org.eclipse.emf.ecp.view.spi.common.di

Class ContextBasedObjectSupplier<A extends Annotation,T>

java.lang.Object

org.eclipse.e4.core.di.suppliers.ExtendedObjectSupplier

org.eclipse.emf.ecp.view.spi.common.di.ContextBasedObjectSupplier<A,T>

Type Parameters:

A - my qualifier annotation type

T - my value type

Direct Known Subclasses:

RendererSupplier, ViewServiceSupplier

public abstract class ContextBasedObjectSupplier<A extends Annotation,T>
extends org.eclipse.e4.core.di.suppliers.ExtendedObjectSupplier

A partial implementation of an object supplier that computes its results from values in the Eclipse context.

Since:

1.22

Field Summary

Fields inherited from class org.eclipse.e4.core.di.suppliers.ExtendedObjectSupplier

SERVICE_CONTEXT_KEY, SERVICE_NAME

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ContextBasedObjectSupplier(Class<A> qualifierType, Class<T> valueType) Initializes me with the type of value that I supply and the qualifier annotation type that I key on.

Method Summary

Modifier and Type	Method and Description
protected boolean	checkDependencies(A qualifier, Class<? extends T> requestedType, org.eclipse.e4.core.contexts.IEclipseContext context) Check whether the Eclipse context has the dependencies required to compute my result.
protected abstract Optional<? extends T>	compute(A qualifier, Class<? extends T> requestedType, org.eclipse.e4.core.contexts.IEclipseContext context) Compute my value from the Eclipse context.
Object	get(org.eclipse.e4.core.di.suppliers.IObjectDescriptor descriptor, org.eclipse.e4.core.di.suppliers.IRequestor requestor, boolean track, boolean group)

Methods inherited from class java.lang.Object

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

Constructor Detail

ContextBasedObjectSupplier

protected ContextBasedObjectSupplier(Class<A> qualifierType,
                                     Class<T> valueType)

Initializes me with the type of value that I supply and the qualifier annotation type that I key on.

Parameters:

qualifierType - the qualifier annotation type

valueType - the value type

Method Detail

get

public Object get(org.eclipse.e4.core.di.suppliers.IObjectDescriptor descriptor,
                  org.eclipse.e4.core.di.suppliers.IRequestor requestor,
                  boolean track,
                  boolean group)

Specified by:

get in class org.eclipse.e4.core.di.suppliers.ExtendedObjectSupplier

checkDependencies

protected boolean checkDependencies(A qualifier,
                                    Class<? extends T> requestedType,
                                    org.eclipse.e4.core.contexts.IEclipseContext context)

Check whether the Eclipse context has the dependencies required to compute my result. The default implementation just attempts to compute the result, which is useful for simple cases where the computation is not expensive and does not have undesired side-effects if it fails.

Parameters:

qualifier - the qualifier annotation, which may have attributes required for the computation

requestedType - the type requested for injection

context - the Eclipse context

Returns:

true if I can compute a value from this context; false, otherwise

See Also:

#compute(Annotation, IEclipseContext)

compute

protected abstract Optional<? extends T> compute(A qualifier,
                                                 Class<? extends T> requestedType,
                                                 org.eclipse.e4.core.contexts.IEclipseContext context)

Compute my value from the Eclipse context. An empty result indicates that the value does not exist (the IInjector.NOT_A_VALUE special result for the object-supplier protocol). Injection of null values is not supported.

Parameters:

qualifier - the qualifier annotation, which may have attributes required for the computation

requestedType - the type requested for injection

context - the Eclipse context

Returns:

the result of the computation (possibly empty, but not null)