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//===- ASTImporterLookupTable.h - ASTImporter specific lookup--*- 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 the ASTImporterLookupTable class which implements a
// lookup procedure for the import mechanism.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H
#define LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H
#include "clang/AST/DeclBase.h" // lookup_result
#include "clang/AST/DeclarationName.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SetVector.h"
namespace clang {
class NamedDecl;
class DeclContext;
// There are certain cases when normal C/C++ lookup (localUncachedLookup)
// does not find AST nodes. E.g.:
// Example 1:
// template <class T>
// struct X {
// friend void foo(); // this is never found in the DC of the TU.
// };
// Example 2:
// // The fwd decl to Foo is not found in the lookupPtr of the DC of the
// // translation unit decl.
// // Here we could find the node by doing a traverse throught the list of
// // the Decls in the DC, but that would not scale.
// struct A { struct Foo *p; };
// This is a severe problem because the importer decides if it has to create a
// new Decl or not based on the lookup results.
// To overcome these cases we need an importer specific lookup table which
// holds every node and we are not interested in any C/C++ specific visibility
// considerations. Simply, we must know if there is an existing Decl in a
// given DC. Once we found it then we can handle any visibility related tasks.
class ASTImporterLookupTable {
// We store a list of declarations for each name.
// And we collect these lists for each DeclContext.
// We could have a flat map with (DeclContext, Name) tuple as key, but a two
// level map seems easier to handle.
using DeclList = llvm::SmallSetVector<NamedDecl *, 2>;
using NameMap = llvm::SmallDenseMap<DeclarationName, DeclList, 4>;
using DCMap = llvm::DenseMap<DeclContext *, NameMap>;
void add(DeclContext *DC, NamedDecl *ND);
void remove(DeclContext *DC, NamedDecl *ND);
DCMap LookupTable;
public:
ASTImporterLookupTable(TranslationUnitDecl &TU);
void add(NamedDecl *ND);
void remove(NamedDecl *ND);
// Sometimes a declaration is created first with a temporarily value of decl
// context (often the translation unit) and later moved to the final context.
// This happens for declarations that are created before the final declaration
// context. In such cases the lookup table needs to be updated.
// (The declaration is in these cases not added to the temporary decl context,
// only its parent is set.)
// FIXME: It would be better to not add the declaration to the temporary
// context at all in the lookup table, but this requires big change in
// ASTImporter.
// The function should be called when the old context is definitely different
// from the new.
void update(NamedDecl *ND, DeclContext *OldDC);
// Same as 'update' but allow if 'ND' is not in the table or the old context
// is the same as the new.
// FIXME: The old redeclaration context is not handled.
void updateForced(NamedDecl *ND, DeclContext *OldDC);
using LookupResult = DeclList;
LookupResult lookup(DeclContext *DC, DeclarationName Name) const;
// Check if the `ND` is within the lookup table (with its current name) in
// context `DC`. This is intended for debug purposes when the DeclContext of a
// NamedDecl is changed.
bool contains(DeclContext *DC, NamedDecl *ND) const;
void dump(DeclContext *DC) const;
void dump() const;
};
} // namespace clang
#endif // LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H
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