DebugEventHandlers.h

/*
 * Copyright (C) 2018 Ivan Sorokin <vanyacpp@gmail.com>
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#ifndef DEBUG_EVENT_HANDLERS_H_20180312_
#define DEBUG_EVENT_HANDLERS_H_20180312_

#include "Types.h"
#include <list>
#include <memory>

class IDebugEventHandler;
class IDebugEvent;

/*
This class is a container of IDebugEventHandler*. It supports three
operations:
1. add -- Adding IDebugEventHandler*
2. remove -- Removing IDebugEventHandler*
3. execute -- Iterating over added handlers and calling them

The reason why a simple standard container is not enough is that
handlers can be added/removed while the list is being iterated on.
Naive implement would cause accessing an invalid iterator in this
case.

This class supports adding new handlers during iteration. Removing
during iteration is also supported, but is restricted: only the
handler that is currently being executed can be removed.

In order to support removing handlers during iteration the iterator
is incremented before calling corresponding handler.

Recursive calls to execute are forbidden.

Contract violations of this class are unrecoverable and cause
program termination (std::abort is called).
*/
class DebugEventHandlers {
public:
	DebugEventHandlers()                                      = default;
	DebugEventHandlers(const DebugEventHandlers &)            = delete;
	DebugEventHandlers &operator=(const DebugEventHandlers &) = delete;
	~DebugEventHandlers();

	void add(IDebugEventHandler *handler);
	void remove(IDebugEventHandler *handler);
	edb::EventStatus execute(const std::shared_ptr<IDebugEvent> &event);

private:
	/*
	list of registered handlers
	*/
	std::list<IDebugEventHandler *> handlers_;

	/*
	the current handler that is being executed
	nullptr means that none is being executed at the moment
	*/
	IDebugEventHandler *currentHandler_ = nullptr;
};

#endif