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| 1 | pmbaty | 1 | /* |
| 2 | * This file is part of the DXX-Rebirth project <https://www.dxx-rebirth.com/>. |
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| 3 | * It is copyright by its individual contributors, as recorded in the |
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| 4 | * project's Git history. See COPYING.txt at the top level for license |
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| 5 | * terms and a link to the Git history. |
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| 6 | */ |
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| 7 | #pragma once |
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| 8 | |||
| 9 | #include <inttypes.h> |
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| 10 | #include <iterator> |
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| 11 | #include "dxxsconf.h" |
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| 12 | #include "partial_range.h" |
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| 13 | #include "ephemeral_range.h" |
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| 14 | #include <tuple> |
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| 15 | #include <type_traits> |
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| 16 | |||
| 17 | /* |
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| 18 | * This could have been done using a std::pair, but using a custom type |
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| 19 | * allows for more descriptive member names. |
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| 20 | */ |
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| 21 | template <typename range_value_type, typename index_type> |
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| 22 | struct enumerated_value |
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| 23 | { |
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| 24 | range_value_type value; |
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| 25 | const index_type idx; |
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| 26 | }; |
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| 27 | |||
| 28 | namespace d_enumerate { |
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| 29 | |||
| 30 | namespace detail { |
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| 31 | |||
| 32 | template <typename result_type, typename index_type> |
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| 33 | struct adjust_iterator_dereference_type : std::false_type |
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| 34 | { |
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| 35 | using value_type = enumerated_value<result_type, index_type>; |
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| 36 | }; |
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| 37 | |||
| 38 | template <typename... T, typename index_type> |
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| 39 | struct adjust_iterator_dereference_type<std::tuple<T...>, index_type> : std::true_type |
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| 40 | { |
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| 41 | using value_type = std::tuple<index_type, T...>; |
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| 42 | }; |
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| 43 | |||
| 44 | } |
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| 45 | |||
| 46 | } |
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| 47 | |||
| 48 | template <typename range_iterator_type, typename index_type, typename iterator_dereference_type> |
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| 49 | class enumerated_iterator |
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| 50 | { |
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| 51 | range_iterator_type m_iter; |
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| 52 | index_type m_idx; |
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| 53 | using adjust_iterator_dereference_type = d_enumerate::detail::adjust_iterator_dereference_type<typename std::remove_cv<iterator_dereference_type>::type, index_type>; |
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| 54 | public: |
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| 55 | using iterator_category = std::forward_iterator_tag; |
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| 56 | using value_type = typename adjust_iterator_dereference_type::value_type; |
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| 57 | using difference_type = std::ptrdiff_t; |
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| 58 | using pointer = value_type *; |
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| 59 | using reference = value_type &; |
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| 60 | enumerated_iterator(const range_iterator_type &iter, const index_type idx) : |
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| 61 | m_iter(iter), m_idx(idx) |
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| 62 | { |
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| 63 | } |
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| 64 | value_type operator*() const |
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| 65 | { |
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| 66 | if constexpr (adjust_iterator_dereference_type::value) |
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| 67 | return std::tuple_cat(std::tuple<index_type>(m_idx), *m_iter); |
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| 68 | else |
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| 69 | return {*m_iter, m_idx}; |
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| 70 | } |
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| 71 | enumerated_iterator &operator++() |
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| 72 | { |
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| 73 | ++ m_iter; |
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| 74 | ++ m_idx; |
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| 75 | return *this; |
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| 76 | } |
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| 77 | bool operator!=(const enumerated_iterator &i) const |
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| 78 | { |
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| 79 | return m_iter != i.m_iter; |
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| 80 | } |
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| 81 | bool operator==(const enumerated_iterator &i) const |
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| 82 | { |
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| 83 | return m_iter == i.m_iter; |
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| 84 | } |
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| 85 | }; |
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| 86 | |||
| 87 | template <typename range_iterator_type, typename index_type> |
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| 88 | class enumerate : partial_range_t<range_iterator_type> |
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| 89 | { |
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| 90 | using base_type = partial_range_t<range_iterator_type>; |
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| 91 | using iterator_dereference_type = decltype(*std::declval<range_iterator_type>()); |
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| 92 | using enumerated_iterator_type = enumerated_iterator< |
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| 93 | range_iterator_type, |
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| 94 | index_type, |
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| 95 | iterator_dereference_type>; |
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| 96 | const index_type m_idx; |
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| 97 | public: |
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| 98 | using range_owns_iterated_storage = std::false_type; |
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| 99 | enumerate(const range_iterator_type b, const range_iterator_type e, const index_type i) : |
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| 100 | base_type(b, e), m_idx(i) |
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| 101 | { |
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| 102 | } |
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| 103 | template <typename range_type> |
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| 104 | enumerate(range_type &&t, const index_type i = 0) : |
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| 105 | base_type(t), m_idx(i) |
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| 106 | { |
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| 107 | static_assert(!any_ephemeral_range<range_type &&>::value, "cannot enumerate storage of ephemeral ranges"); |
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| 108 | static_assert(std::is_rvalue_reference<range_type &&>::value || std::is_lvalue_reference<iterator_dereference_type>::value, "lvalue range must produce lvalue reference enumerated_value"); |
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| 109 | } |
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| 110 | enumerated_iterator_type begin() const |
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| 111 | { |
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| 112 | return enumerated_iterator_type(this->base_type::begin(), m_idx); |
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| 113 | } |
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| 114 | enumerated_iterator_type end() const |
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| 115 | { |
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| 116 | return enumerated_iterator_type(this->base_type::end(), 0 /* unused */); |
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| 117 | } |
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| 118 | }; |
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| 119 | |||
| 120 | template <typename range_type, typename index_type = uint_fast32_t, typename range_iterator_type = decltype(std::begin(std::declval<range_type &>()))> |
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| 121 | enumerate(range_type &&r, const index_type start = index_type(/* value ignored */)) -> enumerate<range_iterator_type, index_type>; |