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/DeclarationName.h" 18 #include "clang/AST/DeclBase.h" 19 #include "clang/AST/DeclCXX.h" 20 #include "clang/AST/Type.h" 21 #include "clang/AST/TypeOrdering.h" 22 #include "llvm/ADT/DenseMap.h" 23 #include "llvm/ADT/SmallSet.h" 24 #include "llvm/ADT/SmallVector.h" 25 #include <list> 26 #include <map> 27 #include <cassert> 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 std::map<QualType, std::pair<bool, unsigned>, QualTypeOrdering> 132 ClassSubobjects; 133 134 /// FindAmbiguities - Whether Sema::IsDerivedFrom should try find 135 /// ambiguous paths while it is looking for a path from a derived 136 /// type to a base type. 137 bool FindAmbiguities; 138 139 /// RecordPaths - Whether Sema::IsDerivedFrom should record paths 140 /// while it is determining whether there are paths from a derived 141 /// type to a base type. 142 bool RecordPaths; 143 144 /// DetectVirtual - Whether Sema::IsDerivedFrom should abort the search 145 /// if it finds a path that goes across a virtual base. The virtual class 146 /// is also recorded. 147 bool DetectVirtual; 148 149 /// ScratchPath - A BasePath that is used by Sema::lookupInBases 150 /// to help build the set of paths. 151 CXXBasePath ScratchPath; 152 153 /// DetectedVirtual - The base class that is virtual. 154 const RecordType *DetectedVirtual; 155 156 /// \brief Array of the declarations that have been found. This 157 /// array is constructed only if needed, e.g., to iterate over the 158 /// results within LookupResult. 159 NamedDecl **DeclsFound; 160 unsigned NumDeclsFound; 161 162 friend class CXXRecordDecl; 163 164 void ComputeDeclsFound(); 165 166 bool lookupInBases(ASTContext &Context, 167 const CXXRecordDecl *Record, 168 CXXRecordDecl::BaseMatchesCallback *BaseMatches, 169 void *UserData); 170 public: 171 typedef std::list<CXXBasePath>::iterator paths_iterator; 172 typedef std::list<CXXBasePath>::const_iterator const_paths_iterator; 173 typedef NamedDecl **decl_iterator; 174 175 /// BasePaths - Construct a new BasePaths structure to record the 176 /// paths for a derived-to-base search. 177 explicit CXXBasePaths(bool FindAmbiguities = true, 178 bool RecordPaths = true, 179 bool DetectVirtual = true) 180 : FindAmbiguities(FindAmbiguities), RecordPaths(RecordPaths), 181 DetectVirtual(DetectVirtual), DetectedVirtual(0), DeclsFound(0), 182 NumDeclsFound(0) { } 183 184 ~CXXBasePaths() { delete [] DeclsFound; } 185 186 paths_iterator begin() { return Paths.begin(); } 187 paths_iterator end() { return Paths.end(); } 188 const_paths_iterator begin() const { return Paths.begin(); } 189 const_paths_iterator end() const { return Paths.end(); } 190 191 CXXBasePath& front() { return Paths.front(); } 192 const CXXBasePath& front() const { return Paths.front(); } 193 194 decl_iterator found_decls_begin(); 195 decl_iterator found_decls_end(); 196 197 /// \brief Determine whether the path from the most-derived type to the 198 /// given base type is ambiguous (i.e., it refers to multiple subobjects of 199 /// the same base type). 200 bool isAmbiguous(CanQualType BaseType); 201 202 /// \brief Whether we are finding multiple paths to detect ambiguities. 203 bool isFindingAmbiguities() const { return FindAmbiguities; } 204 205 /// \brief Whether we are recording paths. 206 bool isRecordingPaths() const { return RecordPaths; } 207 208 /// \brief Specify whether we should be recording paths or not. 209 void setRecordingPaths(bool RP) { RecordPaths = RP; } 210 211 /// \brief Whether we are detecting virtual bases. 212 bool isDetectingVirtual() const { return DetectVirtual; } 213 214 /// \brief The virtual base discovered on the path (if we are merely 215 /// detecting virtuals). 216 const RecordType* getDetectedVirtual() const { 217 return DetectedVirtual; 218 } 219 220 /// \brief Retrieve the type from which this base-paths search 221 /// began 222 CXXRecordDecl *getOrigin() const { return Origin; } 223 void setOrigin(CXXRecordDecl *Rec) { Origin = Rec; } 224 225 /// \brief Clear the base-paths results. 226 void clear(); 227 228 /// \brief Swap this data structure's contents with another CXXBasePaths 229 /// object. 230 void swap(CXXBasePaths &Other); 231 }; 232 233 /// \brief Uniquely identifies a virtual method within a class 234 /// hierarchy by the method itself and a class subobject number. 235 struct UniqueVirtualMethod { 236 UniqueVirtualMethod() : Method(0), Subobject(0), InVirtualSubobject(0) { } 237 238 UniqueVirtualMethod(CXXMethodDecl *Method, unsigned Subobject, 239 const CXXRecordDecl *InVirtualSubobject) 240 : Method(Method), Subobject(Subobject), 241 InVirtualSubobject(InVirtualSubobject) { } 242 243 /// \brief The overriding virtual method. 244 CXXMethodDecl *Method; 245 246 /// \brief The subobject in which the overriding virtual method 247 /// resides. 248 unsigned Subobject; 249 250 /// \brief The virtual base class subobject of which this overridden 251 /// virtual method is a part. Note that this records the closest 252 /// derived virtual base class subobject. 253 const CXXRecordDecl *InVirtualSubobject; 254 255 friend bool operator==(const UniqueVirtualMethod &X, 256 const UniqueVirtualMethod &Y) { 257 return X.Method == Y.Method && X.Subobject == Y.Subobject && 258 X.InVirtualSubobject == Y.InVirtualSubobject; 259 } 260 261 friend bool operator!=(const UniqueVirtualMethod &X, 262 const UniqueVirtualMethod &Y) { 263 return !(X == Y); 264 } 265 }; 266 267 /// \brief The set of methods that override a given virtual method in 268 /// each subobject where it occurs. 269 /// 270 /// The first part of the pair is the subobject in which the 271 /// overridden virtual function occurs, while the second part of the 272 /// pair is the virtual method that overrides it (including the 273 /// subobject in which that virtual function occurs). 274 class OverridingMethods { 275 llvm::DenseMap<unsigned, SmallVector<UniqueVirtualMethod, 4> > 276 Overrides; 277 278 public: 279 // Iterate over the set of subobjects that have overriding methods. 280 typedef llvm::DenseMap<unsigned, SmallVector<UniqueVirtualMethod, 4> > 281 ::iterator iterator; 282 typedef llvm::DenseMap<unsigned, SmallVector<UniqueVirtualMethod, 4> > 283 ::const_iterator const_iterator; 284 iterator begin() { return Overrides.begin(); } 285 const_iterator begin() const { return Overrides.begin(); } 286 iterator end() { return Overrides.end(); } 287 const_iterator end() const { return Overrides.end(); } 288 unsigned size() const { return Overrides.size(); } 289 290 // Iterate over the set of overriding virtual methods in a given 291 // subobject. 292 typedef SmallVector<UniqueVirtualMethod, 4>::iterator 293 overriding_iterator; 294 typedef SmallVector<UniqueVirtualMethod, 4>::const_iterator 295 overriding_const_iterator; 296 297 // Add a new overriding method for a particular subobject. 298 void add(unsigned OverriddenSubobject, UniqueVirtualMethod Overriding); 299 300 // Add all of the overriding methods from "other" into overrides for 301 // this method. Used when merging the overrides from multiple base 302 // class subobjects. 303 void add(const OverridingMethods &Other); 304 305 // Replace all overriding virtual methods in all subobjects with the 306 // given virtual method. 307 void replaceAll(UniqueVirtualMethod Overriding); 308 }; 309 310 /// \brief A mapping from each virtual member function to its set of 311 /// final overriders. 312 /// 313 /// Within a class hierarchy for a given derived class, each virtual 314 /// member function in that hierarchy has one or more "final 315 /// overriders" (C++ [class.virtual]p2). A final overrider for a 316 /// virtual function "f" is the virtual function that will actually be 317 /// invoked when dispatching a call to "f" through the 318 /// vtable. Well-formed classes have a single final overrider for each 319 /// virtual function; in abstract classes, the final overrider for at 320 /// least one virtual function is a pure virtual function. Due to 321 /// multiple, virtual inheritance, it is possible for a class to have 322 /// more than one final overrider. Athough this is an error (per C++ 323 /// [class.virtual]p2), it is not considered an error here: the final 324 /// overrider map can represent multiple final overriders for a 325 /// method, and it is up to the client to determine whether they are 326 /// problem. For example, the following class \c D has two final 327 /// overriders for the virtual function \c A::f(), one in \c C and one 328 /// in \c D: 329 /// 330 /// \code 331 /// struct A { virtual void f(); }; 332 /// struct B : virtual A { virtual void f(); }; 333 /// struct C : virtual A { virtual void f(); }; 334 /// struct D : B, C { }; 335 /// \endcode 336 /// 337 /// This data structure contaings a mapping from every virtual 338 /// function *that does not override an existing virtual function* and 339 /// in every subobject where that virtual function occurs to the set 340 /// of virtual functions that override it. Thus, the same virtual 341 /// function \c A::f can actually occur in multiple subobjects of type 342 /// \c A due to multiple inheritance, and may be overriden by 343 /// different virtual functions in each, as in the following example: 344 /// 345 /// \code 346 /// struct A { virtual void f(); }; 347 /// struct B : A { virtual void f(); }; 348 /// struct C : A { virtual void f(); }; 349 /// struct D : B, C { }; 350 /// \endcode 351 /// 352 /// Unlike in the previous example, where the virtual functions \c 353 /// B::f and \c C::f both overrode \c A::f in the same subobject of 354 /// type \c A, in this example the two virtual functions both override 355 /// \c A::f but in *different* subobjects of type A. This is 356 /// represented by numbering the subobjects in which the overridden 357 /// and the overriding virtual member functions are located. Subobject 358 /// 0 represents the virtua base class subobject of that type, while 359 /// subobject numbers greater than 0 refer to non-virtual base class 360 /// subobjects of that type. 361 class CXXFinalOverriderMap 362 : public llvm::DenseMap<const CXXMethodDecl *, OverridingMethods> { }; 363 364 /// \brief A set of all the primary bases for a class. 365 class CXXIndirectPrimaryBaseSet 366 : public llvm::SmallSet<const CXXRecordDecl*, 32> { }; 367 368 } // end namespace clang 369 370 #endif 371
