ExternalASTSource.h revision c6fbbedb3e90ff2f04828c36fd839e01468679f5
1//===--- ExternalASTSource.h - Abstract External AST Interface --*- 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 ExternalASTSource interface, which enables 11// construction of AST nodes from some external source.x 12// 13//===----------------------------------------------------------------------===// 14#ifndef LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H 15#define LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H 16 17#include "clang/AST/DeclarationName.h" 18#include "clang/AST/Type.h" 19#include "llvm/ADT/SmallVector.h" 20#include <cassert> 21#include <vector> 22namespace clang { 23 24class ASTConsumer; 25class Decl; 26class DeclContext; 27class ExternalSemaSource; // layering violation required for downcasting 28class Stmt; 29 30/// \brief The deserialized representation of a set of declarations 31/// with the same name that are visible in a given context. 32struct VisibleDeclaration { 33 /// \brief The name of the declarations. 34 DeclarationName Name; 35 36 /// \brief The ID numbers of all of the declarations with this name. 37 /// 38 /// These declarations have not necessarily been de-serialized. 39 llvm::SmallVector<unsigned, 4> Declarations; 40}; 41 42/// \brief Abstract interface for external sources of AST nodes. 43/// 44/// External AST sources provide AST nodes constructed from some 45/// external source, such as a precompiled header. External AST 46/// sources can resolve types and declarations from abstract IDs into 47/// actual type and declaration nodes, and read parts of declaration 48/// contexts. 49class ExternalASTSource { 50 /// \brief Whether this AST source also provides information for 51 /// semantic analysis. 52 bool SemaSource; 53 54 friend class ExternalSemaSource; 55 56public: 57 ExternalASTSource() : SemaSource(false) { } 58 59 virtual ~ExternalASTSource(); 60 61 /// \brief Resolve a type ID into a type, potentially building a new 62 /// type. 63 virtual QualType GetType(uint32_t ID) = 0; 64 65 /// \brief Resolve a declaration ID into a declaration, potentially 66 /// building a new declaration. 67 virtual Decl *GetDecl(uint32_t ID) = 0; 68 69 /// \brief Resolve the offset of a statement in the decl stream into a 70 /// statement. 71 /// 72 /// This operation will read a new statement from the external 73 /// source each time it is called, and is meant to be used via a 74 /// LazyOffsetPtr. 75 virtual Stmt *GetDeclStmt(uint64_t Offset) = 0; 76 77 /// \brief Read all of the declarations lexically stored in a 78 /// declaration context. 79 /// 80 /// \param DC The declaration context whose declarations will be 81 /// read. 82 /// 83 /// \param Decls Vector that will contain the declarations loaded 84 /// from the external source. The caller is responsible for merging 85 /// these declarations with any declarations already stored in the 86 /// declaration context. 87 /// 88 /// \returns true if there was an error while reading the 89 /// declarations for this declaration context. 90 virtual bool ReadDeclsLexicallyInContext(DeclContext *DC, 91 llvm::SmallVectorImpl<uint32_t> &Decls) = 0; 92 93 /// \brief Read all of the declarations visible from a declaration 94 /// context. 95 /// 96 /// \param DC The declaration context whose visible declarations 97 /// will be read. 98 /// 99 /// \param Decls A vector of visible declaration structures, 100 /// providing the mapping from each name visible in the declaration 101 /// context to the declaration IDs of declarations with that name. 102 /// 103 /// \returns true if there was an error while reading the 104 /// declarations for this declaration context. 105 virtual bool ReadDeclsVisibleInContext(DeclContext *DC, 106 llvm::SmallVectorImpl<VisibleDeclaration> & Decls) = 0; 107 108 /// \brief Function that will be invoked when we begin parsing a new 109 /// translation unit involving this external AST source. 110 virtual void StartTranslationUnit(ASTConsumer *Consumer) { } 111 112 /// \brief Print any statistics that have been gathered regarding 113 /// the external AST source. 114 virtual void PrintStats(); 115}; 116 117/// \brief A lazy pointer to an AST node (of base type T) that resides 118/// within an external AST source. 119/// 120/// The AST node is identified within the external AST source by a 121/// 63-bit offset, and can be retrieved via an operation on the 122/// external AST source itself. 123template<typename T, T* (ExternalASTSource::*Get)(uint64_t Offset)> 124struct LazyOffsetPtr { 125 /// \brief Either a pointer to an AST node or the offset within the 126 /// external AST source where the AST node can be found. 127 /// 128 /// If the low bit is clear, a pointer to the AST node. If the low 129 /// bit is set, the upper 63 bits are the offset. 130 mutable uint64_t Ptr; 131 132public: 133 LazyOffsetPtr() : Ptr(0) { } 134 135 explicit LazyOffsetPtr(T *Ptr) : Ptr(reinterpret_cast<uint64_t>(Ptr)) { } 136 explicit LazyOffsetPtr(uint64_t Offset) : Ptr((Offset << 1) | 0x01) { 137 assert((Offset << 1 >> 1) == Offset && "Offsets must require < 63 bits"); 138 if (Offset == 0) 139 Ptr = 0; 140 } 141 142 LazyOffsetPtr &operator=(T *Ptr) { 143 this->Ptr = reinterpret_cast<uint64_t>(Ptr); 144 return *this; 145 } 146 147 LazyOffsetPtr &operator=(uint64_t Offset) { 148 assert((Offset << 1 >> 1) == Offset && "Offsets must require < 63 bits"); 149 if (Offset == 0) 150 Ptr = 0; 151 else 152 Ptr = (Offset << 1) | 0x01; 153 154 return *this; 155 } 156 157 /// \brief Whether this pointer is non-NULL. 158 /// 159 /// This operation does not require the AST node to be deserialized. 160 operator bool() const { return Ptr != 0; } 161 162 /// \brief Whether this pointer is currently stored as an offset. 163 bool isOffset() const { return Ptr & 0x01; } 164 165 /// \brief Retrieve the pointer to the AST node that this lazy pointer 166 /// 167 /// \param Source the external AST source. 168 /// 169 /// \returns a pointer to the AST node. 170 T* get(ExternalASTSource *Source) const { 171 if (isOffset()) { 172 assert(Source && 173 "Cannot deserialize a lazy pointer without an AST source"); 174 Ptr = reinterpret_cast<uint64_t>((Source->*Get)(Ptr >> 1)); 175 } 176 return reinterpret_cast<T*>(Ptr); 177 } 178}; 179 180/// \brief A lazy pointer to a statement. 181typedef LazyOffsetPtr<Stmt, &ExternalASTSource::GetDeclStmt> LazyDeclStmtPtr; 182 183} // end namespace clang 184 185#endif // LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H 186