uk.ac.starlink.table

Interface RowSplittable

All Superinterfaces:

java.lang.AutoCloseable, java.io.Closeable, RowData, RowSequence, Sequence, Splittable<RowSplittable>

All Known Implementing Classes:

EmptyRowSequence, MappingRowSplittable, ProgressRowSplittable, RandomRowSplittable, SequentialRowSplittable

public interface RowSplittable
extends RowSequence, Splittable<RowSplittable>

RowSequence subinterface that is also suitable for parallel processing.

Since:

4 Aug 2020

Method Summary

Modifier and Type	Method and Description
java.util.function.LongSupplier	rowIndex() Returns a supplier for the index of the row currently being processed, if possible.

Methods inherited from interface uk.ac.starlink.table.RowSequence

close, getCell, getRow, next

Methods inherited from interface uk.ac.starlink.util.Splittable

split, splittableSize

Method Detail

rowIndex

java.util.function.LongSupplier rowIndex()

Returns a supplier for the index of the row currently being processed, if possible. The row index is a global value; when accessing the first row of a top-level RowSplittable, the value returned by this supplier should be the first index in the table. But for objects resulting from splitting a top-level instance into sub-instances, the return value should reflect the index in the original sequence of rows; each index should be returned from only one of the splittables resulting from splitting a top-level instance.

Typically, the row index will start at 0 and increment for each row, but the numbering may be different depending on the requirements of the implementation or usage.

Before the RowSequence.next() method has been called, the return value will be one less than the first row index. After RowSequence.next has returned false, the value is undefined.

Depending on the implementation, it may not be possible to determine the row index (for instance if the sequence is split into sub-splittables of unknown size). In such cases, this method returns null. The null-ness of the return value must be the same for all instances of the splittable hierarchy for a given sequence, so don't return a non-null value for the first splittable and then null values for some or all of its children.

Returns:

supplier for the globally-referenced row index value of the current row of this sequence, or null