clang-tools-extra/clangd/HeaderSourceSwitch.cpp

   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
  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
  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
 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