#ifndef _IMBASE_H_
#define _IMBASE_H_

#include "list.h"

/**
 * Provides the basic menmory managment for objects.
 */
class IMBase
{
private:

	static util::list<IMBase*> activeList;		///< The list of active objects (with ref_count > 0)
	static util::list<IMBase*> deadList;		///< The list of dead objects (with ref_count == 0)

	long ref_count;			///< Reference variable

public:

	/**
	 * Default constructor
	 * Sets ref variable to 1
	 */
	IMBase()
		:	ref_count(1)
	{
		activeList.push_back(this);	// add this object to the live list
	}

	/**
	 * Called by when a function or an object is using this object.
	 */
	void get()
	{
		ref_count++;	// add another thing using this object
	}

	/**
	 * Called by a function or an object when it is finished using this object.
	 */
	void drop()
	{
		ref_count--;	// an object is done using this object

		if( ref_count <= 0 )
			IMBase::makeDead(this);
	}

	/**
	 * Search for the passed pointer in the activeList and if found, delete
	 * it from the list, and insert it into the deadList.
	 * \param p A pointer of type IMBase*, which is the pointer to delete from activeList
	 * and insert into the deadList.
	 */
	static void makeDead(IMBase* p)
	{
		util::list<IMBase*>::iterator i = activeList.begin();
		for( ; i != activeList.end(); i++ )
			if( (*i) == p ){
				activeList.erase(i);// delete element i from the active list
				deadList.push_back(p);
			}
	}

	/**
	 * Deletes all the items in the deadList from memory.
	 */
	static void collectGarbage()
	{
		util::list<IMBase*>::iterator i = deadList.begin();
		for( ; i != deadList.end(); i++ )
			delete (*i);

	}

	/**
	 * Delete all the items in the deadList and activeList.
	 */
	static void collectAllGarbage()
	{
		collectGarbage();	// delete all in deadList

		// delete all items in the activeList
		util::list<IMBase*>::iterator i = activeList.begin();
		for( ; i != activeList.end(); i++ )
			delete *i;

	}

};

#endif