UniqueID.h

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//===- llvm/Support/FileSystem/UniqueID.h - UniqueID for files --*- 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 is cut out of llvm/Support/FileSystem.h to allow UniqueID to be
// reused without bloating the includes.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_SUPPORT_FILESYSTEM_UNIQUEID_H
#define LLVM_SUPPORT_FILESYSTEM_UNIQUEID_H
 
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/Hashing.h"
#include <cstdint>
#include <utility>
 
namespace llvm {
namespace sys {
namespace fs {
 
class UniqueID {
  uint64_t Device;
  uint64_t File;
 
public:
  UniqueID() = default;
  UniqueID(uint64_t Device, uint64_t File) : Device(Device), File(File) {}
 
  bool operator==(const UniqueID &Other) const {
    return Device == Other.Device && File == Other.File;
  }
  bool operator!=(const UniqueID &Other) const { return !(*this == Other); }
  bool operator<(const UniqueID &Other) const {
    /// Don't use std::tie since it bloats the compile time of this header.
    if (Device < Other.Device)
      return true;
    if (Other.Device < Device)
      return false;
    return File < Other.File;
  }
 
  uint64_t getDevice() const { return Device; }
  uint64_t getFile() const { return File; }
};
 
} // end namespace fs
} // end namespace sys
 
// Support UniqueIDs as DenseMap keys.
template <> struct DenseMapInfo<llvm::sys::fs::UniqueID> {
  static inline llvm::sys::fs::UniqueID getEmptyKey() {
    auto EmptyKey = DenseMapInfo<std::pair<uint64_t, uint64_t>>::getEmptyKey();
    return {EmptyKey.first, EmptyKey.second};
  }
 
  static inline llvm::sys::fs::UniqueID getTombstoneKey() {
    auto TombstoneKey =
        DenseMapInfo<std::pair<uint64_t, uint64_t>>::getTombstoneKey();
    return {TombstoneKey.first, TombstoneKey.second};
  }
 
  static hash_code getHashValue(const llvm::sys::fs::UniqueID &Tag) {
    return hash_value(std::make_pair(Tag.getDevice(), Tag.getFile()));
  }
 
  static bool isEqual(const llvm::sys::fs::UniqueID &LHS,
                      const llvm::sys::fs::UniqueID &RHS) {
    return LHS == RHS;
  }
};
 
} // end namespace llvm
 
#endif // LLVM_SUPPORT_FILESYSTEM_UNIQUEID_H