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/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"
31 class CXXBaseSpecifier;
36 /// \brief Represents an element in a path from a derived class to a
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
47 const CXXBaseSpecifier *Base;
49 /// \brief The record decl of the class that the base is a base of.
50 const CXXRecordDecl *Class;
52 /// \brief Identifies which base class subobject (of type
53 /// \c Base->getType()) this base path element refers to.
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
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.
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 llvm::SmallVector<CXXBasePathElement, 4> {
71 CXXBasePath() : Access(AS_public) {}
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;
78 /// \brief The set of declarations found inside this base class
80 DeclContext::lookup_result Decls;
83 llvm::SmallVectorImpl<CXXBasePathElement>::clear();
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:
94 /// class B : public A { };
95 /// class C : public A { };
96 /// class D : public B, public C{ };
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:
108 /// class B : public virtual A { };
109 /// class C : public virtual A { };
110 /// class D : public B, public C{ };
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.
118 /// \brief The type from which this search originated.
119 CXXRecordDecl *Origin;
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;
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>
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;
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.
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.
149 /// ScratchPath - A BasePath that is used by Sema::lookupInBases
150 /// to help build the set of paths.
151 CXXBasePath ScratchPath;
153 /// DetectedVirtual - The base class that is virtual.
154 const RecordType *DetectedVirtual;
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;
162 friend class CXXRecordDecl;
164 void ComputeDeclsFound();
166 bool lookupInBases(ASTContext &Context,
167 const CXXRecordDecl *Record,
168 CXXRecordDecl::BaseMatchesCallback *BaseMatches,
171 typedef std::list<CXXBasePath>::iterator paths_iterator;
172 typedef std::list<CXXBasePath>::const_iterator const_paths_iterator;
173 typedef NamedDecl **decl_iterator;
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),
184 ~CXXBasePaths() { delete [] DeclsFound; }
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(); }
191 CXXBasePath& front() { return Paths.front(); }
192 const CXXBasePath& front() const { return Paths.front(); }
194 decl_iterator found_decls_begin();
195 decl_iterator found_decls_end();
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);
202 /// \brief Whether we are finding multiple paths to detect ambiguities.
203 bool isFindingAmbiguities() const { return FindAmbiguities; }
205 /// \brief Whether we are recording paths.
206 bool isRecordingPaths() const { return RecordPaths; }
208 /// \brief Specify whether we should be recording paths or not.
209 void setRecordingPaths(bool RP) { RecordPaths = RP; }
211 /// \brief Whether we are detecting virtual bases.
212 bool isDetectingVirtual() const { return DetectVirtual; }
214 /// \brief The virtual base discovered on the path (if we are merely
215 /// detecting virtuals).
216 const RecordType* getDetectedVirtual() const {
217 return DetectedVirtual;
220 /// \brief Retrieve the type from which this base-paths search
222 CXXRecordDecl *getOrigin() const { return Origin; }
223 void setOrigin(CXXRecordDecl *Rec) { Origin = Rec; }
225 /// \brief Clear the base-paths results.
228 /// \brief Swap this data structure's contents with another CXXBasePaths
230 void swap(CXXBasePaths &Other);
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) { }
238 UniqueVirtualMethod(CXXMethodDecl *Method, unsigned Subobject,
239 const CXXRecordDecl *InVirtualSubobject)
240 : Method(Method), Subobject(Subobject),
241 InVirtualSubobject(InVirtualSubobject) { }
243 /// \brief The overriding virtual method.
244 CXXMethodDecl *Method;
246 /// \brief The subobject in which the overriding virtual method
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;
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;
261 friend bool operator!=(const UniqueVirtualMethod &X,
262 const UniqueVirtualMethod &Y) {
267 /// \brief The set of methods that override a given virtual method in
268 /// each subobject where it occurs.
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, llvm::SmallVector<UniqueVirtualMethod, 4> >
279 // Iterate over the set of subobjects that have overriding methods.
280 typedef llvm::DenseMap<unsigned, llvm::SmallVector<UniqueVirtualMethod, 4> >
282 typedef llvm::DenseMap<unsigned, llvm::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(); }
290 // Iterate over the set of overriding virtual methods in a given
292 typedef llvm::SmallVector<UniqueVirtualMethod, 4>::iterator
294 typedef llvm::SmallVector<UniqueVirtualMethod, 4>::const_iterator
295 overriding_const_iterator;
297 // Add a new overriding method for a particular subobject.
298 void add(unsigned OverriddenSubobject, UniqueVirtualMethod Overriding);
300 // Add all of the overriding methods from "other" into overrides for
301 // this method. Used when merging the overrides from multiple base
303 void add(const OverridingMethods &Other);
305 // Replace all overriding virtual methods in all subobjects with the
306 // given virtual method.
307 void replaceAll(UniqueVirtualMethod Overriding);
310 /// \brief A mapping from each virtual member function to its set of
311 /// final overriders.
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
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 { };
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:
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 { };
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> { };
364 /// \brief A set of all the primary bases for a class.
365 class CXXIndirectPrimaryBaseSet
366 : public llvm::SmallSet<const CXXRecordDecl*, 32> { };
368 } // end namespace clang