Interface IEvaluationService
- All Superinterfaces:
IDisposable
,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);
- This service is available globally.
- Since:
- 3.4
- Restriction:
- This interface is not intended to be implemented by clients.
- Restriction:
- This interface is not intended to be extended by clients.
-
Field Summary
-
Method Summary
Modifier and TypeMethodDescriptionaddEvaluationListener
(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
Re-add a property change listener that has already been removed byremoveEvaluationListener(IEvaluationReference)
.void
addServiceListener
(IPropertyChangeListener listener) When a source change starts recalculating expressions thePROP_NOTIFYING
property change is fired with the newValue=Boolean.TRUE
.Get an IEvaluationContext that contains the current state of the workbench application context.void
Remove the listener represented by the evaluation reference.void
removeServiceListener
(IPropertyChangeListener listener) Remove the listener forPROP_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.Methods inherited from interface org.eclipse.ui.services.IDisposable
dispose
Methods inherited from interface org.eclipse.ui.services.IServiceWithSources
addSourceProvider, removeSourceProvider
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Field Details
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RESULT
A general property that can be used.- See Also:
-
PROP_NOTIFYING
The property used to notify any service listeners.- See Also:
-
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Method Details
-
addServiceListener
When a source change starts recalculating expressions thePROP_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.
- Parameters:
listener
- The listener to be notified. Must not benull
. Has no effect if the listener has already been added.
-
removeServiceListener
Remove the listener forPROP_NOTIFYING
property changes.- Parameters:
listener
- The listener to remove. Must not benull
. Has no effect if the listener is not currently registered.
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addEvaluationListener
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.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.
- Parameters:
expression
- the core expression to evaluate.listener
- the listener to be notified.property
- the property contained in the notification- Returns:
- a token that can be used to remove this listener.
removeEvaluationListener(IEvaluationReference)
-
addEvaluationReference
Re-add a property change listener that has already been removed byremoveEvaluationListener(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.
- Parameters:
ref
- The listener to re-add.- See Also:
-
removeEvaluationListener
Remove the listener represented by the evaluation reference.- Parameters:
ref
- the reference to be removed.
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getCurrentState
IEvaluationContext getCurrentState()Get an IEvaluationContext that contains the current state of the workbench application context. This context changes with the application state, but becomes invalid when the global current selection changes.Note: This context should not be modified.
- Returns:
- the latest context.
- See Also:
-
requestEvaluation
Request that this service re-evaluate all registered core expressions that contain a property tester for the given property name. This will fire aPROP_NOTIFYING
property change event to service listeners.Notes:
- the property must be able to return the new value before this re-evaluation is requested
- limit calls to this method to avoid unnecessary churn
- A re-evaluation that does not change the value of an expression will not fire a property change event
- Parameters:
propertyName
- The fully qualified property name, likeorg.eclipse.core.resources.name
. Must not benull
.- Since:
- 3.4
-