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Copy pathslice.hpp
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156 lines (131 loc) · 4.23 KB
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#ifndef ITER_SLICE_HPP_
#define ITER_SLICE_HPP_
#include "internal/iterator_wrapper.hpp"
#include "internal/iterbase.hpp"
#include <iterator>
#include <type_traits>
namespace iter {
namespace impl {
template <typename Container, typename DifferenceType>
class Sliced;
struct SliceFn;
}
}
template <typename Container, typename DifferenceType>
class iter::impl::Sliced {
private:
Container container_;
DifferenceType start_;
DifferenceType stop_;
DifferenceType step_;
friend SliceFn;
Sliced(Container&& container, DifferenceType start, DifferenceType stop,
DifferenceType step)
: container_(std::forward<Container>(container)),
start_{start < stop && step > 0 ? start : stop},
stop_{stop},
step_{step} {}
public:
Sliced(Sliced&&) = default;
class Iterator : public std::iterator<std::input_iterator_tag,
iterator_traits_deref<Container>> {
private:
IteratorWrapper<Container> sub_iter_;
IteratorWrapper<Container> sub_end_;
DifferenceType current_;
DifferenceType stop_;
DifferenceType step_;
public:
Iterator(IteratorWrapper<Container>&& sub_iter,
IteratorWrapper<Container>&& sub_end, DifferenceType start,
DifferenceType stop, DifferenceType step)
: sub_iter_{std::move(sub_iter)},
sub_end_{std::move(sub_end)},
current_{start},
stop_{stop},
step_{step} {}
iterator_deref<Container> operator*() {
return *sub_iter_;
}
iterator_arrow<Container> operator->() {
return apply_arrow(sub_iter_);
}
Iterator& operator++() {
dumb_advance(sub_iter_, sub_end_, step_);
current_ += step_;
if (stop_ < current_) {
current_ = stop_;
}
return *this;
}
Iterator operator++(int) {
auto ret = *this;
++*this;
return ret;
}
bool operator!=(const Iterator& other) const {
return sub_iter_ != other.sub_iter_ && current_ != other.current_;
}
bool operator==(const Iterator& other) const {
return !(*this != other);
}
};
Iterator begin() {
auto it = get_begin(container_);
dumb_advance(it, get_end(container_), start_);
return {std::move(it), get_end(container_), start_, stop_, step_};
}
Iterator end() {
return {get_end(container_), get_end(container_), stop_, stop_, step_};
}
};
struct iter::impl::SliceFn {
private:
template <typename DifferenceType>
class FnPartial : public Pipeable<FnPartial<DifferenceType>> {
public:
template <typename Container>
Sliced<Container, DifferenceType> operator()(Container&& container) const {
return {std::forward<Container>(container), start_, stop_, step_};
}
private:
friend SliceFn;
constexpr FnPartial(
DifferenceType start, DifferenceType stop, DifferenceType step) noexcept
: start_{start}, stop_{stop}, step_{step} {}
DifferenceType start_;
DifferenceType stop_;
DifferenceType step_;
};
public:
template <typename Container, typename DifferenceType,
typename = std::enable_if_t<is_iterable<Container>>>
Sliced<Container, DifferenceType> operator()(Container&& container,
DifferenceType start, DifferenceType stop,
DifferenceType step = 1) const {
return {std::forward<Container>(container), start, stop, step};
}
// only given the end, assume step_ is 1 and begin is 0
template <typename Container, typename DifferenceType,
typename = std::enable_if_t<is_iterable<Container>>>
iter::impl::Sliced<Container, DifferenceType> operator()(
Container&& container, DifferenceType stop) const {
return {std::forward<Container>(container), 0, stop, 1};
}
template <typename DifferenceType,
typename = std::enable_if_t<!is_iterable<DifferenceType>>>
constexpr FnPartial<DifferenceType> operator()(DifferenceType stop) const
noexcept {
return {0, stop, 1};
}
template <typename DifferenceType,
typename = std::enable_if_t<!is_iterable<DifferenceType>>>
constexpr FnPartial<DifferenceType> operator()(DifferenceType start,
DifferenceType stop, DifferenceType step = 1) const noexcept {
return {start, stop, step};
}
};
namespace iter {
constexpr impl::SliceFn slice{};
}
#endif