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The basic runtime tools and interfaces for intarsys components.

There is a newer version: 4.11

package de.intarsys.tools.tree;

import java.util.HashMap;
import java.util.Map;
import java.util.WeakHashMap;

import de.intarsys.tools.attribute.Attribute;

/**
 * The common implementation of a {@link CommonNode} factory.
 * 
 * This implementation ensures uniqueness of an object->node association within
 * the parent node. This means within a given parent context, the node returned
 * for a given object is always the same.
 * 

 * While all factories have their own way of creating a node based on the POJO,
 * they all share the ability to "fine tune" the node creation in a certain
 * context (role).
 * 
 * For fine tuning node creation, just register some other node factories using
 * "registerFactory". Upon creation of a node for this specific role, all
 * registered factories are searched if there is a more specific one for the
 * creation based on the objects's class.
 * 
 * @param 
 */
abstract public class CommonNodeFactory {

	private Map, CommonNodeFactory> children;

	final private Map nodeMap = new WeakHashMap();

	final private Attribute attrNodeMap = new Attribute("nodeMap");

	protected CommonNodeFactory() {
		super();
	}

	abstract public T createNode(CommonNode parent, Object object);

	synchronized public CommonNodeFactory lookupFactory(Object object) {
		if (children == null) {
			return this;
		}
		Class clazz = object.getClass();
		while (clazz != null) {
			CommonNodeFactory factory = children.get(clazz);
			if (factory != null) {
				return factory;
			}
			clazz = clazz.getSuperclass();
		}
		return this;
	}

	synchronized public CommonNode lookupNode(CommonNode parent, Object object) {
		if (parent == null) {
			return nodeMap.get(object);
		}
		// we make a lookup per role (attrNodeMap is instance scope)
		// do not move this to CommonNode
		Map tempNodeMap = (Map) parent
				.getAttribute(attrNodeMap);
		if (tempNodeMap == null) {
			return null;
		}
		return tempNodeMap.get(object);
	}

	synchronized public void registerFactory(Class clazz,
			CommonNodeFactory factory) {
		if (children == null) {
			children = new HashMap, CommonNodeFactory>();
		}
		children.put(clazz, factory);
	}

	synchronized public void registerNode(CommonNode parent, CommonNode node) {
		if (parent == null) {
			nodeMap.put(node.getObject(), node);
		} else {
			// we make a registration per role (attrNodeMap is instance scope)
			// do not move this to CommonNode
			Map tempNodeMap = (Map) parent
					.getAttribute(attrNodeMap);
			if (tempNodeMap == null) {
				tempNodeMap = new WeakHashMap();
				parent.setAttribute(attrNodeMap, tempNodeMap);
			}
			tempNodeMap.put(node.getObject(), node);
		}
	}

}