libcruft-util/serialise/std.hpp

/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2022, Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include "./converter.hpp"
#include "./ops.hpp"


///////////////////////////////////////////////////////////////////////////////
template <typename ElementT>
struct cruft::serialise::converter<std::vector<ElementT>> {
    using value_type = std::vector<ElementT>;

    static std::size_t
    size (value_type const &val)
    {
        std::size_t accum = sizeof (typename value_type::size_type);
        for (auto const &i: val)
            accum += converter<ElementT>::size (i);
        return accum;
    }

    static
    cruft::view<std::byte*>
    to_bytes [[nodiscard]] (
        cruft::view<std::byte*> dst,
        value_type const &src
    ) {
        dst = ::cruft::serialise::to_bytes (dst, src.size ());

        for (auto const &i: src)
            dst = ::cruft::serialise::to_bytes (dst, i);

        return dst;
    }

    static
    value_type
    from_bytes (cruft::view<std::byte*> &src)
    {
        auto const len = ::cruft::serialise::from_bytes<typename std::vector<ElementT>::size_type> (src);

        std::vector<ElementT> res;
        res.reserve (len);

        for (std::size_t i = 0; i != len; ++i)
            res.push_back (::cruft::serialise::from_bytes<ElementT> (src));

        return res;
    }
};


///////////////////////////////////////////////////////////////////////////////
template <>
struct cruft::serialise::converter<std::string> {
    using value_type = std::string;

    static std::size_t
    size (value_type const &val)
    {
        return sizeof (value_type::size_type) + sizeof (value_type::value_type) * val.size ();
    }

    static
    cruft::view<std::byte*>
    to_bytes [[nodiscard]] (
        cruft::view<std::byte*> dst,
        value_type const &src
    ) {
        dst = ::cruft::serialise::to_bytes (dst, src.size ());
        for (auto const &i: src)
            dst = ::cruft::serialise::to_bytes (dst, i);
        return dst;
    }

    static
    value_type
    from_bytes (cruft::view<std::byte*> &src)
    {
        std::string res;
        res.resize (::cruft::serialise::converter<std::string::size_type>::from_bytes (src));
        for (auto &i: res)
            i = ::cruft::serialise::converter<std::string::value_type>::from_bytes (src);
        return res;
    }
};


///////////////////////////////////////////////////////////////////////////////
template <typename A, typename B>
struct cruft::serialise::converter<std::pair<A, B>> {
    using value_type = std::pair<A, B>;

    static std::size_t
    size (value_type const &val)
    {
        return converter<A>::size (val.first) + converter<B>::size (val.second);
    }

    static
    cruft::view<std::byte*>
    to_bytes [[nodiscard]] (
        cruft::view<std::byte*> dst,
        value_type const &src
    ) {
        dst = ::cruft::serialise::to_bytes (dst, src.first);
        dst = ::cruft::serialise::to_bytes (dst, src.second);
        return dst;
    }

    static
    value_type
    from_bytes (cruft::view<std::byte*> &src)
    {
        return {
            cruft::serialise::converter<A>::from_bytes (src),
            cruft::serialise::converter<B>::from_bytes (src),
        };
    }
};


///////////////////////////////////////////////////////////////////////////////
template <typename ...ElementT>
struct cruft::serialise::converter<std::tuple<ElementT...>> {
    using value_type = std::tuple<ElementT...>;

    static std::size_t
    size (value_type const &val)
    {
        return size (val, std::make_index_sequence<sizeof ...(ElementT)> {});
    }

    static
    cruft::view<std::byte*>
    to_bytes [[nodiscard]] (
        cruft::view<std::byte*> dst,
        value_type const &src
    ) {
        return to_bytes (dst, src, std::make_index_sequence<sizeof... (ElementT)> {});
    }

    static
    value_type
    from_bytes (cruft::view<std::byte*> &src)
    {
        return from_bytes (src, std::make_index_sequence<sizeof... (ElementT)> {});
    }

private:
    template <std::size_t ...Index>
    static std::size_t
    size (value_type const &val, std::index_sequence<Index...> const &)
    {
        return (
            converter<
                std::tuple_element_t<Index, value_type>
            >::size (
                std::get<Index> (val)
            ) + ... + 0uz
        );
    }


    template <std::size_t ...IndexV>
    static
    cruft::view<std::byte*>
    to_bytes [[nodiscard]] (
        cruft::view<std::byte*> dst,
        value_type const &src,
        std::index_sequence<IndexV...> const&
    ) {
        return ::cruft::serialise::to_bytes (dst, std::get<IndexV> (src)...);
    }


    template <std::size_t ...IndexV>
    static
    value_type
    from_bytes (cruft::view<std::byte*> &src, std::index_sequence<IndexV...> const&)
    {
        return std::tuple {
            ::cruft::serialise::from_bytes<ElementT> (src)...,
        };
    }
};