ranges.h

 
#pragma once
 
#include <ranges>
#include <stdexcept>
#include <algorithm>
#include "span.h"
#include "min-cpp-version/cpp20.h"
 
namespace ghassanpl
{

 
    using std::ranges::random_access_range;
    using std::ranges::contiguous_range;
    using std::random_access_iterator;

    template <typename RANGE>
    using range_value = std::ranges::range_value_t<std::decay_t<RANGE>>;

    template <typename RANGE>
    using range_iterator = std::ranges::iterator_t<std::decay_t<RANGE>>;

    template <typename RANGE, typename FUNC>
    concept range_predicate = requires (FUNC func, RANGE range) { { func(*std::ranges::begin(range)) } -> std::convertible_to<bool>; };

    [[nodiscard]] constexpr bool valid_index(random_access_range auto& range, std::integral auto index)
    {
        return index >= 0 && index < std::ranges::size(range);
    }

    [[nodiscard]] constexpr auto modulo_index(size_t range_size, std::integral auto index)
    {
        const auto cpp_modulo_sucks = (index % static_cast<decltype(index)>(range_size));
        return ((index < 0) ? (range_size + cpp_modulo_sucks) : cpp_modulo_sucks) % static_cast<decltype(index)>(range_size);
    }

    [[nodiscard]] constexpr auto modulo_index(random_access_range auto& range, std::integral auto index)
    {
        const auto range_size = std::ranges::size(range);
        return modulo_index(range_size, index);
    }

    [[nodiscard]] constexpr decltype(auto) at(random_access_range auto& range, std::integral auto index)
    {
        if (!valid_index(range, index))
            throw std::invalid_argument("index");
        return *(std::ranges::begin(range) + index);
    }

    [[nodiscard]] constexpr auto at_ptr(random_access_range auto& range, std::integral auto index)
        -> decltype(std::to_address(std::ranges::begin(range) + index))
    {
        if (!valid_index(range, index))
            return nullptr;
        return std::to_address(std::ranges::begin(range) + index);
    }

    [[nodiscard]] constexpr decltype(auto) modulo_at(random_access_range auto& range, std::integral auto index)
    {
        return at(range, modulo_index(range, index)); 
    }

    template <random_access_range RANGE, typename T>
    [[nodiscard]] constexpr auto index_of(RANGE const& range, T&& value) -> std::iter_difference_t<range_iterator<RANGE>>
    requires requires (T value, RANGE range) { { *std::ranges::begin(range) == value } -> std::convertible_to<bool>; }
    {
        const auto it = std::ranges::find(range, std::forward<T>(value));
        if (it == std::ranges::end(range))
            return -1;
        return std::ranges::distance(std::ranges::begin(range), it);
    }

    template <random_access_range RANGE, typename T = range_value<RANGE>>
    [[nodiscard]] constexpr auto at_or_default(RANGE&& range, std::integral auto index, T&& default_value)
    {
        if (!valid_index(range, index)) [[unlikely]] return std::forward<T>(default_value);
        return at(range, index);
    }

    template <random_access_range RANGE, typename FUNC>
    requires range_predicate<RANGE, FUNC>
    [[nodiscard]] constexpr auto find_index(RANGE const& range, FUNC&& pred) -> std::iter_difference_t<range_iterator<RANGE>>
    {
        const auto it = std::ranges::find_if(range, std::forward<FUNC>(pred));
        if (it == std::ranges::end(range))
            return -1;
        return std::ranges::distance(std::ranges::begin(range), it);
    }
    
    template <std::ranges::range RANGE, typename FUNC>
    requires range_predicate<RANGE, FUNC>
    [[nodiscard]] constexpr auto find_ptr(RANGE& range, FUNC&& pred)
    {
        const auto it = std::ranges::find_if(range, std::forward<FUNC>(pred));
        return it == std::ranges::end(range) ? nullptr : std::to_address(it);
    }

    template <random_access_range RANGE, typename FUNC, typename DEF_TYPE = range_value<RANGE>>
    requires range_predicate<RANGE, FUNC>
    [[nodiscard]] auto find_if_or_default(RANGE& range, FUNC&& pred, DEF_TYPE&& default_value = DEF_TYPE{})
    {
        auto it = std::ranges::find_if(range, std::forward<FUNC>(pred));
        if (it == std::ranges::end(range))
            return range_value<RANGE>{std::forward<DEF_TYPE>(default_value)};
        return *it;
    }

    [[nodiscard]] constexpr auto to_index(random_access_iterator auto iterator, random_access_range auto const& range)
    {
        return std::ranges::distance(std::ranges::begin(range), iterator);
    }

    template <contiguous_range RANGE>
    [[nodiscard]] constexpr bool valid_address(RANGE&& range, range_value<RANGE>* pointer)
    {
        if (std::ranges::empty(range)) return false;
        return pointer >= std::to_address(std::ranges::begin(range)) && pointer < std::to_address(std::ranges::end(range));
    }

    
    template <typename T, size_t N = std::dynamic_extent>
    [[nodiscard]] constexpr std::pair<span<T>, span<T>> split_at(span<T, N> spn, size_t index)
    {
        if (index >= spn.size())
            return { spn, span<T>{} };
        return { spn.subspan(0, index), spn.subspan(index) };
    }
 
    template <typename T, size_t N = std::dynamic_extent>
    [[nodiscard]] constexpr std::array<span<T>, 3> split_at(span<T, N> spn, size_t index, size_t size)
    {
        if (index >= spn.size() || index + size >= spn.size())
            return { spn, span<T>{}, span<T>{} };
        return { spn.subspan(0, index), spn.subspan(index, size), spn.subspan(index + size) };
    }
    
    template <typename T, size_t N = std::dynamic_extent>
    [[nodiscard]] constexpr std::pair<T*, T*> as_range(span<T, N> spn)
    {
        return { spn.data(), spn.data() + spn.size() };
    }
 
    [[nodiscard]] constexpr auto as_span(std::ranges::range auto & range)
    {
        return std::span{ range };
    }

    template <typename TO, typename FROM, size_t N = std::dynamic_extent>
    [[nodiscard]] auto span_cast(span<FROM, N> bytes) noexcept
    {
        return span<TO>{ reinterpret_cast<TO*>(bytes.data()), (bytes.size() * sizeof(FROM)) / sizeof(TO) };
    }
 
    template <typename T1, size_t N1, typename T2, size_t N2>
    [[nodiscard]] constexpr bool are_adjacent(span<T1, N1> s1, span<T2, N2> s2)
    {
        return reinterpret_cast<char const*>(s1.data() + s1.size()) == reinterpret_cast<char const*>(s2.data())
            || reinterpret_cast<char const*>(s2.data() + s2.size()) == reinterpret_cast<char const*>(s1.data());
    }
 
    template <typename T1, size_t N1, typename T2, size_t N2>
    [[nodiscard]] constexpr bool are_overlapping(span<T1, N1> s1, span<T2, N2> s2)
    {
        return valid_address(s1, s2.data()) || valid_address(s2, s1.data());
    }
 
    template <typename T, size_t N1, typename U, size_t N2>
    requires std::same_as<std::remove_cvref_t<T>, std::remove_cvref_t<U>>
    [[nodiscard]] constexpr bool ends_with(span<T, N1> s1, span<U, N2> s2)
    {
        if (s1.size() < s2.size()) return false;
        return std::ranges::equal(s1.subspan(s1.size() - s2.size()), s2);
    }
 
    template <typename T, size_t N1, typename U, size_t N2>
    requires std::same_as<std::remove_cvref_t<T>, std::remove_cvref_t<U>>
    [[nodiscard]] constexpr bool starts_with(span<T, N1> s1, span<U, N2> s2)
    {
        if (s1.size() < s2.size()) return false;
        return std::ranges::equal(s1.subspan(0, s2.size()), s2);
    }


    
    template <typename T, std::size_t... Ns>
    [[nodiscard]] constexpr auto join(std::array<T, Ns>... arrays)
    {
        std::array<T, (Ns + ...)> result;
        std::size_t index = 0;
        ((std::copy_n(std::make_move_iterator(arrays.begin()), Ns, result.begin() + index), index += Ns), ...);
        return result;
    }
 
    template<typename T, size_t LL, typename... ARGS>
    requires (std::same_as<std::remove_cvref_t<ARGS>, T> && ...)
    [[nodiscard]] constexpr auto join(std::array<T, LL> rhs, ARGS&&... args)
    {
        std::array<T, LL + sizeof...(ARGS)> ar;
        auto current = std::move(rhs.begin(), rhs.end(), ar.begin());
        ((*current++ = args), ...);
        return ar;
    }


 
#ifndef __cpp_lib_ranges_contains
 
    struct __contains_fn
    {
        template <std::input_iterator I, std::sentinel_for<I> S, class T, class Proj = std::identity>
        requires std::indirect_binary_predicate<std::ranges::equal_to, std::projected<I, Proj>, const T*>
        constexpr bool operator()(I first, S last, const T& value, Proj proj = {}) const
        {
            return std::ranges::find(std::move(first), last, value, proj) != last;
        }
 
        template <std::ranges::input_range R, class T, class Proj = std::identity>
        requires std::indirect_binary_predicate<std::ranges::equal_to, std::projected<std::ranges::iterator_t<R>, Proj>, const T*>
        constexpr bool operator()(R&& r, const T& value, Proj proj = {}) const
        {
            return (*this)(std::ranges::begin(r), std::ranges::end(r), std::move(value), proj);
        }
    };

    constexpr inline __contains_fn contains{};
 
 
    struct __contains_subrange_fn
    {
        template <std::forward_iterator I1, std::sentinel_for<I1> S1, std::forward_iterator I2, std::sentinel_for<I2> S2, class Pred = std::ranges::equal_to, class Proj1 = std::identity, class Proj2 = std::identity>
        requires std::indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
        constexpr bool operator()(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const
        {
            return (first2 == last2) || !std::ranges::search(first1, last1, first2, last2, pred, proj1, proj2).empty();
        }
 
        template <std::ranges::forward_range R1, std::ranges::forward_range R2, class Pred = std::ranges::equal_to, class Proj1 = std::identity, class Proj2 = std::identity>
            requires std::indirectly_comparable<std::ranges::iterator_t<R1>, std::ranges::iterator_t<R2>, Pred, Proj1, Proj2>
        constexpr bool operator()(R1&& r1, R2&& r2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const
        {
            return (*this)(std::ranges::begin(r1), std::ranges::end(r1), std::ranges::begin(r2), std::ranges::end(r2), std::move(pred), std::move(proj1), std::move(proj2));
        }
    };
 

    constexpr inline __contains_subrange_fn contains_subrange{};
 
#endif
 
#ifndef __cpp_lib_ranges_to_container
 
    namespace detail
    {
        struct from_range_t { explicit from_range_t() = default; };
        constexpr inline from_range_t from_range;
 
        template <class RANGE, class CONTAINER>
        concept _Ref_converts = std::convertible_to<std::ranges::range_reference_t<RANGE>, std::ranges::range_value_t<CONTAINER>>;
 
        template <class RANGE, class CONTAINER, class... TYPES>
        concept _Converts_direct_constructible = _Ref_converts<RANGE, CONTAINER>
            && std::constructible_from<CONTAINER, RANGE, TYPES...>;
 
        template <class RANGE, class CONTAINER, class... TYPES>
        concept _Converts_tag_constructible = _Ref_converts<RANGE, CONTAINER>
            && std::constructible_from<CONTAINER, const from_range_t&, RANGE, TYPES...>;
 
        template <class RANGE, class CONTAINER, class... TYPES>
        concept _Converts_and_common_constructible = _Ref_converts<RANGE, CONTAINER> && std::ranges::common_range<RANGE> //
            && std::input_iterator<std::ranges::iterator_t<RANGE>> //
            && std::constructible_from<CONTAINER, std::ranges::iterator_t<RANGE>, std::ranges::iterator_t<RANGE>, TYPES...>;
 
        template <class CONTAINER, class REFERENCE>
        concept can_push_back = requires (CONTAINER& container, REFERENCE ref) {
            container.push_back(ref);
        };
 
        template <class CONTAINER, class REFERENCE>
        concept can_insert_at_end = requires (CONTAINER & container, REFERENCE ref) {
            container.insert(container.end(), ref);
        };
 
        // clang-format off
        template <class RANGE, class CONTAINER, class... TYPES>
        concept _Converts_constructible_insertable = _Ref_converts<RANGE, CONTAINER>
            && std::constructible_from<CONTAINER, TYPES...>
            && (can_push_back<CONTAINER, std::ranges::range_reference_t<RANGE>>
                || can_insert_at_end<CONTAINER, std::ranges::range_reference_t<RANGE>>);
        // clang-format on
 
        template <class REFERENCE, class CONTAINER>
        [[nodiscard]] constexpr auto container_inserter(CONTAINER& _Cont)
        {
            if constexpr (can_push_back<CONTAINER, REFERENCE>) {
                return std::back_insert_iterator{ _Cont };
            }
            else {
                return std::insert_iterator{ _Cont, _Cont.end() };
            }
        }
 
        template <class RANGE, class CONTAINER>
        concept sized_and_reservable =
            std::ranges::sized_range<RANGE> &&
            std::ranges::sized_range<CONTAINER> &&
            requires(CONTAINER & container, const std::ranges::range_size_t<CONTAINER> count) {
            container.reserve(count);
            { container.capacity() } -> std::same_as<std::ranges::range_size_t<CONTAINER>>;
            { container.max_size() } -> std::same_as<std::ranges::range_size_t<CONTAINER>>;
        };
 
        template <std::ranges::input_range RANGE>
        struct phony_input_iterator
        {
            using iterator_category = std::input_iterator_tag;
            using value_type = std::ranges::range_value_t<RANGE>;
            using difference_type = ptrdiff_t;
            using pointer = std::add_pointer_t<std::ranges::range_reference_t<RANGE>>;
            using reference = std::ranges::range_reference_t<RANGE>;
 
            reference operator*() const;
            pointer operator->() const;
 
            phony_input_iterator& operator++();
            phony_input_iterator operator++(int);
 
            bool operator==(const phony_input_iterator&) const;
        };
 
        template <template <class...> class CONTAINER, class RANGE, class... ARGS>
        auto to_helper()
        {
            if constexpr (requires (RANGE range, ARGS... args) { CONTAINER(range, args...); })
                return static_cast<decltype(CONTAINER(std::declval<RANGE>(), std::declval<ARGS>()...))*>(nullptr);
            else if constexpr (requires (RANGE range, ARGS... args) { CONTAINER(from_range, range, args...); })
                return static_cast<decltype(CONTAINER(from_range, std::declval<RANGE>(), std::declval<ARGS>()...))*>(nullptr);
            else if constexpr (requires (phony_input_iterator<RANGE> it, ARGS... args) { CONTAINER(it, it, args...);})
                return static_cast<decltype(CONTAINER(std::declval<phony_input_iterator<RANGE>>(), std::declval<phony_input_iterator<RANGE>>(), std::declval<ARGS>()...))*>(nullptr);
        }
 
    }

    template <class CONTAINER, std::ranges::input_range RANGE, class... TYPES>
    requires (!std::ranges::view<CONTAINER>)
    [[nodiscard]] constexpr CONTAINER to(RANGE&& range, TYPES&&... args)
    {
        using namespace detail;
        if constexpr (_Converts_direct_constructible<RANGE, CONTAINER, TYPES...>)
            return CONTAINER(std::forward<RANGE>(range), std::forward<TYPES>(args)...);
        else if constexpr (_Converts_tag_constructible<RANGE, CONTAINER, TYPES...>)
            return CONTAINER(from_range, std::forward<RANGE>(range), std::forward<TYPES>(args)...);
        else if constexpr (_Converts_and_common_constructible<RANGE, CONTAINER, TYPES...>)
            return CONTAINER(std::ranges::begin(range), std::ranges::end(range), std::forward<TYPES>(args)...);
        else if constexpr (_Converts_constructible_insertable<RANGE, CONTAINER, TYPES...>)
        {
            CONTAINER container(std::forward<TYPES>(args)...);
            if constexpr (sized_and_reservable<RANGE, CONTAINER>) {
                container.reserve(std::ranges::size(range));
            }
            std::ranges::copy(range, detail::container_inserter<std::ranges::range_reference_t<RANGE>>(container));
            return container;
        }
        else if constexpr (std::ranges::input_range<std::ranges::range_reference_t<RANGE>>)
        {
            const auto transform = [](auto&& _Elem) {
                return ghassanpl::to<std::ranges::range_value_t<CONTAINER>>(std::forward<decltype(_Elem)>(_Elem));
                };
            return ghassanpl::to<CONTAINER>(std::ranges::views::transform(range, transform), std::forward<TYPES>(args)...);
        }
        else
            static_assert(::ghassanpl::always_false<CONTAINER>, "the program is ill-formed per N4910 [range.utility.conv.to]/1.3");
    }
 
    template <template <class...> class CONTAINER, std::ranges::input_range RANGE, class... TYPES, class _Deduced = std::remove_pointer_t<decltype(detail::to_helper<CONTAINER, RANGE, TYPES...>())>>
    [[nodiscard]] constexpr _Deduced to(RANGE&& _Range, TYPES&&... ARGS)
    {
        return to<_Deduced>(std::forward<RANGE>(_Range), std::forward<TYPES>(ARGS)...);
    }

#else
 
    using std::ranges::to;
 
#endif

 
    /*
    template <class _Ty = void>
    struct plus_equals
    {
        [[nodiscard]] constexpr _Ty operator()(_Ty& left, const _Ty& right) const { return left += right; }
    };
 
    template <>
    struct plus_equals<void>
    {
        template <class _Ty1, class _Ty2>
        [[nodiscard]] constexpr auto operator()(_Ty1& _Left, _Ty2&& _Right) const noexcept(noexcept(static_cast<_Ty1&>(_Left) + static_cast<_Ty2&&>(_Right)))
            -> decltype(static_cast<_Ty1&>(_Left) + static_cast<_Ty2&&>(_Right))
        {
            return static_cast<_Ty1&>(_Left) + static_cast<_Ty2&&>(_Right);
        }
        using is_transparent = int;
    };
 
    template <std::ranges::range RANGE, std::movable FOLD_VALUE, typename FOLD_FUNC = std::plus<>>
    requires std::is_invocable_v<FOLD_FUNC, FOLD_VALUE&, std::ranges::range_reference_t<RANGE>>
    auto fold(RANGE&& r, FOLD_VALUE init, FOLD_FUNC&& op = {})
    {
        auto first = std::ranges::begin(r);
        auto const last = std::ranges::end(r);
        for (; first != last; ++first)
            init = std::invoke(op, std::move(init), *first);
        return init;
    }
 
    template <std::ranges::range RANGE, typename FOLD_VALUE, typename FOLD_FUNC = plus_equals<>>
    decltype(auto) fold_while(RANGE&& r, FOLD_VALUE&& init, FOLD_FUNC&& op = {})
    requires std::is_invocable_r_v<bool, FOLD_FUNC, FOLD_VALUE&, std::ranges::range_reference_t<RANGE>>
    {
        auto first = std::ranges::begin(r);
        auto const last = std::ranges::end(r);
        for (; first != last; ++first)
        {
            if (!std::invoke(op, std::ref(init), *first))
                break;
        }
        return init;
    }
    */
}