Source/WTF/wtf/persistence/PersistentEncoder.h

/*
 * Copyright (C) 2010 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 <wtf/EnumTraits.h>
#include <wtf/SHA1.h>
#include <wtf/Vector.h>
#include <wtf/persistence/PersistentCoder.h>

namespace WTF {
namespace Persistence {

class Encoder;
class DataReference;

class Encoder {
    WTF_MAKE_FAST_ALLOCATED;
public:
    WTF_EXPORT_PRIVATE Encoder();
    WTF_EXPORT_PRIVATE ~Encoder();

    WTF_EXPORT_PRIVATE void encodeChecksum();
    WTF_EXPORT_PRIVATE void encodeFixedLengthData(const uint8_t*, size_t);

    template<typename E> auto encode(E value) -> std::enable_if_t<std::is_enum<E>::value>
    {
        static_assert(sizeof(E) <= sizeof(uint64_t), "Enum type must not be larger than 64 bits.");

        ASSERT(isValidEnum<E>(static_cast<uint64_t>(value)));
        encode(static_cast<uint64_t>(value));
    }

    template<typename T> void encodeEnum(T t)
    {
        COMPILE_ASSERT(sizeof(T) <= sizeof(uint64_t), enum_type_must_not_be_larger_than_64_bits);

        encode(static_cast<uint64_t>(t));
    }

    template<typename T> auto encode(const T& t) -> std::enable_if_t<!std::is_enum<T>::value>
    {
        Coder<T>::encode(*this, t);
    }

    template<typename T> Encoder& operator<<(const T& t)
    {
        encode(t);
        return *this;
    }

    const uint8_t* buffer() const { return m_buffer.data(); }
    size_t bufferSize() const { return m_buffer.size(); }

    WTF_EXPORT_PRIVATE static void updateChecksumForData(SHA1&, const uint8_t*, size_t);
    template <typename Type> static void updateChecksumForNumber(SHA1&, Type);

    static const bool isIPCEncoder = false;

private:
    WTF_EXPORT_PRIVATE void encode(bool);
    WTF_EXPORT_PRIVATE void encode(uint8_t);
    WTF_EXPORT_PRIVATE void encode(uint16_t);
    WTF_EXPORT_PRIVATE void encode(uint32_t);
    WTF_EXPORT_PRIVATE void encode(uint64_t);
    WTF_EXPORT_PRIVATE void encode(int32_t);
    WTF_EXPORT_PRIVATE void encode(int64_t);
    WTF_EXPORT_PRIVATE void encode(float);
    WTF_EXPORT_PRIVATE void encode(double);

    template<typename Type> void encodeNumber(Type);

    uint8_t* grow(size_t);

    template <typename Type> struct Salt;

    Vector<uint8_t, 4096> m_buffer;
    SHA1 m_sha1;
};

template <> struct Encoder::Salt<bool> { static const unsigned value = 3; };
template <> struct Encoder::Salt<uint8_t> { static const  unsigned value = 5; };
template <> struct Encoder::Salt<uint16_t> { static const unsigned value = 7; };
template <> struct Encoder::Salt<uint32_t> { static const unsigned value = 11; };
template <> struct Encoder::Salt<uint64_t> { static const unsigned value = 13; };
template <> struct Encoder::Salt<int32_t> { static const unsigned value = 17; };
template <> struct Encoder::Salt<int64_t> { static const unsigned value = 19; };
template <> struct Encoder::Salt<float> { static const unsigned value = 23; };
template <> struct Encoder::Salt<double> { static const unsigned value = 29; };
template <> struct Encoder::Salt<uint8_t*> { static const unsigned value = 101; };

template <typename Type>
void Encoder::updateChecksumForNumber(SHA1& sha1, Type value)
{
    auto typeSalt = Salt<Type>::value;
    sha1.addBytes(reinterpret_cast<uint8_t*>(&typeSalt), sizeof(typeSalt));
    sha1.addBytes(reinterpret_cast<uint8_t*>(&value), sizeof(value));
}

}
}