layout_utils.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 "sparrow/buffer/u8_buffer.hpp"
#include "sparrow/utils/functor_index_iterator.hpp"
#include "sparrow/utils/ranges.hpp"
 
namespace sparrow::detail
{
    // Functor to get the value of the layout at index i.
    //
    // This is usefull to create a iterator over the values of a layout.
    // This functor will be passed to the functor_index_iterator.
    template <class LAYOUT_TYPE, class VALUE_TYPE>
    class layout_value_functor
    {
    public:
 
        using value_type = VALUE_TYPE;
        using layout_type = LAYOUT_TYPE;
 
        constexpr explicit layout_value_functor(layout_type* layout_ = nullptr)
            : p_layout(layout_)
        {
        }
 
        [[nodiscard]] value_type operator()(std::size_t i) const
        {
            return this->p_layout->value(i);
        }
 
    private:
 
        layout_type* p_layout;
    };
 
    // Functor to get the optional-value of the layout at index i.
    //
    // This is usefull to create a iterator over the nullable-values of a layout.
    // This functor will be passed to the functor_index_iterator.
    template <class LAYOUT_TYPE, class VALUE_TYPE>
    class layout_bracket_functor
    {
    public:
 
        using value_type = VALUE_TYPE;
        using layout_type = LAYOUT_TYPE;
 
        constexpr explicit layout_bracket_functor(layout_type* layout_ = nullptr)
            : p_layout(layout_)
        {
        }
 
        value_type operator()(std::size_t i) const
        {
            return this->p_layout->operator[](i);
        }
 
    private:
 
        layout_type* p_layout;
    };
 
    template <layout_offset OFFSET_TYPE, std::ranges::range SIZES_RANGE>
        requires(std::unsigned_integral<std::ranges::range_value_t<SIZES_RANGE>>)
    [[nodiscard]] sparrow::u8_buffer<OFFSET_TYPE> offset_buffer_from_sizes(SIZES_RANGE&& sizes)
    {
        sparrow::u8_buffer<OFFSET_TYPE> buffer(range_size(sizes) + 1);
 
        OFFSET_TYPE offset = 0;
        auto it = buffer.begin();
        for (auto size : sizes)
        {
            *it = offset;
            offset += static_cast<OFFSET_TYPE>(size);
            ++it;
        }
        *it = offset;
        return buffer;
    }
 
}  // namespace sparrow