clang-tools  11.0.0git
HeaderSourceSwitch.cpp
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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 "clang/AST/Decl.h"
15 
16 namespace clang {
17 namespace clangd {
18 
19 llvm::Optional<Path> getCorrespondingHeaderOrSource(
20  const Path &OriginalFile,
21  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_lower(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_lower(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 = llvm::StringRef(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 NewPath.str().str(); // First str() to convert from SmallString to
61  // StringRef, second to convert from StringRef
62  // to std::string
63 
64  // Also check NewExt in upper-case, just in case.
65  llvm::sys::path::replace_extension(NewPath, NewExt.upper());
66  if (VFS->exists(NewPath))
67  return NewPath.str().str();
68  }
69  return None;
70 }
71 
72 llvm::Optional<Path> getCorrespondingHeaderOrSource(const Path &OriginalFile,
73  ParsedAST &AST,
74  const SymbolIndex *Index) {
75  if (!Index) {
76  // FIXME: use the AST to do the inference.
77  return None;
78  }
79  LookupRequest Request;
80  // Find all symbols present in the original file.
81  for (const auto *D : getIndexableLocalDecls(AST)) {
82  if (auto ID = getSymbolID(D))
83  Request.IDs.insert(*ID);
84  }
85  llvm::StringMap<int> Candidates; // Target path => score.
86  auto AwardTarget = [&](const char *TargetURI) {
87  if (auto TargetPath = URI::resolve(TargetURI, OriginalFile)) {
88  if (*TargetPath != OriginalFile) // exclude the original file.
89  ++Candidates[*TargetPath];
90  } else {
91  elog("Failed to resolve URI {0}: {1}", TargetURI, TargetPath.takeError());
92  }
93  };
94  // If we switch from a header, we are looking for the implementation
95  // file, so we use the definition loc; otherwise we look for the header file,
96  // we use the decl loc;
97  //
98  // For each symbol in the original file, we get its target location (decl or
99  // def) from the index, then award that target file.
100  bool IsHeader = isHeaderFile(OriginalFile, AST.getLangOpts());
101  Index->lookup(Request, [&](const Symbol &Sym) {
102  if (IsHeader)
103  AwardTarget(Sym.Definition.FileURI);
104  else
105  AwardTarget(Sym.CanonicalDeclaration.FileURI);
106  });
107  // FIXME: our index doesn't have any interesting information (this could be
108  // that the background-index is not finished), we should use the decl/def
109  // locations from the AST to do the inference (from .cc to .h).
110  if (Candidates.empty())
111  return None;
112 
113  // Pickup the winner, who contains most of symbols.
114  // FIXME: should we use other signals (file proximity) to help score?
115  auto Best = Candidates.begin();
116  for (auto It = Candidates.begin(); It != Candidates.end(); ++It) {
117  if (It->second > Best->second)
118  Best = It;
119  else if (It->second == Best->second && It->first() < Best->first())
120  // Select the first one in the lexical order if we have multiple
121  // candidates.
122  Best = It;
123  }
124  return Path(std::string(Best->first()));
125 }
126 
127 std::vector<const Decl *> getIndexableLocalDecls(ParsedAST &AST) {
128  std::vector<const Decl *> Results;
129  std::function<void(Decl *)> TraverseDecl = [&](Decl *D) {
130  auto *ND = llvm::dyn_cast<NamedDecl>(D);
131  if (!ND || ND->isImplicit())
132  return;
133  if (!SymbolCollector::shouldCollectSymbol(*ND, D->getASTContext(), {},
134  /*IsMainFileSymbol=*/false))
135  return;
136  if (!llvm::isa<FunctionDecl>(ND)) {
137  // Visit the children, but we skip function decls as we are not interested
138  // in the function body.
139  if (auto *Scope = llvm::dyn_cast<DeclContext>(ND)) {
140  for (auto *D : Scope->decls())
141  TraverseDecl(D);
142  }
143  }
144  if (llvm::isa<NamespaceDecl>(D))
145  return; // namespace is indexable, but we're not interested.
146  Results.push_back(D);
147  };
148  // Traverses the ParsedAST directly to collect all decls present in the main
149  // file.
150  for (auto *TopLevel : AST.getLocalTopLevelDecls())
151  TraverseDecl(TopLevel);
152  return Results;
153 }
154 
155 } // namespace clangd
156 } // namespace clang
virtual void lookup(const LookupRequest &Req, llvm::function_ref< void(const Symbol &)> Callback) const =0
Looks up symbols with any of the given symbol IDs and applies Callback on each matched symbol...
const FunctionDecl * Decl
const LangOptions & getLangOpts() const
Definition: ParsedAST.h:81
llvm::Optional< SymbolID > getSymbolID(const Decl *D)
Gets the symbol ID for a declaration, if possible.
Definition: AST.cpp:285
Interface for symbol indexes that can be used for searching or matching symbols among a set of symbol...
Definition: Index.h:85
llvm::DenseSet< SymbolID > IDs
Definition: Index.h:64
llvm::StringRef PathRef
A typedef to represent a ref to file path.
Definition: Path.h:23
std::vector< CodeCompletionResult > Results
ArrayRef< Decl * > getLocalTopLevelDecls()
This function returns top-level decls present in the main file of the AST.
Definition: ParsedAST.cpp:487
void elog(const char *Fmt, Ts &&... Vals)
Definition: Logger.h:56
std::vector< const Decl * > getIndexableLocalDecls(ParsedAST &AST)
Returns all indexable decls that are present in the main file of the AST.
SymbolLocation Definition
The location of the symbol&#39;s definition, if one was found.
Definition: Symbol.h:47
std::string Path
A typedef to represent a file path.
Definition: Path.h:20
SymbolLocation CanonicalDeclaration
The location of the preferred declaration of the symbol.
Definition: Symbol.h:56
Stores and provides access to parsed AST.
Definition: ParsedAST.h:48
static bool shouldCollectSymbol(const NamedDecl &ND, const ASTContext &ASTCtx, const Options &Opts, bool IsMainFileSymbol)
Returns true is ND should be collected.
The class presents a C++ symbol, e.g.
Definition: Symbol.h:36
llvm::Optional< Path > getCorrespondingHeaderOrSource(const Path &OriginalFile, llvm::IntrusiveRefCntPtr< llvm::vfs::FileSystem > VFS)
Given a header file, returns the best matching source file, and vice visa.
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
bool isHeaderFile(llvm::StringRef FileName, llvm::Optional< LangOptions > LangOpts)
Infers whether this is a header from the FileName and LangOpts (if presents).
static llvm::Expected< std::string > resolve(const URI &U, llvm::StringRef HintPath="")
Resolves the absolute path of U.
Definition: URI.cpp:232
const SymbolIndex * Index
Definition: Dexp.cpp:95