src/theory/strings/theory_strings.h

   1 /*********************                                                        */
   2 /*! \file theory_strings.h
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Tianyi Liang, Andrew Reynolds, Tim King
   6  ** This file is part of the CVC4 project.
   7  ** Copyright (c) 2009-2016 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 Theory of strings
  13  **
  14  ** Theory of strings.
  15  **/
  16
  17 #include "cvc4_private.h"
  18
  19 #ifndef __CVC4__THEORY__STRINGS__THEORY_STRINGS_H
  20 #define __CVC4__THEORY__STRINGS__THEORY_STRINGS_H
  21
  22 #include "theory/theory.h"
  23 #include "theory/uf/equality_engine.h"
  24 #include "theory/strings/theory_strings_preprocess.h"
  25 #include "theory/strings/regexp_operation.h"
  26
  27 #include "context/cdchunk_list.h"
  28 #include "context/cdhashset.h"
  29 #include "expr/attribute.h"
  30
  31 #include <climits>
  32 #include <deque>
  33
  34 namespace CVC4 {
  35 namespace theory {
  36
  37 namespace quantifiers{
  38   class TermArgTrie;
  39 }
  40
  41 namespace strings {
  42
  43 /**
  44  * Decision procedure for strings.
  45  *
  46  */
  47
  48 struct StringsProxyVarAttributeId {};
  49 typedef expr::Attribute< StringsProxyVarAttributeId, bool > StringsProxyVarAttribute;
  50
  51 class TheoryStrings : public Theory {
  52   typedef context::CDChunkList<Node> NodeList;
  53   typedef context::CDHashMap<Node, bool, NodeHashFunction> NodeBoolMap;
  54   typedef context::CDHashMap<Node, int, NodeHashFunction> NodeIntMap;
  55   typedef context::CDHashMap<Node, Node, NodeHashFunction> NodeNodeMap;
  56   typedef context::CDHashSet<Node, NodeHashFunction> NodeSet;
  57
  58 public:
  59   TheoryStrings(context::Context* c, context::UserContext* u,
  60                 OutputChannel& out, Valuation valuation,
  61                 const LogicInfo& logicInfo);
  62   ~TheoryStrings();
  63
  64   void setMasterEqualityEngine(eq::EqualityEngine* eq);
  65
  66   std::string identify() const { return std::string("TheoryStrings"); }
  67
  68 public:
  69   void propagate(Effort e);
  70   bool propagate(TNode literal);
  71   void explain( TNode literal, std::vector<TNode>& assumptions );
  72   Node explain( TNode literal );
  73
  74
  75   // NotifyClass for equality engine
  76   class NotifyClass : public eq::EqualityEngineNotify {
  77     TheoryStrings& d_str;
  78   public:
  79     NotifyClass(TheoryStrings& t_str): d_str(t_str) {}
  80     bool eqNotifyTriggerEquality(TNode equality, bool value) {
  81       Debug("strings") << "NotifyClass::eqNotifyTriggerEquality(" << equality << ", " << (value ? "true" : "false" )<< ")" << std::endl;
  82       if (value) {
  83         return d_str.propagate(equality);
  84       } else {
  85         // We use only literal triggers so taking not is safe
  86         return d_str.propagate(equality.notNode());
  87       }
  88     }
  89     bool eqNotifyTriggerPredicate(TNode predicate, bool value) {
  90       Debug("strings") << "NotifyClass::eqNotifyTriggerPredicate(" << predicate << ", " << (value ? "true" : "false") << ")" << std::endl;
  91       if (value) {
  92         return d_str.propagate(predicate);
  93       } else {
  94          return d_str.propagate(predicate.notNode());
  95       }
  96     }
  97     bool eqNotifyTriggerTermEquality(TheoryId tag, TNode t1, TNode t2, bool value) {
  98       Debug("strings") << "NotifyClass::eqNotifyTriggerTermMerge(" << tag << ", " << t1 << ", " << t2 << ")" << std::endl;
  99       if (value) {
 100       return d_str.propagate(t1.eqNode(t2));
 101       } else {
 102       return d_str.propagate(t1.eqNode(t2).notNode());
 103       }
 104     }
 105     void eqNotifyConstantTermMerge(TNode t1, TNode t2) {
 106       Debug("strings") << "NotifyClass::eqNotifyConstantTermMerge(" << t1 << ", " << t2 << ")" << std::endl;
 107       d_str.conflict(t1, t2);
 108     }
 109     void eqNotifyNewClass(TNode t) {
 110       Debug("strings") << "NotifyClass::eqNotifyNewClass(" << t << std::endl;
 111       d_str.eqNotifyNewClass(t);
 112     }
 113     void eqNotifyPreMerge(TNode t1, TNode t2) {
 114       Debug("strings") << "NotifyClass::eqNotifyPreMerge(" << t1 << ", " << t2 << std::endl;
 115       d_str.eqNotifyPreMerge(t1, t2);
 116     }
 117     void eqNotifyPostMerge(TNode t1, TNode t2) {
 118       Debug("strings") << "NotifyClass::eqNotifyPostMerge(" << t1 << ", " << t2 << std::endl;
 119       d_str.eqNotifyPostMerge(t1, t2);
 120     }
 121     void eqNotifyDisequal(TNode t1, TNode t2, TNode reason) {
 122       Debug("strings") << "NotifyClass::eqNotifyDisequal(" << t1 << ", " << t2 << ", " << reason << std::endl;
 123       d_str.eqNotifyDisequal(t1, t2, reason);
 124     }
 125   };/* class TheoryStrings::NotifyClass */
 126
 127 private:
 128   // Constants
 129   Node d_emptyString;
 130   Node d_emptyRegexp;
 131   Node d_true;
 132   Node d_false;
 133   Node d_zero;
 134   Node d_one;
 135   CVC4::Rational RMAXINT;
 136   unsigned d_card_size;
 137   // Helper functions
 138   Node getRepresentative( Node t );
 139   bool hasTerm( Node a );
 140   bool areEqual( Node a, Node b );
 141   bool areDisequal( Node a, Node b );
 142   // t is representative, te = t, add lt = te to explanation exp
 143   Node getLengthExp( Node t, std::vector< Node >& exp, Node te );
 144   Node getLength( Node t, std::vector< Node >& exp );
 145
 146 private:
 147   /** The notify class */
 148   NotifyClass d_notify;
 149   /** Equaltity engine */
 150   eq::EqualityEngine d_equalityEngine;
 151   /** Are we in conflict */
 152   context::CDO<bool> d_conflict;
 153   //list of pairs of nodes to merge
 154   std::map< Node, Node > d_pending_exp;
 155   std::vector< Node > d_pending;
 156   std::vector< Node > d_lemma_cache;
 157   std::map< Node, bool > d_pending_req_phase;
 158   /** inferences: maintained to ensure ref count for internally introduced nodes */
 159   NodeList d_infer;
 160   NodeList d_infer_exp;
 161   /** normal forms */
 162   std::map< Node, Node > d_normal_forms_base;
 163   std::map< Node, std::vector< Node > > d_normal_forms;
 164   std::map< Node, std::vector< Node > > d_normal_forms_exp;
 165   std::map< Node, std::map< Node, std::map< bool, int > > > d_normal_forms_exp_depend;
 166   //map of pairs of terms that have the same normal form
 167   NodeIntMap d_nf_pairs;
 168   std::map< Node, std::vector< Node > > d_nf_pairs_data;
 169   void addNormalFormPair( Node n1, Node n2 );
 170   bool isNormalFormPair( Node n1, Node n2 );
 171   bool isNormalFormPair2( Node n1, Node n2 );
 172   // loop ant
 173   NodeSet d_loop_antec;
 174   NodeSet d_length_intro_vars;
 175   // preReg cache
 176   NodeSet d_pregistered_terms_cache;
 177   NodeSet d_registered_terms_cache;
 178   // preprocess cache
 179   StringsPreprocess d_preproc;
 180   NodeBoolMap d_preproc_cache;
 181   // extended functions inferences cache
 182   NodeSet d_extf_infer_cache;
 183   NodeSet d_extf_infer_cache_u;
 184   std::vector< Node > d_empty_vec;
 185   //
 186   NodeList d_ee_disequalities;
 187 private:
 188   NodeSet d_congruent;
 189   std::map< Node, Node > d_eqc_to_const;
 190   std::map< Node, Node > d_eqc_to_const_base;
 191   std::map< Node, Node > d_eqc_to_const_exp;
 192   Node getConstantEqc( Node eqc );
 193
 194   std::map< Node, Node > d_eqc_to_len_term;
 195   std::vector< Node > d_strings_eqc;
 196   Node d_emptyString_r;
 197   class TermIndex {
 198   public:
 199     Node d_data;
 200     std::map< TNode, TermIndex > d_children;
 201     Node add( TNode n, unsigned index, TheoryStrings* t, Node er, std::vector< Node >& c );
 202     void clear(){ d_children.clear(); }
 203   };
 204   std::map< Kind, TermIndex > d_term_index;
 205   //list of non-congruent concat terms in each eqc
 206   std::map< Node, std::vector< Node > > d_eqc;
 207   std::map< Node, std::vector< Node > > d_flat_form;
 208   std::map< Node, std::vector< int > > d_flat_form_index;
 209
 210   void debugPrintFlatForms( const char * tc );
 211   void debugPrintNormalForms( const char * tc );
 212   /////////////////////////////////////////////////////////////////////////////
 213   // MODEL GENERATION
 214   /////////////////////////////////////////////////////////////////////////////
 215 public:
 216   void collectModelInfo(TheoryModel* m, bool fullModel);
 217
 218   /////////////////////////////////////////////////////////////////////////////
 219   // NOTIFICATIONS
 220   /////////////////////////////////////////////////////////////////////////////
 221 public:
 222   void presolve();
 223   void shutdown() { }
 224
 225   /////////////////////////////////////////////////////////////////////////////
 226   // MAIN SOLVER
 227   /////////////////////////////////////////////////////////////////////////////
 228 private:
 229   void addSharedTerm(TNode n);
 230   EqualityStatus getEqualityStatus(TNode a, TNode b);
 231
 232 private:
 233   class EqcInfo {
 234   public:
 235     EqcInfo( context::Context* c );
 236     ~EqcInfo(){}
 237     //constant in this eqc
 238     context::CDO< Node > d_const_term;
 239     context::CDO< Node > d_length_term;
 240     context::CDO< unsigned > d_cardinality_lem_k;
 241     // 1 = added length lemma
 242     context::CDO< Node > d_normalized_length;
 243   };
 244   /** map from representatives to information necessary for equivalence classes */
 245   std::map< Node, EqcInfo* > d_eqc_info;
 246   EqcInfo * getOrMakeEqcInfo( Node eqc, bool doMake = true );
 247   //maintain which concat terms have the length lemma instantiated
 248   NodeNodeMap d_proxy_var;
 249   NodeNodeMap d_proxy_var_to_length;
 250   /** All the function terms that the theory has seen */
 251   context::CDList<TNode> d_functionsTerms;
 252 private:
 253   //extended string terms, map to whether they are active
 254   NodeBoolMap d_ext_func_terms;
 255   //any non-reduced extended functions exist
 256   context::CDO< bool > d_has_extf;
 257   // static information about extf
 258   class ExtfInfo {
 259   public:
 260     //all variables in this term
 261     std::vector< Node > d_vars;
 262   };
 263   // non-static information about extf
 264   class ExtfInfoTmp {
 265   public:
 266     void init(){
 267       d_pol = 0;
 268       d_model_active = true;
 269     }
 270     // list of terms that something (does not) contain and their explanation
 271     std::map< bool, std::vector< Node > > d_ctn;
 272     std::map< bool, std::vector< Node > > d_ctn_from;
 273     //polarity
 274     int d_pol;
 275     //explanation
 276     std::vector< Node > d_exp;
 277     //reps -> list of variables
 278     std::map< Node, std::vector< Node > > d_rep_vars;
 279     //false if it is reduced in the model
 280     bool d_model_active;
 281   };
 282   std::map< Node, ExtfInfo > d_extf_info;
 283   std::map< Node, ExtfInfoTmp > d_extf_info_tmp;
 284   //collect extended operator terms
 285   void collectExtendedFuncTerms( Node n, std::map< Node, bool >& visited );
 286   void addExtendedFuncTerm( Node n );
 287 private:
 288   class InferInfo {
 289   public:
 290     unsigned d_i;
 291     unsigned d_j;
 292     bool d_rev;
 293     std::vector< Node > d_ant;
 294     std::vector< Node > d_antn;
 295     std::vector< Node > d_non_emp_vars;
 296     Node d_conc;
 297     unsigned d_id;
 298     std::map< Node, bool > d_pending_phase;
 299     const char * getId() {
 300       switch( d_id ){
 301       case 1:return "S-Split(CST-P)-prop";break;
 302       case 2:return "S-Split(VAR)-prop";break;
 303       case 3:return "Len-Split(Len)";break;
 304       case 4:return "Len-Split(Emp)";break;
 305       case 5:return "S-Split(CST-P)-binary";break;
 306       case 6:return "S-Split(CST-P)";break;
 307       case 7:return "S-Split(VAR)";break;
 308       case 8:return "F-Loop";break;
 309       default:break;
 310       }
 311       return "";
 312     }
 313     bool sendAsLemma();
 314   };
 315   //initial check
 316   void checkInit();
 317   void checkConstantEquivalenceClasses( TermIndex* ti, std::vector< Node >& vecc );
 318   //extended functions evaluation check
 319   void checkExtfEval( int effort = 0 );
 320   void checkExtfInference( Node n, Node nr, ExtfInfoTmp& in, int effort );
 321   void collectVars( Node n, std::vector< Node >& vars, std::map< Node, bool >& visited );
 322   Node getSymbolicDefinition( Node n, std::vector< Node >& exp );
 323   //check extf reduction
 324   void checkExtfReductions( int effort );
 325   void checkExtfReduction( Node atom, int pol, int effort );
 326   //flat forms check
 327   void checkFlatForms();
 328   Node checkCycles( Node eqc, std::vector< Node >& curr, std::vector< Node >& exp );
 329   //normal forms check
 330   void checkNormalForms();
 331   void normalizeEquivalenceClass( Node n );
 332   void getNormalForms( Node &eqc, std::vector< std::vector< Node > > &normal_forms, std::vector< Node > &normal_form_src,
 333                        std::vector< std::vector< Node > > &normal_forms_exp, std::vector< std::map< Node, std::map< bool, int > > >& normal_forms_exp_depend);
 334   bool detectLoop(std::vector< std::vector< Node > > &normal_forms, int i, int j, int index, int &loop_in_i, int &loop_in_j);
 335   bool processLoop( std::vector< std::vector< Node > > &normal_forms, std::vector< Node > &normal_form_src,
 336                     int i, int j, int loop_n_index, int other_n_index,int loop_index, int index, InferInfo& info );
 337   void processNEqc( std::vector< std::vector< Node > > &normal_forms, std::vector< Node > &normal_form_src,
 338                     std::vector< std::vector< Node > > &normal_forms_exp, std::vector< std::map< Node, std::map< bool, int > > >& normal_forms_exp_depend );
 339   void processReverseNEq( std::vector< std::vector< Node > > &normal_forms, std::vector< Node > &normal_form_src,
 340                           std::vector< std::vector< Node > > &normal_forms_exp, std::vector< std::map< Node, std::map< bool, int > > >& normal_forms_exp_depend,
 341                           unsigned i, unsigned j, unsigned& index, unsigned rproc, std::vector< InferInfo >& pinfer );
 342   void processSimpleNEq( std::vector< std::vector< Node > > &normal_forms, std::vector< Node > &normal_form_src,
 343                          std::vector< std::vector< Node > > &normal_forms_exp, std::vector< std::map< Node, std::map< bool, int > > >& normal_forms_exp_depend,
 344                          unsigned i, unsigned j, unsigned& index, bool isRev, unsigned rproc, std::vector< InferInfo >& pinfer );
 345   bool processDeq( Node n1, Node n2 );
 346   int processReverseDeq( std::vector< Node >& nfi, std::vector< Node >& nfj, Node ni, Node nj );
 347   int processSimpleDeq( std::vector< Node >& nfi, std::vector< Node >& nfj, Node ni, Node nj, unsigned& index, bool isRev );
 348   void checkDeqNF();
 349   void getExplanationVectorForPrefix( std::vector< std::vector< Node > > &normal_forms_exp, std::vector< std::map< Node, std::map< bool, int > > >& normal_forms_exp_depend,
 350                                       unsigned i, int index, bool isRev, std::vector< Node >& curr_exp );
 351   void getExplanationVectorForPrefixEq( std::vector< std::vector< Node > > &normal_forms, std::vector< Node > &normal_form_src,
 352                                         std::vector< std::vector< Node > > &normal_forms_exp, std::vector< std::map< Node, std::map< bool, int > > >& normal_forms_exp_depend,
 353                                         unsigned i, unsigned j, int index_i, int index_j, bool isRev, std::vector< Node >& curr_exp );
 354
 355   Node collectConstantStringAt( std::vector< Node >& vec, int& index, bool isRev );
 356
 357   //check membership constraints
 358   Node mkRegExpAntec(Node atom, Node ant);
 359   Node normalizeRegexp(Node r);
 360   bool normalizePosMemberships( std::map< Node, std::vector< Node > > &memb_with_exps );
 361   bool applyRConsume( CVC4::String &s, Node &r );
 362   Node applyRSplit( Node s1, Node s2, Node r );
 363   bool applyRLen( std::map< Node, std::vector< Node > > &XinR_with_exps );
 364   bool checkMembershipsWithoutLength( std::map< Node, std::vector< Node > > &memb_with_exps,
 365                                       std::map< Node, std::vector< Node > > &XinR_with_exps);
 366   void checkMemberships();
 367   bool checkMemberships2();
 368   bool checkPDerivative( Node x, Node r, Node atom, bool &addedLemma,
 369                          std::vector< Node > &processed, std::vector< Node > &cprocessed,
 370                          std::vector< Node > &nf_exp);
 371   //check contains
 372   void checkPosContains( std::vector< Node >& posContains );
 373   void checkNegContains( std::vector< Node >& negContains );
 374   //lengths normalize check
 375   void checkLengthsEqc();
 376   //cardinality check
 377   void checkCardinality();
 378
 379 private:
 380   void addCarePairs( quantifiers::TermArgTrie * t1, quantifiers::TermArgTrie * t2, unsigned arity, unsigned depth );
 381 public:
 382   /** preregister term */
 383   void preRegisterTerm(TNode n);
 384   /** Expand definition */
 385   Node expandDefinition(LogicRequest &logicRequest, Node n);
 386   /** Check at effort e */
 387   void check(Effort e);
 388   /** needs check last effort */
 389   bool needsCheckLastEffort();
 390   /** Conflict when merging two constants */
 391   void conflict(TNode a, TNode b);
 392   /** called when a new equivalence class is created */
 393   void eqNotifyNewClass(TNode t);
 394   /** called when two equivalence classes will merge */
 395   void eqNotifyPreMerge(TNode t1, TNode t2);
 396   /** called when two equivalence classes have merged */
 397   void eqNotifyPostMerge(TNode t1, TNode t2);
 398   /** called when two equivalence classes are made disequal */
 399   void eqNotifyDisequal(TNode t1, TNode t2, TNode reason);
 400   /** get preprocess */
 401   StringsPreprocess * getPreprocess() { return &d_preproc; }
 402 protected:
 403   /** compute care graph */
 404   void computeCareGraph();
 405
 406   //do pending merges
 407   void assertPendingFact(Node atom, bool polarity, Node exp);
 408   void doPendingFacts();
 409   void doPendingLemmas();
 410   bool hasProcessed();
 411   void addToExplanation( Node a, Node b, std::vector< Node >& exp );
 412   void addToExplanation( Node lit, std::vector< Node >& exp );
 413
 414   //register term
 415   void registerTerm( Node n, int effort );
 416   //send lemma
 417   void sendInference( std::vector< Node >& exp, std::vector< Node >& exp_n, Node eq, const char * c, bool asLemma = false );
 418   void sendInference( std::vector< Node >& exp, Node eq, const char * c, bool asLemma = false );
 419   void sendLemma( Node ant, Node conc, const char * c );
 420   void sendInfer( Node eq_exp, Node eq, const char * c );
 421   void sendSplit( Node a, Node b, const char * c, bool preq = true );
 422   void sendLengthLemma( Node n );
 423   /** mkConcat **/
 424   inline Node mkConcat( Node n1, Node n2 );
 425   inline Node mkConcat( Node n1, Node n2, Node n3 );
 426   inline Node mkConcat( const std::vector< Node >& c );
 427   inline Node mkLength( Node n );
 428   //mkSkolem
 429   enum {
 430     sk_id_c_spt,
 431     sk_id_vc_spt,
 432     sk_id_vc_bin_spt,
 433     sk_id_v_spt,
 434     sk_id_ctn_pre,
 435     sk_id_ctn_post,
 436     sk_id_deq_x,
 437     sk_id_deq_y,
 438     sk_id_deq_z,
 439   };
 440   std::map< Node, std::map< Node, std::map< int, Node > > > d_skolem_cache;
 441   NodeSet d_skolem_cache_ne_reg;
 442   Node mkSkolemCached( Node a, Node b, int id, const char * c, int isLenSplit = 0 );
 443   inline Node mkSkolemS(const char * c, int isLenSplit = 0);
 444   void registerNonEmptySkolem( Node sk );
 445   //inline Node mkSkolemI(const char * c);
 446   /** mkExplain **/
 447   Node mkExplain( std::vector< Node >& a );
 448   Node mkExplain( std::vector< Node >& a, std::vector< Node >& an );
 449   /** mkAnd **/
 450   Node mkAnd( std::vector< Node >& a );
 451   /** get concat vector */
 452   void getConcatVec( Node n, std::vector< Node >& c );
 453
 454   //get equivalence classes
 455   void getEquivalenceClasses( std::vector< Node >& eqcs );
 456
 457   //separate into collections with equal length
 458   void separateByLength( std::vector< Node >& n, std::vector< std::vector< Node > >& col, std::vector< Node >& lts );
 459   void printConcat( std::vector< Node >& n, const char * c );
 460
 461   void inferSubstitutionProxyVars( Node n, std::vector< Node >& vars, std::vector< Node >& subs, std::vector< Node >& unproc );
 462
 463   // Symbolic Regular Expression
 464 private:
 465   // regular expression memberships
 466   NodeList d_regexp_memberships;
 467   NodeSet d_regexp_ucached;
 468   NodeSet d_regexp_ccached;
 469   // stored assertions
 470   NodeIntMap d_pos_memberships;
 471   std::map< Node, std::vector< Node > > d_pos_memberships_data;
 472   NodeIntMap d_neg_memberships;
 473   std::map< Node, std::vector< Node > > d_neg_memberships_data;
 474   unsigned getNumMemberships( Node n, bool isPos );
 475   Node getMembership( Node n, bool isPos, unsigned i );
 476   // semi normal forms for symbolic expression
 477   std::map< Node, Node > d_nf_regexps;
 478   std::map< Node, std::vector< Node > > d_nf_regexps_exp;
 479   // intersection
 480   NodeNodeMap d_inter_cache;
 481   NodeIntMap d_inter_index;
 482   // processed memberships
 483   NodeSet d_processed_memberships;
 484   // antecedant for why regexp membership must be true
 485   NodeNodeMap d_regexp_ant;
 486   // membership length
 487   //std::map< Node, bool > d_membership_length;
 488   // regular expression operations
 489   RegExpOpr d_regexp_opr;
 490
 491   CVC4::String getHeadConst( Node x );
 492   bool deriveRegExp( Node x, Node r, Node ant );
 493   void addMembership(Node assertion);
 494   Node getNormalString(Node x, std::vector<Node> &nf_exp);
 495   Node getNormalSymRegExp(Node r, std::vector<Node> &nf_exp);
 496
 497
 498   // Finite Model Finding
 499 private:
 500   NodeSet d_input_vars;
 501   context::CDO< Node > d_input_var_lsum;
 502   context::CDHashMap< int, Node > d_cardinality_lits;
 503   context::CDO< int > d_curr_cardinality;
 504 public:
 505   //for finite model finding
 506   Node getNextDecisionRequest();
 507   //ppRewrite
 508   Node ppRewrite(TNode atom);
 509 public:
 510 /** statistics class */
 511   class Statistics {
 512   public:
 513     IntStat d_splits;
 514     IntStat d_eq_splits;
 515     IntStat d_deq_splits;
 516     IntStat d_loop_lemmas;
 517     IntStat d_new_skolems;
 518     Statistics();
 519     ~Statistics();
 520   };/* class TheoryStrings::Statistics */
 521   Statistics d_statistics;
 522 };/* class TheoryStrings */
 523
 524 }/* CVC4::theory::strings namespace */
 525 }/* CVC4::theory namespace */
 526 }/* CVC4 namespace */
 527
 528 #endif /* __CVC4__THEORY__STRINGS__THEORY_STRINGS_H */