public class FirstInSortOrderFilter implements ITableRowFilter {

	List<ITableRow> m_acceptedRows;

	public FirstInSortOrderFilter(IColumn<?> referenceColumn) {

		int[] indices;
		boolean isSortColumn;

		ITable table;

		if (referenceColumn != null) {
			// check if column is selected for sorting

			table = referenceColumn.getTable();
			isSortColumn = table.getColumnSet().isSortColumn(referenceColumn);
			m_acceptedRows = table.getRows();

			if (isSortColumn && !referenceColumn.isEmpty() && table.isSortEnabled()) {
				// only do something if there are duplicate values in the reference column
				if (referenceColumn.containsDuplicateValues()) {

					List<Object> values = new ArrayList<Object>(referenceColumn.getValues());
					Set<Object> uniqueValues = new HashSet<Object>(values);

					indices = new int[uniqueValues.size()];

					int i = 0;
					for (Object value : uniqueValues) {
						indices[i] = Collections.indexOfSubList(values, Collections.singletonList(value));
						i++;
					}
					m_acceptedRows = table.getRows(indices);
				}
			}
		}
	}

	@Override
	public boolean accept(ITableRow row) {
		return m_acceptedRows.contains(row);
	}
}