PluginRepository.java

package org.dcache.gplazma.loader;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * PluginRepository is a container class that provides information about zero
 * or more plugins. For each plugin, a {@link PluginMetadata} object is
 * stored, which stores the static metadata for this plugin.
 * <p>
 * The class allows the discovery of the number of stored plugins, discovery
 * of a plugin by name and support an arbitrary processing of stored plugins
 * via the PluginMetadataProcessor interface.
 */
public class PluginRepository
{
    private final Set<PluginMetadata> _plugins = new HashSet<>();

    private final Map<String, PluginMetadata> _pluginByName =
            new HashMap<>();

    public void addPlugin(PluginMetadata metadata)
    {
        _plugins.add(metadata);

        for( String name : metadata.getPluginNames()) {
            _pluginByName.put(name, metadata);
        }
    }


    public boolean hasPluginWithName(String name)
    {
        return _pluginByName.containsKey(name);
    }


    public PluginMetadata getPlugin(String name) throws PluginLoadingException
    {
        PluginMetadata metadata = _pluginByName.get(name);

        if(metadata == null) {
            throw new PluginLoadingException("no such plugin");
        }

        return metadata;
    }

    public void processPluginsWith(PluginMetadataProcessor processor)
    {
        for( PluginMetadata plugin : _plugins) {
            processor.process( plugin);
        }
    }

    public int size()
    {
        return _plugins.size();
    }

    /**
     * Classes that implement this method accept each stored PluginMetadata,
     * one at a time, allowing arbitrary processing of that plugin's static
     * metadata.
     */
    public interface PluginMetadataProcessor
    {
        void process(PluginMetadata plugin);
    }
}