com.hardcode.gdbms.engine.strategies
Class DistinctDataSource

java.lang.Object
  com.hardcode.gdbms.engine.strategies.OperationDataSource
      com.hardcode.gdbms.engine.strategies.DistinctDataSource

All Implemented Interfaces:

DataSource, ReadAccess

public class DistinctDataSource
extends OperationDataSource

DOCUMENT ME!

Author:

Fernando González Cortés

Field Summary

Fields inherited from interface com.hardcode.gdbms.engine.data.DataSource

COHERENT_ROW_ORDER, DIRECT_MODE, DISPATCH, IGNORE, STORE

Constructor Summary

DistinctDataSource(DataSource ds, Expression[] expressions)
Crea un nuevo DistinctDataSource.

Method Summary

void	filter() DOCUMENT ME!
Metadata	getDataSourceMetadata() Gets the meta data about the source of this DataSource
Value	getFieldValue(long rowIndex, int fieldId) Obtiene el valor que se encuentra en la fila y columna indicada
Memento	getMemento() Gets a memento object with the current status of the DataSource
long	getRowCount() Obtiene el número de registros del DataSource
void	start() Opens the DataSource to access the data it contains.
void	stop() Closes the DataSource.

Methods inherited from class com.hardcode.gdbms.engine.strategies.OperationDataSource

addEditionListener, addField, addField, addMetadataEditionListener, addSelectionListener, beginTrans, canRedo, canUndo, check, commitTrans, deleteRow, getAlias, getAsString, getDataSourceFactory, getDispatchingMode, getDriver, getDriverMetadata, getFieldIndexByName, getFieldNames, getName, getRow, getSelectedRows, getSQL, getWhereFilter, insertEmptyRow, insertEmptyRowAt, insertFilledRow, insertFilledRowAt, isModified, redo, remove, removeEditionListener, removeField, removeMetadataEditionListener, removeSelectionListener, rollBackTrans, saveData, setAlias, setDataSourceFactory, setDispatchingMode, setFieldName, setFieldValue, setName, setSelectedRows, setSQL, undo

Methods inherited from class java.lang.Object

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

Constructor Detail

DistinctDataSource

public DistinctDataSource(DataSource ds,
                          Expression[] expressions)

Crea un nuevo DistinctDataSource.

Parameters:

ds - DOCUMENT ME!

expressions - DOCUMENT ME!

Throws:

DriverException

Method Detail

start

public void start()
           throws DriverException

Description copied from interface: DataSource

Opens the DataSource to access the data it contains. If the data is accessed without a previous opening a ClosedDataSourceException is thrown. If this method is invoked twice then only the second call to stop will close the DataSource.
If the DataSource was obtained with an AUTOMATIC_OPENING mode, there's no need to open the DataSource. Indeed start calls are ignored. It's possible to close the DataSource by a single call to the close method

Throws:

DriverException - if the operation fails

See Also:

DataSource.start()

stop

public void stop()
          throws DriverException

Description copied from interface: DataSource

Closes the DataSource. After a DataSource is closed it's data cannot be retrieved. Any attempt to do so will result in a DataSourceClosedException

Throws:

DriverException - If the operation fails

See Also:

DataSource.stop()

getMemento

public Memento getMemento()
                   throws MementoException

Description copied from interface: DataSource

Gets a memento object with the current status of the DataSource

Specified by:

getMemento in interface DataSource

Overrides:

getMemento in class OperationDataSource

Returns:

DataSourceMemento

Throws:

MementoException - If the state cannot be obtained

See Also:

DataSource.getMemento()

getFieldValue

public Value getFieldValue(long rowIndex,
                           int fieldId)
                    throws DriverException

Description copied from interface: ReadAccess

Obtiene el valor que se encuentra en la fila y columna indicada

Parameters:

rowIndex - fila

fieldId - columna

Returns:

subclase de Value con el valor del origen de datos. Never null (use ValueFactory.createNullValue() instead)

Throws:

DriverException - Si se produce un error accediendo al DataSource

See Also:

ReadAccess.getFieldValue(long, int)

getRowCount

public long getRowCount()
                 throws DriverException

Description copied from interface: ReadAccess

Obtiene el número de registros del DataSource

Returns:

Throws:

DriverException - Si se produce algún error accediendo al DataSource

See Also:

ReadAccess.getRowCount()

filter

public void filter()
            throws DriverException,
                   EvaluationException

DOCUMENT ME!

Throws:

DriverException - DOCUMENT ME!

EvaluationException - DOCUMENT ME!

java.lang.RuntimeException - DOCUMENT ME!

getDataSourceMetadata

public Metadata getDataSourceMetadata()
                               throws DriverException

Description copied from interface: DataSource

Gets the meta data about the source of this DataSource

Returns:

DataSourceMetadata

Throws:

DriverException - If cannot get the DataSource metadata