clang  3.7.0
CXXInheritance.h
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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"
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.
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.
48 
49  /// \brief The record decl of the class that the base is a base of.
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.
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:
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.
77 
78  /// \brief The set of declarations found inside this base class
79  /// subobject.
81 
82  void 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.
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,
168  void *UserData);
169 public:
170  typedef std::list<CXXBasePath>::iterator paths_iterator;
171  typedef std::list<CXXBasePath>::const_iterator const_paths_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;
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).
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.
236  : Method(nullptr), Subobject(0), InVirtualSubobject(nullptr) { }
237 
240  : Method(Method), Subobject(Subobject),
241  InVirtualSubobject(InVirtualSubobject) { }
242 
243  /// \brief The overriding virtual 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.
254 
255  friend bool operator==(const UniqueVirtualMethod &X,
256  const UniqueVirtualMethod &Y) {
257  return X.Method == Y.Method && X.Subobject == Y.Subobject &&
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).
276  typedef llvm::MapVector<unsigned, ValuesT> MapType;
277  MapType Overrides;
278 
279 public:
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.
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 contains 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 overridden 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 virtual base class subobject of that type, while
358 /// subobject numbers greater than 0 refer to non-virtual base class
359 /// subobjects of that type.
361  : public llvm::MapVector<const CXXMethodDecl *, OverridingMethods> { };
362 
363 /// \brief A set of all the primary bases for a class.
365  : public llvm::SmallSet<const CXXRecordDecl*, 32> { };
366 
367 } // end namespace clang
368 
369 #endif
const RecordType * getDetectedVirtual() const
The virtual base discovered on the path (if we are merely detecting virtuals).
void setOrigin(CXXRecordDecl *Rec)
void swap(CXXBasePaths &Other)
Swap this data structure's contents with another CXXBasePaths object.
MapType::iterator iterator
AccessSpecifier
A C++ access specifier (public, private, protected), plus the special value "none" which means differ...
Definition: Specifiers.h:83
Represents a path from a specific derived class (which is not represented as part of the path) to a p...
DeclContext::lookup_result Decls
The set of declarations found inside this base class subobject.
void clear()
Clear the base-paths results.
MapType::const_iterator const_iterator
std::list< CXXBasePath >::const_iterator const_paths_iterator
bool isFindingAmbiguities() const
Whether we are finding multiple paths to detect ambiguities.
friend bool operator!=(const UniqueVirtualMethod &X, const UniqueVirtualMethod &Y)
void setRecordingPaths(bool RP)
Specify whether we should be recording paths or not.
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:89
The results of name lookup within a DeclContext. This is either a single result (with no stable stora...
Definition: DeclBase.h:1034
bool isRecordingPaths() const
Whether we are recording paths.
void add(unsigned OverriddenSubobject, UniqueVirtualMethod Overriding)
CXXMethodDecl * Method
The overriding virtual method.
The set of methods that override a given virtual method in each subobject where it occurs...
bool isDetectingVirtual() const
Whether we are detecting virtual bases.
unsigned size() const
UniqueVirtualMethod(CXXMethodDecl *Method, unsigned Subobject, const CXXRecordDecl *InVirtualSubobject)
ASTContext * Context
const_paths_iterator end() const
Allows QualTypes to be sorted and hence used in maps and sets.
const CXXBasePath & front() const
NamedDecl ** decl_iterator
int SubobjectNumber
Identifies which base class subobject (of type Base->getType()) this base path element refers to...
Uniquely identifies a virtual method within a class hierarchy by the method itself and a class subobj...
decl_range found_decls()
const CXXBaseSpecifier * Base
The base specifier that states the link from a derived class to a base class, which will be followed ...
SmallVectorImpl< UniqueVirtualMethod >::const_iterator overriding_const_iterator
A set of all the primary bases for a class.
bool BaseMatchesCallback(const CXXBaseSpecifier *Specifier, CXXBasePath &Path, void *UserData)
Function type used by lookupInBases() to determine whether a specific base class subobject matches th...
Definition: DeclCXX.h:1506
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1717
paths_iterator begin()
virtual void clear()
const_paths_iterator begin() const
Represents an element in a path from a derived class to a base class.
SmallVectorImpl< UniqueVirtualMethod >::iterator overriding_iterator
unsigned Subobject
The subobject in which the overriding virtual method resides.
A mapping from each virtual member function to its set of final overriders.
const_iterator begin() const
bool isAmbiguous(CanQualType BaseType)
Determine whether the path from the most-derived type to the given base type is ambiguous (i...
friend bool operator==(const UniqueVirtualMethod &X, const UniqueVirtualMethod &Y)
CXXRecordDecl * getOrigin() const
Retrieve the type from which this base-paths search began.
llvm::iterator_range< decl_iterator > decl_range
CXXBasePath & front()
Represents a base class of a C++ class.
Definition: DeclCXX.h:157
CXXBasePaths(bool FindAmbiguities=true, bool RecordPaths=true, bool DetectVirtual=true)
X
Definition: SemaDecl.cpp:11429
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
Represents a C++ struct/union/class.
Definition: DeclCXX.h:285
AccessSpecifier Access
The access along this inheritance path. This is only calculated when recording paths. AS_none is a special value used to indicate a path which permits no legal access.
const CXXRecordDecl * InVirtualSubobject
The virtual base class subobject of which this overridden virtual method is a part. Note that this records the closest derived virtual base class subobject.
void replaceAll(UniqueVirtualMethod Overriding)
paths_iterator end()
const CXXRecordDecl * Class
The record decl of the class that the base is a base of.
std::list< CXXBasePath >::iterator paths_iterator
const_iterator end() const