1 files changed, 184 insertions, 0 deletions
diff --git a/include/clang/AST/ExternalASTSource.h b/include/clang/AST/ExternalASTSource.h
new file mode 100644
index 0000000..4219bd5
--- /dev/null
+++ b/include/clang/AST/ExternalASTSource.h
@@ -0,0 +1,184 @@
+//===--- ExternalASTSource.h - Abstract External AST Interface --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the ExternalASTSource interface, which enables
+//  construction of AST nodes from some external source.x
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H
+#define LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H
+
+#include "clang/AST/DeclarationName.h"
+#include "clang/AST/Type.h"
+#include "llvm/ADT/SmallVector.h"
+#include <cassert>
+namespace clang {
+
+class ASTConsumer;
+class Decl;
+class DeclContext;
+class ExternalSemaSource; // layering violation required for downcasting
+class Stmt;
+
+/// \brief The deserialized representation of a set of declarations
+/// with the same name that are visible in a given context.
+struct VisibleDeclaration {
+  /// \brief The name of the declarations.
+  DeclarationName Name;
+
+  /// \brief The ID numbers of all of the declarations with this name. 
+  ///
+  /// These declarations have not necessarily been de-serialized.
+  llvm::SmallVector<unsigned, 4> Declarations;
+};
+
+/// \brief Abstract interface for external sources of AST nodes.
+///
+/// External AST sources provide AST nodes constructed from some
+/// external source, such as a precompiled header. External AST
+/// sources can resolve types and declarations from abstract IDs into
+/// actual type and declaration nodes, and read parts of declaration
+/// contexts.
+class ExternalASTSource {
+  /// \brief Whether this AST source also provides information for
+  /// semantic analysis.
+  bool SemaSource;
+
+  friend class ExternalSemaSource;
+
+public:
+  ExternalASTSource() : SemaSource(false) { }
+
+  virtual ~ExternalASTSource();
+
+  /// \brief Resolve a type ID into a type, potentially building a new
+  /// type.
+  virtual QualType GetType(uint32_t ID) = 0;
+
+  /// \brief Resolve a declaration ID into a declaration, potentially
+  /// building a new declaration.
+  virtual Decl *GetDecl(uint32_t ID) = 0;
+
+  /// \brief Resolve the offset of a statement in the decl stream into a
+  /// statement.
+  ///
+  /// This operation will read a new statement from the external
+  /// source each time it is called, and is meant to be used via a
+  /// LazyOffsetPtr.
+  virtual Stmt *GetDeclStmt(uint64_t Offset) = 0;
+
+  /// \brief Read all of the declarations lexically stored in a
+  /// declaration context.
+  ///
+  /// \param DC The declaration context whose declarations will be
+  /// read.
+  ///
+  /// \param Decls Vector that will contain the declarations loaded
+  /// from the external source. The caller is responsible for merging
+  /// these declarations with any declarations already stored in the
+  /// declaration context.
+  ///
+  /// \returns true if there was an error while reading the
+  /// declarations for this declaration context.
+  virtual bool ReadDeclsLexicallyInContext(DeclContext *DC,
+                                  llvm::SmallVectorImpl<uint32_t> &Decls) = 0;
+
+  /// \brief Read all of the declarations visible from a declaration
+  /// context.
+  ///
+  /// \param DC The declaration context whose visible declarations
+  /// will be read.
+  ///
+  /// \param Decls A vector of visible declaration structures,
+  /// providing the mapping from each name visible in the declaration
+  /// context to the declaration IDs of declarations with that name.
+  ///
+  /// \returns true if there was an error while reading the
+  /// declarations for this declaration context.
+  virtual bool ReadDeclsVisibleInContext(DeclContext *DC,
+                       llvm::SmallVectorImpl<VisibleDeclaration> & Decls) = 0;
+
+  /// \brief Function that will be invoked when we begin parsing a new
+  /// translation unit involving this external AST source.
+  virtual void StartTranslationUnit(ASTConsumer *Consumer) { }
+
+  /// \brief Print any statistics that have been gathered regarding
+  /// the external AST source.
+  virtual void PrintStats();
+};
+
+/// \brief A lazy pointer to an AST node (of base type T) that resides
+/// within an external AST source.
+///
+/// The AST node is identified within the external AST source by a
+/// 63-bit offset, and can be retrieved via an operation on the
+/// external AST source itself.
+template<typename T, T* (ExternalASTSource::*Get)(uint64_t Offset)>
+struct LazyOffsetPtr {
+  /// \brief Either a pointer to an AST node or the offset within the
+  /// external AST source where the AST node can be found.
+  ///
+  /// If the low bit is clear, a pointer to the AST node. If the low
+  /// bit is set, the upper 63 bits are the offset.
+  mutable uint64_t Ptr;
+
+public:
+  LazyOffsetPtr() : Ptr(0) { }
+
+  explicit LazyOffsetPtr(T *Ptr) : Ptr(reinterpret_cast<uint64_t>(Ptr)) { }
+  explicit LazyOffsetPtr(uint64_t Offset) : Ptr((Offset << 1) | 0x01) {
+    assert((Offset << 1 >> 1) == Offset && "Offsets must require < 63 bits");
+    if (Offset == 0)
+      Ptr = 0;
+  }
+
+  LazyOffsetPtr &operator=(T *Ptr) {
+    this->Ptr = reinterpret_cast<uint64_t>(Ptr);
+    return *this;
+  }
+  
+  LazyOffsetPtr &operator=(uint64_t Offset) {
+    assert((Offset << 1 >> 1) == Offset && "Offsets must require < 63 bits");
+    if (Offset == 0)
+      Ptr = 0;
+    else
+      Ptr = (Offset << 1) | 0x01;
+
+    return *this;
+  }
+
+  /// \brief Whether this pointer is non-NULL.
+  ///
+  /// This operation does not require the AST node to be deserialized.
+  operator bool() const { return Ptr != 0; }
+
+  /// \brief Whether this pointer is currently stored as an offset.
+  bool isOffset() const { return Ptr & 0x01; }
+
+  /// \brief Retrieve the pointer to the AST node that this lazy pointer
+  ///
+  /// \param Source the external AST source.
+  ///
+  /// \returns a pointer to the AST node.
+  T* get(ExternalASTSource *Source) const {
+    if (isOffset()) {
+      assert(Source && 
+             "Cannot deserialize a lazy pointer without an AST source");
+      Ptr = reinterpret_cast<uint64_t>((Source->*Get)(Ptr >> 1));
+    }
+    return reinterpret_cast<T*>(Ptr);
+  }
+};
+
+/// \brief A lazy pointer to a statement.
+typedef LazyOffsetPtr<Stmt, &ExternalASTSource::GetDeclStmt> LazyDeclStmtPtr;
+
+} // end namespace clang
+
+#endif // LLVM_CLANG_AST_EXTERNAL_AST_SOURCE_H