// FILE. . . . . d:/hak/hlt/src/hlt/math/matrix/sources/SuccsIterator.java
// EDIT BY . . . Hassan Ait-Kaci
// ON MACHINE. . Hak-Laptop
// STARTED ON. . Fri Nov 29 00:07:28 2019
/**
* @version Last modified on Fri Nov 29 11:22:22 2019 by hak
* @author Hassan Aït-Kaci
* @copyright © by the author
*/
package hlt.math.matrix;
import hlt.language.util.IntIterator;
/**
* This is a class implementing the hlt.language.util.IntIterator
* interface for iterating through the right nodes that are the
* successors of a given left node in a BipartiteGraph.
*
* @see BipartiteGraph
* @see PredsIterator
*/
public class SuccsIterator implements IntIterator
{
/**
* The BipartiteGraph concerned by this
* SuccsIterator.
*/
private BipartiteGraph graph;
/**
* The left node index concerned by this SuccsIterator.
*/
private int left;
/**
* The number of right nodes
*/
private int rights;
/**
* The index of the first right node successor of left in
* graph, or -1 if there is none.
*/
private int first;
/**
* The index of the last right node successor of left in
* graph, or -1 if there is none.
*/
private int last;
/**
* Current right node index in this SuccsIterator.
*/
private int index;
/**
* Construct a SuccsIterator for left in the given
* graph.
*/
public SuccsIterator (BipartiteGraph graph, int left)
{
this.graph = graph;
this.left = left;
rights = graph.order();
first = graph.firstSuccessor(left); // -1 if no successors
last = graph.lastSuccessor(left); // -1 if no successors
index = first;
}
/**
* Return true iff this SuccsIterator has more
* indices remaining.
*/
public final boolean hasNext ()
{
if (index > last)
return false;
while (index <= last && !graph.isEdge(left,index))
index++;
return index <= last; // NB: if left has no successors, this returns false (since last = -1)
}
/**
* Return the index of the first successor of left, or
* -1 if none exists.
*/
public final int first ()
{
return first;
}
/**
* Return the index of the last successor of left, or
* -1 if none exists.
*/
public final int last ()
{
return last;
}
/**
* Return the next successor node index in this
* SuccsIterator, or -1 if there is none
* remaining.
*/
public final int next ()
{
return index == rights ? -1 : index++;
}
}