public interface IEvaluationService extends IServiceWithSources
IPropertyChangeListener
that will be notified as changes
occur.
This can be used to implement core expressions in client extension points
similar to the <enabledWhen> of
org.eclipse.ui.handlers/handler
elements.
The service will fire Boolean.TRUE
and
Boolean.FALSE
for the oldValue and newValue in the property
change events.
Adding the evaluation listener will fire one change with oldValue=null
and newValue="evaluated expression". Remove the
IEvaluationReference
will fire one change with
oldValue="last evaluated value" and newValue=null
.
Adding a service listener will fire the PROP_NOTIFYING
property
change event with newValue=Boolean.TRUE
when a source change
causes expression evaluations to update and another PROP_NOTIFYING
property change event with newValue=Boolean.FALSE
when the
changes that started with a specific source change have finished. The
PROP_NOTIFYING
change events will not be fired for source changes
caused by the outer most recalculations.
Variable sources can be provided to this service using the org.eclipse.ui.services
Extension Point. This makes the available to <with/> expressions.
This service can be acquired from your service locator:
IEvaluationService service = (IEvaluationService) getSite().getService(IEvaluationService.class);
Modifier and Type | Field and Description |
---|---|
static String |
PROP_NOTIFYING
The property used to notify any service listeners.
|
static String |
RESULT
A general property that can be used.
|
Modifier and Type | Method and Description |
---|---|
IEvaluationReference |
addEvaluationListener(Expression expression,
IPropertyChangeListener listener,
String property)
Add a listener that can be notified when the workbench application
context causes the expression evaluation value to change.
|
void |
addEvaluationReference(IEvaluationReference ref)
Re-add a property change listener that has already been removed by
removeEvaluationListener(IEvaluationReference) . |
void |
addServiceListener(IPropertyChangeListener listener)
When a source change starts recalculating expressions the
PROP_NOTIFYING property change is fired with the newValue=Boolean.TRUE . |
IEvaluationContext |
getCurrentState()
Get an IEvaluationContext that contains the current state of the
workbench application context.
|
void |
removeEvaluationListener(IEvaluationReference ref)
Remove the listener represented by the evaluation reference.
|
void |
removeServiceListener(IPropertyChangeListener listener)
Remove the listener for
PROP_NOTIFYING property changes. |
void |
requestEvaluation(String propertyName)
Request that this service re-evaluate all registered core expressions
that contain a property tester for the given property name.
|
addSourceProvider, removeSourceProvider
dispose
static final String RESULT
static final String PROP_NOTIFYING
void addServiceListener(IPropertyChangeListener listener)
PROP_NOTIFYING
property change is fired with the newValue=Boolean.TRUE
.
This property is not fired for any source changes caused by the outer
recalculations.
Note: listeners should be removed when no longer necessary. If not, they will be removed when the IServiceLocator used to acquire this service is disposed.
listener
- The listener to be notified. Must not be null
.
Has no effect if the listener has already been added.void removeServiceListener(IPropertyChangeListener listener)
PROP_NOTIFYING
property changes.listener
- The listener to remove. Must not be null
. Has
no effect if the listener is not currently registered.IEvaluationReference addEvaluationListener(Expression expression, IPropertyChangeListener listener, String property)
Note: listeners should be removed when no longer necessary. If not, they will be removed when the IServiceLocator used to acquire this service is disposed.
expression
- the core expression to evaluate.listener
- the listener to be notified.property
- the property contained in the notificationremoveEvaluationListener(IEvaluationReference)
void addEvaluationReference(IEvaluationReference ref)
removeEvaluationListener(IEvaluationReference)
.
It will only accept IEvaluationReferences returned from a previous call
to
addEvaluationListener(Expression, IPropertyChangeListener, String)
on this service.
Note: references should be removed when no longer necessary. If not, they will be removed when the IServiceLocator used to acquire this service is disposed.
ref
- The listener to re-add.removeEvaluationListener(IEvaluationReference)
void removeEvaluationListener(IEvaluationReference ref)
ref
- the reference to be removed.IEvaluationContext getCurrentState()
Note: This context should not be modified.
ISources.ACTIVE_CURRENT_SELECTION_NAME
void requestEvaluation(String propertyName)
PROP_NOTIFYING
property change event to service
listeners.
Notes:
propertyName
- The fully qualified property name, like
org.eclipse.core.resources.name
. Must not be
null
.
Copyright (c) 2000, 2015 Eclipse Contributors and others. All rights reserved.Guidelines for using Eclipse APIs.