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"
27 class ExternalSemaSource; // layering violation required for downcasting
30 /// \brief The deserialized representation of a set of declarations
31 /// with the same name that are visible in a given context.
32 struct VisibleDeclaration {
33 /// \brief The name of the declarations.
36 /// \brief The ID numbers of all of the declarations with this name.
38 /// These declarations have not necessarily been de-serialized.
39 llvm::SmallVector<unsigned, 4> Declarations;
42 /// \brief Abstract interface for external sources of AST nodes.
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
49 class ExternalASTSource {
50 /// \brief Whether this AST source also provides information for
51 /// semantic analysis.
54 friend class ExternalSemaSource;
57 ExternalASTSource() : SemaSource(false) { }
59 virtual ~ExternalASTSource();
61 /// \brief Resolve a type ID into a type, potentially building a new
63 virtual QualType GetType(uint32_t ID) = 0;
65 /// \brief Resolve a declaration ID into a declaration, potentially
66 /// building a new declaration.
67 virtual Decl *GetDecl(uint32_t ID) = 0;
69 /// \brief Resolve a selector ID into a selector.
70 virtual Selector GetSelector(uint32_t ID) = 0;
72 /// \brief Returns the number of selectors known to the external AST
74 virtual uint32_t GetNumKnownSelectors() = 0;
76 /// \brief Resolve the offset of a statement in the decl stream into a
79 /// This operation will read a new statement from the external
80 /// source each time it is called, and is meant to be used via a
82 virtual Stmt *GetDeclStmt(uint64_t Offset) = 0;
84 /// \brief Read all of the declarations lexically stored in a
85 /// declaration context.
87 /// \param DC The declaration context whose declarations will be
90 /// \param Decls Vector that will contain the declarations loaded
91 /// from the external source. The caller is responsible for merging
92 /// these declarations with any declarations already stored in the
93 /// declaration context.
95 /// \returns true if there was an error while reading the
96 /// declarations for this declaration context.
97 virtual bool ReadDeclsLexicallyInContext(DeclContext *DC,
98 llvm::SmallVectorImpl<uint32_t> &Decls) = 0;
100 /// \brief Read all of the declarations visible from a declaration
103 /// \param DC The declaration context whose visible declarations
106 /// \param Decls A vector of visible declaration structures,
107 /// providing the mapping from each name visible in the declaration
108 /// context to the declaration IDs of declarations with that name.
110 /// \returns true if there was an error while reading the
111 /// declarations for this declaration context.
112 virtual bool ReadDeclsVisibleInContext(DeclContext *DC,
113 llvm::SmallVectorImpl<VisibleDeclaration> & Decls) = 0;
115 /// \brief Function that will be invoked when we begin parsing a new
116 /// translation unit involving this external AST source.
117 virtual void StartTranslationUnit(ASTConsumer *Consumer) { }
119 /// \brief Print any statistics that have been gathered regarding
120 /// the external AST source.
121 virtual void PrintStats();
124 /// \brief A lazy pointer to an AST node (of base type T) that resides
125 /// within an external AST source.
127 /// The AST node is identified within the external AST source by a
128 /// 63-bit offset, and can be retrieved via an operation on the
129 /// external AST source itself.
130 template<typename T, T* (ExternalASTSource::*Get)(uint64_t Offset)>
131 struct LazyOffsetPtr {
132 /// \brief Either a pointer to an AST node or the offset within the
133 /// external AST source where the AST node can be found.
135 /// If the low bit is clear, a pointer to the AST node. If the low
136 /// bit is set, the upper 63 bits are the offset.
137 mutable uint64_t Ptr;
140 LazyOffsetPtr() : Ptr(0) { }
142 explicit LazyOffsetPtr(T *Ptr) : Ptr(reinterpret_cast<uint64_t>(Ptr)) { }
143 explicit LazyOffsetPtr(uint64_t Offset) : Ptr((Offset << 1) | 0x01) {
144 assert((Offset << 1 >> 1) == Offset && "Offsets must require < 63 bits");
149 LazyOffsetPtr &operator=(T *Ptr) {
150 this->Ptr = reinterpret_cast<uint64_t>(Ptr);
154 LazyOffsetPtr &operator=(uint64_t Offset) {
155 assert((Offset << 1 >> 1) == Offset && "Offsets must require < 63 bits");
159 Ptr = (Offset << 1) | 0x01;
164 /// \brief Whether this pointer is non-NULL.
166 /// This operation does not require the AST node to be deserialized.
167 operator bool() const { return Ptr != 0; }
169 /// \brief Whether this pointer is currently stored as an offset.
170 bool isOffset() const { return Ptr & 0x01; }
172 /// \brief Retrieve the pointer to the AST node that this lazy pointer
174 /// \param Source the external AST source.
176 /// \returns a pointer to the AST node.
177 T* get(ExternalASTSource *Source) const {
180 "Cannot deserialize a lazy pointer without an AST source");
181 Ptr = reinterpret_cast<uint64_t>((Source->*Get)(Ptr >> 1));
183 return reinterpret_cast<T*>(Ptr);
187 /// \brief A lazy pointer to a statement.
188 typedef LazyOffsetPtr<Stmt, &ExternalASTSource::GetDeclStmt> LazyDeclStmtPtr;
190 } // end namespace clang
192 #endif // LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H