Source/WebKit/Shared/WebBackForwardListCounts.h

/*
 * Copyright (C) 2020 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include "Decoder.h"
#include "Encoder.h"

namespace WebKit {

struct WebBackForwardListCounts {
    uint32_t backCount { 0 };
    uint32_t forwardCount { 0 };

    void encode(IPC::Encoder& encoder) const
    {
        encoder << backCount;
        encoder << forwardCount;
    }

    static std::optional<WebBackForwardListCounts> decode(IPC::Decoder& decoder)
    {
        std::optional<uint32_t> backCount;
        decoder >> backCount;
        if (!backCount)
            return std::nullopt;

        std::optional<uint32_t> forwardCount;
        decoder >> forwardCount;
        if (!forwardCount)
            return std::nullopt;

        return WebBackForwardListCounts { *backCount, *forwardCount };
    }
};

} // namespace WebKit