1 //===--- HeaderSourceSwitch.cpp - --------------------------------*- 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 #include "HeaderSourceSwitch.h"
10 #include "AST.h"
11 #include "SourceCode.h"
12 #include "index/SymbolCollector.h"
13 #include "support/Logger.h"
14 #include "support/Path.h"
15 #include "clang/AST/Decl.h"
16
17 namespace clang {
18 namespace clangd {
19
getCorrespondingHeaderOrSource(PathRef OriginalFile,llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS)20 llvm::Optional<Path> getCorrespondingHeaderOrSource(
21 PathRef OriginalFile, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS) {
22 llvm::StringRef SourceExtensions[] = {".cpp", ".c", ".cc", ".cxx",
23 ".c++", ".m", ".mm"};
24 llvm::StringRef HeaderExtensions[] = {".h", ".hh", ".hpp", ".hxx", ".inc"};
25
26 llvm::StringRef PathExt = llvm::sys::path::extension(OriginalFile);
27
28 // Lookup in a list of known extensions.
29 auto *SourceIter =
30 llvm::find_if(SourceExtensions, [&PathExt](PathRef SourceExt) {
31 return SourceExt.equals_insensitive(PathExt);
32 });
33 bool IsSource = SourceIter != std::end(SourceExtensions);
34
35 auto *HeaderIter =
36 llvm::find_if(HeaderExtensions, [&PathExt](PathRef HeaderExt) {
37 return HeaderExt.equals_insensitive(PathExt);
38 });
39 bool IsHeader = HeaderIter != std::end(HeaderExtensions);
40
41 // We can only switch between the known extensions.
42 if (!IsSource && !IsHeader)
43 return None;
44
45 // Array to lookup extensions for the switch. An opposite of where original
46 // extension was found.
47 llvm::ArrayRef<llvm::StringRef> NewExts;
48 if (IsSource)
49 NewExts = HeaderExtensions;
50 else
51 NewExts = SourceExtensions;
52
53 // Storage for the new path.
54 llvm::SmallString<128> NewPath = OriginalFile;
55
56 // Loop through switched extension candidates.
57 for (llvm::StringRef NewExt : NewExts) {
58 llvm::sys::path::replace_extension(NewPath, NewExt);
59 if (VFS->exists(NewPath))
60 return Path(NewPath);
61
62 // Also check NewExt in upper-case, just in case.
63 llvm::sys::path::replace_extension(NewPath, NewExt.upper());
64 if (VFS->exists(NewPath))
65 return Path(NewPath);
66 }
67 return None;
68 }
69
getCorrespondingHeaderOrSource(PathRef OriginalFile,ParsedAST & AST,const SymbolIndex * Index)70 llvm::Optional<Path> getCorrespondingHeaderOrSource(PathRef OriginalFile,
71 ParsedAST &AST,
72 const SymbolIndex *Index) {
73 if (!Index) {
74 // FIXME: use the AST to do the inference.
75 return None;
76 }
77 LookupRequest Request;
78 // Find all symbols present in the original file.
79 for (const auto *D : getIndexableLocalDecls(AST)) {
80 if (auto ID = getSymbolID(D))
81 Request.IDs.insert(ID);
82 }
83 llvm::StringMap<int> Candidates; // Target path => score.
84 auto AwardTarget = [&](const char *TargetURI) {
85 if (auto TargetPath = URI::resolve(TargetURI, OriginalFile)) {
86 if (!pathEqual(*TargetPath, OriginalFile)) // exclude the original file.
87 ++Candidates[*TargetPath];
88 } else {
89 elog("Failed to resolve URI {0}: {1}", TargetURI, TargetPath.takeError());
90 }
91 };
92 // If we switch from a header, we are looking for the implementation
93 // file, so we use the definition loc; otherwise we look for the header file,
94 // we use the decl loc;
95 //
96 // For each symbol in the original file, we get its target location (decl or
97 // def) from the index, then award that target file.
98 bool IsHeader = isHeaderFile(OriginalFile, AST.getLangOpts());
99 Index->lookup(Request, [&](const Symbol &Sym) {
100 if (IsHeader)
101 AwardTarget(Sym.Definition.FileURI);
102 else
103 AwardTarget(Sym.CanonicalDeclaration.FileURI);
104 });
105 // FIXME: our index doesn't have any interesting information (this could be
106 // that the background-index is not finished), we should use the decl/def
107 // locations from the AST to do the inference (from .cc to .h).
108 if (Candidates.empty())
109 return None;
110
111 // Pickup the winner, who contains most of symbols.
112 // FIXME: should we use other signals (file proximity) to help score?
113 auto Best = Candidates.begin();
114 for (auto It = Candidates.begin(); It != Candidates.end(); ++It) {
115 if (It->second > Best->second)
116 Best = It;
117 else if (It->second == Best->second && It->first() < Best->first())
118 // Select the first one in the lexical order if we have multiple
119 // candidates.
120 Best = It;
121 }
122 return Path(Best->first());
123 }
124
getIndexableLocalDecls(ParsedAST & AST)125 std::vector<const Decl *> getIndexableLocalDecls(ParsedAST &AST) {
126 std::vector<const Decl *> Results;
127 std::function<void(Decl *)> TraverseDecl = [&](Decl *D) {
128 auto *ND = llvm::dyn_cast<NamedDecl>(D);
129 if (!ND || ND->isImplicit())
130 return;
131 if (!SymbolCollector::shouldCollectSymbol(*ND, D->getASTContext(), {},
132 /*IsMainFileSymbol=*/false))
133 return;
134 if (!llvm::isa<FunctionDecl>(ND)) {
135 // Visit the children, but we skip function decls as we are not interested
136 // in the function body.
137 if (auto *Scope = llvm::dyn_cast<DeclContext>(ND)) {
138 for (auto *D : Scope->decls())
139 TraverseDecl(D);
140 }
141 }
142 if (llvm::isa<NamespaceDecl>(D))
143 return; // namespace is indexable, but we're not interested.
144 Results.push_back(D);
145 };
146 // Traverses the ParsedAST directly to collect all decls present in the main
147 // file.
148 for (auto *TopLevel : AST.getLocalTopLevelDecls())
149 TraverseDecl(TopLevel);
150 return Results;
151 }
152
153 } // namespace clangd
154 } // namespace clang
155