u8_buffer.hpp

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// Copyright 2024 Man Group Operations Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#pragma once
 
#include <cmath>
#include <ranges>
#include <type_traits>
 
#include "sparrow/buffer/buffer_adaptor.hpp"
#include "sparrow/utils/ranges.hpp"
 
namespace sparrow
{
 
    namespace detail
    {
        template <class T>
        class holder
        {
        public:
 
            template <class... Args>
            holder(Args&&... args)
                : value(std::forward<Args>(args)...)
            {
            }
 
            T value;
 
            [[nodiscard]] T extract_storage() &&
            {
                return std::move(value);
            }
 
            [[nodiscard]] const T& storage() const
            {
                return value;
            }
 
            [[nodiscard]] T& storage()
            {
                return value;
            }
 
            void assign(T&& other)
            {
                value = std::move(other);
            }
        };
    }
 
    // like buffer<T> but for any type T, nut always use buffer<std::uint8_t> as storage
    // This internal storage can be extracted
    template <class T>
    class u8_buffer : private detail::holder<buffer<std::uint8_t>>,
                      public buffer_adaptor<T, buffer<std::uint8_t>&>
    {
    public:
 
        using holder_type = detail::holder<buffer<std::uint8_t>>;
        using buffer_adaptor_type = buffer_adaptor<T, buffer<std::uint8_t>&>;
        using holder_type::extract_storage;
 
        u8_buffer(u8_buffer&& other);
        u8_buffer(const u8_buffer& other);
        u8_buffer& operator=(u8_buffer&& other) = delete;
        u8_buffer& operator=(u8_buffer& other) = delete;
 
        u8_buffer(std::size_t n, const T& val = T{});
        template <std::ranges::input_range R>
            requires(!std::same_as<u8_buffer<T>, std::decay_t<R>> && std::convertible_to<std::ranges::range_value_t<R>, T>)
        u8_buffer(R&& range);
        u8_buffer(std::initializer_list<T> ilist);
    };
 
    template <class T>
    u8_buffer<T>::u8_buffer(u8_buffer&& other)
        : holder_type(std::move(other).extract_storage())
        , buffer_adaptor_type(holder_type::value)
    {
    }
 
    template <class T>
    u8_buffer<T>::u8_buffer(const u8_buffer& other)
        : holder_type(other.storage())
        , buffer_adaptor_type(holder_type::value)
    {
    }
 
    template <class T>
    u8_buffer<T>::u8_buffer(std::size_t n, const T& val)
        : holder_type{n * sizeof(T)}
        , buffer_adaptor_type(holder_type::value)
    {
        std::fill(this->begin(), this->end(), val);
    }
 
    template <class T>
    template <std::ranges::input_range R>
        requires(!std::same_as<u8_buffer<T>, std::decay_t<R>>
                 && std::convertible_to<std::ranges::range_value_t<R>, T>)
    u8_buffer<T>::u8_buffer(R&& range)
        : holder_type{range_size(range) * sizeof(T)}
        , buffer_adaptor_type(holder_type::value)
    {
        std::ranges::copy(range, this->begin());
    }
 
    template <class T>
    u8_buffer<T>::u8_buffer(std::initializer_list<T> ilist)
        : holder_type{ilist.size() * sizeof(T)}
        , buffer_adaptor_type(holder_type::value)
    {
        std::copy(ilist.begin(), ilist.end(), this->begin());
    }
}