text: /*
   * Copyright (c) 2011 Juli Mallett. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #ifndef	COMMON_REGISTRAR_H
  #define	COMMON_REGISTRAR_H
  
  #include <set>
  
  /*
   * U is merely a type used as a unique key, so that multiple Registrars of
   * objects with the same type can coexist.
   */
  template<typename U, typename T>
  class Registrar {
  	std::set<T> registered_set_;
  
  	Registrar(void)
  	: registered_set_()
  	{ }
  
  	~Registrar()
  	{ }
  public:
  	void enter(T item)
  	{
  		registered_set_.insert(item);
  	}
  
  	std::set<T> enumerate(void) const
  	{
  		return (registered_set_);
  	}
  
  	static Registrar *instance(void)
  	{
  		static Registrar *instance;
  
  		if (instance == NULL)
  			instance = new Registrar();
  		return (instance);
  	}
  };
  
  #endif /* !COMMON_REGISTRAR_H */
  