1 | //===- ASTImporterLookupTable.h - ASTImporter specific lookup--*- C++ -*---===// |
2 | // |
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 |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | // |
9 | // This file defines the ASTImporterLookupTable class which implements a |
10 | // lookup procedure for the import mechanism. |
11 | // |
12 | //===----------------------------------------------------------------------===// |
13 | |
14 | #ifndef LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H |
15 | #define LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H |
16 | |
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" |
21 | |
22 | namespace clang { |
23 | |
24 | class NamedDecl; |
25 | class DeclContext; |
26 | |
27 | // There are certain cases when normal C/C++ lookup (localUncachedLookup) |
28 | // does not find AST nodes. E.g.: |
29 | // Example 1: |
30 | // template <class T> |
31 | // struct X { |
32 | // friend void foo(); // this is never found in the DC of the TU. |
33 | // }; |
34 | // Example 2: |
35 | // // The fwd decl to Foo is not found in the lookupPtr of the DC of the |
36 | // // translation unit decl. |
37 | // // Here we could find the node by doing a traverse throught the list of |
38 | // // the Decls in the DC, but that would not scale. |
39 | // struct A { struct Foo *p; }; |
40 | // This is a severe problem because the importer decides if it has to create a |
41 | // new Decl or not based on the lookup results. |
42 | // To overcome these cases we need an importer specific lookup table which |
43 | // holds every node and we are not interested in any C/C++ specific visibility |
44 | // considerations. Simply, we must know if there is an existing Decl in a |
45 | // given DC. Once we found it then we can handle any visibility related tasks. |
46 | class ASTImporterLookupTable { |
47 | |
48 | // We store a list of declarations for each name. |
49 | // And we collect these lists for each DeclContext. |
50 | // We could have a flat map with (DeclContext, Name) tuple as key, but a two |
51 | // level map seems easier to handle. |
52 | using DeclList = llvm::SmallSetVector<NamedDecl *, 2>; |
53 | using NameMap = llvm::SmallDenseMap<DeclarationName, DeclList, 4>; |
54 | using DCMap = llvm::DenseMap<DeclContext *, NameMap>; |
55 | |
56 | void add(DeclContext *DC, NamedDecl *ND); |
57 | void remove(DeclContext *DC, NamedDecl *ND); |
58 | |
59 | DCMap LookupTable; |
60 | |
61 | public: |
62 | ASTImporterLookupTable(TranslationUnitDecl &TU); |
63 | void add(NamedDecl *ND); |
64 | void remove(NamedDecl *ND); |
65 | // Sometimes a declaration is created first with a temporarily value of decl |
66 | // context (often the translation unit) and later moved to the final context. |
67 | // This happens for declarations that are created before the final declaration |
68 | // context. In such cases the lookup table needs to be updated. |
69 | // (The declaration is in these cases not added to the temporary decl context, |
70 | // only its parent is set.) |
71 | // FIXME: It would be better to not add the declaration to the temporary |
72 | // context at all in the lookup table, but this requires big change in |
73 | // ASTImporter. |
74 | // The function should be called when the old context is definitely different |
75 | // from the new. |
76 | void update(NamedDecl *ND, DeclContext *OldDC); |
77 | // Same as 'update' but allow if 'ND' is not in the table or the old context |
78 | // is the same as the new. |
79 | // FIXME: The old redeclaration context is not handled. |
80 | void updateForced(NamedDecl *ND, DeclContext *OldDC); |
81 | using LookupResult = DeclList; |
82 | LookupResult lookup(DeclContext *DC, DeclarationName Name) const; |
83 | // Check if the `ND` is within the lookup table (with its current name) in |
84 | // context `DC`. This is intended for debug purposes when the DeclContext of a |
85 | // NamedDecl is changed. |
86 | bool contains(DeclContext *DC, NamedDecl *ND) const; |
87 | void dump(DeclContext *DC) const; |
88 | void dump() const; |
89 | }; |
90 | |
91 | } // namespace clang |
92 | |
93 | #endif // LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H |
94 | |