Line data    Source code

       1             : // Copyright (c) 2022-2026 The Dash Core developers
       2             : // Distributed under the MIT software license, see the accompanying
       3             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4             : 
       5             : #ifndef BITCOIN_UTIL_STD23_H
       6             : #define BITCOIN_UTIL_STD23_H
       7             : 
       8             : #include <algorithm>
       9             : #include <functional>
      10             : #include <iterator>
      11             : #include <ranges>
      12             : #include <type_traits>
      13             : #include <utility>
      14             : 
      15             : namespace std23 {
      16             : #if __cplusplus >= 202302L
      17             : using std::to_underlying;
      18             : #else
      19             : /**
      20             :  * @tparam E enumeration type, automatically deduced
      21             :  * @param e the enumerated value to convert
      22             :  * @return the underlying value in base type
      23             :  */
      24             : template <typename E>
      25       29971 : [[nodiscard]] inline constexpr std::underlying_type_t<E> to_underlying(E e) noexcept
      26             : {
      27       29971 :     return static_cast<std::underlying_type_t<E>>(e);
      28             : }
      29             : #endif // __cplusplus >= 202302L
      30             : namespace ranges {
      31             : #if __cplusplus >= 202302L
      32             : using std::ranges::contains;
      33             : using std::ranges::fold_left;
      34             : #else
      35             : /**
      36             :  * @tparam R range type, automatically deduced
      37             :  * @tparam T value type to search for, automatically deduced
      38             :  * @tparam Proj projection type
      39             :  * @param range the range to search in
      40             :  * @param value the value to search for
      41             :  * @param proj optional projection to apply to elements before comparison
      42             :  * @return true if the range contains the value, false otherwise
      43             :  *
      44             :  * @see https://github.com/llvm/llvm-project/blob/llvmorg-22.1.0/libcxx/include/__algorithm/ranges_contains.h
      45             :  */
      46             : template <typename R, typename T, typename Proj = std::identity>
      47           7 : inline constexpr bool contains(R&& range, const T& value, Proj proj = {})
      48             : {
      49           7 :     return std::ranges::find(std::ranges::begin(range), std::ranges::end(range), value, proj) != std::ranges::end(range);
      50             : }
      51             : 
      52             : /**
      53             :  * @tparam R range type, automatically deduced
      54             :  * @tparam T initial value type, automatically deduced
      55             :  * @tparam F binary operation type, automatically deduced
      56             :  * @param range the range to fold
      57             :  * @param init the initial value
      58             :  * @param f binary operation to apply
      59             :  * @return the result of left-folding the range with f
      60             :  *
      61             :  * @see https://github.com/llvm/llvm-project/blob/llvmorg-22.1.0/libcxx/include/__algorithm/ranges_fold.h
      62             :  */
      63             : template <typename R, typename T, typename F>
      64       36473 : inline constexpr auto fold_left(R&& range, T init, F f)
      65             : {
      66             :     using I = decltype(std::ranges::begin(range));
      67             :     using U = std::decay_t<std::invoke_result_t<F&, T, std::iter_reference_t<I>>>;
      68             : 
      69       36473 :     auto first = std::ranges::begin(range);
      70       36473 :     auto last = std::ranges::end(range);
      71       36473 :     if (first == last) {
      72           0 :         return U(std::move(init));
      73             :     }
      74             : 
      75       36473 :     U accum = std::invoke(f, std::move(init), *first);
      76      182356 :     for (++first; first != last; ++first) {
      77      145883 :         accum = std::invoke(f, std::move(accum), *first);
      78      145883 :     }
      79       36473 :     return accum;
      80       36473 : }
      81             : #endif // __cplusplus >= 202302L
      82             : namespace views {
      83             : #if __cplusplus >= 202302L
      84             : using std::ranges::views::enumerate;
      85             : #else
      86             : /**
      87             :  * @tparam T type of iterable, automatically deduced
      88             :  * @tparam TIter begin of container
      89             :  * @param iterable an iterable object, can be a temporary
      90             :  * @return struct containing a size_t index, and it's element in iterable
      91             :  */
      92             : template <typename T,
      93             :           typename TIter = decltype(std::begin(std::declval<T>())),
      94             :           typename = decltype(std::end(std::declval<T>()))>
      95         499 : inline constexpr auto enumerate(T && iterable)
      96             : {
      97             :     struct iterator {
      98             :         size_t i;
      99             :         TIter iter;
     100        1496 :         bool operator!=(const iterator& other) const { return iter != other.iter; }
     101         997 :         void operator++()
     102             :         {
     103         997 :             ++i;
     104         997 :             ++iter;
     105         997 :         }
     106         997 :         auto operator*() const { return std::tie(i, *iter); }
     107             :     };
     108             :     struct iterable_wrapper {
     109             :         T iterable;
     110         499 :         auto begin() { return iterator{0, std::begin(iterable)}; }
     111         499 :         auto end() { return iterator{0, std::end(iterable)}; }
     112             :     };
     113         499 :     return iterable_wrapper{std::forward<T>(iterable)};
     114             : }
     115             : #endif // __cplusplus >= 202302L
     116             : } // namespace views
     117             : } // namespace ranges
     118             : namespace views {
     119             : using namespace std23::ranges::views;
     120             : } // namespace views
     121             : } // namespace std23
     122             : 
     123             : #endif // BITCOIN_UTIL_STD23_H