Collector.h

#pragma once
 
#include <tuple>
#include <type_traits>
 
#include "Common.h"
 
namespace CXXIter {
 
    // ################################################################################################
    // INTO COLLECTOR
    // ################################################################################################
    template<typename TChainInput, typename TContainer>
    struct IntoCollector {};
    template<typename TChainInput, typename TContainer>
    requires util::BackInsertableContainer<TContainer, typename TChainInput::ItemOwned>
    struct IntoCollector<TChainInput, TContainer> {
        using Item = typename TChainInput::Item;
 
        static constexpr void collectInto(TChainInput& input, TContainer& container) {
            if constexpr(util::ReservableContainer<TContainer>) {
                container.reserve( container.size() + input.sizeHint().expectedResultSize() );
            }
            input.forEach([&container](Item&& item) { container.push_back( std::forward<Item>(item) ); });
        }
    };
    template<typename TChainInput, typename TContainer>
    requires (!util::BackInsertableContainer<TContainer, typename TChainInput::ItemOwned>)
        && util::InsertableContainer<TContainer, typename TChainInput::ItemOwned>
    struct IntoCollector<TChainInput, TContainer> {
        using Item = typename TChainInput::Item;
 
        static constexpr void collectInto(TChainInput& input, TContainer& container) {
            if constexpr(util::ReservableContainer<TContainer>) {
                container.reserve( container.size() + input.sizeHint().expectedResultSize() );
            }
            input.forEach([&container](Item&& item) { container.insert( std::forward<Item>(item) ); });
        }
    };
    template<typename TChainInput, typename TContainer>
    requires util::StdArrayContainer<TContainer, typename TChainInput::ItemOwned>
    struct IntoCollector<TChainInput, TContainer> {
        using Item = typename TChainInput::Item;
 
        static constexpr void collectInto(TChainInput& input, TContainer& container) {
            size_t idx = 0;
            input
                .take(container.max_size())
                .forEach([&idx, &container](Item&& item) { container[idx++] = item; });
        }
    };
 
 
    // ################################################################################################
    // COLLECTOR
    // ################################################################################################
    template<typename TChainInput, template <typename...> typename TContainer, typename... TContainerArgs>
    struct Collector {};
    template<typename TChainInput, template <typename...> typename TContainer, typename... TContainerArgs>
    requires util::BackInsertableContainerTemplate<TContainer, typename TChainInput::ItemOwned, TContainerArgs...>
        || util::InsertableContainerTemplate<TContainer, typename TChainInput::ItemOwned, TContainerArgs...>
    struct Collector<TChainInput, TContainer, TContainerArgs...> {
        template<typename Item, typename ItemOwned>
        static constexpr TContainer<ItemOwned, TContainerArgs...> collect(TChainInput& input) {
            TContainer<ItemOwned, TContainerArgs...> container;
            IntoCollector<TChainInput, decltype(container)>::collectInto(input, container);
            return container;
        }
    };
    template<typename TChainInput, template <typename...> typename TContainer, typename... TContainerArgs>
    requires (!util::BackInsertableContainerTemplate<TContainer, typename TChainInput::ItemOwned, TContainerArgs...>)
        && util::is_pair<typename TChainInput::ItemOwned>
        && util::AssocContainerTemplate<TContainer, std::tuple_element_t<0, typename TChainInput::ItemOwned>, std::tuple_element_t<1, typename TChainInput::ItemOwned>, TContainerArgs...>
    struct Collector<TChainInput, TContainer, TContainerArgs...> {
        template<typename Item, typename ItemOwned>
        static constexpr auto collect(TChainInput& input) {
            using TKey = std::remove_const_t<std::tuple_element_t<0, typename TChainInput::ItemOwned>>;
            using TValue = std::tuple_element_t<1, typename TChainInput::ItemOwned>;
            TContainer<TKey, TValue, TContainerArgs...> container;
            IntoCollector<TChainInput, decltype(container)>::collectInto(input, container);
            return container;
        }
    };
 
}