org.scijava.plugin.PluginIndex Maven / Gradle / Ivy
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package org.scijava.plugin;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.scijava.object.SortedObjectIndex;
/**
* Data structure for managing registered plugins.
*
* The plugin index is a special type of {@link org.scijava.object.ObjectIndex}
* that classifies each {@link PluginInfo} object into a type hierarchy
* compatible with its associated plugin type (i.e.,
* {@link PluginInfo#getPluginType()}), rather than {@link PluginInfo}'s type
* hierarchy (i.e., {@link PluginInfo}, {@link org.scijava.UIDetails},
* {@link org.scijava.Instantiable}, etc.).
*
*
* NB: This type hierarchy will typically not include the plugin class
* itself; for example, the {@link org.scijava.plugin.DefaultPluginService} has
* a plugin type of {@link org.scijava.service.Service}, and hence will be
* categorized beneath {@code Service.class}, not
* {@code DefaultPluginService.class} or {@code PluginService.class}. The
* rationale is that to fully classify each plugin including its own class, said
* class would need to be loaded, which SciJava makes an effort not to do until
* the plugin is actually needed for the first time.
*
*
* @author Curtis Rueden
*/
public class PluginIndex extends SortedObjectIndex> {
/**
* The plugin finder which will be used to discover plugins.
*
* @see #discover()
*/
private final PluginFinder pluginFinder;
/** Exception table from last invocation of {@link #discover()}. */
private Map exceptions;
/**
* Constructs a new plugin index which uses a {@link DefaultPluginFinder} to
* discover plugins.
*/
public PluginIndex() {
this(new DefaultPluginFinder());
}
/**
* Constructs a new plugin index which uses the given {@link PluginFinder} to
* discover plugins.
*
* A null PluginFinder is allowed, in which case no plugins will be discovered
* during {@link #discover()} calls.
*
*/
@SuppressWarnings({ "rawtypes", "unchecked" })
public PluginIndex(final PluginFinder pluginFinder) {
// NB: See: http://stackoverflow.com/questions/4765520/
super((Class) PluginInfo.class);
this.pluginFinder = pluginFinder;
}
// -- PluginIndex methods --
/**
* Adds all plugins discovered by the attached {@link PluginFinder} to this
* index, or does nothing if the attached {@link PluginFinder} is null.
*/
public void discover() {
if (pluginFinder == null) return;
final ArrayList> plugins = new ArrayList<>();
exceptions = pluginFinder.findPlugins(plugins);
addAll(plugins);
}
/**
* Gets the exceptions which occurred during the last invocation of
* {@link #discover()}.
*/
public Map getExceptions() {
return exceptions;
}
/**
* Gets a list of registered plugins compatible with the given type.
*
* This method is more specific than {@link #get(Class)} since that method
* returns only a {@code List>}, whereas this one is guaranteed
* to return a {@code List>}.
*
*
* @return Read-only list of registered objects of the given type, or an empty
* list if no such objects exist (this method never returns null).
*/
public List> getPlugins(
final Class type)
{
final List> list = get(type);
@SuppressWarnings({ "rawtypes", "unchecked" })
final List> result = (List) list;
return result;
}
// -- Internal methods --
/**
* Overrides the type by which the entries are indexed.
*
* @see PluginInfo#getPluginType()
*/
@Override
protected Class getType(final PluginInfo info) {
return info.getPluginType();
}
/**
* Removes the plugin from all type lists compatible with its plugin type.
*
* NB: This behavior differs from the default
* {@link org.scijava.object.ObjectIndex} behavior in that the {@code info}
* object's actual type hierarchy is not used for classification, but rather
* the object is classified according to {@link PluginInfo#getPluginType()}.
*
*
* @see PluginInfo#getPluginType()
*/
@Override
protected boolean remove(final Object o, final boolean batch) {
if (!(o instanceof PluginInfo)) return false;
final PluginInfo info = (PluginInfo) o;
return remove(info, info.getPluginType(), batch);
}
}