/* linbox/element/envelope.h
 * Copyright (C) 1999-2001 William J Turner,
 *               2001 Bradford Hovinen
 *
 * Written by William J Turner <wjturner@math.ncsu.edu>,
 *            Bradford Hovinen <hovinen@cis.udel.edu>
 *
 * ========LICENCE========
 * This file is part of the library LinBox.
 *
  * LinBox is free software: you can redistribute it and/or modify
 * it under the terms of the  GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * ========LICENCE========
 */

#ifndef __LINBOX_element_envelope_H
#define __LINBOX_element_envelope_H

#include <iostream>

#include "linbox/element/abstract.h"

namespace LinBox
{
	// Forward declarations
	template <class Field> class RingEnvelope;
	template <class Field> class FieldEnvelope;
	template <class Field> class RandIterEnvelope;

	/** \brief Adaptor from archetypical interface to abstract interface, a technicality.

	 * A class meeting the interface specified in ElementArchetype is adapted
	 * to be a child class of ElementAbstract.
	 * A concrete instance of ElementArchetype representing
	 * the adapted class can then be constructed.
	 *
	 * All this is in support of the FieldArchetype system.
	 \ingroup element

*/
	template <class Field>
	class ElementEnvelope : public ElementAbstract {
	public:

		/** Default Constructor.
		*/
		ElementEnvelope () {}

		/** Constructor from the Field element to be wrapped.
		 * @param elem Field element object to be wrapped.
		 */
		ElementEnvelope (const typename Field::Element &elem) :
			_elem (elem)
		{}

		/** Copy constructor.
		 * Constructs ElementEnvelope object by copying the element
		 * it wraps.
		 * This is required to allow element objects to be passed by value
		 * into functions.
		 * In this implementation, this means copying the element \c E._elem.
		 * @param  E FieldEnvelope object.
		 */
		ElementEnvelope (const ElementAbstract &E) :
			_elem (static_cast<const ElementEnvelope&>(E)._elem)
		{}

		/** Virtual copy constructor.
		 * Required because constructors cannot be virtual.
		 * Passes construction on to derived classes.
		 * @return pointer to new element object in dynamic memory.
		 */
		ElementAbstract* clone (void) const { return new ElementEnvelope (*this); }

		/** Assignment operator.
		 * @return reference to self
		 * @param  E parameterized field base element
		 */
		ElementAbstract &operator= (const ElementAbstract &E)
		{
			if (this != &E) // guard against self-assignment
				_elem = static_cast<const ElementEnvelope&>(E)._elem;
			return *this;
		}

		/** Destructor.
		*/
		~ElementEnvelope () {}

	private:

		// Friend declarations
		friend class RingEnvelope<Field>;
		friend class FieldEnvelope<Field>;
		friend class RandIterEnvelope<Field>;

		typename Field::Element _elem;

	}; // class ElementEnvelope

} // namespace LinBox

#endif // __LINBOX_element_envelope_H


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