALL:
  49     os << "EFFORT_LAST_CALL"; break;
  50   default:
  51       Unreachable();
  52   }
  53   return os;
  54 }/* ostream& operator<<(ostream&, Theory::Effort) */
  55
  56 Theory::Theory(TheoryId id,
  57                context::Context* satContext,
  58                context::UserContext* userContext,
  59                OutputChannel& out,
  60                Valuation valuation,
  61                const LogicInfo& logicInfo,
  62                ProofNodeManager* pnm,
  63                std::string name)
  64     : d_id(id),
  65       d_satContext(satContext),
  66       d_userContext(userContext),
  67       d_logicInfo(logicInfo),
  68       d_facts(satContext),
  69       d_factsHead(satContext, 0),
  70       d_sharedTermsIndex(satContext, 0),
  71       d_careGraph(NULL),
  72       d_quantEngine(NULL),
  73       d_decManager(nullptr),
  74       d_instanceName(name),
  75       d_checkTime(getStatsPrefix(id) + name + "::checkTime"),
  76       d_computeCareGraphTime(getStatsPrefix(id) + name
  77                              + "::computeCareGraphTime"),
  78       d_sharedTerms(satContext),
  79       d_out(&out),
  80       d_valuation(valuation),
  81       d_equalityEngine(nullptr),
  82       d_allocEqualityEngine(nullptr),
  83       d_theoryState(nullptr),
  84       d_inferManager(nullptr),
  85       d_pnm(pnm)
  86 {
  87   smtStatisticsRegistry()->registerStat(&d_checkTime);
  88   smtStatisticsRegistry()->registerStat(&d_computeCareGraphTime);
  89 }
  90
  91 Theory::~Theory() {
  92   smtStatisticsRegistry()->unregisterStat(&d_checkTime);
  93   smtStatisticsRegistry()->unregisterStat(&d_computeCareGraphTime);
  94 }
  95
  96 bool Theory::needsEqualityEngine(EeSetupInfo& esi)
  97 {
  98   // by default, this theory does not use an (official) equality engine
  99   return false;
 100 }
 101
 102 void Theory::setEqualityEngine(eq::EqualityEngine* ee)
 103 {
 104   // set the equality engine pointer
 105   d_equalityEngine = ee;
 106   if (d_theoryState != nullptr)
 107   {
 108     d_theoryState->setEqualityEngine(ee);
 109   }
 110   if (d_inferManager != nullptr)
 111   {
 112     d_inferManager->setEqualityEngine(ee);
 113   }
 114 }
 115
 116 void Theory::setQuantifiersEngine(QuantifiersEngine* qe)
 117 {
 118   Assert(d_quantEngine == nullptr);
 119   // quantifiers engine may be null if not in quantified logic
 120   d_quantEngine = qe;
 121 }
 122
 123 void Theory::setDecisionManager(DecisionManager* dm)
 124 {
 125   Assert(d_decManager == nullptr);
 126   Assert(dm != nullptr);
 127   d_decManager = dm;
 128 }
 129
 130 void Theory::finishInitStandalone()
 131 {
 132   EeSetupInfo esi;
 133   if (needsEqualityEngine(esi))
 134   {
 135     // always associated with the same SAT context as the theory (d_satContext)
 136     d_allocEqualityEngine.reset(new eq::EqualityEngine(
 137         *esi.d_notify, d_satContext, esi.d_name, esi.d_constantsAreTriggers));
 138     // use it as the official equality engine
 139     setEqualityEngine(d_allocEqualityEngine.get());
 140   }
 141   finishInit();
 142 }
 143
 144 TheoryId Theory::theoryOf(options::TheoryOfMode mode, TNode node)
 145 {
 146   TheoryId tid = THEORY_BUILTIN;
 147   switch(mode) {
 148     case options::TheoryOfMode::THEORY_OF_TYPE_BASED:
 149       // Constants, variables, 0-ary constructors
 150       if (node.isVar())
 151       {
 152         if (node.getKind() == kind::BOOLEAN_TERM_VARIABLE)
 153         {
 154           tid = THEORY_UF;
 155         }
 156         else
 157         {
 158           tid = Theory::theoryOf(node.getType());
 159         }
 160       }
 161       else if (node.isConst())
 162       {
 163         tid = Theory::theoryOf(node.getType());
 164       }
 165       else if (node.getKind() == kind::EQUAL)
 166       {
 167         // Equality is owned by the theory that owns the domain
 168         tid = Theory::theoryOf(node[0].getType());
 169       }
 170       else
 171       {
 172         // Regular nodes are owned by the kind
 173         tid = kindToTheoryId(node.getKind());
 174       }
 175       break;
 176     case options::TheoryOfMode::THEORY_OF_TERM_BASED:
 177       // Variables
 178       if (node.isVar())
 179       {
 180         if (Theory::theoryOf(node.getType()) != theory::THEORY_BOOL)
 181         {
 182           // We treat the variables as uninterpreted
 183           tid = s_uninterpretedSortOwner;
 184         }
 185         else
 186         {
 187           if (node.getKind() == kind::BOOLEAN_TERM_VARIABLE)
 188           {
 189             // Boolean vars go to UF
 190             tid = THEORY_UF;
 191           }
 192           else
 193           {
 194             // Except for the Boolean ones
 195             tid = THEORY_BOOL;
 196           }
 197         }
 198       }
 199       else if (node.isConst())
 200       {
 201         // Constants go to the theory of the type
 202         tid = Theory::theoryOf(node.getType());
 203       }
 204       else if (node.getKind() == kind::EQUAL)
 205       {  // Equality
 206         // If one of them is an ITE, it's irelevant, since they will get
 207         // replaced out anyhow
 208         if (node[0].getKind() == kind::ITE)
 209         {
 210           tid = Theory::theoryOf(node[0].getType());
 211         }
 212         else if (node[1].getKind() == kind::ITE)
 213         {
 214           tid = Theory::theoryOf(node[1].getType());
 215         }
 216         else
 217         {
 218           TNode l = node[0];
 219           TNode r = node[1];
 220           TypeNode ltype = l.getType();
 221           TypeNode rtype = r.getType();
 222           if (ltype != rtype)
 223           {
 224             tid = Theory::theoryOf(l.getType());
 225           }
 226           else
 227           {
 228             // If both sides belong to the same theory the choice is easy
 229             TheoryId T1 = Theory::theoryOf(l);
 230             TheoryId T2 = Theory::theoryOf(r);
 231             if (T1 == T2)
 232             {
 233               tid = T1;
 234             }
 235             else
 236             {
 237               TheoryId T3 = Theory::theoryOf(ltype);
 238               // This is a case of
 239               // * x*y = f(z) -> UF
 240               // * x = c      -> UF
 241               // * f(x) = read(a, y) -> either UF or ARRAY
 242               // at least one of the theories has to be parametric, i.e. theory
 243               // of the type is different from the theory of the term
 244               if (T1 == T3)
 245               {
 246                 tid = T2;
 247               }
 248               else if (T2 == T3)
 249               {
 250                 tid = T1;
 251               }
 252               else
 253               {
 254                 // If both are parametric, we take the smaller one (arbitrary)
 255                 tid = T1 < T2 ? T1 : T2;
 256               }
 257             }
 258           }
 259         }
 260       }
 261       else
 262       {
 263         // Regular nodes are owned by the kind
 264         tid = kindToTheoryId(node.getKind());
 265       }
 266     break;
 267   default:
 268     Unreachable();
 269   }
 270   Trace("theory::internal") << "theoryOf(" << mode << ", " << node << ") -> " << tid << std::endl;
 271   return tid;
 272 }
 273
 274 void Theory::notifySharedTerm(TNode n)
 275 {
 276   // do nothing
 277 }
 278
 279 void Theory::computeCareGraph() {
 280   Debug("sharing") << "Theory::computeCareGraph<" << getId() << ">()" << endl;
 281   for (unsigned i = 0; i < d_sharedTerms.size(); ++ i) {
 282     TNode a = d_sharedTerms[i];
 283     TypeNode aType = a.getType();
 284     for (unsigned j = i + 1; j < d_sharedTerms.size(); ++ j) {
 285       TNode b = d_sharedTerms[j];
 286       if (b.getType() != aType) {
 287         // We don't care about the terms of different types
 288         continue;
 289       }
 290       switch (d_valuation.getEqualityStatus(a, b)) {
 291       case EQUALITY_TRUE_AND_PROPAGATED:
 292       case EQUALITY_FALSE_AND_PROPAGATED:
 293         // If we know about it, we should have propagated it, so we can skip
 294         break;
 295       default:
 296         // Let's split on it
 297         addCarePair(a, b);
 298         break;
 299       }
 300     }
 301   }
 302 }
 303
 304 void Theory::printFacts(std::ostream& os) const {
 305   unsigned i, n = d_facts.size();
 306   for(i = 0; i < n; i++){
 307     const Assertion& a_i = d_facts[i];
 308     Node assertion  = a_i;
 309     os << d_id << '[' << i << ']' << " " << assertion << endl;
 310   }
 311 }
 312
 313 void Theory::debugPrintFacts() const{
 314   DebugChannel.getStream() << "Theory::debugPrintFacts()" << endl;
 315   printFacts(DebugChannel.getStream());
 316 }
 317
 318 bool Theory::isLegalElimination(TNode x, TNode val)
 319 {
 320   Assert(x.isVar());
 321   if (x.getKind() == kind::BOOLEAN_TERM_VARIABLE
 322       || val.getKind() == kind::BOOLEAN_TERM_VARIABLE)
 323   {
 324     return false;
 325   }
 326   if (expr::hasSubterm(val, x))
 327   {
 328     return false;
 329   }
 330   if (!val.getType().isSubtypeOf(x.getType()))
 331   {
 332     return false;
 333   }
 334   if (!options::produceModels())
 335   {
 336     // don't care about the model, we are fine
 337     return true;
 338   }
 339   // if there is a model object
 340   TheoryModel* tm = d_valuation.getModel();
 341   Assert(tm != nullptr);
 342   return tm->isLegalElimination(x, val);
 343 }
 344
 345 std::unordered_set<TNode, TNodeHashFunction> Theory::currentlySharedTerms() const{
 346   std::unordered_set<TNode, TNodeHashFunction> currentlyShared;
 347   for (shared_terms_iterator i = shared_terms_begin(),
 348            i_end = shared_terms_end(); i != i_end; ++i) {
 349     currentlyShared.insert (*i);
 350   }
 351   return currentlyShared;
 352 }
 353
 354 bool Theory::collectModelInfo(TheoryModel* m, const std::set<Node>& termSet)
 355 {
 356   // if we are using an equality engine, assert it to the model
 357   if (d_equalityEngine != nullptr)
 358   {
 359     if (!m->assertEqualityEngine(d_equalityEngine, &termSet))
 360     {
 361       return false;
 362     }
 363   }
 364   // now, collect theory-specific value assigments
 365   return collectModelValues(m, termSet);
 366 }
 367
 368 void Theory::computeRelevantTerms(std::set<Node>& termSet)
 369 {
 370   // by default, there are no additional relevant terms
 371 }
 372
 373 bool Theory::collectModelValues(TheoryModel* m, const std::set<Node>& termSet)
 374 {
 375   return true;
 376 }
 377
 378 Theory::PPAssertStatus Theory::ppAssert(TrustNode tin,
 379                                         TrustSubstitutionMap& outSubstitutions)
 380 {
 381   TNode in = tin.getNode();
 382   if (in.getKind() == kind::EQUAL)
 383   {
 384     // (and (= x t) phi) can be replaced by phi[x/t] if
 385     // 1) x is a variable
 386     // 2) x is not in the term t
 387     // 3) x : T and t : S, then S <: T
 388     if (in[0].isVar() && isLegalElimination(in[0], in[1])
 389         && in[0].getKind() != kind::BOOLEAN_TERM_VARIABLE)
 390     {
 391       outSubstitutions.addSubstitutionSolved(in[0], in[1], tin);
 392       return PP_ASSERT_STATUS_SOLVED;
 393     }
 394     if (in[1].isVar() && isLegalElimination(in[1], in[0])
 395         && in[1].getKind() != kind::BOOLEAN_TERM_VARIABLE)
 396     {
 397       outSubstitutions.addSubstitutionSolved(in[1], in[0], tin);
 398       return PP_ASSERT_STATUS_SOLVED;
 399     }
 400     if (in[0].isConst() && in[1].isConst())
 401     {
 402       if (in[0] != in[1])
 403       {
 404         return PP_ASSERT_STATUS_CONFLICT;
 405       }
 406     }
 407   }
 408
 409   return PP_ASSERT_STATUS_UNSOLVED;
 410 }
 411
 412 std::pair<bool, Node> Theory::entailmentCheck(TNode lit)
 413 {
 414   return make_pair(false, Node::null());
 415 }
 416
 417 void Theory::addCarePair(TNode t1, TNode t2) {
 418   if (d_careGraph) {
 419     d_careGraph->insert(CarePair(t1, t2, d_id));
 420   }
 421 }
 422
 423 void Theory::getCareGraph(CareGraph* careGraph) {
 424   Assert(careGraph != NULL);
 425
 426   Trace("sharing") << "Theory<" << getId() << ">::getCareGraph()" << std::endl;
 427   TimerStat::CodeTimer computeCareGraphTime(d_computeCareGraphTime);
 428   d_careGraph = careGraph;
 429   computeCareGraph();
 430   d_careGraph = NULL;
 431 }
 432
 433 EqualityStatus Theory::getEqualityStatus(TNode a, TNode b)
 434 {
 435   // if not using an equality engine, then by default we don't know the status
 436   if (d_equalityEngine == nullptr)
 437   {
 438     return EQUALITY_UNKNOWN;
 439   }
 440   Trace("sharing") << "Theory<" << getId() << ">::getEqualityStatus(" << a << ", " << b << ")" << std::endl;
 441   Assert(d_equalityEngine->hasTerm(a) && d_equalityEngine->hasTerm(b));
 442
 443   // Check for equality (simplest)
 444   if (d_equalityEngine->areEqual(a, b))
 445   {
 446     // The terms are implied to be equal
 447     return EQUALITY_TRUE;
 448   }
 449
 450   // Check for disequality
 451   if (d_equalityEngine->areDisequal(a, b, false))
 452   {
 453     // The terms are implied to be dis-equal
 454     return EQUALITY_FALSE;
 455   }
 456
 457   // All other terms are unknown, which is conservative. A theory may override
 458   // this method if it knows more information.
 459   return EQUALITY_UNKNOWN;
 460 }
 461
 462 void Theory::check(Effort level)
 463 {
 464   // see if we are already done (as an optimization)
 465   if (done() && level < EFFORT_FULL)
 466   {
 467     return;
 468   }
 469   Assert(d_theoryState!=nullptr);
 470   // standard calls for resource, stats
 471   d_out->spendResource(ResourceManager::Resource::TheoryCheckStep);
 472   TimerStat::CodeTimer checkTimer(d_checkTime);
 473   Trace("theory-check") << "Theory::preCheck " << level << " " << d_id
 474                         << std::endl;
 475   // pre-check at level
 476   if (preCheck(level))
 477   {
 478     // check aborted for a theory-specific reason
 479     return;
 480   }
 481   Assert(d_theoryState != nullptr);
 482   Trace("theory-check") << "Theory::process fact queue " << d_id << std::endl;
 483   // process the pending fact queue
 484   while (!done() && !d_theoryState->isInConflict())
 485   {
 486     // Get the next assertion from the fact queue
 487     Assertion assertion = get();
 488     TNode fact = assertion.d_assertion;
 489     Trace("theory-check") << "Theory::preNotifyFact " << fact << " " << d_id
 490                           << std::endl;
 491     bool polarity = fact.getKind() != kind::NOT;
 492     TNode atom = polarity ? fact : fact[0];
 493     // call the pre-notify method
 494     if (preNotifyFact(atom, polarity, fact, assertion.d_isPreregistered, false))
 495     {
 496       // handled in theory-specific way that doesn't involve equality engine
 497       continue;
 498     }
 499     Trace("theory-check") << "Theory::assert " << fact << " " << d_id
 500                           << std::endl;
 501     // Theories that don't have an equality engine should always return true
 502     // for preNotifyFact
 503     Assert(d_equalityEngine != nullptr);
 504     // assert to the equality engine
 505     if (atom.getKind() == kind::EQUAL)
 506     {
 507       d_equalityEngine->assertEquality(atom, polarity, fact);
 508     }
 509     else
 510     {
 511       d_equalityEngine->assertPredicate(atom, polarity, fact);
 512     }
 513     Trace("theory-check") << "Theory::notifyFact " << fact << " " << d_id
 514                           << std::endl;
 515     // notify the theory of the new fact, which is not internal
 516     notifyFact(atom, polarity, fact, false);
 517   }
 518   Trace("theory-check") << "Theory::postCheck " << d_id << std::endl;
 519   // post-check at level
 520   postCheck(level);
 521   Trace("theory-check") << "Theory::finish check " << d_id << std::endl;
 522 }
 523
 524 bool Theory::preCheck(Effort level) { return false; }
 525
 526 void Theory::postCheck(Effort level) {}
 527
 528 bool Theory::preNotifyFact(
 529     TNode atom, bool polarity, TNode fact, bool isPrereg, bool isInternal)
 530 {
 531   return false;
 532 }
 533
 534 void Theory::notifyFact(TNode atom, bool polarity, TNode fact, bool isInternal)
 535 {
 536 }
 537
 538 void Theory::preRegisterTerm(TNode node) {}
 539
 540 void Theory::addSharedTerm(TNode n)
 541 {
 542   Debug("sharing") << "Theory::addSharedTerm<" << getId() << ">(" << n << ")"
 543                    << std::endl;
 544   Debug("theory::assertions")
 545       << "Theory::addSharedTerm<" << getId() << ">(" << n << ")" << std::endl;
 546   d_sharedTerms.push_back(n);
 547   // now call theory-specific method notifySharedTerm
 548   notifySharedTerm(n);
 549   // if we have an equality engine, add the trigger term
 550   if (d_equalityEngine != nullptr)
 551   {
 552     d_equalityEngine->addTriggerTerm(n, d_id);
 553   }
 554 }
 555
 556 eq::EqualityEngine* Theory::getEqualityEngine()
 557 {
 558   // get the assigned equality engine, which is a pointer stored in this class
 559   return d_equalityEngine;
 560 }
 561
 562 }/* CVC4::theory namespace */
 563 }/* CVC4 namespace */