MemValue.java

/*
 * Copyright Aduna (http://www.aduna-software.com/) (c) 1997-2006.
 *
 * Licensed under the Aduna BSD-style license.
 */
package org.openrdf.sail.memory.model;

import org.openrdf.model.Value;

/**
 * A MemoryStore-specific extension of the Value interface, giving it node
 * properties.
 */
public interface MemValue extends Value {

	/*-----------*
	 * Constants *
	 *-----------*/

	/**
	 * A shared empty MemStatementList that is returned by MemURI and MemBNode to
	 * represent an empty list. The use of a shared list reduces memory usage.
	 */
	static final MemStatementList EMPTY_LIST = new MemStatementList(0);

	/*---------*
	 * Methods *
	 *---------*/

	/**
	 * Returns the object that created this MemValue. MemValues are only unique
	 * within a single repository, but an application could use several
	 * repositories at the same time, passing MemValues generated by one Sail to
	 * another Sail. In such situations, the MemValue of the first Sail cannot be
	 * used by the second Sail.
	 */
	public Object getCreator();

	/**
	 * Gets the list of statements for which this MemValue is the object.
	 * 
	 * @return A MemStatementList containing the statements.
	 */
	public MemStatementList getObjectStatementList();

	/**
	 * Gets the number of statements for which this MemValue is the object.
	 * 
	 * @return An integer larger than or equal to 0.
	 */
	public int getObjectStatementCount();

	/**
	 * Adds a statement to this MemValue's list of statements for which it is the
	 * object.
	 */
	public void addObjectStatement(MemStatement st);

	/**
	 * Removes a statement from this MemValue's list of statements for which it
	 * is the object.
	 */
	public void removeObjectStatement(MemStatement st);
}