org.scijava.plugin.SingletonService Maven / Gradle / Ivy
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package org.scijava.plugin;
import java.util.ArrayList;
import java.util.List;
import org.scijava.object.LazyObjects;
import org.scijava.object.ObjectService;
/**
* A service for managing {@link SingletonPlugin}s of a particular type. The
* {@code SingletonService} creates and maintain a list of singleton instances.
*
* Note that like {@link PTService}, {@link TypedService} and
* {@link WrapperService}, {@code SingletonService} is not a service interface
* defining API for a specific concrete service implementation, but rather a
* more general layer in a type hierarchy intended to ease creation of services
* that fit its pattern.
*
*
* @author Curtis Rueden
* @param Plugin type of the plugins being managed.
* @see PTService
*/
public interface SingletonService extends
PTService
{
/** Gets the {@link ObjectService} upon which this service depends. */
default ObjectService objectService() {
return context().getService(ObjectService.class);
}
/**
* Gets the list of plugin instances. There will be one singleton instance for
* each available plugin.
*/
List getInstances();
/** Gets the singleton plugin instance of the given class. */
P getInstance(Class
pluginClass);
/**
* Filters the given list of instances by this service's inclusion criteria.
*
* @param list the initial list of instances
* @return the filtered list of instances
*/
default List filterInstances(final List list) {
return list;
}
// -- PTService methods --
@Override
default P create(final Class
pluginClass) {
throw new UnsupportedOperationException(
"Cannot create singleton plugin instance. "
+ "Use getInstance(Class) instead.");
}
// -- Service methods --
@Override
default void initialize() {
// add singleton instances to the object index... IN THE FUTURE!
objectService().getIndex().addLater(new LazyObjects