#ifndef ITER_UNIQUE_JUSTSEEN_HPP

#define ITER_UNIQUE_JUSTSEEN_HPP

#include "groupby.hpp"

#include "imap.hpp"

#include <iterator>

#include <utility>

namespace iter {

namespace impl {

struct UniqueJustseenFn

: PipeableAndBindOptionalSecond<UniqueJustseenFn, Identity> {

public:

using PipeableAndBindOptionalSecond<UniqueJustseenFn, Identity>::

operator();

template <typename Container, typename KeyFunc>

auto operator()(Container&& container, KeyFunc key_fn) const {

// decltype(auto) return type in lambda so reference types are preserved

return imap(

[](auto&& group) -> decltype(auto) {

return *get_begin(group.second);

},

groupby(std::forward<Container>(container), std::move(key_fn)));

}

};

}

inline constexpr impl::UniqueJustseenFn unique_justseen{};

}

#endif