com.hardcode.gdbms.engine.strategies
Class FilteredDataSource

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

All Implemented Interfaces:

DataSource, ReadAccess

public class FilteredDataSource
extends OperationDataSource

Representa una fuente de datos que contiene una cláusula where mediante la cual se filtran los campos

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

FilteredDataSource(DataSource source, Expression whereExpression)
Creates a new FilteredDataSource object.

Method Summary

Value[]	aggregatedFilter(Expression[] fields)
void	filtrar() Método que construye el array de índices de las posiciones que las filas filtradas ocupan en el DataSource origen
Metadata	getDataSourceMetadata() Gets the meta data about the source of this DataSource
int	getFieldIndexByName(java.lang.String fieldName) Obtiene el indice de un campo a partir de su nombre o -1 si no existe un campo con ese nombre
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
long[]	getWhereFilter() DOCUMENT ME!
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, getFieldNames, getName, getRow, getSelectedRows, getSQL, 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

FilteredDataSource

public FilteredDataSource(DataSource source,
                          Expression whereExpression)

Creates a new FilteredDataSource object.

Parameters:

source - DataSource que se va a filtrar

whereExpression - Expresión de la cláusula where

Method Detail

aggregatedFilter

public Value[] aggregatedFilter(Expression[] fields)
                         throws IncompatibleTypesException,
                                DriverException,
                                EvaluationException,
                                java.io.IOException

Throws:

IncompatibleTypesException

DriverException

EvaluationException

java.io.IOException

filtrar

public void filtrar()
             throws DriverException,
                    java.io.IOException,
                    SemanticException,
                    EvaluationException

Método que construye el array de índices de las posiciones que las filas filtradas ocupan en el DataSource origen

Throws:

DriverException - Si se produce un fallo en el driver al acceder a los datos

java.io.IOException - Si se produce un error usando las estructuras de datos internas

SemanticException - Si se produce algún error semántico al evaluar la expresión

IncompatibleTypesException - Si la expresión where no evalua a booleano

EvaluationException - If the expression evaluation fails

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:

com.hardcode.gdbms.engine.data.DataSource#open()

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:

com.hardcode.gdbms.engine.data.DataSource#close()

getFieldIndexByName

public int getFieldIndexByName(java.lang.String fieldName)
                        throws DriverException

Description copied from interface: DataSource

Obtiene el indice de un campo a partir de su nombre o -1 si no existe un campo con ese nombre

Specified by:

getFieldIndexByName in interface DataSource

Overrides:

getFieldIndexByName in class OperationDataSource

Parameters:

fieldName - Nombre del campo

Returns:

Indice del campo con el nombre dado o -1 si el campo no existe

Throws:

DriverException - Si se produce un error accediendo a los datos

See Also:

com.hardcode.gdbms.engine.data.FieldNameAccess#getFieldIndexByName(java.lang.String)

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()

getWhereFilter

public long[] getWhereFilter()
                      throws java.io.IOException

DOCUMENT ME!

Specified by:

getWhereFilter in interface DataSource

Overrides:

getWhereFilter in class OperationDataSource

Returns:

DOCUMENT ME!

Throws:

java.io.IOException

See Also:

DataSource.getWhereFilter()

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()

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