src/theory/strings/theory_strings.h

   1 /*********************                                                        */
   2 /*! \file theory_strings.h
   3  ** \verbatim
   4  ** Original author: Tianyi Liang
   5  ** Major contributors: none
   6  ** Minor contributors (to current version): none
   7  ** This file is part of the CVC4 project.
   8  ** Copyright (c) 2009-2013  New York University and The University of Iowa
   9  ** See the file COPYING in the top-level source directory for licensing
  10  ** 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
  30 namespace CVC4 {
  31 namespace theory {
  32 namespace strings {
  33
  34 /**
  35  * Decision procedure for strings.
  36  *
  37  */
  38
  39 class TheoryStrings : public Theory {
  40         typedef context::CDChunkList<Node> NodeList;
  41         typedef context::CDHashMap<Node, NodeList*, NodeHashFunction> NodeListMap;
  42         typedef context::CDHashMap<Node, bool, NodeHashFunction> NodeBoolMap;
  43         typedef context::CDHashMap<Node, int, NodeHashFunction> NodeIntMap;
  44         typedef context::CDHashMap<Node, Node, NodeHashFunction> NodeNodeMap;
  45         typedef context::CDHashSet<Node, NodeHashFunction> NodeSet;
  46
  47 public:
  48         TheoryStrings(context::Context* c, context::UserContext* u, OutputChannel& out, Valuation valuation, const LogicInfo& logicInfo);
  49         ~TheoryStrings();
  50
  51         void setMasterEqualityEngine(eq::EqualityEngine* eq);
  52
  53         std::string identify() const { return std::string("TheoryStrings"); }
  54
  55 public:
  56         void propagate(Effort e);
  57         bool propagate(TNode literal);
  58         void explain( TNode literal, std::vector<TNode>& assumptions );
  59         Node explain( TNode literal );
  60
  61
  62         // NotifyClass for equality engine
  63         class NotifyClass : public eq::EqualityEngineNotify {
  64                 TheoryStrings& d_str;
  65         public:
  66                 NotifyClass(TheoryStrings& t_str): d_str(t_str) {}
  67                 bool eqNotifyTriggerEquality(TNode equality, bool value) {
  68                   Debug("strings") << "NotifyClass::eqNotifyTriggerEquality(" << equality << ", " << (value ? "true" : "false" )<< ")" << std::endl;
  69                   if (value) {
  70                         return d_str.propagate(equality);
  71                   } else {
  72                         // We use only literal triggers so taking not is safe
  73                         return d_str.propagate(equality.notNode());
  74                   }
  75                 }
  76                 bool eqNotifyTriggerPredicate(TNode predicate, bool value) {
  77                   Debug("strings") << "NotifyClass::eqNotifyTriggerPredicate(" << predicate << ", " << (value ? "true" : "false") << ")" << std::endl;
  78                   if (value) {
  79                         return d_str.propagate(predicate);
  80                   } else {
  81                    return d_str.propagate(predicate.notNode());
  82                   }
  83                 }
  84                 bool eqNotifyTriggerTermEquality(TheoryId tag, TNode t1, TNode t2, bool value) {
  85                   Debug("strings") << "NotifyClass::eqNotifyTriggerTermMerge(" << tag << ", " << t1 << ", " << t2 << ")" << std::endl;
  86                   if (value) {
  87                         return d_str.propagate(t1.eqNode(t2));
  88                   } else {
  89                         return d_str.propagate(t1.eqNode(t2).notNode());
  90                   }
  91                 }
  92                 void eqNotifyConstantTermMerge(TNode t1, TNode t2) {
  93                   Debug("strings") << "NotifyClass::eqNotifyConstantTermMerge(" << t1 << ", " << t2 << ")" << std::endl;
  94                   d_str.conflict(t1, t2);
  95                 }
  96                 void eqNotifyNewClass(TNode t) {
  97                   Debug("strings") << "NotifyClass::eqNotifyNewClass(" << t << std::endl;
  98                   d_str.eqNotifyNewClass(t);
  99                 }
 100                 void eqNotifyPreMerge(TNode t1, TNode t2) {
 101                   Debug("strings") << "NotifyClass::eqNotifyPreMerge(" << t1 << ", " << t2 << std::endl;
 102                   d_str.eqNotifyPreMerge(t1, t2);
 103                 }
 104                 void eqNotifyPostMerge(TNode t1, TNode t2) {
 105                   Debug("strings") << "NotifyClass::eqNotifyPostMerge(" << t1 << ", " << t2 << std::endl;
 106                   d_str.eqNotifyPostMerge(t1, t2);
 107                 }
 108                 void eqNotifyDisequal(TNode t1, TNode t2, TNode reason) {
 109                   Debug("strings") << "NotifyClass::eqNotifyDisequal(" << t1 << ", " << t2 << ", " << reason << std::endl;
 110                   d_str.eqNotifyDisequal(t1, t2, reason);
 111                 }
 112         };/* class TheoryStrings::NotifyClass */
 113
 114 private:
 115         // Constants
 116     Node d_emptyString;
 117         Node d_emptyRegexp;
 118     Node d_true;
 119     Node d_false;
 120     Node d_zero;
 121         Node d_one;
 122         // Options
 123         bool d_opt_fmf;
 124         bool d_opt_regexp_gcd;
 125         // Helper functions
 126         Node getRepresentative( Node t );
 127         bool hasTerm( Node a );
 128         bool areEqual( Node a, Node b );
 129         bool areDisequal( Node a, Node b );
 130         Node getLengthTerm( Node t );
 131         Node getLength( Node t );
 132
 133 private:
 134     /** The notify class */
 135     NotifyClass d_notify;
 136     /** Equaltity engine */
 137     eq::EqualityEngine d_equalityEngine;
 138     /** Are we in conflict */
 139     context::CDO<bool> d_conflict;
 140         //list of pairs of nodes to merge
 141         std::map< Node, Node > d_pending_exp;
 142         std::vector< Node > d_pending;
 143         std::vector< Node > d_lemma_cache;
 144         std::map< Node, bool > d_pending_req_phase;
 145         /** inferences */
 146         NodeList d_infer;
 147         NodeList d_infer_exp;
 148         /** normal forms */
 149         std::map< Node, Node > d_normal_forms_base;
 150         std::map< Node, std::vector< Node > > d_normal_forms;
 151         std::map< Node, std::vector< Node > > d_normal_forms_exp;
 152         //map of pairs of terms that have the same normal form
 153         NodeListMap d_nf_pairs;
 154         void addNormalFormPair( Node n1, Node n2 );
 155         bool isNormalFormPair( Node n1, Node n2 );
 156         bool isNormalFormPair2( Node n1, Node n2 );
 157         // loop ant
 158         NodeSet d_loop_antec;
 159         NodeSet d_length_intro_vars;
 160
 161         /////////////////////////////////////////////////////////////////////////////
 162         // MODEL GENERATION
 163         /////////////////////////////////////////////////////////////////////////////
 164 public:
 165         void collectModelInfo(TheoryModel* m, bool fullModel);
 166
 167         /////////////////////////////////////////////////////////////////////////////
 168         // NOTIFICATIONS
 169         /////////////////////////////////////////////////////////////////////////////
 170 public:
 171         void presolve();
 172         void shutdown() { }
 173
 174         /////////////////////////////////////////////////////////////////////////////
 175         // MAIN SOLVER
 176         /////////////////////////////////////////////////////////////////////////////
 177 private:
 178         void addSharedTerm(TNode n);
 179         EqualityStatus getEqualityStatus(TNode a, TNode b);
 180
 181 private:
 182         class EqcInfo {
 183         public:
 184                 EqcInfo( context::Context* c );
 185                 ~EqcInfo(){}
 186                 //constant in this eqc
 187                 context::CDO< Node > d_const_term;
 188                 context::CDO< Node > d_length_term;
 189                 context::CDO< unsigned > d_cardinality_lem_k;
 190                 // 1 = added length lemma
 191                 context::CDO< Node > d_normalized_length;
 192         };
 193         /** map from representatives to information necessary for equivalence classes */
 194         std::map< Node, EqcInfo* > d_eqc_info;
 195         EqcInfo * getOrMakeEqcInfo( Node eqc, bool doMake = true );
 196         //maintain which concat terms have the length lemma instantiated
 197         NodeSet d_length_inst;
 198         NodeBoolMap d_length_nodes;
 199 private:
 200         void mergeCstVec(std::vector< Node > &vec_strings);
 201     bool getNormalForms(Node &eqc, std::vector< Node > & visited, std::vector< Node > & nf,
 202                                                 std::vector< std::vector< Node > > &normal_forms,
 203                                                 std::vector< std::vector< Node > > &normal_forms_exp,
 204                                                 std::vector< Node > &normal_form_src);
 205         bool detectLoop(std::vector< std::vector< Node > > &normal_forms,
 206                                         int i, int j, int index_i, int index_j,
 207                                         int &loop_in_i, int &loop_in_j);
 208         bool processLoop(std::vector< Node > &antec,
 209                                          std::vector< std::vector< Node > > &normal_forms,
 210                                          std::vector< Node > &normal_form_src,
 211                                          int i, int j, int loop_n_index, int other_n_index,
 212                                          int loop_index, int index, int other_index);
 213         bool processNEqc(std::vector< std::vector< Node > > &normal_forms,
 214                                          std::vector< std::vector< Node > > &normal_forms_exp,
 215                                          std::vector< Node > &normal_form_src);
 216         bool processReverseNEq(std::vector< std::vector< Node > > &normal_forms,
 217                                                    std::vector< Node > &normal_form_src, std::vector< Node > &curr_exp, unsigned i, unsigned j );
 218         bool processSimpleNEq( std::vector< std::vector< Node > > &normal_forms,
 219                                                    std::vector< Node > &normal_form_src, std::vector< Node > &curr_exp, unsigned i, unsigned j,
 220                                                    unsigned& index_i, unsigned& index_j, bool isRev );
 221     bool normalizeEquivalenceClass( Node n, std::vector< Node > & visited, std::vector< Node > & nf, std::vector< Node > & nf_exp );
 222     bool processDeq( Node n1, Node n2 );
 223         int processReverseDeq( std::vector< Node >& nfi, std::vector< Node >& nfj, Node ni, Node nj );
 224         int processSimpleDeq( std::vector< Node >& nfi, std::vector< Node >& nfj, Node ni, Node nj, unsigned& index, bool isRev );
 225         //bool unrollStar( Node atom );
 226         Node mkRegExpAntec(Node atom, Node ant);
 227
 228         bool checkSimple();
 229     bool checkNormalForms();
 230         void checkDeqNF();
 231         bool checkLengthsEqc();
 232     bool checkCardinality();
 233     bool checkInductiveEquations();
 234         bool checkMemberships();
 235         bool checkPDerivative(Node x, Node r, Node atom, bool &addedLemma, std::vector< Node > &processed, std::vector< Node > &cprocessed);
 236         bool checkContains();
 237         bool checkPosContains();
 238         bool checkNegContains();
 239
 240 public:
 241         void preRegisterTerm(TNode n);
 242         void check(Effort e);
 243
 244         /** Conflict when merging two constants */
 245         void conflict(TNode a, TNode b);
 246         /** called when a new equivalence class is created */
 247         void eqNotifyNewClass(TNode t);
 248         /** called when two equivalence classes will merge */
 249         void eqNotifyPreMerge(TNode t1, TNode t2);
 250         /** called when two equivalence classes have merged */
 251         void eqNotifyPostMerge(TNode t1, TNode t2);
 252         /** called when two equivalence classes are made disequal */
 253         void eqNotifyDisequal(TNode t1, TNode t2, TNode reason);
 254 protected:
 255         /** compute care graph */
 256         void computeCareGraph();
 257
 258         //do pending merges
 259         void doPendingFacts();
 260         void doPendingLemmas();
 261
 262         void sendLemma( Node ant, Node conc, const char * c );
 263         void sendInfer( Node eq_exp, Node eq, const char * c );
 264         void sendSplit( Node a, Node b, const char * c, bool preq = true );
 265         /** mkConcat **/
 266         Node mkConcat( Node n1, Node n2 );
 267         Node mkConcat( std::vector< Node >& c );
 268         /** mkExplain **/
 269         Node mkExplain( std::vector< Node >& a );
 270         Node mkExplain( std::vector< Node >& a, std::vector< Node >& an );
 271         /** mkAnd **/
 272         Node mkAnd( std::vector< Node >& a );
 273         /** get concat vector */
 274         void getConcatVec( Node n, std::vector< Node >& c );
 275
 276         //get equivalence classes
 277         void getEquivalenceClasses( std::vector< Node >& eqcs );
 278         //get final normal form
 279         void getFinalNormalForm( Node n, std::vector< Node >& nf, std::vector< Node >& exp );
 280
 281         //separate into collections with equal length
 282         void separateByLength( std::vector< Node >& n, std::vector< std::vector< Node > >& col, std::vector< Node >& lts );
 283         void printConcat( std::vector< Node >& n, const char * c );
 284
 285 private:
 286         Node mkSplitEq( const char * c, const char * info, Node lhs, Node rhs, bool lgtZero );
 287
 288         // Special String Functions
 289         NodeList d_str_pos_ctn;
 290         NodeList d_str_neg_ctn;
 291         NodeSet d_neg_ctn_eqlen;
 292         NodeSet d_neg_ctn_ulen;
 293         NodeSet d_pos_ctn_cached;
 294         NodeSet d_neg_ctn_cached;
 295
 296         // Regular Expression
 297 private:
 298         // regular expression memberships
 299         NodeList d_regexp_memberships;
 300         NodeSet d_regexp_ucached;
 301         NodeSet d_regexp_ccached;
 302         // antecedant for why regexp membership must be true
 303         NodeNodeMap d_regexp_ant;
 304         // membership length
 305         //std::map< Node, bool > d_membership_length;
 306         // regular expression operations
 307         RegExpOpr d_regexp_opr;
 308
 309         CVC4::String getHeadConst( Node x );
 310         bool splitRegExp( Node x, Node r, Node ant );
 311         bool addMembershipLength(Node atom);
 312
 313
 314         // Finite Model Finding
 315 private:
 316         NodeSet d_input_vars;
 317         context::CDO< Node > d_input_var_lsum;
 318         context::CDHashMap< int, Node > d_cardinality_lits;
 319         context::CDO< int > d_curr_cardinality;
 320 public:
 321         //for finite model finding
 322     Node getNextDecisionRequest();
 323         void assertNode( Node lit );
 324
 325 public:
 326 /** statistics class */
 327   class Statistics {
 328   public:
 329     IntStat d_splits;
 330     IntStat d_eq_splits;
 331     IntStat d_deq_splits;
 332     IntStat d_loop_lemmas;
 333     IntStat d_new_skolems;
 334     Statistics();
 335     ~Statistics();
 336   };/* class TheoryStrings::Statistics */
 337   Statistics d_statistics;
 338 };/* class TheoryStrings */
 339
 340 }/* CVC4::theory::strings namespace */
 341 }/* CVC4::theory namespace */
 342 }/* CVC4 namespace */
 343
 344 #endif /* __CVC4__THEORY__STRINGS__THEORY_STRINGS_H */