1//===- DeclFriend.h - Classes for C++ friend declarations -------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the section of the AST representing C++ friend
10// declarations.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_AST_DECLFRIEND_H
15#define LLVM_CLANG_AST_DECLFRIEND_H
16
17#include "clang/AST/Decl.h"
18#include "clang/AST/DeclBase.h"
19#include "clang/AST/DeclCXX.h"
20#include "clang/AST/DeclTemplate.h"
21#include "clang/AST/ExternalASTSource.h"
22#include "clang/AST/TypeLoc.h"
23#include "clang/Basic/LLVM.h"
24#include "clang/Basic/SourceLocation.h"
25#include "llvm/ADT/ArrayRef.h"
26#include "llvm/ADT/None.h"
27#include "llvm/ADT/PointerUnion.h"
28#include "llvm/Support/Casting.h"
29#include "llvm/Support/Compiler.h"
30#include "llvm/Support/TrailingObjects.h"
31#include <cassert>
32#include <iterator>
33
34namespace clang {
35
36class ASTContext;
37
38/// FriendDecl - Represents the declaration of a friend entity,
39/// which can be a function, a type, or a templated function or type.
40/// For example:
41///
42/// @code
43/// template <typename T> class A {
44/// friend int foo(T);
45/// friend class B;
46/// friend T; // only in C++0x
47/// template <typename U> friend class C;
48/// template <typename U> friend A& operator+=(A&, const U&) { ... }
49/// };
50/// @endcode
51///
52/// The semantic context of a friend decl is its declaring class.
53class FriendDecl final
54 : public Decl,
55 private llvm::TrailingObjects<FriendDecl, TemplateParameterList *> {
56 virtual void anchor();
57
58public:
59 using FriendUnion = llvm::PointerUnion<NamedDecl *, TypeSourceInfo *>;
60
61private:
62 friend class CXXRecordDecl;
63 friend class CXXRecordDecl::friend_iterator;
64
65 // The declaration that's a friend of this class.
66 FriendUnion Friend;
67
68 // A pointer to the next friend in the sequence.
69 LazyDeclPtr NextFriend;
70
71 // Location of the 'friend' specifier.
72 SourceLocation FriendLoc;
73
74 /// True if this 'friend' declaration is unsupported. Eventually we
75 /// will support every possible friend declaration, but for now we
76 /// silently ignore some and set this flag to authorize all access.
77 unsigned UnsupportedFriend : 1;
78
79 // The number of "outer" template parameter lists in non-templatic
80 // (currently unsupported) friend type declarations, such as
81 // template <class T> friend class A<T>::B;
82 unsigned NumTPLists : 31;
83
84 FriendDecl(DeclContext *DC, SourceLocation L, FriendUnion Friend,
85 SourceLocation FriendL,
86 ArrayRef<TemplateParameterList *> FriendTypeTPLists)
87 : Decl(Decl::Friend, DC, L), Friend(Friend), FriendLoc(FriendL),
88 UnsupportedFriend(false), NumTPLists(FriendTypeTPLists.size()) {
89 for (unsigned i = 0; i < NumTPLists; ++i)
90 getTrailingObjects<TemplateParameterList *>()[i] = FriendTypeTPLists[i];
91 }
92
93 FriendDecl(EmptyShell Empty, unsigned NumFriendTypeTPLists)
94 : Decl(Decl::Friend, Empty), UnsupportedFriend(false),
95 NumTPLists(NumFriendTypeTPLists) {}
96
97 FriendDecl *getNextFriend() {
98 if (!NextFriend.isOffset())
99 return cast_or_null<FriendDecl>(NextFriend.get(nullptr));
100 return getNextFriendSlowCase();
101 }
102
103 FriendDecl *getNextFriendSlowCase();
104
105public:
106 friend class ASTDeclReader;
107 friend class ASTDeclWriter;
108 friend class ASTNodeImporter;
109 friend TrailingObjects;
110
111 static FriendDecl *Create(ASTContext &C, DeclContext *DC,
112 SourceLocation L, FriendUnion Friend_,
113 SourceLocation FriendL,
114 ArrayRef<TemplateParameterList*> FriendTypeTPLists
115 = None);
116 static FriendDecl *CreateDeserialized(ASTContext &C, unsigned ID,
117 unsigned FriendTypeNumTPLists);
118
119 /// If this friend declaration names an (untemplated but possibly
120 /// dependent) type, return the type; otherwise return null. This
121 /// is used for elaborated-type-specifiers and, in C++0x, for
122 /// arbitrary friend type declarations.
123 TypeSourceInfo *getFriendType() const {
124 return Friend.dyn_cast<TypeSourceInfo*>();
125 }
126
127 unsigned getFriendTypeNumTemplateParameterLists() const {
128 return NumTPLists;
129 }
130
131 TemplateParameterList *getFriendTypeTemplateParameterList(unsigned N) const {
132 assert(N < NumTPLists);
133 return getTrailingObjects<TemplateParameterList *>()[N];
134 }
135
136 /// If this friend declaration doesn't name a type, return the inner
137 /// declaration.
138 NamedDecl *getFriendDecl() const {
139 return Friend.dyn_cast<NamedDecl *>();
140 }
141
142 /// Retrieves the location of the 'friend' keyword.
143 SourceLocation getFriendLoc() const {
144 return FriendLoc;
145 }
146
147 /// Retrieves the source range for the friend declaration.
148 SourceRange getSourceRange() const override LLVM_READONLY {
149 if (NamedDecl *ND = getFriendDecl()) {
150 if (const auto *FD = dyn_cast<FunctionDecl>(ND))
151 return FD->getSourceRange();
152 if (const auto *FTD = dyn_cast<FunctionTemplateDecl>(ND))
153 return FTD->getSourceRange();
154 if (const auto *CTD = dyn_cast<ClassTemplateDecl>(ND))
155 return CTD->getSourceRange();
156 if (const auto *DD = dyn_cast<DeclaratorDecl>(ND)) {
157 if (DD->getOuterLocStart() != DD->getInnerLocStart())
158 return DD->getSourceRange();
159 }
160 return SourceRange(getFriendLoc(), ND->getEndLoc());
161 }
162 else if (TypeSourceInfo *TInfo = getFriendType()) {
163 SourceLocation StartL =
164 (NumTPLists == 0) ? getFriendLoc()
165 : getTrailingObjects<TemplateParameterList *>()[0]
166 ->getTemplateLoc();
167 return SourceRange(StartL, TInfo->getTypeLoc().getEndLoc());
168 }
169 else
170 return SourceRange(getFriendLoc(), getLocation());
171 }
172
173 /// Determines if this friend kind is unsupported.
174 bool isUnsupportedFriend() const {
175 return UnsupportedFriend;
176 }
177 void setUnsupportedFriend(bool Unsupported) {
178 UnsupportedFriend = Unsupported;
179 }
180
181 // Implement isa/cast/dyncast/etc.
182 static bool classof(const Decl *D) { return classofKind(D->getKind()); }
183 static bool classofKind(Kind K) { return K == Decl::Friend; }
184};
185
186/// An iterator over the friend declarations of a class.
187class CXXRecordDecl::friend_iterator {
188 friend class CXXRecordDecl;
189
190 FriendDecl *Ptr;
191
192 explicit friend_iterator(FriendDecl *Ptr) : Ptr(Ptr) {}
193
194public:
195 friend_iterator() = default;
196
197 using value_type = FriendDecl *;
198 using reference = FriendDecl *;
199 using pointer = FriendDecl *;
200 using difference_type = int;
201 using iterator_category = std::forward_iterator_tag;
202
203 reference operator*() const { return Ptr; }
204
205 friend_iterator &operator++() {
206 assert(Ptr && "attempt to increment past end of friend list");
207 Ptr = Ptr->getNextFriend();
208 return *this;
209 }
210
211 friend_iterator operator++(int) {
212 friend_iterator tmp = *this;
213 ++*this;
214 return tmp;
215 }
216
217 bool operator==(const friend_iterator &Other) const {
218 return Ptr == Other.Ptr;
219 }
220
221 bool operator!=(const friend_iterator &Other) const {
222 return Ptr != Other.Ptr;
223 }
224
225 friend_iterator &operator+=(difference_type N) {
226 assert(N >= 0 && "cannot rewind a CXXRecordDecl::friend_iterator");
227 while (N--)
228 ++*this;
229 return *this;
230 }
231
232 friend_iterator operator+(difference_type N) const {
233 friend_iterator tmp = *this;
234 tmp += N;
235 return tmp;
236 }
237};
238
239inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_begin() const {
240 return friend_iterator(getFirstFriend());
241}
242
243inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_end() const {
244 return friend_iterator(nullptr);
245}
246
247inline CXXRecordDecl::friend_range CXXRecordDecl::friends() const {
248 return friend_range(friend_begin(), friend_end());
249}
250
251inline void CXXRecordDecl::pushFriendDecl(FriendDecl *FD) {
252 assert(!FD->NextFriend && "friend already has next friend?");
253 FD->NextFriend = data().FirstFriend;
254 data().FirstFriend = FD;
255}
256
257} // namespace clang
258
259#endif // LLVM_CLANG_AST_DECLFRIEND_H
260