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