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 29namespace clang { 30 31class CXXBaseSpecifier; 32class CXXMethodDecl; 33class CXXRecordDecl; 34class 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. 43struct 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. 69class CXXBasePath : public SmallVector<CXXBasePathElement, 4> { 70public: 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. 117class 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); 169public: 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(nullptr), 181 DeclsFound(nullptr), 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 typedef llvm::iterator_range<decl_iterator> decl_range; 194 decl_range found_decls(); 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. 234struct UniqueVirtualMethod { 235 UniqueVirtualMethod() 236 : Method(nullptr), Subobject(0), InVirtualSubobject(nullptr) { } 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). 274class OverridingMethods { 275 typedef SmallVector<UniqueVirtualMethod, 4> ValuesT; 276 typedef llvm::MapVector<unsigned, ValuesT> MapType; 277 MapType Overrides; 278 279public: 280 // Iterate over the set of subobjects that have overriding methods. 281 typedef MapType::iterator iterator; 282 typedef MapType::const_iterator const_iterator; 283 iterator begin() { return Overrides.begin(); } 284 const_iterator begin() const { return Overrides.begin(); } 285 iterator end() { return Overrides.end(); } 286 const_iterator end() const { return Overrides.end(); } 287 unsigned size() const { return Overrides.size(); } 288 289 // Iterate over the set of overriding virtual methods in a given 290 // subobject. 291 typedef SmallVectorImpl<UniqueVirtualMethod>::iterator 292 overriding_iterator; 293 typedef SmallVectorImpl<UniqueVirtualMethod>::const_iterator 294 overriding_const_iterator; 295 296 // Add a new overriding method for a particular subobject. 297 void add(unsigned OverriddenSubobject, UniqueVirtualMethod Overriding); 298 299 // Add all of the overriding methods from "other" into overrides for 300 // this method. Used when merging the overrides from multiple base 301 // class subobjects. 302 void add(const OverridingMethods &Other); 303 304 // Replace all overriding virtual methods in all subobjects with the 305 // given virtual method. 306 void replaceAll(UniqueVirtualMethod Overriding); 307}; 308 309/// \brief A mapping from each virtual member function to its set of 310/// final overriders. 311/// 312/// Within a class hierarchy for a given derived class, each virtual 313/// member function in that hierarchy has one or more "final 314/// overriders" (C++ [class.virtual]p2). A final overrider for a 315/// virtual function "f" is the virtual function that will actually be 316/// invoked when dispatching a call to "f" through the 317/// vtable. Well-formed classes have a single final overrider for each 318/// virtual function; in abstract classes, the final overrider for at 319/// least one virtual function is a pure virtual function. Due to 320/// multiple, virtual inheritance, it is possible for a class to have 321/// more than one final overrider. Athough this is an error (per C++ 322/// [class.virtual]p2), it is not considered an error here: the final 323/// overrider map can represent multiple final overriders for a 324/// method, and it is up to the client to determine whether they are 325/// problem. For example, the following class \c D has two final 326/// overriders for the virtual function \c A::f(), one in \c C and one 327/// in \c D: 328/// 329/// \code 330/// struct A { virtual void f(); }; 331/// struct B : virtual A { virtual void f(); }; 332/// struct C : virtual A { virtual void f(); }; 333/// struct D : B, C { }; 334/// \endcode 335/// 336/// This data structure contaings a mapping from every virtual 337/// function *that does not override an existing virtual function* and 338/// in every subobject where that virtual function occurs to the set 339/// of virtual functions that override it. Thus, the same virtual 340/// function \c A::f can actually occur in multiple subobjects of type 341/// \c A due to multiple inheritance, and may be overriden by 342/// different virtual functions in each, as in the following example: 343/// 344/// \code 345/// struct A { virtual void f(); }; 346/// struct B : A { virtual void f(); }; 347/// struct C : A { virtual void f(); }; 348/// struct D : B, C { }; 349/// \endcode 350/// 351/// Unlike in the previous example, where the virtual functions \c 352/// B::f and \c C::f both overrode \c A::f in the same subobject of 353/// type \c A, in this example the two virtual functions both override 354/// \c A::f but in *different* subobjects of type A. This is 355/// represented by numbering the subobjects in which the overridden 356/// and the overriding virtual member functions are located. Subobject 357/// 0 represents the virtua base class subobject of that type, while 358/// subobject numbers greater than 0 refer to non-virtual base class 359/// subobjects of that type. 360class CXXFinalOverriderMap 361 : public llvm::MapVector<const CXXMethodDecl *, OverridingMethods> { }; 362 363/// \brief A set of all the primary bases for a class. 364class CXXIndirectPrimaryBaseSet 365 : public llvm::SmallSet<const CXXRecordDecl*, 32> { }; 366 367} // end namespace clang 368 369#endif 370