69 lines
1.5 KiB
C++
69 lines
1.5 KiB
C++
|
// Copyright (C) 2022 Andrei Avram
|
||
|
|
|
||
|
|
#ifndef MSD_CHANNEL_BLOCKING_ITERATOR_HPP_
|
||
|
|
#define MSD_CHANNEL_BLOCKING_ITERATOR_HPP_
|
||
|
|
|
||
|
|
#include <iterator>
|
||
|
|
#include <mutex>
|
||
|
|
|
||
|
|
namespace msd {
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief An iterator that block the current thread,
|
||
|
|
* waiting to fetch elements from the channel.
|
||
|
|
*
|
||
|
|
* Used to implement channel range-based for loop.
|
||
|
|
*
|
||
|
|
* @tparam Channel Instance of channel.
|
||
|
|
*/
|
||
|
|
template <typename channel>
|
||
|
|
class blocking_iterator {
|
||
|
|
public:
|
||
|
|
using value_type = typename channel::value_type;
|
||
|
|
|
||
|
|
explicit blocking_iterator(channel& ch) : ch_{ch} {}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Advances to next element in the channel.
|
||
|
|
*/
|
||
|
|
blocking_iterator<channel> operator++() const noexcept { return *this; }
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns an element from the channel.
|
||
|
|
*/
|
||
|
|
value_type operator*() const
|
||
|
|
{
|
||
|
|
value_type value;
|
||
|
|
value << ch_;
|
||
|
|
|
||
|
|
return value;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Makes iteration continue until the channel is closed and empty.
|
||
|
|
*/
|
||
|
|
bool operator!=(blocking_iterator<channel>) const
|
||
|
|
{
|
||
|
|
std::unique_lock<std::mutex> lock{ch_.mtx_};
|
||
|
|
ch_.waitBeforeRead(lock);
|
||
|
|
|
||
|
|
return !(ch_.closed() && ch_.empty());
|
||
|
|
}
|
||
|
|
|
||
|
|
private:
|
||
|
|
channel& ch_;
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace msd
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief Output iterator specialization
|
||
|
|
*/
|
||
|
|
template <typename T>
|
||
|
|
struct std::iterator_traits<msd::blocking_iterator<T>> {
|
||
|
|
using value_type = typename msd::blocking_iterator<T>::value_type;
|
||
|
|
using iterator_category = std::output_iterator_tag;
|
||
|
|
};
|
||
|
|
|
||
|
|
#endif // MSD_CHANNEL_BLOCKING_ITERATOR_HPP_
|