122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
/*
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* This file is part of the DXX-Rebirth project <https://www.dxx-rebirth.com/>.
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* It is copyright by its individual contributors, as recorded in the
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* project's Git history. See COPYING.txt at the top level for license
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* terms and a link to the Git history.
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*/
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#pragma once
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#include <inttypes.h>
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#include <iterator>
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#include "dxxsconf.h"
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#include "partial_range.h"
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#include "ephemeral_range.h"
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#include <tuple>
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#include <type_traits>
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/*
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* This could have been done using a std::pair, but using a custom type
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* allows for more descriptive member names.
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*/
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template <typename range_value_type, typename index_type>
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struct enumerated_value
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{
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range_value_type value;
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const index_type idx;
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};
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namespace d_enumerate {
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namespace detail {
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template <typename result_type, typename index_type>
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struct adjust_iterator_dereference_type : std::false_type
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{
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using value_type = enumerated_value<result_type, index_type>;
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};
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template <typename... T, typename index_type>
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struct adjust_iterator_dereference_type<std::tuple<T...>, index_type> : std::true_type
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{
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using value_type = std::tuple<index_type, T...>;
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};
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}
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}
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template <typename range_iterator_type, typename index_type, typename iterator_dereference_type>
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class enumerated_iterator
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{
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range_iterator_type m_iter;
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index_type m_idx;
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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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public:
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using iterator_category = std::forward_iterator_tag;
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using value_type = typename adjust_iterator_dereference_type::value_type;
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using difference_type = std::ptrdiff_t;
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using pointer = value_type *;
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using reference = value_type &;
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enumerated_iterator(const range_iterator_type &iter, const index_type idx) :
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m_iter(iter), m_idx(idx)
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{
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}
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value_type operator*() const
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{
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if constexpr (adjust_iterator_dereference_type::value)
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return std::tuple_cat(std::tuple<index_type>(m_idx), *m_iter);
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else
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return {*m_iter, m_idx};
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}
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enumerated_iterator &operator++()
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{
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++ m_iter;
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++ m_idx;
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return *this;
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}
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bool operator!=(const enumerated_iterator &i) const
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{
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return m_iter != i.m_iter;
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}
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bool operator==(const enumerated_iterator &i) const
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{
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return m_iter == i.m_iter;
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}
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};
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template <typename range_iterator_type, typename index_type>
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class enumerate : partial_range_t<range_iterator_type>
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{
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using base_type = partial_range_t<range_iterator_type>;
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using iterator_dereference_type = decltype(*std::declval<range_iterator_type>());
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using enumerated_iterator_type = enumerated_iterator<
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range_iterator_type,
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index_type,
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iterator_dereference_type>;
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const index_type m_idx;
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public:
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using range_owns_iterated_storage = std::false_type;
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enumerate(const range_iterator_type b, const range_iterator_type e, const index_type i) :
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base_type(b, e), m_idx(i)
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{
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}
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template <typename range_type>
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enumerate(range_type &&t, const index_type i = 0) :
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base_type(t), m_idx(i)
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{
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static_assert(!any_ephemeral_range<range_type &&>::value, "cannot enumerate storage of ephemeral ranges");
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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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}
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enumerated_iterator_type begin() const
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{
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return enumerated_iterator_type(this->base_type::begin(), m_idx);
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}
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enumerated_iterator_type end() const
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{
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return enumerated_iterator_type(this->base_type::end(), 0 /* unused */);
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}
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};
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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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enumerate(range_type &&r, const index_type start = index_type(/* value ignored */)) -> enumerate<range_iterator_type, index_type>;
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