src/expr/symbol_table.cpp

   1 /*********************                                                        */
   2 /*! \file symbol_table.cpp
   3  ** \verbatim
   4  ** Top contributors (to current version):
   5  **   Andrew Reynolds, Tim King, Morgan Deters
   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 Convenience class for scoping variable and type
  13  ** declarations (implementation)
  14  **
  15  ** Convenience class for scoping variable and type declarations
  16  ** (implementation).
  17  **/
  18
  19 #include "expr/symbol_table.h"
  20
  21 #include <ostream>
  22 #include <string>
  23 #include <unordered_map>
  24 #include <utility>
  25
  26 #include "context/cdhashmap.h"
  27 #include "context/cdhashset.h"
  28 #include "context/context.h"
  29 #include "expr/expr.h"
  30 #include "expr/expr_manager_scope.h"
  31 #include "expr/type.h"
  32
  33 namespace CVC4 {
  34
  35 using ::CVC4::context::CDHashMap;
  36 using ::CVC4::context::CDHashSet;
  37 using ::CVC4::context::Context;
  38 using ::std::copy;
  39 using ::std::endl;
  40 using ::std::ostream_iterator;
  41 using ::std::pair;
  42 using ::std::string;
  43 using ::std::vector;
  44
  45 /** Overloaded type trie.
  46  *
  47  * This data structure stores a trie of expressions with
  48  * the same name, and must be distinguished by their argument types.
  49  * It is context-dependent.
  50  *
  51  * Using the argument allowFunVariants,
  52  * it may either be configured to allow function variants or not,
  53  * where a function variant is function that expects the same
  54  * argument types as another.
  55  *
  56  * For example, the following definitions introduce function
  57  * variants for the symbol f:
  58  *
  59  * 1. (declare-fun f (Int) Int) and
  60  *    (declare-fun f (Int) Bool)
  61  *
  62  * 2. (declare-fun f (Int) Int) and
  63  *    (declare-fun f (Int) Int)
  64  *
  65  * 3. (declare-datatypes ((Tup 0)) ((f (data Int)))) and
  66  *    (declare-fun f (Int) Tup)
  67  *
  68  * 4. (declare-datatypes ((Tup 0)) ((mkTup (f Int)))) and
  69  *    (declare-fun f (Tup) Bool)
  70  *
  71  * If function variants is set to true, we allow function variants
  72  * but not function redefinition. In examples 2 and 3, f is
  73  * declared twice as a symbol of identical argument and range
  74  * types. We never accept these definitions. However, we do
  75  * allow examples 1 and 4 above when allowFunVariants is true.
  76  *
  77  * For 0-argument functions (constants), we always allow
  78  * function variants.  That is, we always accept these examples:
  79  *
  80  * 5.  (declare-fun c () Int)
  81  *     (declare-fun c () Bool)
  82  *
  83  * 6.  (declare-datatypes ((Enum 0)) ((c)))
  84  *     (declare-fun c () Int)
  85  *
  86  * and always reject constant redefinition such as:
  87  *
  88  * 7. (declare-fun c () Int)
  89  *    (declare-fun c () Int)
  90  *
  91  * 8. (declare-datatypes ((Enum 0)) ((c))) and
  92  *    (declare-fun c () Enum)
  93  */
  94 class OverloadedTypeTrie {
  95  public:
  96   OverloadedTypeTrie(Context* c, bool allowFunVariants = false)
  97       : d_overloaded_symbols(new (true) CDHashSet<Expr, ExprHashFunction>(c)),
  98         d_allowFunctionVariants(allowFunVariants)
  99   {
 100   }
 101   ~OverloadedTypeTrie() { d_overloaded_symbols->deleteSelf(); }
 102
 103   /** is this function overloaded? */
 104   bool isOverloadedFunction(Expr fun) const;
 105
 106   /** Get overloaded constant for type.
 107    * If possible, it returns a defined symbol with name
 108    * that has type t. Otherwise returns null expression.
 109    */
 110   Expr getOverloadedConstantForType(const std::string& name, Type t) const;
 111
 112   /**
 113    * If possible, returns a defined function for a name
 114    * and a vector of expected argument types. Otherwise returns
 115    * null expression.
 116    */
 117   Expr getOverloadedFunctionForTypes(const std::string& name,
 118                                      const std::vector<Type>& argTypes) const;
 119   /** called when obj is bound to name, and prev_bound_obj was already bound to
 120    * name Returns false if the binding is invalid.
 121    */
 122   bool bind(const string& name, Expr prev_bound_obj, Expr obj);
 123
 124  private:
 125   /** Marks expression obj with name as overloaded.
 126    * Adds relevant information to the type arg trie data structure.
 127    * It returns false if there is already an expression bound to that name
 128    * whose type expects the same arguments as the type of obj but is not
 129    * identical to the type of obj.  For example, if we declare :
 130    *
 131    * (declare-datatypes () ((List (cons (hd Int) (tl List)) (nil))))
 132    * (declare-fun cons (Int List) List)
 133    *
 134    * cons : constructor_type( Int, List, List )
 135    * cons : function_type( Int, List, List )
 136    *
 137    * These are put in the same place in the trie but do not have identical type,
 138    * hence we return false.
 139    */
 140   bool markOverloaded(const string& name, Expr obj);
 141   /** the null expression */
 142   Expr d_nullExpr;
 143   // The (context-independent) trie storing that maps expected argument
 144   // vectors to symbols. All expressions stored in d_symbols are only
 145   // interpreted as active if they also appear in the context-dependent
 146   // set d_overloaded_symbols.
 147   class TypeArgTrie {
 148    public:
 149     // children of this node
 150     std::map<Type, TypeArgTrie> d_children;
 151     // symbols at this node
 152     std::map<Type, Expr> d_symbols;
 153   };
 154   /** for each string with operator overloading, this stores the data structure
 155    * above. */
 156   std::unordered_map<std::string, TypeArgTrie> d_overload_type_arg_trie;
 157   /** The set of overloaded symbols. */
 158   CDHashSet<Expr, ExprHashFunction>* d_overloaded_symbols;
 159   /** allow function variants
 160    * This is true if we allow overloading (non-constant) functions that expect
 161    * the same argument types.
 162    */
 163   bool d_allowFunctionVariants;
 164   /** get unique overloaded function
 165   * If tat->d_symbols contains an active overloaded function, it
 166   * returns that function, where that function must be unique
 167   * if reqUnique=true.
 168   * Otherwise, it returns the null expression.
 169   */
 170   Expr getOverloadedFunctionAt(const TypeArgTrie* tat, bool reqUnique=true) const;
 171 };
 172
 173 bool OverloadedTypeTrie::isOverloadedFunction(Expr fun) const {
 174   return d_overloaded_symbols->find(fun) != d_overloaded_symbols->end();
 175 }
 176
 177 Expr OverloadedTypeTrie::getOverloadedConstantForType(const std::string& name,
 178                                                       Type t) const {
 179   std::unordered_map<std::string, TypeArgTrie>::const_iterator it =
 180       d_overload_type_arg_trie.find(name);
 181   if (it != d_overload_type_arg_trie.end()) {
 182     std::map<Type, Expr>::const_iterator its = it->second.d_symbols.find(t);
 183     if (its != it->second.d_symbols.end()) {
 184       Expr expr = its->second;
 185       // must be an active symbol
 186       if (isOverloadedFunction(expr)) {
 187         return expr;
 188       }
 189     }
 190   }
 191   return d_nullExpr;
 192 }
 193
 194 Expr OverloadedTypeTrie::getOverloadedFunctionForTypes(
 195     const std::string& name, const std::vector<Type>& argTypes) const {
 196   std::unordered_map<std::string, TypeArgTrie>::const_iterator it =
 197       d_overload_type_arg_trie.find(name);
 198   if (it != d_overload_type_arg_trie.end()) {
 199     const TypeArgTrie* tat = &it->second;
 200     for (unsigned i = 0; i < argTypes.size(); i++) {
 201       std::map<Type, TypeArgTrie>::const_iterator itc =
 202           tat->d_children.find(argTypes[i]);
 203       if (itc != tat->d_children.end()) {
 204         tat = &itc->second;
 205       } else {
 206         Trace("parser-overloading")
 207             << "Could not find overloaded function " << name << std::endl;
 208         // it may be a parametric datatype
 209         TypeNode tna = TypeNode::fromType(argTypes[i]);
 210         if (tna.isParametricDatatype())
 211         {
 212           Trace("parser-overloading")
 213               << "Parametric overloaded datatype selector " << name << " "
 214               << tna << std::endl;
 215           DatatypeType tnd = static_cast<DatatypeType>(argTypes[i]);
 216           const Datatype& dt = tnd.getDatatype();
 217           // tng is the "generalized" version of the instantiated parametric
 218           // type tna
 219           Type tng = dt.getDatatypeType();
 220           itc = tat->d_children.find(tng);
 221           if (itc != tat->d_children.end())
 222           {
 223             tat = &itc->second;
 224           }
 225         }
 226         if (tat == nullptr)
 227         {
 228           // no functions match
 229           return d_nullExpr;
 230         }
 231       }
 232     }
 233     // we ensure that there is *only* one active symbol at this node
 234     return getOverloadedFunctionAt(tat);
 235   }
 236   return d_nullExpr;
 237 }
 238
 239 bool OverloadedTypeTrie::bind(const string& name, Expr prev_bound_obj,
 240                               Expr obj) {
 241   bool retprev = true;
 242   if (!isOverloadedFunction(prev_bound_obj)) {
 243     // mark previous as overloaded
 244     retprev = markOverloaded(name, prev_bound_obj);
 245   }
 246   // mark this as overloaded
 247   bool retobj = markOverloaded(name, obj);
 248   return retprev && retobj;
 249 }
 250
 251 bool OverloadedTypeTrie::markOverloaded(const string& name, Expr obj) {
 252   Trace("parser-overloading") << "Overloaded function : " << name;
 253   Trace("parser-overloading") << " with type " << obj.getType() << std::endl;
 254   // get the argument types
 255   Type t = obj.getType();
 256   Type rangeType = t;
 257   std::vector<Type> argTypes;
 258   if (t.isFunction()) {
 259     argTypes = static_cast<FunctionType>(t).getArgTypes();
 260     rangeType = static_cast<FunctionType>(t).getRangeType();
 261   } else if (t.isConstructor()) {
 262     argTypes = static_cast<ConstructorType>(t).getArgTypes();
 263     rangeType = static_cast<ConstructorType>(t).getRangeType();
 264   } else if (t.isTester()) {
 265     argTypes.push_back(static_cast<TesterType>(t).getDomain());
 266     rangeType = static_cast<TesterType>(t).getRangeType();
 267   } else if (t.isSelector()) {
 268     argTypes.push_back(static_cast<SelectorType>(t).getDomain());
 269     rangeType = static_cast<SelectorType>(t).getRangeType();
 270   }
 271   // add to the trie
 272   TypeArgTrie* tat = &d_overload_type_arg_trie[name];
 273   for (unsigned i = 0; i < argTypes.size(); i++) {
 274     tat = &(tat->d_children[argTypes[i]]);
 275   }
 276
 277   // check if function variants are allowed here
 278   if (d_allowFunctionVariants || argTypes.empty())
 279   {
 280     // they are allowed, check for redefinition
 281     std::map<Type, Expr>::iterator it = tat->d_symbols.find(rangeType);
 282     if (it != tat->d_symbols.end())
 283     {
 284       Expr prev_obj = it->second;
 285       // if there is already an active function with the same name and expects
 286       // the same argument types and has the same return type, we reject the
 287       // re-declaration here.
 288       if (isOverloadedFunction(prev_obj))
 289       {
 290         return false;
 291       }
 292     }
 293   }
 294   else
 295   {
 296     // they are not allowed, we cannot have any function defined here.
 297     Expr existingFun = getOverloadedFunctionAt(tat, false);
 298     if (!existingFun.isNull())
 299     {
 300       return false;
 301     }
 302   }
 303
 304   // otherwise, update the symbols
 305   d_overloaded_symbols->insert(obj);
 306   tat->d_symbols[rangeType] = obj;
 307   return true;
 308 }
 309
 310 Expr OverloadedTypeTrie::getOverloadedFunctionAt(
 311     const OverloadedTypeTrie::TypeArgTrie* tat, bool reqUnique) const
 312 {
 313   Expr retExpr;
 314   for (std::map<Type, Expr>::const_iterator its = tat->d_symbols.begin();
 315        its != tat->d_symbols.end();
 316        ++its)
 317   {
 318     Expr expr = its->second;
 319     if (isOverloadedFunction(expr))
 320     {
 321       if (retExpr.isNull())
 322       {
 323         if (!reqUnique)
 324         {
 325           return expr;
 326         }
 327         else
 328         {
 329           retExpr = expr;
 330         }
 331       }
 332       else
 333       {
 334         // multiple functions match
 335         return d_nullExpr;
 336       }
 337     }
 338   }
 339   return retExpr;
 340 }
 341
 342 class SymbolTable::Implementation {
 343  public:
 344   Implementation()
 345       : d_context(),
 346         d_exprMap(new (true) CDHashMap<string, Expr>(&d_context)),
 347         d_typeMap(new (true) TypeMap(&d_context))
 348   {
 349     d_overload_trie = new OverloadedTypeTrie(&d_context);
 350   }
 351
 352   ~Implementation() {
 353     d_exprMap->deleteSelf();
 354     d_typeMap->deleteSelf();
 355     delete d_overload_trie;
 356   }
 357
 358   bool bind(const string& name, Expr obj, bool levelZero, bool doOverload);
 359   void bindType(const string& name, Type t, bool levelZero = false);
 360   void bindType(const string& name, const vector<Type>& params, Type t,
 361                 bool levelZero = false);
 362   bool isBound(const string& name) const;
 363   bool isBoundType(const string& name) const;
 364   Expr lookup(const string& name) const;
 365   Type lookupType(const string& name) const;
 366   Type lookupType(const string& name, const vector<Type>& params) const;
 367   size_t lookupArity(const string& name);
 368   void popScope();
 369   void pushScope();
 370   size_t getLevel() const;
 371   void reset();
 372   //------------------------ operator overloading
 373   /** implementation of function from header */
 374   bool isOverloadedFunction(Expr fun) const;
 375
 376   /** implementation of function from header */
 377   Expr getOverloadedConstantForType(const std::string& name, Type t) const;
 378
 379   /** implementation of function from header */
 380   Expr getOverloadedFunctionForTypes(const std::string& name,
 381                                      const std::vector<Type>& argTypes) const;
 382   //------------------------ end operator overloading
 383  private:
 384   /** The context manager for the scope maps. */
 385   Context d_context;
 386
 387   /** A map for expressions. */
 388   CDHashMap<string, Expr>* d_exprMap;
 389
 390   /** A map for types. */
 391   using TypeMap = CDHashMap<string, std::pair<vector<Type>, Type>>;
 392   TypeMap* d_typeMap;
 393
 394   //------------------------ operator overloading
 395   // the null expression
 396   Expr d_nullExpr;
 397   // overloaded type trie, stores all information regarding overloading
 398   OverloadedTypeTrie* d_overload_trie;
 399   /** bind with overloading
 400    * This is called whenever obj is bound to name where overloading symbols is
 401    * allowed. If a symbol is previously bound to that name, it marks both as
 402    * overloaded. Returns false if the binding was invalid.
 403    */
 404   bool bindWithOverloading(const string& name, Expr obj);
 405   //------------------------ end operator overloading
 406 }; /* SymbolTable::Implementation */
 407
 408 bool SymbolTable::Implementation::bind(const string& name, Expr obj,
 409                                        bool levelZero, bool doOverload) {
 410   PrettyCheckArgument(!obj.isNull(), obj, "cannot bind to a null Expr");
 411   ExprManagerScope ems(obj);
 412   if (doOverload) {
 413     if (!bindWithOverloading(name, obj)) {
 414       return false;
 415     }
 416   }
 417   if (levelZero) {
 418     d_exprMap->insertAtContextLevelZero(name, obj);
 419   } else {
 420     d_exprMap->insert(name, obj);
 421   }
 422   return true;
 423 }
 424
 425 bool SymbolTable::Implementation::isBound(const string& name) const {
 426   return d_exprMap->find(name) != d_exprMap->end();
 427 }
 428
 429 Expr SymbolTable::Implementation::lookup(const string& name) const {
 430   Assert(isBound(name));
 431   Expr expr = (*d_exprMap->find(name)).second;
 432   if (isOverloadedFunction(expr)) {
 433     return d_nullExpr;
 434   } else {
 435     return expr;
 436   }
 437 }
 438
 439 void SymbolTable::Implementation::bindType(const string& name, Type t,
 440                                            bool levelZero) {
 441   if (levelZero) {
 442     d_typeMap->insertAtContextLevelZero(name, make_pair(vector<Type>(), t));
 443   } else {
 444     d_typeMap->insert(name, make_pair(vector<Type>(), t));
 445   }
 446 }
 447
 448 void SymbolTable::Implementation::bindType(const string& name,
 449                                            const vector<Type>& params, Type t,
 450                                            bool levelZero) {
 451   if (Debug.isOn("sort")) {
 452     Debug("sort") << "bindType(" << name << ", [";
 453     if (params.size() > 0) {
 454       copy(params.begin(), params.end() - 1,
 455            ostream_iterator<Type>(Debug("sort"), ", "));
 456       Debug("sort") << params.back();
 457     }
 458     Debug("sort") << "], " << t << ")" << endl;
 459   }
 460   if (levelZero) {
 461     d_typeMap->insertAtContextLevelZero(name, make_pair(params, t));
 462   } else {
 463     d_typeMap->insert(name, make_pair(params, t));
 464   }
 465 }
 466
 467 bool SymbolTable::Implementation::isBoundType(const string& name) const {
 468   return d_typeMap->find(name) != d_typeMap->end();
 469 }
 470
 471 Type SymbolTable::Implementation::lookupType(const string& name) const {
 472   pair<vector<Type>, Type> p = (*d_typeMap->find(name)).second;
 473   PrettyCheckArgument(p.first.size() == 0, name,
 474                       "type constructor arity is wrong: "
 475                       "`%s' requires %u parameters but was provided 0",
 476                       name.c_str(), p.first.size());
 477   return p.second;
 478 }
 479
 480 Type SymbolTable::Implementation::lookupType(const string& name,
 481                                              const vector<Type>& params) const {
 482   pair<vector<Type>, Type> p = (*d_typeMap->find(name)).second;
 483   PrettyCheckArgument(p.first.size() == params.size(), params,
 484                       "type constructor arity is wrong: "
 485                       "`%s' requires %u parameters but was provided %u",
 486                       name.c_str(), p.first.size(), params.size());
 487   if (p.first.size() == 0) {
 488     PrettyCheckArgument(p.second.isSort(), name.c_str());
 489     return p.second;
 490   }
 491   if (p.second.isSortConstructor()) {
 492     if (Debug.isOn("sort")) {
 493       Debug("sort") << "instantiating using a sort constructor" << endl;
 494       Debug("sort") << "have formals [";
 495       copy(p.first.begin(), p.first.end() - 1,
 496            ostream_iterator<Type>(Debug("sort"), ", "));
 497       Debug("sort") << p.first.back() << "]" << endl << "parameters   [";
 498       copy(params.begin(), params.end() - 1,
 499            ostream_iterator<Type>(Debug("sort"), ", "));
 500       Debug("sort") << params.back() << "]" << endl
 501                     << "type ctor    " << name << endl
 502                     << "type is      " << p.second << endl;
 503     }
 504
 505     Type instantiation = SortConstructorType(p.second).instantiate(params);
 506
 507     Debug("sort") << "instance is  " << instantiation << endl;
 508
 509     return instantiation;
 510   } else if (p.second.isDatatype()) {
 511     PrettyCheckArgument(DatatypeType(p.second).isParametric(), name,
 512                         "expected parametric datatype");
 513     return DatatypeType(p.second).instantiate(params);
 514   } else {
 515     if (Debug.isOn("sort")) {
 516       Debug("sort") << "instantiating using a sort substitution" << endl;
 517       Debug("sort") << "have formals [";
 518       copy(p.first.begin(), p.first.end() - 1,
 519            ostream_iterator<Type>(Debug("sort"), ", "));
 520       Debug("sort") << p.first.back() << "]" << endl << "parameters   [";
 521       copy(params.begin(), params.end() - 1,
 522            ostream_iterator<Type>(Debug("sort"), ", "));
 523       Debug("sort") << params.back() << "]" << endl
 524                     << "type ctor    " << name << endl
 525                     << "type is      " << p.second << endl;
 526     }
 527
 528     Type instantiation = p.second.substitute(p.first, params);
 529
 530     Debug("sort") << "instance is  " << instantiation << endl;
 531
 532     return instantiation;
 533   }
 534 }
 535
 536 size_t SymbolTable::Implementation::lookupArity(const string& name) {
 537   pair<vector<Type>, Type> p = (*d_typeMap->find(name)).second;
 538   return p.first.size();
 539 }
 540
 541 void SymbolTable::Implementation::popScope() {
 542   if (d_context.getLevel() == 0) {
 543     throw ScopeException();
 544   }
 545   d_context.pop();
 546 }
 547
 548 void SymbolTable::Implementation::pushScope() { d_context.push(); }
 549
 550 size_t SymbolTable::Implementation::getLevel() const {
 551   return d_context.getLevel();
 552 }
 553
 554 void SymbolTable::Implementation::reset() {
 555   this->SymbolTable::Implementation::~Implementation();
 556   new (this) SymbolTable::Implementation();
 557 }
 558
 559 bool SymbolTable::Implementation::isOverloadedFunction(Expr fun) const {
 560   return d_overload_trie->isOverloadedFunction(fun);
 561 }
 562
 563 Expr SymbolTable::Implementation::getOverloadedConstantForType(
 564     const std::string& name, Type t) const {
 565   return d_overload_trie->getOverloadedConstantForType(name, t);
 566 }
 567
 568 Expr SymbolTable::Implementation::getOverloadedFunctionForTypes(
 569     const std::string& name, const std::vector<Type>& argTypes) const {
 570   return d_overload_trie->getOverloadedFunctionForTypes(name, argTypes);
 571 }
 572
 573 bool SymbolTable::Implementation::bindWithOverloading(const string& name,
 574                                                       Expr obj) {
 575   CDHashMap<string, Expr>::const_iterator it = d_exprMap->find(name);
 576   if (it != d_exprMap->end()) {
 577     const Expr& prev_bound_obj = (*it).second;
 578     if (prev_bound_obj != obj) {
 579       return d_overload_trie->bind(name, prev_bound_obj, obj);
 580     }
 581   }
 582   return true;
 583 }
 584
 585 bool SymbolTable::isOverloadedFunction(Expr fun) const {
 586   return d_implementation->isOverloadedFunction(fun);
 587 }
 588
 589 Expr SymbolTable::getOverloadedConstantForType(const std::string& name,
 590                                                Type t) const {
 591   return d_implementation->getOverloadedConstantForType(name, t);
 592 }
 593
 594 Expr SymbolTable::getOverloadedFunctionForTypes(
 595     const std::string& name, const std::vector<Type>& argTypes) const {
 596   return d_implementation->getOverloadedFunctionForTypes(name, argTypes);
 597 }
 598
 599 SymbolTable::SymbolTable()
 600     : d_implementation(new SymbolTable::Implementation()) {}
 601
 602 SymbolTable::~SymbolTable() {}
 603 bool SymbolTable::bind(const string& name,
 604                        Expr obj,
 605                        bool levelZero,
 606                        bool doOverload)
 607 {
 608   return d_implementation->bind(name, obj, levelZero, doOverload);
 609 }
 610
 611 void SymbolTable::bindType(const string& name, Type t, bool levelZero)
 612 {
 613   d_implementation->bindType(name, t, levelZero);
 614 }
 615
 616 void SymbolTable::bindType(const string& name,
 617                            const vector<Type>& params,
 618                            Type t,
 619                            bool levelZero)
 620 {
 621   d_implementation->bindType(name, params, t, levelZero);
 622 }
 623
 624 bool SymbolTable::isBound(const string& name) const
 625 {
 626   return d_implementation->isBound(name);
 627 }
 628 bool SymbolTable::isBoundType(const string& name) const
 629 {
 630   return d_implementation->isBoundType(name);
 631 }
 632 Expr SymbolTable::lookup(const string& name) const
 633 {
 634   return d_implementation->lookup(name);
 635 }
 636 Type SymbolTable::lookupType(const string& name) const
 637 {
 638   return d_implementation->lookupType(name);
 639 }
 640
 641 Type SymbolTable::lookupType(const string& name,
 642                              const vector<Type>& params) const
 643 {
 644   return d_implementation->lookupType(name, params);
 645 }
 646 size_t SymbolTable::lookupArity(const string& name) {
 647   return d_implementation->lookupArity(name);
 648 }
 649 void SymbolTable::popScope() { d_implementation->popScope(); }
 650 void SymbolTable::pushScope() { d_implementation->pushScope(); }
 651 size_t SymbolTable::getLevel() const { return d_implementation->getLevel(); }
 652 void SymbolTable::reset() { d_implementation->reset(); }
 653
 654 }  // namespace CVC4