Package org.eclipse.core.databinding

Class UpdateSetStrategy<S,D>

java.lang.Object

org.eclipse.core.databinding.UpdateSetStrategy<S,D>

Type Parameters:

S - the type of the elements on the source side (i.e. the model side if this is a model-to-target update and the target side if this is a target-to-model update)

D - the type of the elements on the destination side (i.e. the target side if this is a model-to-target update and the model side if this is a target-to-model update)

public class UpdateSetStrategy<S,D>
extends Object

Customizes a Binding between two observable sets. The following behaviors can be customized via the strategy:

• Conversion
• Automatic processing

Conversion:
When elements are added they can be converted to the destination element type.

Automatic processing:
The processing to perform when the source observable changes. This behavior is configured via policies provided on construction of the strategy (e.g. POLICY_NEVER, POLICY_ON_REQUEST, POLICY_UPDATE).

Since:

1.1

See Also:

DataBindingContext.bindSet(IObservableSet, IObservableSet, UpdateSetStrategy, UpdateSetStrategy), IConverter

Field Summary

Fields

Modifier and Type	Field	Description
protected IConverter<? super S,? extends D>	converter
static int	POLICY_NEVER	Policy constant denoting that the source observable's state should not be tracked and that the destination observable's state should never be updated.
static int	POLICY_ON_REQUEST	Policy constant denoting that the source observable's state should not be tracked, but that conversion and updating the destination observable's state should be performed when explicitly requested.
static int	POLICY_UPDATE	Policy constant denoting that the source observable's state should be tracked, and that conversion and updating the destination observable's state should be performed automatically on every change of the source observable state.
protected boolean	provideDefaults

Constructor Summary

Constructors

Constructor	Description
UpdateSetStrategy()	Creates a new update list strategy for automatically updating the destination observable list whenever the source observable list changes.
UpdateSetStrategy(boolean provideDefaults, int updatePolicy)	Creates a new update list strategy with a configurable update policy.
UpdateSetStrategy(int updatePolicy)	Creates a new update list strategy with a configurable update policy.

Method Summary

Modifier and Type	Method	Description
protected void	checkAssignable(Object toType, Object fromType, String errorString)
D	convert(S value)	Converts the value from the source type to the destination type.
static <S,D> UpdateSetStrategy<S,D>	create(IConverter<S,D> converter)	Convenience method that creates an UpdateValueStrategy with the given converter.
protected IConverter<?,?>	createConverter(Object fromType, Object toType)	Tries to create a converter that can convert from values of type fromType.
protected IStatus	doAdd(IObservableSet<? super D> observableSet, D element)	Adds the given element at the given index to the given observable list.
protected IStatus	doRemove(IObservableSet<? super D> observableSet, D element)	Removes the element at the given index from the given observable list.
protected void	fillDefaults(IObservableSet<? extends S> source, IObservableSet<? super D> destination)
int	getUpdatePolicy()
protected Boolean	isAssignableFromTo(Object fromType, Object toType)	Returns Boolean.TRUE if the from type is assignable to the to type, or Boolean.FALSE if it not, or null if unknown.
protected IStatus	logErrorWhileSettingValue(Exception ex)
static <S,D> UpdateSetStrategy<S,D>	never()	Convenience method that creates an update strategy that never updates its observables, using POLICY_NEVER and no defaults.
UpdateSetStrategy<S,D>	setConverter(IConverter<S,D> converter)	Sets the converter to be invoked when converting added elements from the source element type to the destination element type.

Methods inherited from class java.lang.Object

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

Field Detail

POLICY_NEVER

public static final int POLICY_NEVER

Policy constant denoting that the source observable's state should not be tracked and that the destination observable's state should never be updated.

POLICY_ON_REQUEST

public static final int POLICY_ON_REQUEST

Policy constant denoting that the source observable's state should not be tracked, but that conversion and updating the destination observable's state should be performed when explicitly requested.

POLICY_UPDATE

public static final int POLICY_UPDATE

Policy constant denoting that the source observable's state should be tracked, and that conversion and updating the destination observable's state should be performed automatically on every change of the source observable state.

provideDefaults

protected boolean provideDefaults

converter

protected IConverter<? super S,? extends D> converter

Constructor Detail

UpdateSetStrategy

public UpdateSetStrategy()

Creates a new update list strategy for automatically updating the destination observable list whenever the source observable list changes. A default converter will be provided. The defaults can be changed by calling one of the setter methods.

UpdateSetStrategy

public UpdateSetStrategy(int updatePolicy)

Creates a new update list strategy with a configurable update policy. A default converter will be provided. The defaults can be changed by calling one of the setter methods.

Parameters:

updatePolicy - one of POLICY_NEVER, POLICY_ON_REQUEST, or POLICY_UPDATE

UpdateSetStrategy

public UpdateSetStrategy(boolean provideDefaults,
                         int updatePolicy)

Creates a new update list strategy with a configurable update policy. A default converter will be provided if provideDefaults is true, see DataBindingContext. The defaults can be changed by calling one of the setter methods.

Parameters:

provideDefaults - if true, default validators and a default converter will be provided based on the observable list's type, see DataBindingContext

updatePolicy - one of POLICY_NEVER, POLICY_ON_REQUEST, or POLICY_UPDATE

Method Detail

fillDefaults

protected void fillDefaults(IObservableSet<? extends S> source,
                            IObservableSet<? super D> destination)

Parameters:

source - source observable, to be used for its type

destination - destination observable, to be used for its type

getUpdatePolicy

public int getUpdatePolicy()

Returns:

the update policy

setConverter

public UpdateSetStrategy<S,D> setConverter(IConverter<S,D> converter)

Sets the converter to be invoked when converting added elements from the source element type to the destination element type.

If the converter throws any exceptions they are reported as validation errors, using the exception message.

Parameters:

converter - the new converter

Returns:

the receiver, to enable method call chaining

doAdd

protected IStatus doAdd(IObservableSet<? super D> observableSet,
                        D element)

Adds the given element at the given index to the given observable list. Clients may extend but must call the super implementation.

Parameters:

observableSet - the set to add to

element - element to add

Returns:

a status

doRemove

protected IStatus doRemove(IObservableSet<? super D> observableSet,
                           D element)

Removes the element at the given index from the given observable list. Clients may extend but must call the super implementation.

Parameters:

observableSet - the set to remove from

element - the element to remove

Returns:

a status

create

public static <S,D> UpdateSetStrategy<S,D> create(IConverter<S,D> converter)

Convenience method that creates an UpdateValueStrategy with the given converter. It uses POLICY_UPDATE.

Parameters:

converter - the converter

Returns:

the update strategy

Since:

1.8

never

public static <S,D> UpdateSetStrategy<S,D> never()

Convenience method that creates an update strategy that never updates its observables, using POLICY_NEVER and no defaults.

Returns:

the update strategy

Since:

1.8

checkAssignable

protected final void checkAssignable(Object toType,
                                     Object fromType,
                                     String errorString)

createConverter

protected IConverter<?,?> createConverter(Object fromType,
                                                Object toType)

Tries to create a converter that can convert from values of type fromType. Returns null if no converter could be created. Either toType or modelDescription can be null, but not both.

Parameters:

fromType - source type

toType - target type

Returns:

an IConverter, or null if unsuccessful

isAssignableFromTo

protected Boolean isAssignableFromTo(Object fromType,
                                     Object toType)

Returns Boolean.TRUE if the from type is assignable to the to type, or Boolean.FALSE if it not, or null if unknown.

Parameters:

fromType - source type to assign

toType - target type to check assignability against

Returns:

whether fromType is assignable to toType, or null if unknown

logErrorWhileSettingValue

protected IStatus logErrorWhileSettingValue(Exception ex)

Parameters:

ex - the exception, that was caught

Returns:

the validation status

convert

public D convert(S value)

Converts the value from the source type to the destination type.

Default implementation will use the setConverter(IConverter), if one exists. If no converter exists no conversion occurs.

Parameters:

value - source value to convert

Returns:

the converted value