1 //===- ASTImporterLookupTable.h - ASTImporter specific lookup--*- C++ -*---===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file defines the ASTImporterLookupTable class which implements a
10 // lookup procedure for the import mechanism.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H
15 #define LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H
17 #include "clang/AST/DeclBase.h" // lookup_result
18 #include "clang/AST/DeclarationName.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/SetVector.h"
28 // There are certain cases when normal C/C++ lookup (localUncachedLookup)
29 // does not find AST nodes. E.g.:
33 // friend void foo(); // this is never found in the DC of the TU.
36 // // The fwd decl to Foo is not found in the lookupPtr of the DC of the
37 // // translation unit decl.
38 // // Here we could find the node by doing a traverse throught the list of
39 // // the Decls in the DC, but that would not scale.
40 // struct A { struct Foo *p; };
41 // This is a severe problem because the importer decides if it has to create a
42 // new Decl or not based on the lookup results.
43 // To overcome these cases we need an importer specific lookup table which
44 // holds every node and we are not interested in any C/C++ specific visibility
45 // considerations. Simply, we must know if there is an existing Decl in a
46 // given DC. Once we found it then we can handle any visibility related tasks.
47 class ASTImporterLookupTable {
49 // We store a list of declarations for each name.
50 // And we collect these lists for each DeclContext.
51 // We could have a flat map with (DeclContext, Name) tuple as key, but a two
52 // level map seems easier to handle.
53 using DeclList = llvm::SmallSetVector<NamedDecl *, 2>;
54 using NameMap = llvm::SmallDenseMap<DeclarationName, DeclList, 4>;
55 using DCMap = llvm::DenseMap<DeclContext *, NameMap>;
57 void add(DeclContext *DC, NamedDecl *ND);
58 void remove(DeclContext *DC, NamedDecl *ND);
63 ASTImporterLookupTable(TranslationUnitDecl &TU);
64 void add(NamedDecl *ND);
65 void remove(NamedDecl *ND);
66 using LookupResult = DeclList;
67 LookupResult lookup(DeclContext *DC, DeclarationName Name) const;
68 void dump(DeclContext *DC) const;
74 #endif // LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H