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