// FILE. . . . . d:/hak/hlt/src/hlt/math/matrix/sources/RowIterator.java
// EDIT BY . . . Hassan Ait-Kaci
// ON MACHINE. . Hak-Laptop
// STARTED ON. . Thu Nov 28 14:52:31 2019
/**
* @version Last modified on Thu Nov 28 23:48:54 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 rows of the matrix of a
* BipartiteGraph for a given column.
*
* @see ColumnIterator
*/
public class RowIterator implements IntIterator
{
/**
* The BipartiteGraph concerned by this
* RowIterator.
*/
private BipartiteGraph graph;
/**
* The column index concerned by this RowIterator.
*/
private int col;
/**
* The number of rows per column in the matrix of graph.
*/
private int rows;
/**
* The index of the last non-zero row for column in
* graph, or -1 if there is none.
*/
private int last;
/**
* Current row in this RowIterator.
*/
private int row;
/**
* Construct a RowIterator for col in the given
* graph.
*/
public RowIterator (BipartiteGraph graph, int col)
{
this.graph = graph;
this.col = col;
rows = graph.data().length;
last = graph.lastNonZeroRowInColumn(col); // -1 if only 0.0s in this column
row = 0;
}
/**
* Return true iff this RowIterator has more
* indices remaining.
*/
public final boolean hasNext ()
{
if (row > last)
return false;
while (row <= last && !graph.isEdge(row,col))
row++;
return row <= last; // NB: if all 0.0s in column, this returns false (since last = -1)
}
/**
* Return the last non-zero row index in col, or -1
* if none exists.
*/
public final int last ()
{
return last;
}
/**
* Return the next row index in this RowIterator, or
* -1 if there is none remaining.
*/
public final int next ()
{
return row == rows ? -1 : row++;
}
}