edgeiterator.java

Java数据结构开发包

/*
  Copyright (c) 1999, 2000 Brown University, Providence, RI
  
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  without specific, written prior permission.
  
  BROWN UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
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*/

package jdsl.graph.api;

import java.util.NoSuchElementException;

/**
 * Iterator over a set of edges.  No order of the edges is required  
 * by this interface, although order may be promised or required
 * by users of the interface.  Conceptually, the iterator starts out
 * positioned before the first edge to be considered.  With each call
 * to next(), the iterator skips over another edge and returns the edge
 * skipped over, until the iterator is positioned past the last edge.
 * 
 * Note that <code>NoSuchElementException</code> indicates two
 * different failure states:  when the iterator is positioned before
 * the first edge, edge() and element() fail; when the iterator is
 * positioned after the last edge, next() fails.
 *   
 * @version JDSL 2.1.1 
 * @author Mark Handy
 */
public interface EdgeIterator extends jdsl.core.api.PositionIterator {

    /** 
     * @return Next edge to consider
     * @exception NoSuchElementException if iterator has moved past
     * the last edge to be seen
     */
    public Edge nextEdge() throws NoSuchElementException;
    
    /** 
     * @return The edge returned by the most recent next()
     * @exception NoSuchElementException When the iterator is in its
     * initial, before-the-first-edge state
     */
    public Edge edge() throws NoSuchElementException;
    
}