select.hpp

/*
 * This file is part of libtcspc
 * Copyright 2019-2026 Board of Regents of the University of Wisconsin System
 * SPDX-License-Identifier: MIT
 */
 
#pragma once
 
#include "common.hpp"
#include "introspect.hpp"
#include "processor.hpp"
#include "type_list.hpp"
 
#include <type_traits>
#include <utility>
 
namespace tcspc {
 
namespace internal {
 
template <typename EventList, bool Inverted, typename Downstream>
    requires processor<Downstream>
class select {
    Downstream downstream;
 
  public:
    explicit select(Downstream downstream)
        : downstream(std::move(downstream)) {}
 
    [[nodiscard]] auto introspect_node() const -> processor_info {
        return processor_info(this, "select");
    }
 
    [[nodiscard]] auto introspect_graph() const -> processor_graph {
        return downstream.introspect_graph().push_entry_point(this);
    }
 
    template <typename AnyEvent>
        requires(
            (convertible_to_type_list_member<std::remove_cvref_t<AnyEvent>,
                                             EventList> != Inverted) and
            handler_for<Downstream, std::remove_cvref_t<AnyEvent>>)
    void handle(AnyEvent &&event) {
        downstream.handle(std::forward<AnyEvent>(event));
    }
 
    template <typename AnyEvent>
        requires(convertible_to_type_list_member<std::remove_cvref_t<AnyEvent>,
                                                 EventList> == Inverted)
    void handle(AnyEvent && /* event */) {}
 
    void flush() { downstream.flush(); }
};
 
} // namespace internal

template <typename EventList, typename Downstream>
auto select(Downstream downstream) {
    return internal::select<EventList, false, Downstream>(
        std::move(downstream));
}

template <typename Downstream> auto select_none(Downstream downstream) {
    return internal::select<type_list<>, false, Downstream>(
        std::move(downstream));
}

template <typename EventList, typename Downstream>
auto select_except(Downstream downstream) {
    return internal::select<EventList, true, Downstream>(
        std::move(downstream));
}

template <typename Downstream> auto select_all(Downstream downstream) {
    return internal::select<type_list<>, true, Downstream>(
        std::move(downstream));
}
 
} // namespace tcspc