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//===--- HeaderMap.h - A file that acts like dir of symlinks ----*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file defines the HeaderMap interface.
#include "clang/Basic/FileManager.h"
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/Optional.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/MemoryBuffer.h"
#include <memory>
namespace clang {
struct HMapBucket;
struct HMapHeader;
/// Implementation for \a HeaderMap that doesn't depend on \a FileManager.
class HeaderMapImpl {
std::unique_ptr<const llvm::MemoryBuffer> FileBuffer;
bool NeedsBSwap;
HeaderMapImpl(std::unique_ptr<const llvm::MemoryBuffer> File, bool NeedsBSwap)
: FileBuffer(std::move(File)), NeedsBSwap(NeedsBSwap) {}
// Check for a valid header and extract the byte swap.
static bool checkHeader(const llvm::MemoryBuffer &File, bool &NeedsByteSwap);
/// 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;
/// Return the filename of the headermap.
StringRef getFileName() const;
/// Print the contents of this headermap to stderr.
void dump() const;
unsigned getEndianAdjustedWord(unsigned X) const;
const HMapHeader &getHeader() const;
HMapBucket getBucket(unsigned BucketNo) const;
/// Look up the specified string in the string table. If the string index is
/// not valid, return None.
Optional<StringRef> getString(unsigned StrTabIdx) const;
/// 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 : private HeaderMapImpl {
HeaderMap(std::unique_ptr<const llvm::MemoryBuffer> File, bool BSwap)
: HeaderMapImpl(std::move(File), BSwap) {}
/// 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 std::unique_ptr<HeaderMap> Create(const FileEntry *FE,
FileManager &FM);
/// 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".
Optional<FileEntryRef> LookupFile(StringRef Filename, FileManager &FM) const;
using HeaderMapImpl::lookupFilename;
using HeaderMapImpl::getFileName;
using HeaderMapImpl::dump;
} // end namespace clang.