1 //===-- Redeclarable.h - Base for Decls that can be redeclared -*- 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 Redeclarable interface. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_AST_REDECLARABLE_H 15 #define LLVM_CLANG_AST_REDECLARABLE_H 16 17 #include "clang/AST/ExternalASTSource.h" 18 #include "llvm/ADT/PointerIntPair.h" 19 #include "llvm/Support/Casting.h" 20 #include <iterator> 21 22 namespace clang { 23 24 /// \brief Provides common interface for the Decls that can be redeclared. 25 template<typename decl_type> 26 class Redeclarable { 27 protected: 28 class DeclLink { 29 /// A pointer to a known latest declaration, either statically known or 30 /// generationally updated as decls are added by an external source. 31 typedef LazyGenerationalUpdatePtr<const Decl*, Decl*, 32 &ExternalASTSource::CompleteRedeclChain> 33 KnownLatest; 34 35 typedef const ASTContext *UninitializedLatest; 36 typedef Decl *Previous; 37 38 /// A pointer to either an uninitialized latest declaration (where either 39 /// we've not yet set the previous decl or there isn't one), or to a known 40 /// previous declaration. 41 typedef llvm::PointerUnion<Previous, UninitializedLatest> NotKnownLatest; 42 43 mutable llvm::PointerUnion<NotKnownLatest, KnownLatest> Next; 44 45 public: 46 enum PreviousTag { PreviousLink }; 47 enum LatestTag { LatestLink }; 48 49 DeclLink(LatestTag, const ASTContext &Ctx) 50 : Next(NotKnownLatest(&Ctx)) {} 51 DeclLink(PreviousTag, decl_type *D) 52 : Next(NotKnownLatest(Previous(D))) {} 53 54 bool NextIsPrevious() const { 55 return Next.is<NotKnownLatest>() && 56 // FIXME: 'template' is required on the next line due to an 57 // apparent clang bug. 58 Next.get<NotKnownLatest>().template is<Previous>(); 59 } 60 61 bool NextIsLatest() const { return !NextIsPrevious(); } 62 63 decl_type *getNext(const decl_type *D) const { 64 if (Next.is<NotKnownLatest>()) { 65 NotKnownLatest NKL = Next.get<NotKnownLatest>(); 66 if (NKL.is<Previous>()) 67 return static_cast<decl_type*>(NKL.get<Previous>()); 68 69 // Allocate the generational 'most recent' cache now, if needed. 70 Next = KnownLatest(*NKL.get<UninitializedLatest>(), 71 const_cast<decl_type *>(D)); 72 } 73 74 return static_cast<decl_type*>(Next.get<KnownLatest>().get(D)); 75 } 76 77 void setPrevious(decl_type *D) { 78 assert(NextIsPrevious() && "decl became non-canonical unexpectedly"); 79 Next = Previous(D); 80 } 81 82 void setLatest(decl_type *D) { 83 assert(NextIsLatest() && "decl became canonical unexpectedly"); 84 if (Next.is<NotKnownLatest>()) { 85 NotKnownLatest NKL = Next.get<NotKnownLatest>(); 86 Next = KnownLatest(*NKL.get<UninitializedLatest>(), D); 87 } else { 88 auto Latest = Next.get<KnownLatest>(); 89 Latest.set(D); 90 Next = Latest; 91 } 92 } 93 94 void markIncomplete() { Next.get<KnownLatest>().markIncomplete(); } 95 96 Decl *getLatestNotUpdated() const { 97 assert(NextIsLatest() && "expected a canonical decl"); 98 if (Next.is<NotKnownLatest>()) 99 return nullptr; 100 return Next.get<KnownLatest>().getNotUpdated(); 101 } 102 }; 103 104 static DeclLink PreviousDeclLink(decl_type *D) { 105 return DeclLink(DeclLink::PreviousLink, D); 106 } 107 108 static DeclLink LatestDeclLink(const ASTContext &Ctx) { 109 return DeclLink(DeclLink::LatestLink, Ctx); 110 } 111 112 /// \brief Points to the next redeclaration in the chain. 113 /// 114 /// If NextIsPrevious() is true, this is a link to the previous declaration 115 /// of this same Decl. If NextIsLatest() is true, this is the first 116 /// declaration and Link points to the latest declaration. For example: 117 /// 118 /// #1 int f(int x, int y = 1); // <pointer to #3, true> 119 /// #2 int f(int x = 0, int y); // <pointer to #1, false> 120 /// #3 int f(int x, int y) { return x + y; } // <pointer to #2, false> 121 /// 122 /// If there is only one declaration, it is <pointer to self, true> 123 DeclLink RedeclLink; 124 decl_type *First; 125 126 decl_type *getNextRedeclaration() const { 127 return RedeclLink.getNext(static_cast<const decl_type *>(this)); 128 } 129 130 public: 131 Redeclarable(const ASTContext &Ctx) 132 : RedeclLink(LatestDeclLink(Ctx)), First(static_cast<decl_type *>(this)) {} 133 134 /// \brief Return the previous declaration of this declaration or NULL if this 135 /// is the first declaration. 136 decl_type *getPreviousDecl() { 137 if (RedeclLink.NextIsPrevious()) 138 return getNextRedeclaration(); 139 return nullptr; 140 } 141 const decl_type *getPreviousDecl() const { 142 return const_cast<decl_type *>( 143 static_cast<const decl_type*>(this))->getPreviousDecl(); 144 } 145 146 /// \brief Return the first declaration of this declaration or itself if this 147 /// is the only declaration. 148 decl_type *getFirstDecl() { return First; } 149 150 /// \brief Return the first declaration of this declaration or itself if this 151 /// is the only declaration. 152 const decl_type *getFirstDecl() const { return First; } 153 154 /// \brief True if this is the first declaration in its redeclaration chain. 155 bool isFirstDecl() const { return RedeclLink.NextIsLatest(); } 156 157 /// \brief Returns the most recent (re)declaration of this declaration. 158 decl_type *getMostRecentDecl() { 159 return getFirstDecl()->getNextRedeclaration(); 160 } 161 162 /// \brief Returns the most recent (re)declaration of this declaration. 163 const decl_type *getMostRecentDecl() const { 164 return getFirstDecl()->getNextRedeclaration(); 165 } 166 167 /// \brief Set the previous declaration. If PrevDecl is NULL, set this as the 168 /// first and only declaration. 169 void setPreviousDecl(decl_type *PrevDecl); 170 171 /// \brief Iterates through all the redeclarations of the same decl. 172 class redecl_iterator { 173 /// Current - The current declaration. 174 decl_type *Current; 175 decl_type *Starter; 176 bool PassedFirst; 177 178 public: 179 typedef decl_type* value_type; 180 typedef decl_type* reference; 181 typedef decl_type* pointer; 182 typedef std::forward_iterator_tag iterator_category; 183 typedef std::ptrdiff_t difference_type; 184 185 redecl_iterator() : Current(nullptr) { } 186 explicit redecl_iterator(decl_type *C) 187 : Current(C), Starter(C), PassedFirst(false) { } 188 189 reference operator*() const { return Current; } 190 pointer operator->() const { return Current; } 191 192 redecl_iterator& operator++() { 193 assert(Current && "Advancing while iterator has reached end"); 194 // Sanity check to avoid infinite loop on invalid redecl chain. 195 if (Current->isFirstDecl()) { 196 if (PassedFirst) { 197 assert(0 && "Passed first decl twice, invalid redecl chain!"); 198 Current = nullptr; 199 return *this; 200 } 201 PassedFirst = true; 202 } 203 204 // Get either previous decl or latest decl. 205 decl_type *Next = Current->getNextRedeclaration(); 206 Current = (Next != Starter) ? Next : nullptr; 207 return *this; 208 } 209 210 redecl_iterator operator++(int) { 211 redecl_iterator tmp(*this); 212 ++(*this); 213 return tmp; 214 } 215 216 friend bool operator==(redecl_iterator x, redecl_iterator y) { 217 return x.Current == y.Current; 218 } 219 friend bool operator!=(redecl_iterator x, redecl_iterator y) { 220 return x.Current != y.Current; 221 } 222 }; 223 224 typedef llvm::iterator_range<redecl_iterator> redecl_range; 225 226 /// \brief Returns an iterator range for all the redeclarations of the same 227 /// decl. It will iterate at least once (when this decl is the only one). 228 redecl_range redecls() const { 229 return redecl_range(redecl_iterator(const_cast<decl_type *>( 230 static_cast<const decl_type *>(this))), 231 redecl_iterator()); 232 } 233 234 redecl_iterator redecls_begin() const { return redecls().begin(); } 235 redecl_iterator redecls_end() const { return redecls().end(); } 236 237 friend class ASTDeclReader; 238 friend class ASTDeclWriter; 239 }; 240 241 /// \brief Get the primary declaration for a declaration from an AST file. That 242 /// will be the first-loaded declaration. 243 Decl *getPrimaryMergedDecl(Decl *D); 244 245 /// \brief Provides common interface for the Decls that cannot be redeclared, 246 /// but can be merged if the same declaration is brought in from multiple 247 /// modules. 248 template<typename decl_type> 249 class Mergeable { 250 public: 251 Mergeable() {} 252 253 /// \brief Return the first declaration of this declaration or itself if this 254 /// is the only declaration. 255 decl_type *getFirstDecl() { 256 decl_type *D = static_cast<decl_type*>(this); 257 if (!D->isFromASTFile()) 258 return D; 259 return cast<decl_type>(getPrimaryMergedDecl(const_cast<decl_type*>(D))); 260 } 261 262 /// \brief Return the first declaration of this declaration or itself if this 263 /// is the only declaration. 264 const decl_type *getFirstDecl() const { 265 const decl_type *D = static_cast<const decl_type*>(this); 266 if (!D->isFromASTFile()) 267 return D; 268 return cast<decl_type>(getPrimaryMergedDecl(const_cast<decl_type*>(D))); 269 } 270 271 /// \brief Returns true if this is the first declaration. 272 bool isFirstDecl() const { return getFirstDecl() == this; } 273 }; 274 275 } 276 277 #endif 278
