Caster.h

#pragma once
 
#include <cstdlib>
#include <utility>
#include <type_traits>
 
#include "../Common.h"
 
namespace CXXIter {
 
    // ################################################################################################
    // CASTER
    // ################################################################################################
    namespace op {
        template<typename TChainInput, typename TItem>
        requires std::is_object_v<TItem>
        class [[nodiscard(CXXITER_CHAINER_NODISCARD_WARNING)]] Caster : public IterApi<Caster<TChainInput, TItem>> {
            friend struct trait::Iterator<Caster<TChainInput, TItem>>;
            friend struct trait::DoubleEndedIterator<Caster<TChainInput, TItem>>;
            friend struct trait::ExactSizeIterator<Caster<TChainInput, TItem>>;
        private:
            TChainInput input;
        public:
            constexpr Caster(TChainInput&& input) : input(std::move(input)) {}
        };
    }
    // ------------------------------------------------------------------------------------------------
    template<typename TChainInput, typename TItem>
    requires std::is_object_v<TItem>
    struct trait::Iterator<op::Caster<TChainInput, TItem>> {
        using ChainInputIterator = trait::Iterator<TChainInput>;
        // CXXIter Interface
        using Self = op::Caster<TChainInput, TItem>;
        using Item = TItem;
 
        static constexpr inline IterValue<Item> next(Self& self) {
            auto item = ChainInputIterator::next(self.input);
            return item.template map<Item>([](auto&& item) { return static_cast<Item>(item); });
        }
        static constexpr inline SizeHint sizeHint(const Self& self) { return ChainInputIterator::sizeHint(self.input); }
        static constexpr inline size_t advanceBy(Self& self, size_t n) { return ChainInputIterator::advanceBy(self.input, n); }
    };
    template<CXXIterDoubleEndedIterator TChainInput, typename TItem>
    requires std::is_object_v<TItem>
    struct trait::DoubleEndedIterator<op::Caster<TChainInput, TItem>> {
        using ChainInputIterator = trait::DoubleEndedIterator<TChainInput>;
        using Self = op::Caster<TChainInput, TItem>;
        using Item = TItem;
 
        static constexpr inline IterValue<TItem> nextBack(Self& self) {
            auto item = ChainInputIterator::nextBack(self.input);
            return item.template map<Item>([](auto&& item) { return static_cast<Item>(item); });
        }
    };
    template<CXXIterExactSizeIterator TChainInput, typename TItem>
    struct trait::ExactSizeIterator<op::Caster<TChainInput, TItem>> {
        static constexpr inline size_t size(const op::Caster<TChainInput, TItem>& self) { return trait::ExactSizeIterator<TChainInput>::size(self.input); }
    };
 
}