1 //===------ CXXInheritance.h - C++ Inheritance ------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file provides routines that help analyzing C++ inheritance hierarchies. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_AST_CXXINHERITANCE_H 15 #define LLVM_CLANG_AST_CXXINHERITANCE_H 16 17 #include "clang/AST/DeclBase.h" 18 #include "clang/AST/DeclCXX.h" 19 #include "clang/AST/DeclarationName.h" 20 #include "clang/AST/Type.h" 21 #include "clang/AST/TypeOrdering.h" 22 #include "llvm/ADT/MapVector.h" 23 #include "llvm/ADT/SmallSet.h" 24 #include "llvm/ADT/SmallVector.h" 25 #include <cassert> 26 #include <list> 27 #include <map> 28 29 namespace clang { 30 31 class CXXBaseSpecifier; 32 class CXXMethodDecl; 33 class CXXRecordDecl; 34 class NamedDecl; 35 36 /// \brief Represents an element in a path from a derived class to a 37 /// base class. 38 /// 39 /// Each step in the path references the link from a 40 /// derived class to one of its direct base classes, along with a 41 /// base "number" that identifies which base subobject of the 42 /// original derived class we are referencing. 43 struct CXXBasePathElement { 44 /// \brief The base specifier that states the link from a derived 45 /// class to a base class, which will be followed by this base 46 /// path element. 47 const CXXBaseSpecifier *Base; 48 49 /// \brief The record decl of the class that the base is a base of. 50 const CXXRecordDecl *Class; 51 52 /// \brief Identifies which base class subobject (of type 53 /// \c Base->getType()) this base path element refers to. 54 /// 55 /// This value is only valid if \c !Base->isVirtual(), because there 56 /// is no base numbering for the zero or one virtual bases of a 57 /// given type. 58 int SubobjectNumber; 59 }; 60 61 /// \brief Represents a path from a specific derived class 62 /// (which is not represented as part of the path) to a particular 63 /// (direct or indirect) base class subobject. 64 /// 65 /// Individual elements in the path are described by the \c CXXBasePathElement 66 /// structure, which captures both the link from a derived class to one of its 67 /// direct bases and identification describing which base class 68 /// subobject is being used. 69 class CXXBasePath : public SmallVector<CXXBasePathElement, 4> { 70 public: 71 CXXBasePath() : Access(AS_public) {} 72 73 /// \brief The access along this inheritance path. This is only 74 /// calculated when recording paths. AS_none is a special value 75 /// used to indicate a path which permits no legal access. 76 AccessSpecifier Access; 77 78 /// \brief The set of declarations found inside this base class 79 /// subobject. 80 DeclContext::lookup_result Decls; 81 82 void clear() { 83 SmallVectorImpl<CXXBasePathElement>::clear(); 84 Access = AS_public; 85 } 86 }; 87 88 /// BasePaths - Represents the set of paths from a derived class to 89 /// one of its (direct or indirect) bases. For example, given the 90 /// following class hierarchy: 91 /// 92 /// @code 93 /// class A { }; 94 /// class B : public A { }; 95 /// class C : public A { }; 96 /// class D : public B, public C{ }; 97 /// @endcode 98 /// 99 /// There are two potential BasePaths to represent paths from D to a 100 /// base subobject of type A. One path is (D,0) -> (B,0) -> (A,0) 101 /// and another is (D,0)->(C,0)->(A,1). These two paths actually 102 /// refer to two different base class subobjects of the same type, 103 /// so the BasePaths object refers to an ambiguous path. On the 104 /// other hand, consider the following class hierarchy: 105 /// 106 /// @code 107 /// class A { }; 108 /// class B : public virtual A { }; 109 /// class C : public virtual A { }; 110 /// class D : public B, public C{ }; 111 /// @endcode 112 /// 113 /// Here, there are two potential BasePaths again, (D, 0) -> (B, 0) 114 /// -> (A,v) and (D, 0) -> (C, 0) -> (A, v), but since both of them 115 /// refer to the same base class subobject of type A (the virtual 116 /// one), there is no ambiguity. 117 class CXXBasePaths { 118 /// \brief The type from which this search originated. 119 CXXRecordDecl *Origin; 120 121 /// Paths - The actual set of paths that can be taken from the 122 /// derived class to the same base class. 123 std::list<CXXBasePath> Paths; 124 125 /// ClassSubobjects - Records the class subobjects for each class 126 /// type that we've seen. The first element in the pair says 127 /// whether we found a path to a virtual base for that class type, 128 /// while the element contains the number of non-virtual base 129 /// class subobjects for that class type. The key of the map is 130 /// the cv-unqualified canonical type of the base class subobject. 131 llvm::SmallDenseMap<QualType, std::pair<bool, unsigned>, 8> ClassSubobjects; 132 133 /// FindAmbiguities - Whether Sema::IsDerivedFrom should try find 134 /// ambiguous paths while it is looking for a path from a derived 135 /// type to a base type. 136 bool FindAmbiguities; 137 138 /// RecordPaths - Whether Sema::IsDerivedFrom should record paths 139 /// while it is determining whether there are paths from a derived 140 /// type to a base type. 141 bool RecordPaths; 142 143 /// DetectVirtual - Whether Sema::IsDerivedFrom should abort the search 144 /// if it finds a path that goes across a virtual base. The virtual class 145 /// is also recorded. 146 bool DetectVirtual; 147 148 /// ScratchPath - A BasePath that is used by Sema::lookupInBases 149 /// to help build the set of paths. 150 CXXBasePath ScratchPath; 151 152 /// DetectedVirtual - The base class that is virtual. 153 const RecordType *DetectedVirtual; 154 155 /// \brief Array of the declarations that have been found. This 156 /// array is constructed only if needed, e.g., to iterate over the 157 /// results within LookupResult. 158 NamedDecl **DeclsFound; 159 unsigned NumDeclsFound; 160 161 friend class CXXRecordDecl; 162 163 void ComputeDeclsFound(); 164 165 bool lookupInBases(ASTContext &Context, 166 const CXXRecordDecl *Record, 167 CXXRecordDecl::BaseMatchesCallback *BaseMatches, 168 void *UserData); 169 public: 170 typedef std::list<CXXBasePath>::iterator paths_iterator; 171 typedef std::list<CXXBasePath>::const_iterator const_paths_iterator; 172 typedef NamedDecl **decl_iterator; 173 174 /// BasePaths - Construct a new BasePaths structure to record the 175 /// paths for a derived-to-base search. 176 explicit CXXBasePaths(bool FindAmbiguities = true, 177 bool RecordPaths = true, 178 bool DetectVirtual = true) 179 : FindAmbiguities(FindAmbiguities), RecordPaths(RecordPaths), 180 DetectVirtual(DetectVirtual), DetectedVirtual(0), DeclsFound(0), 181 NumDeclsFound(0) { } 182 183 ~CXXBasePaths() { delete [] DeclsFound; } 184 185 paths_iterator begin() { return Paths.begin(); } 186 paths_iterator end() { return Paths.end(); } 187 const_paths_iterator begin() const { return Paths.begin(); } 188 const_paths_iterator end() const { return Paths.end(); } 189 190 CXXBasePath& front() { return Paths.front(); } 191 const CXXBasePath& front() const { return Paths.front(); } 192 193 decl_iterator found_decls_begin(); 194 decl_iterator found_decls_end(); 195 196 /// \brief Determine whether the path from the most-derived type to the 197 /// given base type is ambiguous (i.e., it refers to multiple subobjects of 198 /// the same base type). 199 bool isAmbiguous(CanQualType BaseType); 200 201 /// \brief Whether we are finding multiple paths to detect ambiguities. 202 bool isFindingAmbiguities() const { return FindAmbiguities; } 203 204 /// \brief Whether we are recording paths. 205 bool isRecordingPaths() const { return RecordPaths; } 206 207 /// \brief Specify whether we should be recording paths or not. 208 void setRecordingPaths(bool RP) { RecordPaths = RP; } 209 210 /// \brief Whether we are detecting virtual bases. 211 bool isDetectingVirtual() const { return DetectVirtual; } 212 213 /// \brief The virtual base discovered on the path (if we are merely 214 /// detecting virtuals). 215 const RecordType* getDetectedVirtual() const { 216 return DetectedVirtual; 217 } 218 219 /// \brief Retrieve the type from which this base-paths search 220 /// began 221 CXXRecordDecl *getOrigin() const { return Origin; } 222 void setOrigin(CXXRecordDecl *Rec) { Origin = Rec; } 223 224 /// \brief Clear the base-paths results. 225 void clear(); 226 227 /// \brief Swap this data structure's contents with another CXXBasePaths 228 /// object. 229 void swap(CXXBasePaths &Other); 230 }; 231 232 /// \brief Uniquely identifies a virtual method within a class 233 /// hierarchy by the method itself and a class subobject number. 234 struct UniqueVirtualMethod { 235 UniqueVirtualMethod() : Method(0), Subobject(0), InVirtualSubobject(0) { } 236 237 UniqueVirtualMethod(CXXMethodDecl *Method, unsigned Subobject, 238 const CXXRecordDecl *InVirtualSubobject) 239 : Method(Method), Subobject(Subobject), 240 InVirtualSubobject(InVirtualSubobject) { } 241 242 /// \brief The overriding virtual method. 243 CXXMethodDecl *Method; 244 245 /// \brief The subobject in which the overriding virtual method 246 /// resides. 247 unsigned Subobject; 248 249 /// \brief The virtual base class subobject of which this overridden 250 /// virtual method is a part. Note that this records the closest 251 /// derived virtual base class subobject. 252 const CXXRecordDecl *InVirtualSubobject; 253 254 friend bool operator==(const UniqueVirtualMethod &X, 255 const UniqueVirtualMethod &Y) { 256 return X.Method == Y.Method && X.Subobject == Y.Subobject && 257 X.InVirtualSubobject == Y.InVirtualSubobject; 258 } 259 260 friend bool operator!=(const UniqueVirtualMethod &X, 261 const UniqueVirtualMethod &Y) { 262 return !(X == Y); 263 } 264 }; 265 266 /// \brief The set of methods that override a given virtual method in 267 /// each subobject where it occurs. 268 /// 269 /// The first part of the pair is the subobject in which the 270 /// overridden virtual function occurs, while the second part of the 271 /// pair is the virtual method that overrides it (including the 272 /// subobject in which that virtual function occurs). 273 class OverridingMethods { 274 typedef SmallVector<UniqueVirtualMethod, 4> ValuesT; 275 typedef llvm::MapVector<unsigned, ValuesT> MapType; 276 MapType Overrides; 277 278 public: 279 // Iterate over the set of subobjects that have overriding methods. 280 typedef MapType::iterator iterator; 281 typedef MapType::const_iterator const_iterator; 282 iterator begin() { return Overrides.begin(); } 283 const_iterator begin() const { return Overrides.begin(); } 284 iterator end() { return Overrides.end(); } 285 const_iterator end() const { return Overrides.end(); } 286 unsigned size() const { return Overrides.size(); } 287 288 // Iterate over the set of overriding virtual methods in a given 289 // subobject. 290 typedef SmallVectorImpl<UniqueVirtualMethod>::iterator 291 overriding_iterator; 292 typedef SmallVectorImpl<UniqueVirtualMethod>::const_iterator 293 overriding_const_iterator; 294 295 // Add a new overriding method for a particular subobject. 296 void add(unsigned OverriddenSubobject, UniqueVirtualMethod Overriding); 297 298 // Add all of the overriding methods from "other" into overrides for 299 // this method. Used when merging the overrides from multiple base 300 // class subobjects. 301 void add(const OverridingMethods &Other); 302 303 // Replace all overriding virtual methods in all subobjects with the 304 // given virtual method. 305 void replaceAll(UniqueVirtualMethod Overriding); 306 }; 307 308 /// \brief A mapping from each virtual member function to its set of 309 /// final overriders. 310 /// 311 /// Within a class hierarchy for a given derived class, each virtual 312 /// member function in that hierarchy has one or more "final 313 /// overriders" (C++ [class.virtual]p2). A final overrider for a 314 /// virtual function "f" is the virtual function that will actually be 315 /// invoked when dispatching a call to "f" through the 316 /// vtable. Well-formed classes have a single final overrider for each 317 /// virtual function; in abstract classes, the final overrider for at 318 /// least one virtual function is a pure virtual function. Due to 319 /// multiple, virtual inheritance, it is possible for a class to have 320 /// more than one final overrider. Athough this is an error (per C++ 321 /// [class.virtual]p2), it is not considered an error here: the final 322 /// overrider map can represent multiple final overriders for a 323 /// method, and it is up to the client to determine whether they are 324 /// problem. For example, the following class \c D has two final 325 /// overriders for the virtual function \c A::f(), one in \c C and one 326 /// in \c D: 327 /// 328 /// \code 329 /// struct A { virtual void f(); }; 330 /// struct B : virtual A { virtual void f(); }; 331 /// struct C : virtual A { virtual void f(); }; 332 /// struct D : B, C { }; 333 /// \endcode 334 /// 335 /// This data structure contaings a mapping from every virtual 336 /// function *that does not override an existing virtual function* and 337 /// in every subobject where that virtual function occurs to the set 338 /// of virtual functions that override it. Thus, the same virtual 339 /// function \c A::f can actually occur in multiple subobjects of type 340 /// \c A due to multiple inheritance, and may be overriden by 341 /// different virtual functions in each, as in the following example: 342 /// 343 /// \code 344 /// struct A { virtual void f(); }; 345 /// struct B : A { virtual void f(); }; 346 /// struct C : A { virtual void f(); }; 347 /// struct D : B, C { }; 348 /// \endcode 349 /// 350 /// Unlike in the previous example, where the virtual functions \c 351 /// B::f and \c C::f both overrode \c A::f in the same subobject of 352 /// type \c A, in this example the two virtual functions both override 353 /// \c A::f but in *different* subobjects of type A. This is 354 /// represented by numbering the subobjects in which the overridden 355 /// and the overriding virtual member functions are located. Subobject 356 /// 0 represents the virtua base class subobject of that type, while 357 /// subobject numbers greater than 0 refer to non-virtual base class 358 /// subobjects of that type. 359 class CXXFinalOverriderMap 360 : public llvm::MapVector<const CXXMethodDecl *, OverridingMethods> { }; 361 362 /// \brief A set of all the primary bases for a class. 363 class CXXIndirectPrimaryBaseSet 364 : public llvm::SmallSet<const CXXRecordDecl*, 32> { }; 365 366 } // end namespace clang 367 368 #endif 369
