Enumerate
(src/utils/py-like/enumerate.hpp)

• View this file on GitHub
• Last update: 2022-04-06 16:00:36+09:00
• Include: #include "src/utils/py-like/enumerate.hpp"

Depends on

• Iterator Category (src/utils/iterator/category.hpp)
• Reverse Iterator (src/utils/iterator/reverse.hpp)
• Range (src/utils/py-like/range.hpp)
• Reversed (src/utils/py-like/reversed.hpp)
• Zip (src/utils/py-like/zip.hpp)

Code

#pragma once

/**
 * @file enumerate.hpp
 * @brief Enumerate
 */

#include "range.hpp"
#include "zip.hpp"

#if __cplusplus >= 201703L

namespace workspace {

namespace _enumerate_impl {

constexpr size_t min_size() noexcept { return SIZE_MAX; }

template <class _Container, class... _Args>
constexpr size_t min_size(_Container const &__cont,
                          _Args &&... __args) noexcept {
  return std::min(std::size(__cont), min_size(std::forward<_Args>(__args)...));
}

}  // namespace _enumerate_impl

template <class... _Args>
constexpr decltype(auto) enumerate(_Args &&... __args) noexcept {
  return zip(range(_enumerate_impl::min_size(__args...)),
             std::forward<_Args>(__args)...);
}

template <class... _Args>
constexpr decltype(auto) enumerate(
    std::initializer_list<_Args> const &... __args) noexcept {
  return zip(range(_enumerate_impl::min_size(__args...)),
             std::vector(__args)...);
}

}  // namespace workspace

#endif

#line 2 "src/utils/py-like/enumerate.hpp"

/**
 * @file enumerate.hpp
 * @brief Enumerate
 */

#line 2 "src/utils/py-like/range.hpp"

/**
 * @file range.hpp
 * @brief Range
 */

#line 2 "src/utils/py-like/reversed.hpp"

/**
 * @file reversed.hpp
 * @brief Reversed
 */

#include <vector>

#line 2 "lib/cxx17"

#line 2 "lib/cxx14"

#ifndef _CXX14_CONSTEXPR
#if __cplusplus >= 201402L
#define _CXX14_CONSTEXPR constexpr
#else
#define _CXX14_CONSTEXPR
#endif
#endif
#line 4 "lib/cxx17"

#ifndef _CXX17_CONSTEXPR
#if __cplusplus >= 201703L
#define _CXX17_CONSTEXPR constexpr
#else
#define _CXX17_CONSTEXPR
#endif
#endif

#ifndef _CXX17_STATIC_ASSERT
#if __cplusplus >= 201703L
#define _CXX17_STATIC_ASSERT static_assert
#else
#define _CXX17_STATIC_ASSERT assert
#endif
#endif

#include <iterator>

#if __cplusplus < 201703L

namespace std {

/**
 *  @brief  Return the size of a container.
 *  @param  __cont  Container.
 */
template <typename _Container>
constexpr auto size(const _Container& __cont) noexcept(noexcept(__cont.size()))
    -> decltype(__cont.size()) {
  return __cont.size();
}

/**
 *  @brief  Return the size of an array.
 */
template <typename _Tp, size_t _Nm>
constexpr size_t size(const _Tp (&)[_Nm]) noexcept {
  return _Nm;
}

/**
 *  @brief  Return whether a container is empty.
 *  @param  __cont  Container.
 */
template <typename _Container>
[[nodiscard]] constexpr auto empty(const _Container& __cont) noexcept(
    noexcept(__cont.empty())) -> decltype(__cont.empty()) {
  return __cont.empty();
}

/**
 *  @brief  Return whether an array is empty (always false).
 */
template <typename _Tp, size_t _Nm>
[[nodiscard]] constexpr bool empty(const _Tp (&)[_Nm]) noexcept {
  return false;
}

/**
 *  @brief  Return whether an initializer_list is empty.
 *  @param  __il  Initializer list.
 */
template <typename _Tp>
[[nodiscard]] constexpr bool empty(initializer_list<_Tp> __il) noexcept {
  return __il.size() == 0;
}

struct monostate {};

}  // namespace std

#else

#include <variant>

#endif
#line 11 "src/utils/py-like/reversed.hpp"

namespace workspace {

// Reversed container.
template <class _Container> class reversed {
  _Container __c;

 public:
  template <class _Tp>
  constexpr reversed(_Tp &&__x) noexcept : __c(std::forward<_Container>(__x)) {}

  template <class _Tp>
  constexpr reversed(std::initializer_list<_Tp> __x) noexcept : __c(__x) {}

  constexpr decltype(auto) begin() noexcept { return std::rbegin(__c); }
  constexpr decltype(auto) begin() const noexcept { return std::rbegin(__c); }

  constexpr decltype(auto) end() noexcept { return std::rend(__c); }
  constexpr decltype(auto) end() const noexcept { return std::rend(__c); }

  constexpr bool empty() const noexcept { return std::empty(__c); }

  constexpr decltype(auto) size() const noexcept { return std::size(__c); }

  using iterator = decltype(std::rbegin(__c));
  using const_iterator = decltype(std::crbegin(__c));

  using size_type = decltype(std::size(__c));
  using difference_type =
      typename std::iterator_traits<iterator>::difference_type;
  using value_type = typename std::iterator_traits<iterator>::value_type;

  using reference = typename std::iterator_traits<iterator>::reference;
  using const_reference =
      typename std::iterator_traits<const_iterator>::reference;
};

#if __cpp_deduction_guides >= 201606L

template <class _Tp> reversed(_Tp &&) -> reversed<_Tp>;

template <class _Tp>
reversed(std::initializer_list<_Tp>) -> reversed<std::initializer_list<_Tp>>;

#endif

}  // namespace workspace
#line 9 "src/utils/py-like/range.hpp"

namespace workspace {

template <class _Index> class range {
  _Index __first, __last;

 public:
  class iterator {
    _Index __i;

   public:
    using difference_type = std::ptrdiff_t;
    using value_type = _Index;
    using pointer = void;
    using reference = value_type;
    using iterator_category = std::random_access_iterator_tag;

    constexpr iterator() = default;
    constexpr iterator(const _Index &__x) noexcept : __i(__x) {}

    constexpr bool operator==(const iterator &__x) const noexcept {
      return __i == __x.__i;
    }
    constexpr bool operator!=(const iterator &__x) const noexcept {
      return __i != __x.__i;
    }

    constexpr bool operator<(const iterator &__x) const noexcept {
      return __i < __x.__i;
    }
    constexpr bool operator<=(const iterator &__x) const noexcept {
      return __i <= __x.__i;
    }

    constexpr bool operator>(const iterator &__x) const noexcept {
      return __i > __x.__i;
    }
    constexpr bool operator>=(const iterator &__x) const noexcept {
      return __i >= __x.__i;
    }

    constexpr iterator &operator++() noexcept {
      ++__i;
      return *this;
    }
    constexpr iterator operator++(int) noexcept {
      auto __tmp = *this;
      ++__i;
      return __tmp;
    }

    constexpr iterator &operator--() noexcept {
      --__i;
      return *this;
    }
    constexpr iterator operator--(int) noexcept {
      auto __tmp = *this;
      --__i;
      return __tmp;
    }

    constexpr difference_type operator-(const iterator &__x) const noexcept {
      return __i - __x.__i;
    }

    constexpr iterator &operator+=(difference_type __x) noexcept {
      __i += __x;
      return *this;
    }
    constexpr iterator operator+(difference_type __x) const noexcept {
      return iterator(*this) += __x;
    }

    constexpr iterator &operator-=(difference_type __x) noexcept {
      __i -= __x;
      return *this;
    }
    constexpr iterator operator-(difference_type __x) const noexcept {
      return iterator(*this) -= __x;
    }

    constexpr reference operator*() const noexcept { return __i; }
  };

  using value_type = _Index;
  using reference = value_type;

  using difference_type = std::ptrdiff_t;
  using size_type = std::size_t;

  using const_iterator = iterator;

  using reverse_iterator = std::reverse_iterator<iterator>;
  using const_reverse_iterator = reverse_iterator;

  template <class _Tp1, class _Tp2>
  constexpr range(const _Tp1 &__first, const _Tp2 &__last) noexcept
      : __first(__first), __last(__last) {}

  template <class _Tp>
  constexpr range(const _Tp &__last) noexcept : __first(), __last(__last) {}

  constexpr iterator begin() const noexcept { return {__first}; }
  constexpr const_iterator cbegin() const noexcept { return begin(); }

  constexpr iterator end() const noexcept { return {__last}; }
  constexpr const_iterator cend() const noexcept { return end(); }

  constexpr reverse_iterator rbegin() const noexcept {
    return reverse_iterator{end()};
  }
  constexpr const_reverse_iterator crbegin() const noexcept { return rbegin(); }

  constexpr reverse_iterator rend() const noexcept {
    return reverse_iterator{begin()};
  }
  constexpr const_reverse_iterator crend() const noexcept { return rend(); }

  constexpr size_type size() const noexcept { return __last - __first; }
};

#if __cpp_deduction_guides >= 201606L

template <class _Tp1, class _Tp2>
range(const _Tp1 &, const _Tp2 &)
    -> range<std::decay_t<decltype(++std::declval<_Tp1 &>())>>;

template <class _Tp>
range(const _Tp &) -> range<std::decay_t<decltype(++std::declval<_Tp &>())>>;

template <class... _Args>
constexpr decltype(auto) rrange(_Args &&...__args) noexcept {
  return reversed(range(std::forward<_Args>(__args)...));
}

#endif

}  // namespace workspace
#line 2 "src/utils/py-like/zip.hpp"

/**
 * @file zip.hpp
 * @brief Zip
 */

#include <cstddef>
#include <tuple>
#line 11 "src/utils/py-like/zip.hpp"

#line 2 "src/utils/iterator/category.hpp"

/*
 * @file category.hpp
 * @brief Iterator Category
 */

#line 10 "src/utils/iterator/category.hpp"

namespace workspace {

/*
 * @tparam Tuple Tuple of iterator types
 */
template <class Tuple, size_t N = std::tuple_size<Tuple>::value - 1>
struct common_iterator_category {
  using type = typename std::common_type<
      typename common_iterator_category<Tuple, N - 1>::type,
      typename std::iterator_traits<typename std::tuple_element<
          N, Tuple>::type>::iterator_category>::type;
};

template <class Tuple> struct common_iterator_category<Tuple, 0> {
  using type = typename std::iterator_traits<
      typename std::tuple_element<0, Tuple>::type>::iterator_category;
};

}  // namespace workspace
#line 2 "src/utils/iterator/reverse.hpp"

/*
 * @file reverse_iterator.hpp
 * @brief Reverse Iterator
 */

#if __cplusplus >= 201703L

#line 11 "src/utils/iterator/reverse.hpp"
#include <optional>

namespace workspace {

/*
 * @class reverse_iterator
 * @brief Wrapper class for `std::reverse_iterator`.
 * @see http://gcc.gnu.org/PR51823
 */
template <class Iterator>
class reverse_iterator : public std::reverse_iterator<Iterator> {
  using base_std = std::reverse_iterator<Iterator>;
  std::optional<typename base_std::value_type> deref;

 public:
  using base_std::reverse_iterator;

  constexpr typename base_std::reference operator*() noexcept {
    if (!deref) {
      Iterator tmp = base_std::current;
      deref = *--tmp;
    }
    return deref.value();
  }

  constexpr reverse_iterator &operator++() noexcept {
    base_std::operator++();
    deref.reset();
    return *this;
  }
  constexpr reverse_iterator &operator--() noexcept {
    base_std::operator++();
    deref.reset();
    return *this;
  }
  constexpr reverse_iterator operator++(int) noexcept {
    base_std::operator++();
    deref.reset();
    return *this;
  }
  constexpr reverse_iterator operator--(int) noexcept {
    base_std::operator++();
    deref.reset();
    return *this;
  }
};

}  // namespace workspace

#endif
#line 15 "src/utils/py-like/zip.hpp"

namespace workspace {

template <class _Tuple> class zipped : protected _Tuple {
 public:
  zipped(const _Tuple &__x) : _Tuple(__x) {}

  template <std::size_t _Nm> constexpr decltype(auto) get() const &noexcept {
    return *std::get<_Nm>(*this);
  }

  template <std::size_t _Nm> constexpr decltype(auto) get() &&noexcept {
    auto __tmp = *std::get<_Nm>(*this);
    return __tmp;
  }
};

template <class... _Containers> class zip {
  std::tuple<_Containers...> __c;

  template <std::size_t _Nm = 0>
  constexpr decltype(auto) begin_cat() const noexcept {
    if _CXX17_CONSTEXPR (_Nm != sizeof...(_Containers)) {
      return std::tuple_cat(std::tuple(std::begin(std::get<_Nm>(__c))),
                            begin_cat<_Nm + 1>());
    } else
      return std::tuple<>();
  }

  template <std::size_t _Nm = 0>
  constexpr decltype(auto) end_cat() const noexcept {
    if _CXX17_CONSTEXPR (_Nm != sizeof...(_Containers)) {
      return std::tuple_cat(std::tuple(std::end(std::get<_Nm>(__c))),
                            end_cat<_Nm + 1>());
    } else
      return std::tuple<>();
  }

  using _Iterator_tuple =
      std::tuple<decltype(std::begin(std::declval<_Containers>()))...>;

 public:
  using size_type = std::size_t;

  class iterator : public zipped<_Iterator_tuple> {
    using _Base = zipped<_Iterator_tuple>;

   public:
    using difference_type = std::ptrdiff_t;
    using value_type = _Base;
    using pointer = void;
    using reference = value_type &;
    using iterator_category =
        typename common_iterator_category<_Iterator_tuple>::type;

   protected:
    template <std::size_t _Nm = 0>
    constexpr bool equal(const iterator &__x) const noexcept {
      if _CXX17_CONSTEXPR (_Nm != sizeof...(_Containers)) {
        return std::get<_Nm>(*this) == std::get<_Nm>(__x) ||
               equal<_Nm + 1>(__x);
      } else
        return false;
    }

    template <std::size_t _Nm = 0> constexpr void increment() noexcept {
      if _CXX17_CONSTEXPR (_Nm != sizeof...(_Containers))
        ++std::get<_Nm>(*this), increment<_Nm + 1>();
    }

    template <std::size_t _Nm = 0> constexpr void decrement() noexcept {
      if _CXX17_CONSTEXPR (_Nm != sizeof...(_Containers))
        --std::get<_Nm>(*this), decrement<_Nm + 1>();
    }

    template <std::size_t _Nm = 0>
    constexpr void advance(difference_type __d) noexcept {
      if _CXX17_CONSTEXPR (_Nm != sizeof...(_Containers))
        std::get<_Nm>(*this) += __d, advance<_Nm + 1>(__d);
    }

   public:
    iterator(const _Iterator_tuple &__x) : _Base(__x) {}

    constexpr bool operator==(const iterator &__x) const noexcept {
      return equal(__x);
    }
    constexpr bool operator!=(const iterator &__x) const noexcept {
      return !equal(__x);
    }

    constexpr iterator &operator++() noexcept {
      increment();
      return *this;
    }
    constexpr iterator operator++(int) noexcept {
      auto __tmp = *this;
      increment();
      return __tmp;
    }

    constexpr iterator &operator--() noexcept {
      decrement();
      return *this;
    }
    constexpr iterator operator--(int) noexcept {
      auto __tmp = *this;
      decrement();
      return __tmp;
    }

    constexpr bool operator<(const iterator &__x) const noexcept {
      return std::get<0>(*this) < std::get<0>(__x);
    }
    constexpr bool operator<=(const iterator &__x) const noexcept {
      return std::get<0>(*this) <= std::get<0>(__x);
    }
    constexpr bool operator>(const iterator &__x) const noexcept {
      return !operator<=(__x);
    }
    constexpr bool operator>=(const iterator &__x) const noexcept {
      return !operator>(__x);
    }

    constexpr iterator &operator+=(difference_type __d) noexcept {
      advance(__d);
      return *this;
    }
    constexpr iterator &operator-=(difference_type __d) noexcept {
      advance(-__d);
      return *this;
    }
    constexpr iterator operator+(difference_type __d) const noexcept {
      return iterator{*this} += __d;
    }
    constexpr iterator operator-(difference_type __d) const noexcept {
      return iterator{*this} -= __d;
    }

    constexpr difference_type operator-(const iterator &__x) const noexcept {
      return std::get<0>(*this) - std::get<0>(__x);
    }

    constexpr reference operator*() noexcept { return {*this}; }
  };

  using const_iterator = iterator;

  template <class... _Args>
  constexpr zip(_Args &&...__args) noexcept
      : __c(std::forward<_Args>(__args)...) {}

  template <class... _Args>
  constexpr zip(std::initializer_list<_Args>... __args) noexcept
      : __c(std::forward<_Args>(__args)...) {}

  constexpr iterator begin() const noexcept { return {begin_cat()}; }

  constexpr iterator end() const noexcept { return {end_cat()}; }

  constexpr reverse_iterator<iterator> rbegin() const noexcept {
    return reverse_iterator<iterator>{end()};
  }

  constexpr reverse_iterator<iterator> rend() const noexcept {
    return reverse_iterator<iterator>{begin()};
  }

#if __cplusplus >= 201703L
  constexpr size_type size() const noexcept {
    size_type __n = -1;
    std::apply(
        [&__n](auto &&__x) {
          if (__n < __x.size()) __n = __x.size();
        },
        __c);
    return __n;
  }
#endif
};

#if __cpp_deduction_guides >= 201606L

template <class... _Args> zip(_Args &&...) -> zip<_Args...>;

// For gcc version < 10
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80438
template <class _Tp, class... _Args>
zip(_Tp &&, _Args &&...) -> zip<_Tp, _Args...>;

template <class... _Args>
zip(std::initializer_list<_Args>...) -> zip<std::initializer_list<_Args>...>;

#endif

}  // namespace workspace

namespace std {

template <size_t _Nm, class _Tuple>
struct tuple_element<_Nm, workspace::zipped<_Tuple>> {
  using type = remove_reference_t<
      typename iterator_traits<tuple_element_t<_Nm, _Tuple>>::reference>;
};

template <class _Tuple>
struct tuple_size<workspace::zipped<_Tuple>> : tuple_size<_Tuple> {};

}  // namespace std
#line 10 "src/utils/py-like/enumerate.hpp"

#if __cplusplus >= 201703L

namespace workspace {

namespace _enumerate_impl {

constexpr size_t min_size() noexcept { return SIZE_MAX; }

template <class _Container, class... _Args>
constexpr size_t min_size(_Container const &__cont,
                          _Args &&... __args) noexcept {
  return std::min(std::size(__cont), min_size(std::forward<_Args>(__args)...));
}

}  // namespace _enumerate_impl

template <class... _Args>
constexpr decltype(auto) enumerate(_Args &&... __args) noexcept {
  return zip(range(_enumerate_impl::min_size(__args...)),
             std::forward<_Args>(__args)...);
}

template <class... _Args>
constexpr decltype(auto) enumerate(
    std::initializer_list<_Args> const &... __args) noexcept {
  return zip(range(_enumerate_impl::min_size(__args...)),
             std::vector(__args)...);
}

}  // namespace workspace

#endif

Back to top page