uk.ac.starlink.ttools.plot2.data

Class WrapperDataStoreFactory

java.lang.Object

uk.ac.starlink.ttools.plot2.data.WrapperDataStoreFactory

All Implemented Interfaces:

DataStoreFactory

public abstract class WrapperDataStoreFactory
extends Object
implements DataStoreFactory

DataStoreFactory implementation which allows decoration of the tables used to obtain the data, by providing a custom wrapper for their RowSequence objects.

The implementation is fairly ticklish, since various of the objects that we want to wrap have not only to behave (mostly) like the unwrapped objects to which they delegate, but also to be equal to them (Equality). It works by wrapping each DataSpec in a custom wrapper object any time it is presented to the underlying base DataStoreFactory, either by the methods of this DataStoreFactory implementation or by methods invoked on DataStore objects it dispenses. These wrapper objects obey the equality constraints.

Since:

8 Nov 2013

Author:

Mark Taylor

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	WrapperDataStoreFactory(DataStoreFactory baseFact) Constructor.

Method Summary

Modifier and Type	Method and Description
protected abstract RowAccess	createRowAccess(StarTable table) Creates a row access from a given table.
protected abstract RowSequence	createRowSequence(StarTable table) Creates a row sequence from a given table.
protected abstract RowSplittable	createRowSplittable(StarTable table) Creates a row splittable from a given table.
DataStore	readDataStore(DataSpec[] dataSpecs, DataStore prevStore) Generates a DataStore capable of supplying the data for a given list of DataSpec objects.

Methods inherited from class java.lang.Object

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

Constructor Detail

WrapperDataStoreFactory

protected WrapperDataStoreFactory(DataStoreFactory baseFact)

Constructor.

Parameters:

baseFact - base implementation that actually acquires the data

Method Detail

readDataStore

public DataStore readDataStore(DataSpec[] dataSpecs,
                               DataStore prevStore)
                        throws IOException,
                               InterruptedException

Description copied from interface: DataStoreFactory

Generates a DataStore capable of supplying the data for a given list of DataSpec objects. The prevStore argument may optionally supply the result of a previous invocation of this method. The implementation may choose to make use of the internal state of such an instance for efficiency, for instance by re-using data that has already been read.

Since the bulk data is managed by the DataStore object, care should be taken about what happens to the DataStore objects supplied to and returned from this method. In particular, code both invoking and implementing this method should usually make sure not to keep a reference to the prevStore argument.

This method may perform the actual reading, and therefore take time. It is not intended to be invoked on the event dispatch thread.

Specified by:

readDataStore in interface DataStoreFactory

Parameters:

dataSpecs - data specifications; some elements may be null

prevStore - previously obtained DataStore, or null

Returns:

new data store

Throws:

IOException

InterruptedException

createRowSequence

protected abstract RowSequence createRowSequence(StarTable table)
                                          throws IOException

Creates a row sequence from a given table.

The obvious implementation is table.getRowSequence(), but implementations may decorate that instance to provide useful functionality.

Parameters:

table - table providing data

Returns:

row sequence which will be used to acquire table data

Throws:

IOException

createRowAccess

protected abstract RowAccess createRowAccess(StarTable table)
                                      throws IOException

Creates a row access from a given table.

The obvious implementation is table.getRowAccess(), but implementations may decorate that instance to provide useful functionality.

Parameters:

table - table providing data

Returns:

row access which will be used to acquire table data

Throws:

IOException

createRowSplittable

protected abstract RowSplittable createRowSplittable(StarTable table)
                                              throws IOException

Creates a row splittable from a given table.

The obvious implementation is table.getRowSplittable(), but implementations may decorate that instance to provide useful functionality.

Parameters:

table - table providing data

Returns:

row splittable which will be used to acquire table data

Throws:

IOException