uk.ac.starlink.table

Class StreamTableSink

java.lang.Object

uk.ac.starlink.table.StreamTableSink

All Implemented Interfaces:

TableSink

public abstract class StreamTableSink
extends Object
implements TableSink

TableSink which turns its accepted data into a one-pass table and does something with it (calls scanTable(uk.ac.starlink.table.StarTable) on it). This effectively allows you to 'push' table data by writing it to this TableSink rather than 'pulling' it by implementing a RowSequence; the latter may be a less obvious or more fiddly way to work. Note however this will only work for scanTable implementations which need only a single pass of the data.

See TableSink for usage rules.

Since:

8 Aug 2007

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
StreamTableSink()

Method Summary

Modifier and Type	Method and Description
void	acceptMetadata(StarTable meta) Takes delivery of a row-less StarTable object which defines the metadata of the table to be transmitted.
void	acceptRow(Object[] row) Takes delivery of one row of data.
void	endRows() Signals that there are no more rows to be transmitted.
protected abstract void	scanTable(StarTable table) Does something or other with the table whose data is being pushed into this sink.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StreamTableSink

public StreamTableSink()

Method Detail

scanTable

protected abstract void scanTable(StarTable table)
                           throws IOException

Does something or other with the table whose data is being pushed into this sink. The only data access which will work is a single call to StarTable.getRowSequence(). Subsequent getRowSequence calls will result in a UnrepeatableSequenceException. This method is called in a separate thread than the one in which the accept* calls are made; but any exceptions thrown here are passed back to the latter thread.

Parameters:

table - table to consume

Throws:

IOException

acceptMetadata

public void acceptMetadata(StarTable meta)
                    throws TableFormatException

Description copied from interface: TableSink

Takes delivery of a row-less StarTable object which defines the metadata of the table to be transmitted. If the number of rows that will be transmitted via subsequent calls to acceptRow is known, this value should be made available as the row count of meta (StarTable.getRowCount()); if it is not known, the row count should be -1. However, this object should not attempt to read any of meta's cell data.

The data to be transmitted in subsequent calls of acceptRow must match the metadata transmitted in this call in the same way that rows of a StarTable must match its own metadata (number and content clases of columns etc). If this sink cannot dispose of a table corresponding to meta then it may throw a TableFormatException - this may be the case if for instance meta has columns with types that this sink can't deal with.

Specified by:

acceptMetadata in interface TableSink

Parameters:

meta - table metadata object

Throws:

TableFormatException - if this sink cannot accept table rows matching the given metadata

acceptRow

public void acceptRow(Object[] row)
               throws IOException

Description copied from interface: TableSink

Takes delivery of one row of data. row is an array of objects comprising the contents of one row of the table being transmitted. The number and classes of the elements of row are described by the metadata object previously accepted.

Specified by:

acceptRow in interface TableSink

Parameters:

row - table data row

Throws:

IOException

endRows

public void endRows()
             throws IOException

Description copied from interface: TableSink

Signals that there are no more rows to be transmitted.

Specified by:

endRows in interface TableSink

Throws:

IOException