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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 "llvm/Support/Compiler.h"
     21 
     22 namespace clang {
     23 
     24 /// FriendDecl - Represents the declaration of a friend entity,
     25 /// which can be a function, a type, or a templated function or type.
     26 //  For example:
     27 ///
     28 /// @code
     29 /// template <typename T> class A {
     30 ///   friend int foo(T);
     31 ///   friend class B;
     32 ///   friend T; // only in C++0x
     33 ///   template <typename U> friend class C;
     34 ///   template <typename U> friend A& operator+=(A&, const U&) { ... }
     35 /// };
     36 /// @endcode
     37 ///
     38 /// The semantic context of a friend decl is its declaring class.
     39 class FriendDecl : public Decl {
     40   virtual void anchor();
     41 public:
     42   typedef llvm::PointerUnion<NamedDecl*,TypeSourceInfo*> FriendUnion;
     43 
     44 private:
     45   // The declaration that's a friend of this class.
     46   FriendUnion Friend;
     47 
     48   // A pointer to the next friend in the sequence.
     49   LazyDeclPtr NextFriend;
     50 
     51   // Location of the 'friend' specifier.
     52   SourceLocation FriendLoc;
     53 
     54   /// True if this 'friend' declaration is unsupported.  Eventually we
     55   /// will support every possible friend declaration, but for now we
     56   /// silently ignore some and set this flag to authorize all access.
     57   bool UnsupportedFriend : 1;
     58 
     59   // The number of "outer" template parameter lists in non-templatic
     60   // (currently unsupported) friend type declarations, such as
     61   //     template <class T> friend class A<T>::B;
     62   unsigned NumTPLists : 31;
     63 
     64   // The tail-allocated friend type template parameter lists (if any).
     65   TemplateParameterList* const *getTPLists() const {
     66     return reinterpret_cast<TemplateParameterList* const *>(this + 1);
     67   }
     68   TemplateParameterList **getTPLists() {
     69     return reinterpret_cast<TemplateParameterList**>(this + 1);
     70   }
     71 
     72   friend class CXXRecordDecl::friend_iterator;
     73   friend class CXXRecordDecl;
     74 
     75   FriendDecl(DeclContext *DC, SourceLocation L, FriendUnion Friend,
     76              SourceLocation FriendL,
     77              ArrayRef<TemplateParameterList*> FriendTypeTPLists)
     78     : Decl(Decl::Friend, DC, L),
     79       Friend(Friend),
     80       NextFriend(),
     81       FriendLoc(FriendL),
     82       UnsupportedFriend(false),
     83       NumTPLists(FriendTypeTPLists.size()) {
     84     for (unsigned i = 0; i < NumTPLists; ++i)
     85       getTPLists()[i] = FriendTypeTPLists[i];
     86   }
     87 
     88   FriendDecl(EmptyShell Empty, unsigned NumFriendTypeTPLists)
     89     : Decl(Decl::Friend, Empty), NextFriend(),
     90       NumTPLists(NumFriendTypeTPLists) { }
     91 
     92   FriendDecl *getNextFriend() {
     93     if (!NextFriend.isOffset())
     94       return cast_or_null<FriendDecl>(NextFriend.get(0));
     95     return getNextFriendSlowCase();
     96   }
     97   FriendDecl *getNextFriendSlowCase();
     98 
     99 public:
    100   static FriendDecl *Create(ASTContext &C, DeclContext *DC,
    101                             SourceLocation L, FriendUnion Friend_,
    102                             SourceLocation FriendL,
    103                             ArrayRef<TemplateParameterList*> FriendTypeTPLists
    104                             = ArrayRef<TemplateParameterList*>());
    105   static FriendDecl *CreateDeserialized(ASTContext &C, unsigned ID,
    106                                         unsigned FriendTypeNumTPLists);
    107 
    108   /// If this friend declaration names an (untemplated but possibly
    109   /// dependent) type, return the type; otherwise return null.  This
    110   /// is used for elaborated-type-specifiers and, in C++0x, for
    111   /// arbitrary friend type declarations.
    112   TypeSourceInfo *getFriendType() const {
    113     return Friend.dyn_cast<TypeSourceInfo*>();
    114   }
    115   unsigned getFriendTypeNumTemplateParameterLists() const {
    116     return NumTPLists;
    117   }
    118   TemplateParameterList *getFriendTypeTemplateParameterList(unsigned N) const {
    119     assert(N < NumTPLists);
    120     return getTPLists()[N];
    121   }
    122 
    123   /// If this friend declaration doesn't name a type, return the inner
    124   /// declaration.
    125   NamedDecl *getFriendDecl() const {
    126     return Friend.dyn_cast<NamedDecl*>();
    127   }
    128 
    129   /// Retrieves the location of the 'friend' keyword.
    130   SourceLocation getFriendLoc() const {
    131     return FriendLoc;
    132   }
    133 
    134   /// Retrieves the source range for the friend declaration.
    135   SourceRange getSourceRange() const LLVM_READONLY {
    136     if (NamedDecl *ND = getFriendDecl()) {
    137       if (FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(ND))
    138         return FTD->getSourceRange();
    139       if (DeclaratorDecl *DD = dyn_cast<DeclaratorDecl>(ND)) {
    140         if (DD->getOuterLocStart() != DD->getInnerLocStart())
    141           return DD->getSourceRange();
    142       }
    143       return SourceRange(getFriendLoc(), ND->getLocEnd());
    144     }
    145     else if (TypeSourceInfo *TInfo = getFriendType()) {
    146       SourceLocation StartL = (NumTPLists == 0)
    147         ? getFriendLoc()
    148         : getTPLists()[0]->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 };
    170 
    171 /// An iterator over the friend declarations of a class.
    172 class CXXRecordDecl::friend_iterator {
    173   FriendDecl *Ptr;
    174 
    175   friend class CXXRecordDecl;
    176   explicit friend_iterator(FriendDecl *Ptr) : Ptr(Ptr) {}
    177 public:
    178   friend_iterator() {}
    179 
    180   typedef FriendDecl *value_type;
    181   typedef FriendDecl *reference;
    182   typedef FriendDecl *pointer;
    183   typedef int difference_type;
    184   typedef std::forward_iterator_tag iterator_category;
    185 
    186   reference operator*() const { return Ptr; }
    187 
    188   friend_iterator &operator++() {
    189     assert(Ptr && "attempt to increment past end of friend list");
    190     Ptr = Ptr->getNextFriend();
    191     return *this;
    192   }
    193 
    194   friend_iterator operator++(int) {
    195     friend_iterator tmp = *this;
    196     ++*this;
    197     return tmp;
    198   }
    199 
    200   bool operator==(const friend_iterator &Other) const {
    201     return Ptr == Other.Ptr;
    202   }
    203 
    204   bool operator!=(const friend_iterator &Other) const {
    205     return Ptr != Other.Ptr;
    206   }
    207 
    208   friend_iterator &operator+=(difference_type N) {
    209     assert(N >= 0 && "cannot rewind a CXXRecordDecl::friend_iterator");
    210     while (N--)
    211       ++*this;
    212     return *this;
    213   }
    214 
    215   friend_iterator operator+(difference_type N) const {
    216     friend_iterator tmp = *this;
    217     tmp += N;
    218     return tmp;
    219   }
    220 };
    221 
    222 inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_begin() const {
    223   return friend_iterator(data().FirstFriend);
    224 }
    225 
    226 inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_end() const {
    227   return friend_iterator(0);
    228 }
    229 
    230 inline void CXXRecordDecl::pushFriendDecl(FriendDecl *FD) {
    231   assert(FD->NextFriend == 0 && "friend already has next friend?");
    232   FD->NextFriend = data().FirstFriend;
    233   data().FirstFriend = FD;
    234 }
    235 
    236 }
    237 
    238 #endif
    239