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115 lines (90 loc) · 2.96 KB
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#ifndef ITER_REVERSE_HPP_
#define ITER_REVERSE_HPP_
#include "internal/iterator_wrapper.hpp"
#include "internal/iterbase.hpp"
#include <iterator>
#include <utility>
namespace iter {
namespace impl {
template <typename Container>
using reverse_iterator_type =
decltype(std::rbegin(std::declval<Container&>()));
template <typename Container>
using reverse_iterator_end_type =
decltype(std::rend(std::declval<Container&>()));
// If rbegin and rend return the same type, type will be
// reverse_iterator_type<Container>
// If rbegin and rend return different types, type will be
// IteratorWrapperImpl
template <typename Container, bool same_types>
struct ReverseIteratorWrapperImplType;
template <typename Container>
struct ReverseIteratorWrapperImplType<Container, true>
: type_is<reverse_iterator_type<Container>> {};
template <typename Container>
struct ReverseIteratorWrapperImplType<Container, false>
: type_is<IteratorWrapperImpl<reverse_iterator_type<Container>,
reverse_iterator_end_type<Container>>> {};
template <typename Container>
using ReverseIteratorWrapper =
typename ReverseIteratorWrapperImplType<Container,
std::is_same<impl::reverse_iterator_type<Container>,
impl::reverse_iterator_end_type<Container>>{}>::type;
template <typename Container>
class Reverser;
using ReversedFn = IterToolFn<Reverser>;
}
constexpr impl::ReversedFn reversed{};
}
template <typename Container>
class iter::impl::Reverser {
private:
Container container_;
friend ReversedFn;
Reverser(Container&& container)
: container_(std::forward<Container>(container)) {}
using reverse_iterator_deref =
decltype(*std::declval<reverse_iterator_type<Container>&>());
using reverse_iterator_traits_deref =
std::remove_reference_t<reverse_iterator_deref>;
using reverse_iterator_arrow =
detail::arrow<reverse_iterator_type<Container>>;
public:
Reverser(Reverser&&) = default;
class Iterator : public std::iterator<std::input_iterator_tag,
reverse_iterator_traits_deref> {
private:
ReverseIteratorWrapper<Container> sub_iter_;
public:
Iterator(ReverseIteratorWrapper<Container>&& sub_iter)
: sub_iter_{std::move(sub_iter)} {}
reverse_iterator_deref operator*() {
return *sub_iter_;
}
reverse_iterator_arrow operator->() {
return apply_arrow(sub_iter_);
}
Iterator& operator++() {
++sub_iter_;
return *this;
}
Iterator operator++(int) {
auto ret = *this;
++*this;
return ret;
}
bool operator!=(const Iterator& other) const {
return sub_iter_ != other.sub_iter_;
}
bool operator==(const Iterator& other) const {
return !(*this != other);
}
};
Iterator begin() {
return {std::rbegin(container_)};
}
Iterator end() {
return {std::rend(container_)};
}
};
#endif