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Copy pathdropwhile.hpp
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130 lines (106 loc) · 3.36 KB
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#ifndef ITER_DROPWHILE_H_
#define ITER_DROPWHILE_H_
#include "internal/iterbase.hpp"
#include <utility>
#include <iterator>
#include <initializer_list>
namespace iter {
namespace impl {
template <typename FilterFunc, typename Container>
class Dropper;
}
template <typename FilterFunc, typename Container>
impl::Dropper<FilterFunc, Container> dropwhile(FilterFunc, Container&&);
template <typename FilterFunc, typename T>
impl::Dropper<FilterFunc, std::initializer_list<T>> dropwhile(
FilterFunc, std::initializer_list<T>);
}
template <typename FilterFunc, typename Container>
class iter::impl::Dropper {
private:
Container container;
FilterFunc filter_func;
friend Dropper iter::dropwhile<FilterFunc, Container>(
FilterFunc, Container&&);
template <typename FF, typename T>
friend Dropper<FF, std::initializer_list<T>> iter::dropwhile(
FF, std::initializer_list<T>);
Dropper(FilterFunc in_filter_func, Container&& in_container)
: container(std::forward<Container>(in_container)),
filter_func(in_filter_func) {}
public:
Dropper(Dropper&&) = default;
class Iterator : public std::iterator<std::input_iterator_tag,
iterator_traits_deref<Container>> {
private:
using Holder = DerefHolder<iterator_deref<Container>>;
iterator_type<Container> sub_iter;
iterator_type<Container> sub_end;
Holder item;
FilterFunc* filter_func;
void inc_sub_iter() {
++this->sub_iter;
if (this->sub_iter != this->sub_end) {
this->item.reset(*this->sub_iter);
}
}
// skip all values for which the predicate is true
void skip_passes() {
while (this->sub_iter != this->sub_end
&& (*this->filter_func)(this->item.get())) {
this->inc_sub_iter();
}
}
public:
Iterator(iterator_type<Container>&& iter, iterator_type<Container>&& end,
FilterFunc& in_filter_func)
: sub_iter{std::move(iter)},
sub_end{std::move(end)},
filter_func(&in_filter_func) {
if (this->sub_iter != this->sub_end) {
this->item.reset(*this->sub_iter);
}
this->skip_passes();
}
typename Holder::reference operator*() {
return this->item.get();
}
typename Holder::pointer operator->() {
return this->item.get_ptr();
}
Iterator& operator++() {
this->inc_sub_iter();
return *this;
}
Iterator operator++(int) {
auto ret = *this;
++*this;
return ret;
}
bool operator!=(const Iterator& other) const {
return this->sub_iter != other.sub_iter;
}
bool operator==(const Iterator& other) const {
return !(*this != other);
}
};
Iterator begin() {
return {std::begin(this->container), std::end(this->container),
this->filter_func};
}
Iterator end() {
return {std::end(this->container), std::end(this->container),
this->filter_func};
}
};
template <typename FilterFunc, typename Container>
iter::impl::Dropper<FilterFunc, Container> iter::dropwhile(
FilterFunc filter_func, Container&& container) {
return {filter_func, std::forward<Container>(container)};
}
template <typename FilterFunc, typename T>
iter::impl::Dropper<FilterFunc, std::initializer_list<T>> iter::dropwhile(
FilterFunc filter_func, std::initializer_list<T> il) {
return {filter_func, std::move(il)};
}
#endif