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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 https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the HeaderMap interface.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_LEX_HEADERMAP_H
#define LLVM_CLANG_LEX_HEADERMAP_H
#include "clang/Basic/FileManager.h"
#include "clang/Basic/LLVM.h"
#include "clang/Lex/HeaderMapTypes.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/MemoryBuffer.h"
#include <memory>
#include <optional>
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;
mutable llvm::StringMap<StringRef> ReverseMap;
public:
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);
// Make a call for every Key in the map.
template <typename Func> void forEachKey(Func Callback) const {
const HMapHeader &Hdr = getHeader();
unsigned NumBuckets = getEndianAdjustedWord(Hdr.NumBuckets);
for (unsigned Bucket = 0; Bucket < NumBuckets; ++Bucket) {
HMapBucket B = getBucket(Bucket);
if (B.Key != HMAP_EmptyBucketKey)
if (std::optional<StringRef> Key = getString(B.Key))
Callback(*Key);
}
}
/// 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;
/// Return key for specifed path.
StringRef reverseLookupFilename(StringRef DestPath) const;
private:
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 std::nullopt.
std::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) {}
public:
/// 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(FileEntryRef FE, FileManager &FM);
using HeaderMapImpl::dump;
using HeaderMapImpl::forEachKey;
using HeaderMapImpl::getFileName;
using HeaderMapImpl::lookupFilename;
using HeaderMapImpl::reverseLookupFilename;
};
} // end namespace clang.
#endif
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