blob_encoding.h - mozsearch

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/*

 *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

*/

#ifndef LOGGING_RTC_EVENT_LOG_ENCODER_BLOB_ENCODING_H_

#define LOGGING_RTC_EVENT_LOG_ENCODER_BLOB_ENCODING_H_

#include <stddef.h>

#include <string>

#include <vector>

#include "absl/strings/string_view.h"

namespace webrtc {

// Encode/decode a sequence of strings, whose length is not known to be

// discernable from the blob itself (i.e. without being transmitted OOB),

// in a way that would allow us to separate them again on the decoding side.

// The number of blobs is assumed to be transmitted OOB. For example, if

// multiple sequences of different blobs are sent, but all sequences contain

// the same number of blobs, it is beneficial to not encode the number of blobs.

//

// EncodeBlobs() must be given a non-empty vector. The blobs themselves may

// be equal to "", though.

// EncodeBlobs() may not fail.

// EncodeBlobs() never returns the empty string.

//

// Calling DecodeBlobs() on an empty string, or with `num_of_blobs` set to 0,

// is an error.

// DecodeBlobs() returns an empty vector if it fails, e.g. due to a mismatch

// between `num_of_blobs` and `encoded_blobs`, which can happen if

// `encoded_blobs` is corrupted.

// When successful, DecodeBlobs() returns a vector of string_view objects,

// which refer to the original input (`encoded_blobs`), and therefore may

// not outlive it.

//

// Note that the returned std::string might have been reserved for significantly

// more memory than it ends up using. If the caller to EncodeBlobs() intends

// to store the result long-term, they should consider shrink_to_fit()-ing it.

std::string EncodeBlobs(const std::vector<std::string>& blobs);

std::vector<absl::string_view> DecodeBlobs(absl::string_view encoded_blobs,

                                           size_t num_of_blobs);

}  // namespace webrtc

#endif  // LOGGING_RTC_EVENT_LOG_ENCODER_BLOB_ENCODING_H_