tfEvent.h

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/*******************************************************************************
 * This file is part of Tissue Forge.
 * Copyright (c) 2022-2024 T.J. Sego
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 ******************************************************************************/

 
#ifndef _SOURCE_EVENT_TFEVENT_H_
#define _SOURCE_EVENT_TFEVENT_H_
 
#include <TissueForge_private.h>
 
#include <forward_list>
#include <iostream>
 
 
namespace TissueForge::event { 
 
 
    template<typename event_t> using EventMethodT = HRESULT (*)(const event_t&);
 
    // Flags for providing feedback during predicate and invoke evaluations
    enum class EventFlag : unsigned int {
        REMOVE
    };
 
    // Base class of all events
    struct CAPI_EXPORT EventBase {
 
        // Flags set by invoke and predicate to provide feedback
        std::forward_list<EventFlag> flags;

        FloatP_t last_fired;

        int times_fired;

        virtual HRESULT predicate() = 0;

        virtual HRESULT invoke() = 0;
 
        EventBase() : 
            last_fired(0.0), 
            times_fired(0)
        {}
        virtual ~EventBase() {}
 
        // Tests the predicate and evaluates invoke accordingly
        // Returns 1 if the event was invoked, 0 if not, and a negative value on error
        virtual HRESULT eval(const FloatP_t &time) {
            // check predicate
            if(!predicate()) return 0;
 
            // invoke
            if(invoke() == 1) return -1;
 
            // Update internal data
            times_fired += 1;
            last_fired = time;
 
            return 1;
        }

        void remove() { flags.push_front(EventFlag::REMOVE); }
 
    };
 
    struct Event;
 
    using EventMethod = EventMethodT<Event>;
 
    // Simple event
    struct CAPI_EXPORT Event : EventBase {
        
        Event();

        Event(EventMethod *invokeMethod, EventMethod *predicateMethod);
        virtual ~Event();
 
        HRESULT predicate();
        HRESULT invoke();
        HRESULT eval(const FloatP_t &time);
 
    private:
 
        EventMethod *invokeMethod;
        EventMethod *predicateMethod;
 
    };

    CPPAPI_FUNC(Event*) onEvent(EventMethod *invokeMethod, EventMethod *predicateMethod);
 
};
 
#endif // _SOURCE_EVENT_TFEVENT_H_