// FILE. . . . . d:/hak/hlt/src/hlt/math/matrix/sources/ColumnIterator.java
// EDIT BY . . . Hassan Ait-Kaci
// ON MACHINE. . Hak-Laptop
// STARTED ON. . Thu Nov 28 13:42:19 2019
/**
* @version Last modified on Thu Nov 28 23:48:39 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 columns of the matrix of a
* BipartiteGraph for a given row.
*
* @see RowIterator
*/
public class ColumnIterator implements IntIterator
{
/**
* The BipartiteGraph concerned by this
* ColumnIterator.
*/
private BipartiteGraph graph;
/**
* The row index concerned by this ColumnIterator.
*/
private int row;
/**
* The number of columns per row in the matrix of graph.
*/
private int cols;
/**
* The index of the last non-zero column for row in
* graph, or -1 if there is none.
*/
private int last;
/**
* Current column in this ColumnIterator.
*/
private int col;
/**
* Construct a ColumnIterator for row in the given
* graph.
*/
public ColumnIterator (BipartiteGraph graph, int row)
{
this.graph = graph;
this.row = row;
cols = graph.data().length;
last = graph.lastNonZeroColInRow(row); // -1 if only 0.0s in this row
col = 0;
}
/**
* Return true iff this ColumnIterator has more
* indices remaining.
*/
public final boolean hasNext ()
{
if (col > last)
return false;
while (col <= last && !graph.isEdge(row,col))
col++;
return col <= last; // NB: if all 0.0s in row, this returns false (since last = -1)
}
/**
* Return the last non-zero column index in row, or
* -1 if none exists.
*/
public final int last ()
{
return last;
}
/**
* Return the next column index in this ColumnIterator, or
* -1 if there is none remaining.
*/
public final int next ()
{
return col == cols ? -1 : col++;
}
}