llvm/clang/include/clang/AST/DeclID.h

//===--- DeclID.h - ID number for deserialized declarations  ----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines DeclID class family to describe the deserialized
// declarations. The DeclID is widely used in AST via LazyDeclPtr, or calls to
// `ExternalASTSource::getExternalDecl`. It will be helpful for type safety to
// require the use of `DeclID` to explicit.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_AST_DECLID_H
#define LLVM_CLANG_AST_DECLID_H

#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/iterator.h"

namespace clang {

/// Predefined declaration IDs.
///
/// These declaration IDs correspond to predefined declarations in the AST
/// context, such as the NULL declaration ID. Such declarations are never
/// actually serialized, since they will be built by the AST context when
/// it is created.
enum PredefinedDeclIDs { … };

/// GlobalDeclID means DeclID in the current ASTContext and LocalDeclID means
/// DeclID specific to a certain ModuleFile. Specially, in ASTWriter, the
/// LocalDeclID to the ModuleFile been writting is equal to the GlobalDeclID.
/// Outside the serializer, all the DeclID been used should be GlobalDeclID.
/// We can translate a LocalDeclID to the GlobalDeclID by
/// `ASTReader::getGlobalDeclID()`.

class DeclIDBase { … };

class ASTWriter;
class ASTReader;
namespace serialization {
class ModuleFile;
} // namespace serialization

class LocalDeclID : public DeclIDBase { … };

class GlobalDeclID : public DeclIDBase { … };

/// A helper iterator adaptor to convert the iterators to
/// `SmallVector<SomeDeclID>` to the iterators to `SmallVector<OtherDeclID>`.
template <class FromTy, class ToTy>
class DeclIDIterator
    : public llvm::iterator_adaptor_base<DeclIDIterator<FromTy, ToTy>,
                                         const FromTy *,
                                         std::forward_iterator_tag, ToTy> { … };

} // namespace clang

namespace llvm {
template <> struct DenseMapInfo<clang::GlobalDeclID> { … };

template <> struct DenseMapInfo<clang::LocalDeclID> { … };

} // namespace llvm

#endif