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      1 //===-- DeclContextInternals.h - DeclContext Representation -----*- 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 data structures used in the implementation
     11 //  of DeclContext.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 #ifndef LLVM_CLANG_AST_DECLCONTEXTINTERNALS_H
     15 #define LLVM_CLANG_AST_DECLCONTEXTINTERNALS_H
     16 
     17 #include "clang/AST/Decl.h"
     18 #include "clang/AST/DeclCXX.h"
     19 #include "clang/AST/DeclarationName.h"
     20 #include "llvm/ADT/DenseMap.h"
     21 #include "llvm/ADT/PointerIntPair.h"
     22 #include "llvm/ADT/PointerUnion.h"
     23 #include "llvm/ADT/SmallVector.h"
     24 #include <algorithm>
     25 
     26 namespace clang {
     27 
     28 class DependentDiagnostic;
     29 
     30 /// \brief An array of decls optimized for the common case of only containing
     31 /// one entry.
     32 struct StoredDeclsList {
     33 
     34   /// \brief When in vector form, this is what the Data pointer points to.
     35   typedef SmallVector<NamedDecl *, 4> DeclsTy;
     36 
     37   /// \brief A collection of declarations, with a flag to indicate if we have
     38   /// further external declarations.
     39   typedef llvm::PointerIntPair<DeclsTy *, 1, bool> DeclsAndHasExternalTy;
     40 
     41   /// \brief The stored data, which will be either a pointer to a NamedDecl,
     42   /// or a pointer to a vector with a flag to indicate if there are further
     43   /// external declarations.
     44   llvm::PointerUnion<NamedDecl*, DeclsAndHasExternalTy> Data;
     45 
     46 public:
     47   StoredDeclsList() {}
     48 
     49   StoredDeclsList(StoredDeclsList &&RHS) : Data(RHS.Data) {
     50     RHS.Data = (NamedDecl *)nullptr;
     51   }
     52 
     53   ~StoredDeclsList() {
     54     // If this is a vector-form, free the vector.
     55     if (DeclsTy *Vector = getAsVector())
     56       delete Vector;
     57   }
     58 
     59   StoredDeclsList &operator=(StoredDeclsList &&RHS) {
     60     if (DeclsTy *Vector = getAsVector())
     61       delete Vector;
     62     Data = RHS.Data;
     63     RHS.Data = (NamedDecl *)nullptr;
     64     return *this;
     65   }
     66 
     67   bool isNull() const { return Data.isNull(); }
     68 
     69   NamedDecl *getAsDecl() const {
     70     return Data.dyn_cast<NamedDecl *>();
     71   }
     72 
     73   DeclsAndHasExternalTy getAsVectorAndHasExternal() const {
     74     return Data.dyn_cast<DeclsAndHasExternalTy>();
     75   }
     76 
     77   DeclsTy *getAsVector() const {
     78     return getAsVectorAndHasExternal().getPointer();
     79   }
     80 
     81   bool hasExternalDecls() const {
     82     return getAsVectorAndHasExternal().getInt();
     83   }
     84 
     85   void setHasExternalDecls() {
     86     if (DeclsTy *Vec = getAsVector())
     87       Data = DeclsAndHasExternalTy(Vec, true);
     88     else {
     89       DeclsTy *VT = new DeclsTy();
     90       if (NamedDecl *OldD = getAsDecl())
     91         VT->push_back(OldD);
     92       Data = DeclsAndHasExternalTy(VT, true);
     93     }
     94   }
     95 
     96   void setOnlyValue(NamedDecl *ND) {
     97     assert(!getAsVector() && "Not inline");
     98     Data = ND;
     99     // Make sure that Data is a plain NamedDecl* so we can use its address
    100     // at getLookupResult.
    101     assert(*(NamedDecl **)&Data == ND &&
    102            "PointerUnion mangles the NamedDecl pointer!");
    103   }
    104 
    105   void remove(NamedDecl *D) {
    106     assert(!isNull() && "removing from empty list");
    107     if (NamedDecl *Singleton = getAsDecl()) {
    108       assert(Singleton == D && "list is different singleton");
    109       (void)Singleton;
    110       Data = (NamedDecl *)nullptr;
    111       return;
    112     }
    113 
    114     DeclsTy &Vec = *getAsVector();
    115     DeclsTy::iterator I = std::find(Vec.begin(), Vec.end(), D);
    116     assert(I != Vec.end() && "list does not contain decl");
    117     Vec.erase(I);
    118 
    119     assert(std::find(Vec.begin(), Vec.end(), D)
    120              == Vec.end() && "list still contains decl");
    121   }
    122 
    123   /// \brief Remove any declarations which were imported from an external
    124   /// AST source.
    125   void removeExternalDecls() {
    126     if (isNull()) {
    127       // Nothing to do.
    128     } else if (NamedDecl *Singleton = getAsDecl()) {
    129       if (Singleton->isFromASTFile())
    130         *this = StoredDeclsList();
    131     } else {
    132       DeclsTy &Vec = *getAsVector();
    133       Vec.erase(std::remove_if(Vec.begin(), Vec.end(),
    134                                std::mem_fun(&Decl::isFromASTFile)),
    135                 Vec.end());
    136       // Don't have any external decls any more.
    137       Data = DeclsAndHasExternalTy(&Vec, false);
    138     }
    139   }
    140 
    141   /// getLookupResult - Return an array of all the decls that this list
    142   /// represents.
    143   DeclContext::lookup_result getLookupResult() {
    144     if (isNull())
    145       return DeclContext::lookup_result();
    146 
    147     // If we have a single NamedDecl, return it.
    148     if (NamedDecl *ND = getAsDecl()) {
    149       assert(!isNull() && "Empty list isn't allowed");
    150 
    151       // Data is a raw pointer to a NamedDecl*, return it.
    152       return DeclContext::lookup_result(ND);
    153     }
    154 
    155     assert(getAsVector() && "Must have a vector at this point");
    156     DeclsTy &Vector = *getAsVector();
    157 
    158     // Otherwise, we have a range result.
    159     return DeclContext::lookup_result(Vector);
    160   }
    161 
    162   /// HandleRedeclaration - If this is a redeclaration of an existing decl,
    163   /// replace the old one with D and return true.  Otherwise return false.
    164   bool HandleRedeclaration(NamedDecl *D, bool IsKnownNewer) {
    165     // Most decls only have one entry in their list, special case it.
    166     if (NamedDecl *OldD = getAsDecl()) {
    167       if (!D->declarationReplaces(OldD, IsKnownNewer))
    168         return false;
    169       setOnlyValue(D);
    170       return true;
    171     }
    172 
    173     // Determine if this declaration is actually a redeclaration.
    174     DeclsTy &Vec = *getAsVector();
    175     for (DeclsTy::iterator OD = Vec.begin(), ODEnd = Vec.end();
    176          OD != ODEnd; ++OD) {
    177       NamedDecl *OldD = *OD;
    178       if (D->declarationReplaces(OldD, IsKnownNewer)) {
    179         *OD = D;
    180         return true;
    181       }
    182     }
    183 
    184     return false;
    185   }
    186 
    187   /// AddSubsequentDecl - This is called on the second and later decl when it is
    188   /// not a redeclaration to merge it into the appropriate place in our list.
    189   ///
    190   void AddSubsequentDecl(NamedDecl *D) {
    191     assert(!isNull() && "don't AddSubsequentDecl when we have no decls");
    192 
    193     // If this is the second decl added to the list, convert this to vector
    194     // form.
    195     if (NamedDecl *OldD = getAsDecl()) {
    196       DeclsTy *VT = new DeclsTy();
    197       VT->push_back(OldD);
    198       Data = DeclsAndHasExternalTy(VT, false);
    199     }
    200 
    201     DeclsTy &Vec = *getAsVector();
    202 
    203     // Using directives end up in a special entry which contains only
    204     // other using directives, so all this logic is wasted for them.
    205     // But avoiding the logic wastes time in the far-more-common case
    206     // that we're *not* adding a new using directive.
    207 
    208     // Tag declarations always go at the end of the list so that an
    209     // iterator which points at the first tag will start a span of
    210     // decls that only contains tags.
    211     if (D->hasTagIdentifierNamespace())
    212       Vec.push_back(D);
    213 
    214     // Resolved using declarations go at the front of the list so that
    215     // they won't show up in other lookup results.  Unresolved using
    216     // declarations (which are always in IDNS_Using | IDNS_Ordinary)
    217     // follow that so that the using declarations will be contiguous.
    218     else if (D->getIdentifierNamespace() & Decl::IDNS_Using) {
    219       DeclsTy::iterator I = Vec.begin();
    220       if (D->getIdentifierNamespace() != Decl::IDNS_Using) {
    221         while (I != Vec.end() &&
    222                (*I)->getIdentifierNamespace() == Decl::IDNS_Using)
    223           ++I;
    224       }
    225       Vec.insert(I, D);
    226 
    227     // All other declarations go at the end of the list, but before any
    228     // tag declarations.  But we can be clever about tag declarations
    229     // because there can only ever be one in a scope.
    230     } else if (!Vec.empty() && Vec.back()->hasTagIdentifierNamespace()) {
    231       NamedDecl *TagD = Vec.back();
    232       Vec.back() = D;
    233       Vec.push_back(TagD);
    234     } else
    235       Vec.push_back(D);
    236   }
    237 };
    238 
    239 class StoredDeclsMap
    240   : public llvm::SmallDenseMap<DeclarationName, StoredDeclsList, 4> {
    241 
    242 public:
    243   static void DestroyAll(StoredDeclsMap *Map, bool Dependent);
    244 
    245 private:
    246   friend class ASTContext; // walks the chain deleting these
    247   friend class DeclContext;
    248   llvm::PointerIntPair<StoredDeclsMap*, 1> Previous;
    249 };
    250 
    251 class DependentStoredDeclsMap : public StoredDeclsMap {
    252 public:
    253   DependentStoredDeclsMap() : FirstDiagnostic(nullptr) {}
    254 
    255 private:
    256   friend class DependentDiagnostic;
    257   friend class DeclContext; // iterates over diagnostics
    258 
    259   DependentDiagnostic *FirstDiagnostic;
    260 };
    261 
    262 } // end namespace clang
    263 
    264 #endif
    265