include/cppcoro/sequence_range.hpp

0001 ///////////////////////////////////////////////////////////////////////////////
0002 // Copyright (c) Lewis Baker
0003 // Licenced under MIT license. See LICENSE.txt for details.
0004 ///////////////////////////////////////////////////////////////////////////////
0005 #ifndef CPPCORO_SEQUENCE_RANGE_HPP_INCLUDED
0006 #define CPPCORO_SEQUENCE_RANGE_HPP_INCLUDED
0007
0008 #include <cppcoro/sequence_traits.hpp>
0009
0010 #include <algorithm>
0011 #include <iterator>
0012
0013 namespace cppcoro
0014 {
0015     template<typename SEQUENCE, typename TRAITS = sequence_traits<SEQUENCE>>
0016     class sequence_range
0017     {
0018     public:
0019
0020         using value_type = SEQUENCE;
0021         using difference_type = typename TRAITS::difference_type;
0022         using size_type = typename TRAITS::size_type;
0023
0024         class const_iterator
0025         {
0026         public:
0027
0028             using iterator_category = std::random_access_iterator_tag;
0029             using value_type = SEQUENCE;
0030             using difference_type = typename TRAITS::difference_type;
0031             using reference = const SEQUENCE&;
0032             using pointer = const SEQUENCE*;
0033
0034             explicit constexpr const_iterator(SEQUENCE value) noexcept : m_value(value) {}
0035
0036             const SEQUENCE& operator*() const noexcept { return m_value; }
0037             const SEQUENCE* operator->() const noexcept { return std::addressof(m_value); }
0038
0039             const_iterator& operator++() noexcept { ++m_value; return *this; }
0040             const_iterator& operator--() noexcept { --m_value; return *this; }
0041
0042             const_iterator operator++(int) noexcept { return const_iterator(m_value++); }
0043             const_iterator operator--(int) noexcept { return const_iterator(m_value--); }
0044
0045             constexpr difference_type operator-(const_iterator other) const noexcept { return TRAITS::difference(m_value, other.m_value); }
0046             constexpr const_iterator operator-(difference_type delta) const noexcept { return const_iterator{ static_cast<SEQUENCE>(m_value - delta) }; }
0047             constexpr const_iterator operator+(difference_type delta) const noexcept { return const_iterator{ static_cast<SEQUENCE>(m_value + delta) }; }
0048
0049             constexpr bool operator==(const_iterator other) const noexcept { return m_value == other.m_value; }
0050             constexpr bool operator!=(const_iterator other) const noexcept { return m_value != other.m_value; }
0051
0052         private:
0053
0054             SEQUENCE m_value;
0055
0056         };
0057
0058         constexpr sequence_range() noexcept
0059             : m_begin()
0060             , m_end()
0061         {}
0062
0063         constexpr sequence_range(SEQUENCE begin, SEQUENCE end) noexcept
0064             : m_begin(begin)
0065             , m_end(end)
0066         {}
0067
0068         constexpr const_iterator begin() const noexcept { return const_iterator(m_begin); }
0069         constexpr const_iterator end() const noexcept { return const_iterator(m_end); }
0070
0071         constexpr SEQUENCE front() const noexcept { return m_begin; }
0072         constexpr SEQUENCE back() const noexcept { return m_end - 1; }
0073
0074         constexpr size_type size() const noexcept
0075         {
0076             return static_cast<size_type>(TRAITS::difference(m_end, m_begin));
0077         }
0078
0079         constexpr bool empty() const noexcept
0080         {
0081             return m_begin == m_end;
0082         }
0083
0084         constexpr SEQUENCE operator[](size_type index) const noexcept
0085         {
0086             return m_begin + index;
0087         }
0088
0089         constexpr sequence_range first(size_type count) const noexcept
0090         {
0091             return sequence_range{ m_begin, static_cast<SEQUENCE>(m_begin + std::min(size(), count)) };
0092         }
0093
0094         constexpr sequence_range skip(size_type count) const noexcept
0095         {
0096             return sequence_range{ m_begin + std::min(size(), count), m_end };
0097         }
0098
0099     private:
0100
0101         SEQUENCE m_begin;
0102         SEQUENCE m_end;
0103
0104     };
0105 }
0106
0107 #endif