1//===--- FindTarget.h - What does an AST node refer to? ---------*- 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// Many clangd features are concerned with references in the AST:
10// - xrefs, go-to-definition, explicitly talk about references
11// - hover and code actions relate to things you "target" in the editor
12// - refactoring actions need to know about entities that are referenced
13// to determine whether/how the edit can be applied.
14//
15// Historically, we have used libIndex (IndexDataConsumer) to tie source
16// locations to referenced declarations. This file defines a more decoupled
17// approach based around AST nodes (DynTypedNode), and can be combined with
18// SelectionTree or other traversals.
19//
20//===----------------------------------------------------------------------===//
21
22#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_FINDTARGET_H
23#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_FINDTARGET_H
24
25#include "clang/AST/ASTContext.h"
26#include "clang/AST/ASTTypeTraits.h"
27#include "clang/AST/NestedNameSpecifier.h"
28#include "clang/AST/Stmt.h"
29#include "clang/Basic/SourceLocation.h"
30#include "llvm/ADT/SmallVector.h"
31#include "llvm/Support/raw_ostream.h"
32
33#include <bitset>
34
35namespace clang {
36namespace clangd {
37class HeuristicResolver;
38
39/// Describes the link between an AST node and a Decl it refers to.
40enum class DeclRelation : unsigned;
41/// A bitfield of DeclRelations.
42class DeclRelationSet;
43
44/// targetDecl() finds the declaration referred to by an AST node.
45/// For example a RecordTypeLoc refers to the RecordDecl for the type.
46///
47/// In some cases there are multiple results, e.g. a dependent unresolved
48/// OverloadExpr may have several candidates. All will be returned:
49///
50/// void foo(int); <-- candidate
51/// void foo(double); <-- candidate
52/// template <typename T> callFoo() { foo(T()); }
53/// ^ OverloadExpr
54///
55/// In other cases, there may be choices about what "referred to" means.
56/// e.g. does naming a typedef refer to the underlying type?
57/// The results are marked with a set of DeclRelations, and can be filtered.
58///
59/// struct S{}; <-- candidate (underlying)
60/// using T = S{}; <-- candidate (alias)
61/// T x;
62/// ^ TypedefTypeLoc
63///
64/// Formally, we walk a graph starting at the provided node, and return the
65/// decls that were found. Certain edges in the graph have labels, and for each
66/// decl we return the set of labels seen on a path to the decl.
67/// For the previous example:
68///
69/// TypedefTypeLoc T
70/// |
71/// TypedefType T
72/// / \
73/// [underlying] [alias]
74/// / \
75/// RecordDecl S TypeAliasDecl T
76///
77/// Note that this function only returns NamedDecls. Generally other decls
78/// don't have references in this sense, just the node itself.
79/// If callers want to support such decls, they should cast the node directly.
80///
81/// FIXME: some AST nodes cannot be DynTypedNodes, these cannot be specified.
82llvm::SmallVector<const NamedDecl *, 1>
83targetDecl(const DynTypedNode &, DeclRelationSet Mask,
84 const HeuristicResolver *Resolver);
85
86/// Similar to targetDecl(), however instead of applying a filter, all possible
87/// decls are returned along with their DeclRelationSets.
88/// This is suitable for indexing, where everything is recorded and filtering
89/// is applied later.
90llvm::SmallVector<std::pair<const NamedDecl *, DeclRelationSet>, 1>
91allTargetDecls(const DynTypedNode &, const HeuristicResolver *);
92
93enum class DeclRelation : unsigned {
94 // Template options apply when the declaration is an instantiated template.
95 // e.g. [[vector<int>]] vec;
96
97 /// This is the template instantiation that was referred to.
98 /// e.g. template<> class vector<int> (the implicit specialization)
99 TemplateInstantiation,
100 /// This is the pattern the template specialization was instantiated from.
101 /// e.g. class vector<T> (the pattern within the primary template)
102 TemplatePattern,
103
104 // Alias options apply when the declaration is an alias.
105 // e.g. namespace client { [[X]] x; }
106
107 /// This declaration is an alias that was referred to.
108 /// e.g. using ns::X (the UsingDecl directly referenced),
109 /// using Z = ns::Y (the TypeAliasDecl directly referenced)
110 Alias,
111 /// This is the underlying declaration for a renaming-alias, decltype etc.
112 /// e.g. class ns::Y (the underlying declaration referenced).
113 ///
114 /// Note that we don't treat `using ns::X` as a first-class declaration like
115 /// `using Z = ns::Y`. Therefore reference to X that goes through this
116 /// using-decl is considered a direct reference (without the Underlying bit).
117 /// Nevertheless, we report `using ns::X` as an Alias, so that some features
118 /// like go-to-definition can still target it.
119 Underlying,
120};
121llvm::raw_ostream &operator<<(llvm::raw_ostream &, DeclRelation);
122
123/// Information about a reference written in the source code, independent of the
124/// actual AST node that this reference lives in.
125/// Useful for tools that are source-aware, e.g. refactorings.
126struct ReferenceLoc {
127 /// Contains qualifier written in the code, if any, e.g. 'ns::' for 'ns::foo'.
128 NestedNameSpecifierLoc Qualifier;
129 /// Start location of the last name part, i.e. 'foo' in 'ns::foo<int>'.
130 SourceLocation NameLoc;
131 /// True if the reference is a declaration or definition;
132 bool IsDecl = false;
133 // FIXME: add info about template arguments.
134 /// A list of targets referenced by this name. Normally this has a single
135 /// element, but multiple is also possible, e.g. in case of using declarations
136 /// or unresolved overloaded functions.
137 /// For dependent and unresolved references, Targets can also be empty.
138 llvm::SmallVector<const NamedDecl *, 1> Targets;
139};
140llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, ReferenceLoc R);
141
142/// Recursively traverse \p S and report all references explicitly written in
143/// the code. The main use-case is refactorings that need to process all
144/// references in some subrange of the file and apply simple edits, e.g. add
145/// qualifiers.
146/// FIXME: currently this does not report references to overloaded operators.
147/// FIXME: extend to report location information about declaration names too.
148void findExplicitReferences(const Stmt *S,
149 llvm::function_ref<void(ReferenceLoc)> Out,
150 const HeuristicResolver *Resolver);
151void findExplicitReferences(const Decl *D,
152 llvm::function_ref<void(ReferenceLoc)> Out,
153 const HeuristicResolver *Resolver);
154void findExplicitReferences(const ASTContext &AST,
155 llvm::function_ref<void(ReferenceLoc)> Out,
156 const HeuristicResolver *Resolver);
157
158/// Find declarations explicitly referenced in the source code defined by \p N.
159/// For templates, will prefer to return a template instantiation whenever
160/// possible. However, can also return a template pattern if the specialization
161/// cannot be picked, e.g. in dependent code or when there is no corresponding
162/// Decl for a template instantiation, e.g. for templated using decls:
163/// template <class T> using Ptr = T*;
164/// Ptr<int> x;
165/// ^~~ there is no Decl for 'Ptr<int>', so we return the template pattern.
166/// \p Mask should not contain TemplatePattern or TemplateInstantiation.
167llvm::SmallVector<const NamedDecl *, 1>
168explicitReferenceTargets(DynTypedNode N, DeclRelationSet Mask,
169 const HeuristicResolver *Resolver);
170
171// Boring implementation details of bitfield.
172
173class DeclRelationSet {
174 using Set = std::bitset<static_cast<unsigned>(DeclRelation::Underlying) + 1>;
175 Set S;
176 DeclRelationSet(Set S) : S(S) {}
177
178public:
179 DeclRelationSet() = default;
180 DeclRelationSet(DeclRelation R) { S.set(position: static_cast<unsigned>(R)); }
181
182 explicit operator bool() const { return S.any(); }
183 friend DeclRelationSet operator&(DeclRelationSet L, DeclRelationSet R) {
184 return L.S & R.S;
185 }
186 friend DeclRelationSet operator|(DeclRelationSet L, DeclRelationSet R) {
187 return L.S | R.S;
188 }
189 friend bool operator==(DeclRelationSet L, DeclRelationSet R) {
190 return L.S == R.S;
191 }
192 friend DeclRelationSet operator~(DeclRelationSet R) { return ~R.S; }
193 DeclRelationSet &operator|=(DeclRelationSet Other) {
194 S |= Other.S;
195 return *this;
196 }
197 DeclRelationSet &operator&=(DeclRelationSet Other) {
198 S &= Other.S;
199 return *this;
200 }
201 bool contains(DeclRelationSet Other) const {
202 return (S & Other.S) == Other.S;
203 }
204 friend llvm::raw_ostream &operator<<(llvm::raw_ostream &, DeclRelationSet);
205};
206// The above operators can't be looked up if both sides are enums.
207// over.match.oper.html#3.2
208inline DeclRelationSet operator|(DeclRelation L, DeclRelation R) {
209 return DeclRelationSet(L) | DeclRelationSet(R);
210}
211inline DeclRelationSet operator&(DeclRelation L, DeclRelation R) {
212 return DeclRelationSet(L) & DeclRelationSet(R);
213}
214inline DeclRelationSet operator~(DeclRelation R) { return ~DeclRelationSet(R); }
215llvm::raw_ostream &operator<<(llvm::raw_ostream &, DeclRelationSet);
216
217} // namespace clangd
218} // namespace clang
219
220#endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_FINDTARGET_H
221

source code of clang-tools-extra/clangd/FindTarget.h