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