/* Copyright (C) 2012-2015 John W. Eaton This file is part of Octave. Octave 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 3 of the License, or (at your option) any later version. Octave 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 General Public License along with Octave; see the file COPYING. If not, see <http://www.gnu.org/licenses/>. */ #if !defined (octave_event_queue_h) #define octave_event_queue_h 1 #include <queue> #include <memory> #include "action-container.h" class event_queue : public action_container { public: event_queue (void) : fifo () { } // Destructor should not raise an exception, so all actions // registered should be exception-safe (but setting error_state is // allowed). If you're not sure, see event_queue_safe. ~event_queue (void) { run (); } void add (elem *new_elem) { fifo.push (new_elem); } void run_first (void) { if (! empty ()) { // No leak on exception! std::auto_ptr<elem> ptr (fifo.front ()); fifo.pop (); ptr->run (); } } void discard_first (void) { if (! empty ()) { elem *ptr = fifo.front (); fifo.pop (); delete ptr; } } size_t size (void) const { return fifo.size (); } protected: std::queue<elem *> fifo; private: // No copying! event_queue (const event_queue&); event_queue& operator = (const event_queue&); }; // Like event_queue, but this one will guard against the // possibility of seeing an exception (or interrupt) in the cleanup // actions. Not that we can do much about it, but at least we won't // crash. class event_queue_safe : public event_queue { private: static void gripe_exception (void); public: event_queue_safe (void) : event_queue () { } ~event_queue_safe (void) { while (! empty ()) { try { run_first (); } catch (...) // Yes, the black hole. Remember we're in a dtor. { gripe_exception (); } } } private: // No copying! event_queue_safe (const event_queue_safe&); event_queue_safe& operator = (const event_queue_safe&); }; #endif