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/PointerUnion.h"
27#include "llvm/Support/Casting.h"
28#include "llvm/Support/Compiler.h"
29#include "llvm/Support/TrailingObjects.h"
30#include <cassert>
31#include <iterator>
32
33namespace clang {
34
35class ASTContext;
36
37/// FriendDecl - Represents the declaration of a friend entity,
38/// which can be a function, a type, or a templated function or type.
39/// For example:
40///
41/// @code
42/// template <typename T> class A {
43///   friend int foo(T);
44///   friend class B;
45///   friend T; // only in C++0x
46///   template <typename U> friend class C;
47///   template <typename U> friend A& operator+=(A&, const U&) { ... }
48/// };
49/// @endcode
50///
51/// The semantic context of a friend decl is its declaring class.
52class FriendDecl final
53    : public Decl,
54      private llvm::TrailingObjects<FriendDecl, TemplateParameterList *> {
55  virtual void anchor();
56
57public:
58  using FriendUnion = llvm::PointerUnion<NamedDecl *, TypeSourceInfo *>;
59
60private:
61  friend class CXXRecordDecl;
62  friend class CXXRecordDecl::friend_iterator;
63
64  // The declaration that's a friend of this class.
65  FriendUnion Friend;
66
67  // A pointer to the next friend in the sequence.
68  LazyDeclPtr NextFriend;
69
70  // Location of the 'friend' specifier.
71  SourceLocation FriendLoc;
72
73  /// True if this 'friend' declaration is unsupported.  Eventually we
74  /// will support every possible friend declaration, but for now we
75  /// silently ignore some and set this flag to authorize all access.
76  LLVM_PREFERRED_TYPE(bool)
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 *
112  Create(ASTContext &C, DeclContext *DC, SourceLocation L, FriendUnion Friend_,
113         SourceLocation FriendL,
114         ArrayRef<TemplateParameterList *> FriendTypeTPLists = std::nullopt);
115  static FriendDecl *CreateDeserialized(ASTContext &C, unsigned ID,
116                                        unsigned FriendTypeNumTPLists);
117
118  /// If this friend declaration names an (untemplated but possibly
119  /// dependent) type, return the type; otherwise return null.  This
120  /// is used for elaborated-type-specifiers and, in C++0x, for
121  /// arbitrary friend type declarations.
122  TypeSourceInfo *getFriendType() const {
123    return Friend.dyn_cast<TypeSourceInfo*>();
124  }
125
126  unsigned getFriendTypeNumTemplateParameterLists() const {
127    return NumTPLists;
128  }
129
130  TemplateParameterList *getFriendTypeTemplateParameterList(unsigned N) const {
131    assert(N < NumTPLists);
132    return getTrailingObjects<TemplateParameterList *>()[N];
133  }
134
135  /// If this friend declaration doesn't name a type, return the inner
136  /// declaration.
137  NamedDecl *getFriendDecl() const {
138    return Friend.dyn_cast<NamedDecl *>();
139  }
140
141  /// Retrieves the location of the 'friend' keyword.
142  SourceLocation getFriendLoc() const {
143    return FriendLoc;
144  }
145
146  /// Retrieves the source range for the friend declaration.
147  SourceRange getSourceRange() const override LLVM_READONLY {
148    if (NamedDecl *ND = getFriendDecl()) {
149      if (const auto *FD = dyn_cast<FunctionDecl>(ND))
150        return FD->getSourceRange();
151      if (const auto *FTD = dyn_cast<FunctionTemplateDecl>(ND))
152        return FTD->getSourceRange();
153      if (const auto *CTD = dyn_cast<ClassTemplateDecl>(ND))
154        return CTD->getSourceRange();
155      if (const auto *DD = dyn_cast<DeclaratorDecl>(ND)) {
156        if (DD->getOuterLocStart() != DD->getInnerLocStart())
157          return DD->getSourceRange();
158      }
159      return SourceRange(getFriendLoc(), ND->getEndLoc());
160    }
161    else if (TypeSourceInfo *TInfo = getFriendType()) {
162      SourceLocation StartL =
163          (NumTPLists == 0) ? getFriendLoc()
164                            : getTrailingObjects<TemplateParameterList *>()[0]
165                                  ->getTemplateLoc();
166      return SourceRange(StartL, TInfo->getTypeLoc().getEndLoc());
167    }
168    else
169      return SourceRange(getFriendLoc(), getLocation());
170  }
171
172  /// Determines if this friend kind is unsupported.
173  bool isUnsupportedFriend() const {
174    return UnsupportedFriend;
175  }
176  void setUnsupportedFriend(bool Unsupported) {
177    UnsupportedFriend = Unsupported;
178  }
179
180  // Implement isa/cast/dyncast/etc.
181  static bool classof(const Decl *D) { return classofKind(D->getKind()); }
182  static bool classofKind(Kind K) { return K == Decl::Friend; }
183};
184
185/// An iterator over the friend declarations of a class.
186class CXXRecordDecl::friend_iterator {
187  friend class CXXRecordDecl;
188
189  FriendDecl *Ptr;
190
191  explicit friend_iterator(FriendDecl *Ptr) : Ptr(Ptr) {}
192
193public:
194  friend_iterator() = default;
195
196  using value_type = FriendDecl *;
197  using reference = FriendDecl *;
198  using pointer = FriendDecl *;
199  using difference_type = int;
200  using iterator_category = std::forward_iterator_tag;
201
202  reference operator*() const { return Ptr; }
203
204  friend_iterator &operator++() {
205    assert(Ptr && "attempt to increment past end of friend list");
206    Ptr = Ptr->getNextFriend();
207    return *this;
208  }
209
210  friend_iterator operator++(int) {
211    friend_iterator tmp = *this;
212    ++*this;
213    return tmp;
214  }
215
216  bool operator==(const friend_iterator &Other) const {
217    return Ptr == Other.Ptr;
218  }
219
220  bool operator!=(const friend_iterator &Other) const {
221    return Ptr != Other.Ptr;
222  }
223
224  friend_iterator &operator+=(difference_type N) {
225    assert(N >= 0 && "cannot rewind a CXXRecordDecl::friend_iterator");
226    while (N--)
227      ++*this;
228    return *this;
229  }
230
231  friend_iterator operator+(difference_type N) const {
232    friend_iterator tmp = *this;
233    tmp += N;
234    return tmp;
235  }
236};
237
238inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_begin() const {
239  return friend_iterator(getFirstFriend());
240}
241
242inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_end() const {
243  return friend_iterator(nullptr);
244}
245
246inline CXXRecordDecl::friend_range CXXRecordDecl::friends() const {
247  return friend_range(friend_begin(), friend_end());
248}
249
250inline void CXXRecordDecl::pushFriendDecl(FriendDecl *FD) {
251  assert(!FD->NextFriend && "friend already has next friend?");
252  FD->NextFriend = data().FirstFriend;
253  data().FirstFriend = FD;
254}
255
256} // namespace clang
257
258#endif // LLVM_CLANG_AST_DECLFRIEND_H
259