//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

#pragma once

#include <algorithm>

#include <memory>

#include <string>

#include "rocksdb/env.h"

#include "rocksdb/merge_operator.h"

#include "rocksdb/slice.h"

#include "util/coding.h"

#include "utilities/merge_operators.h"

namespace ROCKSDB_NAMESPACE {

// A 'model' merge operator that XORs two (same sized) array of bytes.

// Implemented as an AssociativeMergeOperator for simplicity and example.

class BytesXOROperator : public AssociativeMergeOperator {

 public:

  // XORs the two array of bytes one byte at a time and stores the result

  // in new_value. len is the number of xored bytes, and the length of new_value

  bool Merge(const Slice& key, const Slice* existing_value, const Slice& value,

             std::string* new_value, Logger* logger) const override;

  static const char* kClassName() { return "BytesXOR"; }

  static const char* kNickName() { return "bytesxor"; }

  const char* NickName() const override { return kNickName(); }

  const char* Name() const override { return kClassName(); }

  void XOR(const Slice* existing_value, const Slice& value,

           std::string* new_value) const;

};

}  // namespace ROCKSDB_NAMESPACE