chromium/third_party/abseil-cpp/absl/crc/internal/crc_cord_state.h

// Copyright 2022 The Abseil Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef ABSL_CRC_INTERNAL_CRC_CORD_STATE_H_
#define ABSL_CRC_INTERNAL_CRC_CORD_STATE_H_

#include <atomic>
#include <cstddef>
#include <deque>

#include "absl/base/config.h"
#include "absl/crc/crc32c.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace crc_internal {

// CrcCordState is a copy-on-write class that holds the chunked CRC32C data
// that allows CrcCord to perform efficient substring operations. CrcCordState
// is used as a member variable in CrcCord. When a CrcCord is converted to a
// Cord, the CrcCordState is shallow-copied into the root node of the Cord. If
// the converted Cord is modified outside of CrcCord, the CrcCordState is
// discarded from the Cord. If the Cord is converted back to a CrcCord, and the
// Cord is still carrying the CrcCordState in its root node, the CrcCord can
// re-use the CrcCordState, making the construction of the CrcCord cheap.
//
// CrcCordState does not try to encapsulate the CRC32C state (CrcCord requires
// knowledge of how CrcCordState represents the CRC32C state). It does
// encapsulate the copy-on-write nature of the state.
class CrcCordState { … };

}  // namespace crc_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_CRC_INTERNAL_CRC_CORD_STATE_H_