From 55dd66d8dd773ed98580d1fac0e15da6244d35b8 Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Tue, 19 Dec 2023 14:04:04 +0100
Subject: moving async to c++ folder

---
 modules/async/async.h | 1023 -------------------------------------------------
 1 file changed, 1023 deletions(-)
 delete mode 100644 modules/async/async.h

(limited to 'modules/async/async.h')

diff --git a/modules/async/async.h b/modules/async/async.h
deleted file mode 100644
index 66afa38..0000000
--- a/modules/async/async.h
+++ /dev/null
@@ -1,1023 +0,0 @@
-#pragma once
-
-#include <forstio/common.h>
-#include <forstio/error.h>
-
-#include <chrono>
-#include <functional>
-#include <limits>
-#include <list>
-#include <queue>
-#include <type_traits>
-
-namespace saw {
-class conveyor_storage;
-class conveyor_node {
-public:
-	conveyor_node();
-	virtual ~conveyor_node() = default;
-
-	/**
-	 * Internal method to retrieve results from children
-	 */
-	virtual void get_result(error_or_value &err_or_val) = 0;
-
-	/**
-	 * Swap out child with another one
-	 */
-	virtual error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&swapee_) = 0;
-
-	/**
-	 * Retrieve the next storage node
-	 */
-	virtual conveyor_storage *next_storage() = 0;
-
-	/**
-	 * Notify that a new parent was attached
-	 * Only relevant for the feeding nodes
-	 */
-	virtual void notify_parent_attached(conveyor_node &){};
-};
-
-class conveyor_node_with_child_mixin final {
-public:
-	own<conveyor_node> child = nullptr;
-
-	conveyor_node_with_child_mixin(own<conveyor_node> &&child_,
-								   conveyor_node &owner_);
-	~conveyor_node_with_child_mixin() = default;
-
-	/**
-	 * Swap out children and return the child ptr, since the caller is the child
-	 * itself. Stack needs to be cleared before the child is destroyed, so the
-	 * swapped out node is returned as well.
-	 */
-	error_or<own<conveyor_node>> swap_child(own<conveyor_node> &&swapee);
-};
-
-class conveyor_node_with_parent_mixin final {
-public:
-	conveyor_node *parent = nullptr;
-
-	error_or<own<conveyor_node>>
-	swap_child_of_parent(own<conveyor_node> &&swapee) {
-		SAW_ASSERT(parent) {
-			return make_error<err::invalid_state>(
-				"Can't swap child, because parent doesn't exist");
-		}
-
-		return parent->swap_child(std::move(swapee));
-	}
-	void change_parent(conveyor_node *p) { parent = p; }
-};
-
-class event_loop;
-class wait_scope;
-/*
- * Event class similar to capn'proto.
- * https://github.com/capnproto/capnproto
- */
-class event {
-private:
-	event_loop &loop_;
-	event **prev_ = nullptr;
-	event *next_ = nullptr;
-
-	friend class event_loop;
-
-public:
-	event();
-	event(event_loop &loop);
-	virtual ~event();
-
-	virtual void fire() = 0;
-
-	void arm_next();
-	void arm_later();
-	void arm_last();
-	void disarm();
-
-	bool is_armed() const;
-};
-
-class conveyor_storage {
-protected:
-	conveyor_storage *parent_ = nullptr;
-
-public:
-	conveyor_storage();
-	virtual ~conveyor_storage();
-
-	virtual size_t space() const = 0;
-	virtual size_t queued() const = 0;
-	virtual void child_has_fired() = 0;
-	virtual void parent_has_fired() = 0;
-
-	virtual void set_parent(conveyor_storage *parent) = 0;
-	conveyor_storage *get_parent() const;
-};
-
-class conveyor_event_storage : public conveyor_storage, public event {
-public:
-	conveyor_event_storage();
-	virtual ~conveyor_event_storage() = default;
-
-	void set_parent(conveyor_storage *parent) override;
-};
-
-class conveyor_base {
-protected:
-	own<conveyor_node> node_;
-
-public:
-	conveyor_base(own<conveyor_node> &&node_p);
-	virtual ~conveyor_base() = default;
-
-	conveyor_base(conveyor_base &&) = default;
-	conveyor_base &operator=(conveyor_base &&) = default;
-
-	void get(error_or_value &err_or_val);
-};
-
-template <typename T> class conveyor;
-
-template <typename T> conveyor<T> chained_conveyor_type(T *);
-
-// template <typename T> Conveyor<T> chainedConveyorType(Conveyor<T> *);
-
-template <typename T> T remove_error_or_type(T *);
-
-template <typename T> T remove_error_or_type(error_or<T> *);
-
-template <typename T>
-using remove_error_or = decltype(remove_error_or_type((T *)nullptr));
-
-template <typename T>
-using chained_conveyors = decltype(chained_conveyor_type((T *)nullptr));
-
-template <typename Func, typename T>
-using conveyor_result =
-	chained_conveyors<remove_error_or<return_type<Func, T>>>;
-
-struct propagate_error {
-public:
-	error operator()(const error &err) const;
-	error operator()(error &&err);
-};
-
-class conveyor_sink {
-private:
-	own<conveyor_node> node_;
-
-public:
-	conveyor_sink();
-	conveyor_sink(own<conveyor_node> &&node);
-
-	conveyor_sink(conveyor_sink &&) = default;
-	conveyor_sink &operator=(conveyor_sink &&) = default;
-};
-
-template <typename T> class merge_conveyor_node_data;
-
-template <typename T> class merge_conveyor {
-private:
-	lent<merge_conveyor_node_data<T>> data_;
-
-public:
-	merge_conveyor() = default;
-	merge_conveyor(lent<merge_conveyor_node_data<T>> d);
-	~merge_conveyor();
-
-	void attach(conveyor<T> conv);
-};
-
-/**
- * Main interface for async operations.
- */
-template <typename T> class conveyor final : public conveyor_base {
-public:
-	/**
-	 * Construct an immediately fulfilled node
-	 */
-	conveyor(fix_void<T> value);
-
-	/**
-	 * Construct an immediately failed node
-	 */
-	conveyor(error &&err);
-
-	/**
-	 * Construct a conveyor with a child node
-	 */
-	conveyor(own<conveyor_node> node_p);
-
-	conveyor(conveyor<T> &&) = default;
-	conveyor<T> &operator=(conveyor<T> &&) = default;
-
-	/**
-	 * This method converts values or errors from children
-	 */
-	template <typename Func, typename ErrorFunc = propagate_error>
-	[[nodiscard]] conveyor_result<Func, T>
-	then(Func &&func, ErrorFunc &&error_func = propagate_error());
-
-	/**
-	 * This method adds a buffer node in the conveyor chains which acts as a
-	 * scheduler interrupt point and collects elements up to the supplied limit.
-	 */
-	[[nodiscard]] conveyor<T>
-	buffer(size_t limit = std::numeric_limits<size_t>::max());
-
-	/**
-	 * This method just takes ownership of any supplied types,
-	 * which are destroyed when the chain gets destroyed.
-	 * Useful for resource lifetime control.
-	 */
-	template <typename... Args>
-	[[nodiscard]] conveyor<T> attach(Args &&...args);
-
-	/** @todo implement
-	 * This method limits the total amount of passed elements
-	 * Be careful where you place this node into the chain.
-	 * If you meant to fork it and destroy paths you shouldn't place
-	 * an interrupt point between the fork and this limiter
-	 */
-	[[nodiscard]] conveyor<T> limit(size_t val = 1);
-
-	/**
-	 *
-	 */
-	[[nodiscard]] std::pair<conveyor<T>, merge_conveyor<T>> merge();
-
-	/**
-	 * Moves the conveyor chain into a thread local storage point which drops
-	 * every element. Use sink() if you want to control the lifetime of a
-	 * conveyor chain
-	 */
-	template <typename ErrorFunc = propagate_error>
-	void detach(ErrorFunc &&err_func = propagate_error());
-	/**
-	 * Creates a local sink which drops elements, but lifetime control remains
-	 * in your hand.
-	 */
-	template <typename ErrorFunc = propagate_error>
-	[[nodiscard]] conveyor_sink
-	sink(ErrorFunc &&error_func = propagate_error());
-
-	/**
-	 * If no sink() or detach() is used you have to take elements out of the
-	 * chain yourself.
-	 */
-	error_or<fix_void<T>> take();
-
-	/** @todo implement
-	 * Specifically pump elements through this chain with the provided
-	 * wait_scope
-	 */
-	void poll(wait_scope &wait_scope);
-
-	// helper
-	static conveyor<T> to_conveyor(own<conveyor_node> node);
-
-	// helper
-	static own<conveyor_node> from_conveyor(conveyor<T> conveyor);
-};
-
-template <typename Func> conveyor_result<Func, void> exec_later(Func &&func);
-
-/*
- * Join Conveyors into a single one
- */
-template <typename... Args>
-conveyor<std::tuple<Args...>>
-join_conveyors(std::tuple<conveyor<Args>...> &conveyors);
-
-template <typename T> class conveyor_feeder {
-public:
-	virtual ~conveyor_feeder() = default;
-
-	virtual void feed(T &&data) = 0;
-	virtual void fail(error &&error) = 0;
-
-	virtual size_t space() const = 0;
-	virtual size_t queued() const = 0;
-
-	virtual error swap(conveyor<T> &&conveyor) noexcept = 0;
-};
-
-template <> class conveyor_feeder<void> {
-public:
-	virtual ~conveyor_feeder() = default;
-
-	virtual void feed(void_t &&value = void_t{}) = 0;
-	virtual void fail(error &&error) = 0;
-
-	virtual size_t space() const = 0;
-	virtual size_t queued() const = 0;
-
-	virtual error swap(conveyor<void_t> &&conveyor) noexcept = 0;
-};
-
-template <typename T> struct conveyor_and_feeder {
-	own<conveyor_feeder<T>> feeder;
-	class conveyor<T> conveyor;
-};
-
-template <typename T> conveyor_and_feeder<T> new_conveyor_and_feeder();
-
-template <typename T> conveyor_and_feeder<T> one_time_conveyor_and_feeder();
-
-enum class Signal : uint8_t { Terminate, User1 };
-
-/**
- * Class which acts as a correspondent between the running framework and outside
- * events which may be signals from the operating system or just other threads.
- * Default EventPorts are supplied by setupAsyncIo() in io.h
- */
-class event_port {
-public:
-	virtual ~event_port() = default;
-
-	virtual conveyor<void> on_signal(Signal signal) = 0;
-
-	virtual void poll() = 0;
-	virtual void wait() = 0;
-	virtual void wait(const std::chrono::steady_clock::duration &) = 0;
-	virtual void wait(const std::chrono::steady_clock::time_point &) = 0;
-
-	virtual void wake() = 0;
-};
-
-class sink_conveyor_node;
-
-class conveyor_sink_set final : public event {
-private:
-	/*
-		class Helper final : public Event {
-		private:
-			void destroySinkConveyorNode(ConveyorNode& sink);
-			void fail(Error&& error);
-
-			std::vector<Own<ConveyorNode>> sink_nodes;
-			std::queue<ConveyorNode*> delete_nodes;
-			std::function<void(Error&& error)> error_handler;
-
-		public:
-			ConveyorSinks() = default;
-			ConveyorSinks(EventLoop& event_loop);
-
-			void add(Conveyor<void> node);
-
-			void fire() override {}
-		};
-
-		gin::Own<Helper> helper;
-	*/
-	friend class sink_conveyor_node;
-
-	void destroy_sink_conveyor_node(conveyor_node &sink_node);
-	void fail(error &&err);
-
-	std::list<own<conveyor_node>> sink_nodes_;
-
-	std::queue<conveyor_node *> delete_nodes_;
-
-	std::function<void(error &&)> error_handler_;
-
-public:
-	// ConveyorSinks();
-	// ConveyorSinks(EventLoop& event_loop);
-	conveyor_sink_set() = default;
-	conveyor_sink_set(event_loop &event_loop);
-
-	void add(conveyor<void> &&node);
-
-	void fire() override;
-};
-
-/*
- * EventLoop class similar to capn'proto.
- * https://github.com/capnproto/capnproto
- */
-class event_loop {
-private:
-	friend class event;
-	event *head_ = nullptr;
-	event **tail_ = &head_;
-	event **next_insert_point_ = &head_;
-	event **later_insert_point_ = &head_;
-
-	bool is_runnable_ = false;
-
-	own<event_port> event_port_ = nullptr;
-
-	own<conveyor_sink_set> daemon_sink_ = nullptr;
-
-	// functions
-	void set_runnable(bool runnable);
-
-	friend class wait_scope;
-	void enter_scope();
-	void leave_scope();
-
-	bool turn_loop();
-	bool turn();
-
-public:
-	event_loop();
-	event_loop(own<event_port> &&port);
-	~event_loop();
-
-	event_loop(event_loop &&) = default;
-	event_loop &operator=(event_loop &&) = default;
-
-	bool wait();
-	bool wait(const std::chrono::steady_clock::duration &);
-	bool wait(const std::chrono::steady_clock::time_point &);
-	bool poll();
-
-	event_port *get_event_port();
-
-	conveyor_sink_set &daemon();
-};
-
-/*
- * WaitScope class similar to capn'proto.
- * https://github.com/capnproto/capnproto
- */
-class wait_scope {
-private:
-	event_loop &loop_;
-
-public:
-	wait_scope(event_loop &loop);
-	~wait_scope();
-
-	void wait();
-	void wait(const std::chrono::steady_clock::duration &);
-	void wait(const std::chrono::steady_clock::time_point &);
-	void poll();
-};
-
-template <typename Func> conveyor_result<Func, void> yield_next(Func &&func);
-
-template <typename Func> conveyor_result<Func, void> yield_later(Func &&func);
-
-template <typename Func> conveyor_result<Func, void> yield_last(Func &&func);
-} // namespace saw
-
-// Secret stuff
-// Aka private semi hidden classes
-namespace saw {
-
-template <typename Out, typename In> struct fix_void_caller {
-	template <typename Func> static Out apply(Func &func, In &&in) {
-		return func(std::move(in));
-	}
-};
-
-template <typename Out> struct fix_void_caller<Out, void_t> {
-	template <typename Func> static Out apply(Func &func, void_t &&in) {
-		(void)in;
-		return func();
-	}
-};
-
-template <typename In> struct fix_void_caller<void_t, In> {
-	template <typename Func> static void_t apply(Func &func, In &&in) {
-		func(std::move(in));
-		return void_t{};
-	}
-};
-
-template <> struct fix_void_caller<void_t, void_t> {
-	template <typename Func> static void_t apply(Func &func, void_t &&in) {
-		(void)in;
-		func();
-		return void_t{};
-	}
-};
-
-template <typename T> class adapt_conveyor_node;
-
-template <typename T>
-class adapt_conveyor_feeder final : public conveyor_feeder<unfix_void<T>> {
-private:
-	adapt_conveyor_node<T> *feedee_ = nullptr;
-
-public:
-	~adapt_conveyor_feeder();
-
-	void set_feedee(adapt_conveyor_node<T> *feedee);
-
-	void feed(T &&value) override;
-	void fail(error &&error) override;
-
-	size_t space() const override;
-	size_t queued() const override;
-
-	error swap(conveyor<T> &&conv) noexcept override;
-};
-
-template <typename T>
-class adapt_conveyor_node final : public conveyor_node,
-								  public conveyor_event_storage {
-private:
-	adapt_conveyor_feeder<T> *feeder_ = nullptr;
-
-	std::queue<error_or<unfix_void<T>>> storage_;
-
-	conveyor_node_with_parent_mixin parent_node_;
-
-public:
-	adapt_conveyor_node();
-	~adapt_conveyor_node();
-
-	void set_feeder(adapt_conveyor_feeder<T> *feeder);
-
-	void feed(T &&value);
-	void fail(error &&error);
-
-	// ConveyorNode
-	void get_result(error_or_value &err_or_val) override;
-
-	error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&swapee) noexcept override;
-
-	conveyor_storage *next_storage() noexcept override;
-	void notify_parent_attached(conveyor_node &) noexcept override;
-
-	// ConveyorStorage
-	size_t space() const override;
-	size_t queued() const override;
-
-	void child_has_fired() override;
-	void parent_has_fired() override;
-
-	// Event
-	void fire() override;
-};
-
-template <typename T> class one_time_conveyor_node;
-
-template <typename T>
-class one_time_conveyor_feeder final : public conveyor_feeder<unfix_void<T>> {
-private:
-	one_time_conveyor_node<T> *feedee_ = nullptr;
-
-public:
-	~one_time_conveyor_feeder();
-
-	void set_feedee(one_time_conveyor_node<T> *feedee);
-
-	void feed(T &&value) override;
-	void fail(error &&error) override;
-
-	size_t space() const override;
-	size_t queued() const override;
-};
-
-template <typename T>
-class one_time_conveyor_node final : public conveyor_node,
-									 public conveyor_storage,
-									 public event {
-private:
-	one_time_conveyor_feeder<T> *feeder_ = nullptr;
-
-	bool passed_ = false;
-	maybe<error_or<T>> storage_ = std::nullopt;
-
-public:
-	~one_time_conveyor_node();
-
-	void set_feeder(one_time_conveyor_feeder<T> *feeder);
-
-	void feed(T &&value);
-	void fail(error &&error);
-
-	// ConveyorNode
-	void get_result(error_or_value &err_or_val) override;
-
-	error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&swapee) override;
-
-	// ConveyorStorage
-	size_t space() const override;
-	size_t queued() const override;
-
-	void child_has_fired() override {}
-	void parent_has_fired() override;
-
-	// Event
-	void fire() override;
-};
-
-/**
- * This class buffers and saves incoming elements and acts as an interrupt node
- * for processing calls
- */
-class queue_buffer_conveyor_node_base : public conveyor_node,
-										public conveyor_event_storage {
-protected:
-	conveyor_node_with_child_mixin child_mixin_;
-
-public:
-	queue_buffer_conveyor_node_base(own<conveyor_node> child_)
-		: conveyor_event_storage{}, child_mixin_{std::move(child_), *this} {}
-	virtual ~queue_buffer_conveyor_node_base() = default;
-
-	/**
-	 * Use mixin
-	 */
-	error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&swapee_) noexcept override;
-
-	conveyor_storage *next_storage() noexcept override {
-		return static_cast<conveyor_storage *>(this);
-	}
-};
-
-template <typename T>
-class queue_buffer_conveyor_node final
-	: public queue_buffer_conveyor_node_base {
-private:
-	std::queue<error_or<T>> storage_;
-	size_t max_store_;
-
-public:
-	queue_buffer_conveyor_node(own<conveyor_node> dep, size_t max_size)
-		: queue_buffer_conveyor_node_base{std::move(dep)}, max_store_{
-															   max_size} {}
-	// Event
-	void fire() override;
-	// ConveyorNode
-	void get_result(error_or_value &eov) noexcept override;
-
-	// ConveyorStorage
-	size_t space() const override;
-	size_t queued() const override;
-
-	void child_has_fired() override;
-	void parent_has_fired() override;
-};
-
-class attach_conveyor_node_base : public conveyor_node {
-protected:
-	conveyor_node_with_child_mixin child_mixin_;
-
-public:
-	attach_conveyor_node_base(own<conveyor_node> &&child_)
-		: child_mixin_{std::move(child_), *this} {}
-
-	virtual ~attach_conveyor_node_base() = default;
-
-	void get_result(error_or_value &err_or_val) noexcept override;
-
-	/**
-	 * Use mixin
-	 */
-	error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&swapee_) noexcept override;
-
-	conveyor_storage *next_storage() noexcept override;
-};
-
-template <typename... Args>
-class attach_conveyor_node final : public attach_conveyor_node_base {
-public:
-	attach_conveyor_node(own<conveyor_node> &&dep, Args &&...args)
-		: attach_conveyor_node_base(std::move(dep)), attached_data_{
-														 std::move(args...)} {}
-
-private:
-	std::tuple<Args...> attached_data_;
-};
-
-class convert_conveyor_node_base : public conveyor_node {
-public:
-	convert_conveyor_node_base(own<conveyor_node> &&dep);
-	virtual ~convert_conveyor_node_base() = default;
-
-	void get_result(error_or_value &err_or_val) override;
-
-	virtual void get_impl(error_or_value &err_or_val) = 0;
-
-	error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&swapee) noexcept override;
-
-	conveyor_storage *next_storage() noexcept override;
-
-protected:
-	conveyor_node_with_child_mixin child_mixin_;
-};
-
-template <typename T, typename DepT, typename Func, typename ErrorFunc>
-class convert_conveyor_node final : public convert_conveyor_node_base {
-private:
-	Func func_;
-	ErrorFunc error_func_;
-
-	static_assert(std::is_same<DepT, remove_error_or<DepT>>::value,
-				  "Should never be of type ErrorOr");
-
-public:
-	convert_conveyor_node(own<conveyor_node> &&dep, Func &&func,
-						  ErrorFunc &&error_func)
-		: convert_conveyor_node_base(std::move(dep)), func_{std::move(func)},
-		  error_func_{std::move(error_func)} {}
-
-	void get_impl(error_or_value &err_or_val) noexcept override {
-		error_or<unfix_void<DepT>> dep_eov;
-		error_or<unfix_void<remove_error_or<T>>> &eov =
-			err_or_val.as<unfix_void<remove_error_or<T>>>();
-		if (child_mixin_.child) {
-			child_mixin_.child->get_result(dep_eov);
-			if (dep_eov.is_value()) {
-				try {
-
-					eov = fix_void_caller<T, DepT>::apply(
-						func_, std::move(dep_eov.get_value()));
-				} catch (const std::bad_alloc &) {
-					eov = make_error<err::out_of_memory>("Out of memory");
-				} catch (const std::exception &) {
-					eov = make_error<err::invalid_state>(
-						"Exception in chain occured. Return ErrorOr<T> if you "
-						"want to handle errors which are recoverable");
-				}
-			} else if (dep_eov.is_error()) {
-				eov = error_func_(std::move(dep_eov.get_error()));
-			} else {
-				eov = make_error<err::invalid_state>("No value set in dependency");
-			}
-		} else {
-			eov = make_error<err::invalid_state>("Conveyor doesn't have child");
-		}
-	}
-};
-
-class sink_conveyor_node final : public conveyor_node,
-								 public conveyor_event_storage {
-private:
-	conveyor_node_with_child_mixin child_mixin_;
-	conveyor_sink_set *conveyor_sink_;
-
-public:
-	sink_conveyor_node(own<conveyor_node> node, conveyor_sink_set &conv_sink)
-		: conveyor_event_storage{}, child_mixin_{std::move(node), *this},
-		  conveyor_sink_{&conv_sink} {}
-
-	sink_conveyor_node(own<conveyor_node> node)
-		: conveyor_event_storage{}, child_mixin_{std::move(node), *this},
-		  conveyor_sink_{nullptr} {}
-
-	// Event only queued if a critical error occured
-	void fire() override {
-		// Queued for destruction of children, because this acts as a sink and
-		// no other event should be here
-		child_mixin_.child = nullptr;
-
-		if (conveyor_sink_) {
-			conveyor_sink_->destroy_sink_conveyor_node(*this);
-			conveyor_sink_ = nullptr;
-		}
-	}
-
-	// ConveyorStorage
-	size_t space() const override { return 1; }
-	size_t queued() const override { return 0; }
-
-	// ConveyorNode
-	void get_result(error_or_value &err_or_val) noexcept override {
-		err_or_val.as<void_t>() =
-			make_error<err::invalid_state>("In a sink node no result can be returned");
-	}
-
-	error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&swapee) noexcept override {
-		return child_mixin_.swap_child(std::move(swapee));
-	}
-
-	// ConveyorStorage
-	void child_has_fired() override {
-		if (child_mixin_.child) {
-			error_or<void> dep_eov;
-			child_mixin_.child->get_result(dep_eov);
-			if (dep_eov.is_error()) {
-				if (dep_eov.get_error().is_critical()) {
-					if (!is_armed()) {
-						arm_last();
-					}
-				}
-				if (conveyor_sink_) {
-					conveyor_sink_->fail(std::move(dep_eov.get_error()));
-				}
-			}
-		}
-	}
-
-	/*
-	 * No parent needs to be fired since we always have space
-	 */
-	void parent_has_fired() override {}
-
-	conveyor_storage *next_storage() override {
-		// Should never happen though
-		assert(false);
-		return nullptr;
-		// return static_cast<ConveyorStorage*>(this);
-	}
-};
-
-class immediate_conveyor_node_base : public conveyor_node,
-									 public conveyor_event_storage {
-private:
-public:
-	immediate_conveyor_node_base();
-
-	virtual ~immediate_conveyor_node_base() = default;
-
-	error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&swapee) noexcept override {
-		(void)swapee;
-		return make_error<err::not_supported>("Node doesn't support swapping");
-	}
-
-	conveyor_storage *next_storage() noexcept override {
-		return static_cast<conveyor_storage *>(this);
-	}
-};
-
-template <typename T>
-class immediate_conveyor_node final : public immediate_conveyor_node_base {
-private:
-	error_or<fix_void<T>> value_;
-	uint8_t retrieved_;
-
-public:
-	immediate_conveyor_node(fix_void<T> &&val);
-	immediate_conveyor_node(error &&error);
-
-	// ConveyorStorage
-	size_t space() const override;
-	size_t queued() const override;
-
-	void child_has_fired() override;
-	void parent_has_fired() override;
-
-	// ConveyorNode
-	void get_result(error_or_value &err_or_val) noexcept override {
-		if (retrieved_ > 0) {
-			err_or_val.as<fix_void<T>>() =
-				make_error<err::buffer_exhausted>("Already taken value");
-		} else {
-			err_or_val.as<fix_void<T>>() = std::move(value_);
-		}
-		if (queued() > 0) {
-			++retrieved_;
-		}
-	}
-
-	// Event
-	void fire() override;
-};
-
-/*
- * Collects every incoming value and throws it in one lane
- */
-class merge_conveyor_node_base : public conveyor_node,
-								 public conveyor_event_storage {
-public:
-	merge_conveyor_node_base();
-
-	virtual ~merge_conveyor_node_base() = default;
-
-	conveyor_storage *next_storage() noexcept override {
-		return static_cast<conveyor_storage *>(this);
-	}
-};
-
-template <typename T>
-class merge_conveyor_node : public merge_conveyor_node_base {
-private:
-	class appendage final : public conveyor_node, public conveyor_storage {
-	public:
-		own<conveyor_node> child;
-		merge_conveyor_node *merger;
-
-		maybe<error_or<fix_void<T>>> error_or_value_;
-
-	public:
-		appendage(own<conveyor_node> n, merge_conveyor_node &m)
-			: conveyor_storage{}, child{std::move(n)}, merger{&m},
-			  error_or_value_{std::nullopt} {}
-
-		bool child_storage_has_element_queued() const {
-			if (!child) {
-				return false;
-			}
-			conveyor_storage *storage = child->next_storage();
-			if (storage) {
-				return storage->queued() > 0;
-			}
-			return false;
-		}
-
-		void get_appendage_result(error_or_value &eov);
-
-		/**
-		 * ConveyorNode
-		 */
-		error_or<own<conveyor_node>>
-		swap_child(own<conveyor_node> &&swapee_) override;
-
-		conveyor_storage *next_storage() noexcept override {
-			return static_cast<conveyor_storage *>(this);
-		}
-
-		void get_result(error_or_value &err_or_val) override;
-
-		/**
-		 * ConveyorStorage
-		 */
-		size_t space() const override;
-
-		size_t queued() const override;
-
-		void child_has_fired() override;
-
-		void parent_has_fired() override;
-
-		void set_parent(conveyor_storage *par) override;
-	};
-
-	friend class merge_conveyor_node_data<T>;
-	friend class appendage;
-
-	our<merge_conveyor_node_data<T>> data_;
-	size_t next_appendage_ = 0;
-
-public:
-	merge_conveyor_node(our<merge_conveyor_node_data<T>> data);
-	~merge_conveyor_node();
-	// ConveyorNode
-	error_or<own<conveyor_node>>
-	swap_child(own<conveyor_node> &&c) noexcept override;
-
-	// Event
-	void get_result(error_or_value &err_or_val) noexcept override;
-
-	void fire() override;
-
-	// ConveyorStorage
-	size_t space() const override;
-	size_t queued() const override;
-	void child_has_fired() override;
-	void parent_has_fired() override;
-};
-
-template <typename T> class merge_conveyor_node_data {
-public:
-	std::vector<own<typename merge_conveyor_node<T>::appendage>> appendages;
-
-	merge_conveyor_node<T> *merger = nullptr;
-
-public:
-	void attach(conveyor<T> conv);
-
-	void governing_node_destroyed();
-};
-
-/*
-class JoinConveyorNodeBase : public ConveyorNode, public ConveyorEventStorage {
-private:
-
-public:
-};
-
-template <typename... Args>
-class JoinConveyorNode final : public JoinConveyorNodeBase {
-private:
-	template<typename T>
-	class Appendage : public ConveyorEventStorage {
-	private:
-		Maybe<T> data = std::nullopt;
-
-	public:
-		size_t space() const override;
-		size_t queued() const override;
-
-		void fire() override;
-		void get_result(ErrorOrValue& eov) override;
-	};
-
-	std::tuple<Appendage<Args>...> appendages;
-
-public:
-};
-
-*/
-
-} // namespace saw
-
-#include "async.tmpl.h"
-- 
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