clang-tools-extra/clangd/index/CanonicalIncludes.h

   1 //===-- CanonicalIncludes.h - remap #include header -------------*- 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 // At indexing time, we decide which file to #included for a symbol.
  10 // Usually this is the file with the canonical decl, but there are exceptions:
  11 // - private headers may have pragmas pointing to the matching public header.
  12 //   (These are "IWYU" pragmas, named after the include-what-you-use tool).
  13 // - the standard library is implemented in many files, without any pragmas.
  14 //   We have a lookup table for common standard library implementations.
  15 //   libstdc++ puts char_traits in bits/char_traits.h, but we #include <string>.
  16 //
  17 //===----------------------------------------------------------------------===//
  18
  19 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_CANONICALINCLUDES_H
  20 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_CANONICALINCLUDES_H
  21
  22 #include "clang/Basic/FileEntry.h"
  23 #include "clang/Basic/LangOptions.h"
  24 #include "llvm/ADT/StringMap.h"
  25 #include "llvm/ADT/StringRef.h"
  26
  27 namespace clang {
  28 namespace clangd {
  29
  30 /// Maps a definition location onto an #include file, based on a set of filename
  31 /// rules.
  32 /// Only const methods (i.e. mapHeader) in this class are thread safe.
  33 class CanonicalIncludes {
  34 public:
  35   /// Returns the overridden verbatim spelling for files in \p Header that can
  36   /// be directly included (i.e., contains quotes "" or angled brackets <>), or
  37   /// "" if the spelling could not be found.
  38   llvm::StringRef mapHeader(llvm::StringRef HeaderPath) const;
  39
  40   /// Adds mapping for system headers and some special symbols (e.g. STL symbols
  41   /// in <iosfwd> need to be mapped individually). Approximately, the following
  42   /// system headers are handled:
  43   ///   - C++ standard library e.g. bits/basic_string.h$ -> <string>
  44   ///   - Posix library e.g. bits/pthreadtypes.h$ -> <pthread.h>
  45   ///   - Compiler extensions, e.g. include/avx512bwintrin.h$ -> <immintrin.h>
  46   /// The mapping is hardcoded and hand-maintained, so it might not cover all
  47   /// headers.
  48   void addSystemHeadersMapping(const LangOptions &Language);
  49
  50 private:
  51   /// A map from a suffix (one or components of a path) to a canonical path.
  52   /// Used only for mapping standard headers.
  53   const llvm::StringMap<llvm::StringRef> *StdSuffixHeaderMapping = nullptr;
  54 };
  55 } // namespace clangd
  56 } // namespace clang
  57
  58 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_CANONICALINCLUDES_H