HeaderMap.h

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//===--- HeaderMap.h - A file that acts like dir of symlinks ----*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the HeaderMap interface.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LEX_HEADERMAP_H
#define LLVM_CLANG_LEX_HEADERMAP_H

#include "clang/Basic/LLVM.h"
#include "llvm/Support/Compiler.h"

#include <memory>

namespace llvm {
  class MemoryBuffer;
}
namespace clang {
  class FileEntry;
  class FileManager;
  struct HMapBucket;
  struct HMapHeader;

/// This class represents an Apple concept known as a 'header map'.  To the
/// \#include file resolution process, it basically acts like a directory of
/// symlinks to files.  Its advantages are that it is dense and more efficient
/// to create and process than a directory of symlinks.
class HeaderMap {
  HeaderMap(const HeaderMap &) LLVM_DELETED_FUNCTION;
  void operator=(const HeaderMap &) LLVM_DELETED_FUNCTION;

  std::unique_ptr<const llvm::MemoryBuffer> FileBuffer;
  bool NeedsBSwap;

  HeaderMap(std::unique_ptr<const llvm::MemoryBuffer> File, bool BSwap)
      : FileBuffer(std::move(File)), NeedsBSwap(BSwap) {}
public:
  /// HeaderMap::Create - This attempts to load the specified file as a header
  /// map.  If it doesn't look like a HeaderMap, it gives up and returns null.
  static const HeaderMap *Create(const FileEntry *FE, FileManager &FM);

  /// LookupFile - Check to see if the specified relative filename is located in
  /// this HeaderMap.  If so, open it and return its FileEntry.
  /// If RawPath is not NULL and the file is found, RawPath will be set to the
  /// raw path at which the file was found in the file system. For example,
  /// for a search path ".." and a filename "../file.h" this would be
  /// "../../file.h".
  const FileEntry *LookupFile(StringRef Filename, FileManager &FM) const;

  /// If the specified relative filename is located in this HeaderMap return
  /// the filename it is mapped to, otherwise return an empty StringRef.
  StringRef lookupFilename(StringRef Filename,
                           SmallVectorImpl<char> &DestPath) const;

  /// getFileName - Return the filename of the headermap.
  const char *getFileName() const;

  /// dump - Print the contents of this headermap to stderr.
  void dump() const;

private:
  unsigned getEndianAdjustedWord(unsigned X) const;
  const HMapHeader &getHeader() const;
  HMapBucket getBucket(unsigned BucketNo) const;
  const char *getString(unsigned StrTabIdx) const;
};

} // end namespace clang.

#endif