1 //===--- ExternalASTSource.h - Abstract External AST Interface --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the ExternalASTSource interface, which enables
11 // construction of AST nodes from some external source.x
13 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H
15 #define LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H
17 #include "clang/AST/DeclarationName.h"
18 #include "clang/AST/Type.h"
19 #include "llvm/ADT/SmallVector.h"
26 class ExternalSemaSource; // layering violation required for downcasting
29 /// \brief The deserialized representation of a set of declarations
30 /// with the same name that are visible in a given context.
31 struct VisibleDeclaration {
32 /// \brief The name of the declarations.
35 /// \brief The ID numbers of all of the declarations with this name.
37 /// These declarations have not necessarily been de-serialized.
38 llvm::SmallVector<unsigned, 4> Declarations;
41 /// \brief Abstract interface for external sources of AST nodes.
43 /// External AST sources provide AST nodes constructed from some
44 /// external source, such as a precompiled header. External AST
45 /// sources can resolve types and declarations from abstract IDs into
46 /// actual type and declaration nodes, and read parts of declaration
48 class ExternalASTSource {
49 /// \brief Whether this AST source also provides information for
50 /// semantic analysis.
53 friend class ExternalSemaSource;
56 ExternalASTSource() : SemaSource(false) { }
58 virtual ~ExternalASTSource();
60 /// \brief Resolve a type ID into a type, potentially building a new
62 virtual QualType GetType(unsigned ID) = 0;
64 /// \brief Resolve a declaration ID into a declaration, potentially
65 /// building a new declaration.
66 virtual Decl *GetDecl(unsigned ID) = 0;
68 /// \brief Resolve the offset of a statement in the decl stream into a
71 /// This operation will read a new statement from the external
72 /// source each time it is called, and is meant to be used via a
74 virtual Stmt *GetDeclStmt(uint64_t Offset) = 0;
76 /// \brief Read all of the declarations lexically stored in a
77 /// declaration context.
79 /// \param DC The declaration context whose declarations will be
82 /// \param Decls Vector that will contain the declarations loaded
83 /// from the external source. The caller is responsible for merging
84 /// these declarations with any declarations already stored in the
85 /// declaration context.
87 /// \returns true if there was an error while reading the
88 /// declarations for this declaration context.
89 virtual bool ReadDeclsLexicallyInContext(DeclContext *DC,
90 llvm::SmallVectorImpl<uint32_t> &Decls) = 0;
92 /// \brief Read all of the declarations visible from a declaration
95 /// \param DC The declaration context whose visible declarations
98 /// \param Decls A vector of visible declaration structures,
99 /// providing the mapping from each name visible in the declaration
100 /// context to the declaration IDs of declarations with that name.
102 /// \returns true if there was an error while reading the
103 /// declarations for this declaration context.
104 virtual bool ReadDeclsVisibleInContext(DeclContext *DC,
105 llvm::SmallVectorImpl<VisibleDeclaration> & Decls) = 0;
107 /// \brief Function that will be invoked when we begin parsing a new
108 /// translation unit involving this external AST source.
109 virtual void StartTranslationUnit(ASTConsumer *Consumer) { }
111 /// \brief Print any statistics that have been gathered regarding
112 /// the external AST source.
113 virtual void PrintStats();
116 /// \brief A lazy pointer to an AST node (of base type T) that resides
117 /// within an external AST source.
119 /// The AST node is identified within the external AST source by a
120 /// 63-bit offset, and can be retrieved via an operation on the
121 /// external AST source itself.
122 template<typename T, T* (ExternalASTSource::*Get)(uint64_t Offset)>
123 struct LazyOffsetPtr {
124 /// \brief Either a pointer to an AST node or the offset within the
125 /// external AST source where the AST node can be found.
127 /// If the low bit is clear, a pointer to the AST node. If the low
128 /// bit is set, the upper 63 bits are the offset.
129 mutable uint64_t Ptr;
132 LazyOffsetPtr() : Ptr(0) { }
134 explicit LazyOffsetPtr(T *Ptr) : Ptr(reinterpret_cast<uint64_t>(Ptr)) { }
135 explicit LazyOffsetPtr(uint64_t Offset) : Ptr((Offset << 1) | 0x01) {
136 assert((Offset << 1 >> 1) == Offset && "Offsets must require < 63 bits");
141 LazyOffsetPtr &operator=(T *Ptr) {
142 this->Ptr = reinterpret_cast<uint64_t>(Ptr);
146 LazyOffsetPtr &operator=(uint64_t Offset) {
147 assert((Offset << 1 >> 1) == Offset && "Offsets must require < 63 bits");
151 Ptr = (Offset << 1) | 0x01;
156 /// \brief Whether this pointer is non-NULL.
158 /// This operation does not require the AST node to be deserialized.
159 operator bool() const { return Ptr != 0; }
161 /// \brief Whether this pointer is currently stored as an offset.
162 bool isOffset() const { return Ptr & 0x01; }
164 /// \brief Retrieve the pointer to the AST node that this lazy pointer
166 /// \param Source the external AST source.
168 /// \returns a pointer to the AST node.
169 T* get(ExternalASTSource *Source) const {
172 "Cannot deserialize a lazy pointer without an AST source");
173 Ptr = reinterpret_cast<uint64_t>((Source->*Get)(Ptr >> 1));
175 return reinterpret_cast<T*>(Ptr);
179 /// \brief A lazy pointer to a statement.
180 typedef LazyOffsetPtr<Stmt, &ExternalASTSource::GetDeclStmt> LazyDeclStmtPtr;
182 } // end namespace clang
184 #endif // LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H