uk.ac.starlink.table

Class SelectorStarTable

java.lang.Object

uk.ac.starlink.table.WrapperStarTable

uk.ac.starlink.table.SelectorStarTable

All Implemented Interfaces:

Closeable, AutoCloseable, StarTable

public abstract class SelectorStarTable
extends WrapperStarTable

Sequential wrapper table which selects only certain rows of its base table. No random access is provided, and the row sequence evaluates the abstract isIncluded(uk.ac.starlink.table.RowSequence) method for each row of the base table as it is iterated over.

Since:

11 Feb 2005

Author:

Mark Taylor (Starlink)

Field Summary

Fields inherited from class uk.ac.starlink.table.WrapperStarTable

baseTable

Constructor Summary

Constructors

Constructor and Description
SelectorStarTable(StarTable baseTable) Constructor.

Method Summary

Modifier and Type	Method and Description
Object	getCell(int icol)
Object[]	getRow()
RowAccess	getRowAccess() Returns an object which can provide random access to this table's data, if random access is implemented.
long	getRowCount() Returns -1 (length unknown).
RowSequence	getRowSequence() Returns an object which can iterate over all the rows in the table sequentially.
RowSplittable	getRowSplittable() Returns an object which can iterate over all the rows in the table, but which may also be requested to split recursively for potentially parallel processing.
abstract boolean	isIncluded(RowSequence baseSeq) Evaluated to determine whether rows of the base table are included in this one.
boolean	isRandom() Returns false.

Methods inherited from class uk.ac.starlink.table.WrapperStarTable

checkedLongToInt, close, getBaseTable, getCell, getColumnAuxDataInfos, getColumnCount, getColumnInfo, getName, getParameterByName, getParameters, getRow, getURL, setName, setParameter, setURL, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

SelectorStarTable

public SelectorStarTable(StarTable baseTable)

Constructor.

Parameters:

baseTable - table on which this is based

Method Detail

isIncluded

public abstract boolean isIncluded(RowSequence baseSeq)
                            throws IOException

Evaluated to determine whether rows of the base table are included in this one.

Parameters:

baseSeq - row sequence of the base table

Returns:

true iff the current row of baseSeq is to be included

Throws:

IOException

isRandom

public boolean isRandom()

Returns false.

Specified by:

isRandom in interface StarTable

Overrides:

isRandom in class WrapperStarTable

Returns:

true if table random access methods are available

getRowCount

public long getRowCount()

Returns -1 (length unknown).

Specified by:

getRowCount in interface StarTable

Overrides:

getRowCount in class WrapperStarTable

Returns:

the number of rows, or -1

getRow

public Object[] getRow()

getCell

public Object getCell(int icol)

getRowSequence

public RowSequence getRowSequence()
                           throws IOException

Description copied from interface: StarTable

Returns an object which can iterate over all the rows in the table sequentially. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.

Specified by:

getRowSequence in interface StarTable

Overrides:

getRowSequence in class WrapperStarTable

Returns:

new RowSequence

Throws:

IOException - if there is an error providing access

getRowSplittable

public RowSplittable getRowSplittable()
                               throws IOException

Description copied from interface: StarTable

Returns an object which can iterate over all the rows in the table, but which may also be requested to split recursively for potentially parallel processing.

The return value must be non-null, and may provide splitting arrangements specially appropriate for the implementation. If this table 'wraps' an upstream table, it is usually best to base the implementation on calls to the the upstream getRowSplittable method, so that upstream policy about how to divide up the table is respected. However, implementations without special requirements may return Tables.getDefaultRowSplittable(this).

Specified by:

getRowSplittable in interface StarTable

Overrides:

getRowSplittable in class WrapperStarTable

Returns:

new RowSplittable

Throws:

IOException

See Also:

RowRunner

getRowAccess

public RowAccess getRowAccess()

Description copied from interface: StarTable

Returns an object which can provide random access to this table's data, if random access is implemented. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.

Specified by:

getRowAccess in interface StarTable

Overrides:

getRowAccess in class WrapperStarTable

Returns:

new RowAccess