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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 : public Decl {
     41   virtual void anchor();
     42 public:
     43   typedef llvm::PointerUnion<NamedDecl*,TypeSourceInfo*> FriendUnion;
     44 
     45 private:
     46   // The declaration that's a friend of this class.
     47   FriendUnion Friend;
     48 
     49   // A pointer to the next friend in the sequence.
     50   LazyDeclPtr NextFriend;
     51 
     52   // Location of the 'friend' specifier.
     53   SourceLocation FriendLoc;
     54 
     55   /// True if this 'friend' declaration is unsupported.  Eventually we
     56   /// will support every possible friend declaration, but for now we
     57   /// silently ignore some and set this flag to authorize all access.
     58   bool UnsupportedFriend : 1;
     59 
     60   // The number of "outer" template parameter lists in non-templatic
     61   // (currently unsupported) friend type declarations, such as
     62   //     template <class T> friend class A<T>::B;
     63   unsigned NumTPLists : 31;
     64 
     65   // The tail-allocated friend type template parameter lists (if any).
     66   TemplateParameterList* const *getTPLists() const {
     67     return reinterpret_cast<TemplateParameterList* const *>(this + 1);
     68   }
     69   TemplateParameterList **getTPLists() {
     70     return reinterpret_cast<TemplateParameterList**>(this + 1);
     71   }
     72 
     73   friend class CXXRecordDecl::friend_iterator;
     74   friend class CXXRecordDecl;
     75 
     76   FriendDecl(DeclContext *DC, SourceLocation L, FriendUnion Friend,
     77              SourceLocation FriendL,
     78              ArrayRef<TemplateParameterList*> FriendTypeTPLists)
     79     : Decl(Decl::Friend, DC, L),
     80       Friend(Friend),
     81       NextFriend(),
     82       FriendLoc(FriendL),
     83       UnsupportedFriend(false),
     84       NumTPLists(FriendTypeTPLists.size()) {
     85     for (unsigned i = 0; i < NumTPLists; ++i)
     86       getTPLists()[i] = FriendTypeTPLists[i];
     87   }
     88 
     89   FriendDecl(EmptyShell Empty, unsigned NumFriendTypeTPLists)
     90     : Decl(Decl::Friend, Empty), NextFriend(),
     91       NumTPLists(NumFriendTypeTPLists) { }
     92 
     93   FriendDecl *getNextFriend() {
     94     if (!NextFriend.isOffset())
     95       return cast_or_null<FriendDecl>(NextFriend.get(nullptr));
     96     return getNextFriendSlowCase();
     97   }
     98   FriendDecl *getNextFriendSlowCase();
     99 
    100 public:
    101   static FriendDecl *Create(ASTContext &C, DeclContext *DC,
    102                             SourceLocation L, FriendUnion Friend_,
    103                             SourceLocation FriendL,
    104                             ArrayRef<TemplateParameterList*> FriendTypeTPLists
    105                             = None);
    106   static FriendDecl *CreateDeserialized(ASTContext &C, unsigned ID,
    107                                         unsigned FriendTypeNumTPLists);
    108 
    109   /// If this friend declaration names an (untemplated but possibly
    110   /// dependent) type, return the type; otherwise return null.  This
    111   /// is used for elaborated-type-specifiers and, in C++0x, for
    112   /// arbitrary friend type declarations.
    113   TypeSourceInfo *getFriendType() const {
    114     return Friend.dyn_cast<TypeSourceInfo*>();
    115   }
    116   unsigned getFriendTypeNumTemplateParameterLists() const {
    117     return NumTPLists;
    118   }
    119   TemplateParameterList *getFriendTypeTemplateParameterList(unsigned N) const {
    120     assert(N < NumTPLists);
    121     return getTPLists()[N];
    122   }
    123 
    124   /// If this friend declaration doesn't name a type, return the inner
    125   /// declaration.
    126   NamedDecl *getFriendDecl() const {
    127     return Friend.dyn_cast<NamedDecl*>();
    128   }
    129 
    130   /// Retrieves the location of the 'friend' keyword.
    131   SourceLocation getFriendLoc() const {
    132     return FriendLoc;
    133   }
    134 
    135   /// Retrieves the source range for the friend declaration.
    136   SourceRange getSourceRange() const override LLVM_READONLY {
    137     if (NamedDecl *ND = getFriendDecl()) {
    138       if (FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))
    139         return FD->getSourceRange();
    140       if (FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(ND))
    141         return FTD->getSourceRange();
    142       if (ClassTemplateDecl *CTD = dyn_cast<ClassTemplateDecl>(ND))
    143         return CTD->getSourceRange();
    144       if (DeclaratorDecl *DD = dyn_cast<DeclaratorDecl>(ND)) {
    145         if (DD->getOuterLocStart() != DD->getInnerLocStart())
    146           return DD->getSourceRange();
    147       }
    148       return SourceRange(getFriendLoc(), ND->getLocEnd());
    149     }
    150     else if (TypeSourceInfo *TInfo = getFriendType()) {
    151       SourceLocation StartL = (NumTPLists == 0)
    152         ? getFriendLoc()
    153         : getTPLists()[0]->getTemplateLoc();
    154       return SourceRange(StartL, TInfo->getTypeLoc().getEndLoc());
    155     }
    156     else
    157       return SourceRange(getFriendLoc(), getLocation());
    158   }
    159 
    160   /// Determines if this friend kind is unsupported.
    161   bool isUnsupportedFriend() const {
    162     return UnsupportedFriend;
    163   }
    164   void setUnsupportedFriend(bool Unsupported) {
    165     UnsupportedFriend = Unsupported;
    166   }
    167 
    168   // Implement isa/cast/dyncast/etc.
    169   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    170   static bool classofKind(Kind K) { return K == Decl::Friend; }
    171 
    172   friend class ASTDeclReader;
    173   friend class ASTDeclWriter;
    174 };
    175 
    176 /// An iterator over the friend declarations of a class.
    177 class CXXRecordDecl::friend_iterator {
    178   FriendDecl *Ptr;
    179 
    180   friend class CXXRecordDecl;
    181   explicit friend_iterator(FriendDecl *Ptr) : Ptr(Ptr) {}
    182 public:
    183   friend_iterator() {}
    184 
    185   typedef FriendDecl *value_type;
    186   typedef FriendDecl *reference;
    187   typedef FriendDecl *pointer;
    188   typedef int difference_type;
    189   typedef std::forward_iterator_tag iterator_category;
    190 
    191   reference operator*() const { return Ptr; }
    192 
    193   friend_iterator &operator++() {
    194     assert(Ptr && "attempt to increment past end of friend list");
    195     Ptr = Ptr->getNextFriend();
    196     return *this;
    197   }
    198 
    199   friend_iterator operator++(int) {
    200     friend_iterator tmp = *this;
    201     ++*this;
    202     return tmp;
    203   }
    204 
    205   bool operator==(const friend_iterator &Other) const {
    206     return Ptr == Other.Ptr;
    207   }
    208 
    209   bool operator!=(const friend_iterator &Other) const {
    210     return Ptr != Other.Ptr;
    211   }
    212 
    213   friend_iterator &operator+=(difference_type N) {
    214     assert(N >= 0 && "cannot rewind a CXXRecordDecl::friend_iterator");
    215     while (N--)
    216       ++*this;
    217     return *this;
    218   }
    219 
    220   friend_iterator operator+(difference_type N) const {
    221     friend_iterator tmp = *this;
    222     tmp += N;
    223     return tmp;
    224   }
    225 };
    226 
    227 inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_begin() const {
    228   return friend_iterator(getFirstFriend());
    229 }
    230 
    231 inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_end() const {
    232   return friend_iterator(nullptr);
    233 }
    234 
    235 inline CXXRecordDecl::friend_range CXXRecordDecl::friends() const {
    236   return friend_range(friend_begin(), friend_end());
    237 }
    238 
    239 inline void CXXRecordDecl::pushFriendDecl(FriendDecl *FD) {
    240   assert(!FD->NextFriend && "friend already has next friend?");
    241   FD->NextFriend = data().FirstFriend;
    242   data().FirstFriend = FD;
    243 }
    244 
    245 }
    246 
    247 #endif
    248