generic_event.cpp

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/*
    Copyright (C) 2006 - 2024
    by Joerg Hinrichs <joerg.hinrichs@alice-dsl.de>
    Part of the Battle for Wesnoth Project https://www.wesnoth.org/
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 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.
 
    See the COPYING file for more details.
*/
 
#include "generic_event.hpp"
 
#include <algorithm>
 
namespace events{
 
generic_event::generic_event(const std::string& name) :
    name_(name),
    observers_(),
    change_handler_(false),
    notify_active_(false)
{
}
 
bool generic_event::attach_handler(observer* obs){
    bool handler_attached = false;
 
    //make sure observers are not notified right now
    if (!notify_active_){
        change_handler_ = true;
        try{
            std::vector<observer*>::const_iterator it = std::find(observers_.begin(), observers_.end(), obs);
            if (it != observers_.end()){
                handler_attached = false;
            }
            else{
                observers_.push_back(obs);
                handler_attached = true;
            }
        }
        catch (...){
            change_handler_ = false;
            throw;
        }
        change_handler_ = false;
    }
 
    return handler_attached;
}
 
bool generic_event::detach_handler(observer* obs){
    bool handler_detached = false;
 
    //make sure observers are not notified right now
    if (!notify_active_){
        auto it = std::find(observers_.begin(), observers_.end(), obs);
        if (it == observers_.end()){
            handler_detached = false;
        }
        else{
            observers_.erase(it);
            handler_detached = true;
        }
        change_handler_ = false;
    }
 
    return handler_detached;
}
 
void generic_event::notify_observers(){
    if (!change_handler_){
        notify_active_ = true;
        try{
            for (std::vector<observer*>::const_iterator it = observers_.begin();
                it != observers_.end(); ++it){
                (*it)->handle_generic_event(name_);
            }
        }
        catch (...){
            //reset the flag if event handlers throw exceptions and don't catch them
            notify_active_ = false;
            throw;
        }
        notify_active_ = false;
    }
}
 
} //namespace events