/*
  This file is part of Ingen.
  Copyright 2007-2017 David Robillard <http://drobilla.net/>

  Ingen is free software: you can redistribute it and/or modify it under the
  terms of the GNU Affero General Public License as published by the Free
  Software Foundation, either version 3 of the License, or any later version.

  Ingen 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 Affero General Public License for details.

  You should have received a copy of the GNU Affero General Public License
  along with Ingen.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef INGEN_ENGINE_WORK_HPP
#define INGEN_ENGINE_WORK_HPP

#include <vector>

namespace Ingen {
namespace Server {

template<typename Unit>
class Work {
public:
	enum class Mode {
		UNIT,        ///< Single unit to run
		SEQUENTIAL,  ///< Elements must be run sequentially in order
		PARALLEL     ///< Elements may be run in any order in parallel
	};

	static Work unit(Unit& unit) { return Work(Mode::UNIT, &unit); }
	static Work sequential()     { return Work(Mode::SEQUENTIAL); }
	static Work parallel()       { return Work(Mode::PARALLEL); }

	void prepend(Work&& work) { _children.emplace_back(std::move(work)); }

	Unit*                    unit()     const { return _unit; }
	Mode                     mode()     const { return _mode; }
	const std::vector<Work>& children() const { return _children; }

private:
	Work(Mode mode, Unit* unit = nullptr) : _unit(unit), _mode(mode) {}

	std::vector<Work> _children; ///< Children in reverse execution order
	Unit* const       _unit;     ///< Used for UNIT mode only
	const Mode        _mode;     ///< Execution mode
};

} // namespace Server
} // namespace Ingen

#endif // INGEN_ENGINE_WORK_HPP