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/*
* Copyright (C) 2014-2021 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 <span>
#include <wtf/EnumTraits.h>
#include <wtf/SHA1.h>
#include <wtf/persistence/PersistentCoders.h>
namespace WTF::Persistence {
template<typename> struct Coder;
class Decoder {
WTF_MAKE_FAST_ALLOCATED;
public:
WTF_EXPORT_PRIVATE Decoder(std::span<const uint8_t>);
WTF_EXPORT_PRIVATE ~Decoder();
size_t length() const { return m_buffer.size(); }
size_t currentOffset() const { return static_cast<size_t>(std::distance(m_buffer.begin(), m_bufferPosition)); }
WTF_EXPORT_PRIVATE WARN_UNUSED_RETURN bool rewind(size_t);
WTF_EXPORT_PRIVATE WARN_UNUSED_RETURN bool verifyChecksum();
WTF_EXPORT_PRIVATE WARN_UNUSED_RETURN bool decodeFixedLengthData(std::span<uint8_t>);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<bool>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<uint8_t>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<uint16_t>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<uint32_t>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<uint64_t>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<int16_t>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<int32_t>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<int64_t>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<float>&);
WTF_EXPORT_PRIVATE Decoder& operator>>(std::optional<double>&);
template<typename T, std::enable_if_t<!std::is_arithmetic<typename std::remove_const<T>>::value && !std::is_enum<T>::value>* = nullptr>
Decoder& operator>>(std::optional<T>& result)
{
result = Coder<T>::decodeForPersistence(*this);
return *this;
}
template<typename E, std::enable_if_t<std::is_enum<E>::value>* = nullptr>
Decoder& operator>>(std::optional<E>& result)
{
static_assert(sizeof(E) <= 8, "Enum type T must not be larger than 64 bits!");
std::optional<uint64_t> value;
*this >> value;
if (!value)
return *this;
if (!isValidEnumForPersistence<E>(*value))
return *this;
result = static_cast<E>(*value);
return *this;
}
template<typename T> WARN_UNUSED_RETURN
bool bufferIsLargeEnoughToContain(size_t numElements) const
{
static_assert(std::is_arithmetic<T>::value, "Type T must have a fixed, known encoded size!");
return numElements <= std::numeric_limits<size_t>::max() / sizeof(T) && bufferIsLargeEnoughToContain(numElements * sizeof(T));
}
WTF_EXPORT_PRIVATE WARN_UNUSED_RETURN std::span<const uint8_t> bufferPointerForDirectRead(size_t numBytes);
private:
WTF_EXPORT_PRIVATE WARN_UNUSED_RETURN bool bufferIsLargeEnoughToContain(size_t) const;
template<typename Type> Decoder& decodeNumber(std::optional<Type>&);
const std::span<const uint8_t> m_buffer;
std::span<const uint8_t>::iterator m_bufferPosition;
SHA1 m_sha1;
};
}
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