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//===- FileSystemStatCache.h - Caching for 'stat' calls ---------*- 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
//
//===----------------------------------------------------------------------===//
//
/// \file
/// Defines the FileSystemStatCache interface.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H
#define LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/VirtualFileSystem.h"
#include <cstdint>
#include <ctime>
#include <memory>
#include <optional>
#include <string>
#include <utility>
namespace clang {
/// Abstract interface for introducing a FileManager cache for 'stat'
/// system calls, which is used by precompiled and pretokenized headers to
/// improve performance.
class FileSystemStatCache {
virtual void anchor();
public:
virtual ~FileSystemStatCache() = default;
/// Get the 'stat' information for the specified path, using the cache
/// to accelerate it if possible.
///
/// \returns \c true if the path does not exist or \c false if it exists.
///
/// If isFile is true, then this lookup should only return success for files
/// (not directories). If it is false this lookup should only return
/// success for directories (not files). On a successful file lookup, the
/// implementation can optionally fill in \p F with a valid \p File object and
/// the client guarantees that it will close it.
static std::error_code
get(StringRef Path, llvm::vfs::Status &Status, bool isFile,
std::unique_ptr<llvm::vfs::File> *F,
FileSystemStatCache *Cache, llvm::vfs::FileSystem &FS);
protected:
// FIXME: The pointer here is a non-owning/optional reference to the
// unique_ptr. std::optional<unique_ptr<vfs::File>&> might be nicer, but
// Optional needs some work to support references so this isn't possible yet.
virtual std::error_code getStat(StringRef Path, llvm::vfs::Status &Status,
bool isFile,
std::unique_ptr<llvm::vfs::File> *F,
llvm::vfs::FileSystem &FS) = 0;
};
/// A stat "cache" that can be used by FileManager to keep
/// track of the results of stat() calls that occur throughout the
/// execution of the front end.
class MemorizeStatCalls : public FileSystemStatCache {
public:
/// The set of stat() calls that have been seen.
llvm::StringMap<llvm::vfs::Status, llvm::BumpPtrAllocator> StatCalls;
using iterator =
llvm::StringMap<llvm::vfs::Status,
llvm::BumpPtrAllocator>::const_iterator;
iterator begin() const { return StatCalls.begin(); }
iterator end() const { return StatCalls.end(); }
std::error_code getStat(StringRef Path, llvm::vfs::Status &Status,
bool isFile,
std::unique_ptr<llvm::vfs::File> *F,
llvm::vfs::FileSystem &FS) override;
};
} // namespace clang
#endif // LLVM_CLANG_BASIC_FILESYSTEMSTATCACHE_H
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