Package org.openrefine.operations

Class ExpressionBasedOperation

java.lang.Object

org.openrefine.operations.EngineDependentOperation

org.openrefine.operations.RowMapOperation

org.openrefine.operations.ExpressionBasedOperation

All Implemented Interfaces:

Operation

Direct Known Subclasses:

ColumnAdditionByFetchingURLsOperation, ColumnAdditionOperation, MassEditOperation, TextTransformOperation

public abstract class ExpressionBasedOperation
extends RowMapOperation

Base class for an operation which evaluates an expression on rows or records, and then uses it to derive the new grid. Depending on whether the expression is local or not, the operation will compute it lazily (with a RowMapper or RecordMapper) or will evaluate it eagerly and store the evaluation results in a ChangeData object, so that expensive evaluations (or expressions with side effects) are not evaluated multiple times.

Author:

Antonin Delpeuch

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	ExpressionBasedOperation.NegativeRowMapper
protected static class	ExpressionBasedOperation.PositiveRowMapper	Row mapper which calls a change data producer (to evaluate the expression) and directly calls the corresponding change data joiner (to insert the results in the row).

Nested classes/interfaces inherited from class org.openrefine.operations.RowMapOperation

RowMapOperation.GridMap

Field Summary

Fields

Modifier and Type	Field	Description
protected String	_baseColumnName
protected String	_changeDataId
protected Evaluable	_eval
protected String	_expression
protected boolean	_forceEagerEvaluation
protected OnError	_onError
protected int	_repeatCount

Fields inherited from class org.openrefine.operations.EngineDependentOperation

_engineConfig

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ExpressionBasedOperation(EngineConfig engineConfig, String expression, String baseColumnName, OnError onError, int repeatCount)

Method Summary

Modifier and Type	Method	Description
ChangeResult	apply(Grid projectState, ChangeContext context)	Derives the new grid state from the current grid state.
protected abstract RowInRecordChangeDataJoiner	changeDataJoiner(Grid grid, ChangeContext context)	Returns the joiner used to insert the result of the evaluation of the expression into a row or record.
static RowInRecordChangeDataProducer<Cell>	evaluatingChangeDataProducer(int columnIndex, String baseColumnName, OnError onError, int repeatCount, Evaluable eval, ColumnModel columnModel, Map<String,OverlayModel> overlayModels, long projectId)
protected RowInRecordChangeDataProducer<Cell>	getChangeDataProducer(Grid state, ChangeContext context)
protected Evaluable	getEvaluable()
protected RowMapOperation.GridMap	getGridMap(Grid state, ChangeContext context)	Returns the function that is applied to each row and row index, the new column model applied to the grid, and the new overlay models.
protected ColumnModel	getNewColumnModel(Grid state, ChangeContext context, Evaluable eval)	Returns the new column model after the operation has run.
protected Map<String,OverlayModel>	getNewOverlayModels(Grid state, ChangeContext context, Evaluable evaluable)	Returns the new overlay models after this change is applied.
protected Grid	postTransform(Grid state, ChangeContext context, Evaluable eval)

Methods inherited from class org.openrefine.operations.RowMapOperation

getNegativeRowMapper, getNewColumnModel, getNewOverlayModels, getPositiveRowMapper, postTransform

Methods inherited from class org.openrefine.operations.EngineDependentOperation

getEngine, getEngineConfig

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.openrefine.operations.Operation

getDescription, getOperationId, isReproducible

Field Detail

_expression

protected final String _expression

_baseColumnName

protected final String _baseColumnName

_onError

protected final OnError _onError

_repeatCount

protected final int _repeatCount

_changeDataId

protected String _changeDataId

_forceEagerEvaluation

protected boolean _forceEagerEvaluation

_eval

protected Evaluable _eval

Constructor Detail

ExpressionBasedOperation

protected ExpressionBasedOperation(EngineConfig engineConfig,
                                   String expression,
                                   String baseColumnName,
                                   OnError onError,
                                   int repeatCount)

Method Detail

changeDataJoiner

protected abstract RowInRecordChangeDataJoiner changeDataJoiner(Grid grid,
                                                                ChangeContext context)
                                                         throws OperationException

Returns the joiner used to insert the result of the evaluation of the expression into a row or record. Depending on whether the expression is local or not (see Evaluable.isLocal()), this will either be used to build a row / record mapper to apply the change lazily on the grid, or the results of the evaluation will be stored in a ChangeData object which will then be joined by this joiner.

Parameters:

grid - the initial state of the grid

Throws:

OperationException

getNewColumnModel

protected ColumnModel getNewColumnModel(Grid state,
                                        ChangeContext context,
                                        Evaluable eval)
                                 throws OperationException

Returns the new column model after the operation has run.

Throws:

OperationException

getNewOverlayModels

protected Map<String,OverlayModel> getNewOverlayModels(Grid state,
                                                             ChangeContext context,
                                                             Evaluable evaluable)
                                                      throws OperationException

Returns the new overlay models after this change is applied.

Throws:

OperationException

postTransform

protected Grid postTransform(Grid state,
                             ChangeContext context,
                             Evaluable eval)
                      throws OperationException

Throws:

OperationException

apply

public ChangeResult apply(Grid projectState,
                          ChangeContext context)
                   throws OperationException

Description copied from interface: Operation

Derives the new grid state from the current grid state. Executing this method should be quick (even on large datasets) since it is expected to just derive the new grid from the existing one without actually executing any expensive computation. Long-running computations should rather go in the derivation of a ChangeData which will be fetched asynchronously.

Specified by:

apply in interface Operation

Overrides:

apply in class RowMapOperation

Parameters:

projectState - the state of the grid before the change

Returns:

an object which bundles up various pieces of information produced by the operation: primarily, the new grid after applying the operation. This object can be subclassed to expose more information, which should be serializable with Jackson so that it reaches the frontend.

Throws:

OperationException - when the change cannot be applied to the given grid

getEvaluable

protected Evaluable getEvaluable()
                          throws OperationException

Throws:

OperationException

getGridMap

protected RowMapOperation.GridMap getGridMap(Grid state,
                                             ChangeContext context)
                                      throws OperationException

Description copied from class: RowMapOperation

Returns the function that is applied to each row and row index, the new column model applied to the grid, and the new overlay models. Computing these in one go can be useful in certain situations, for instance when the number of columns added to the column model depends on the data. If a subclass needs to return only one non-default value out of mapper, column model and overlay models it can instead override the corresponding method.

Overrides:

getGridMap in class RowMapOperation

Parameters:

state - the initial column model

Throws:

OperationException - if the change does not apply to the given grid

getChangeDataProducer

protected RowInRecordChangeDataProducer<Cell> getChangeDataProducer(Grid state,
                                                                    ChangeContext context)
                                                             throws OperationException

Throws:

OperationException

evaluatingChangeDataProducer

public static RowInRecordChangeDataProducer<Cell> evaluatingChangeDataProducer(int columnIndex,
                                                                               String baseColumnName,
                                                                               OnError onError,
                                                                               int repeatCount,
                                                                               Evaluable eval,
                                                                               ColumnModel columnModel,
                                                                               Map<String,OverlayModel> overlayModels,
                                                                               long projectId)