/*
 * Copyright 2002-2005 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.metadata.support;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import org.springframework.metadata.Attributes;

/**
 * Convenient superclass for Attributes implementations.
 * Implements filtering and saves attribute packages.
 *
 * <p>TODO could implement caching here for efficiency,
 * or add a caching decorator (probably a better idea).
 *
 * @author Rod Johnson
 */
public abstract class AbstractAttributes implements Attributes {
	
	/**
	 * @see org.springframework.metadata.Attributes#getAttributes(java.lang.Class, java.lang.Class)
	 */
	public final Collection getAttributes(Class targetClass, Class filter) {
		return filter(getAttributes(targetClass), filter);
	}

	/**
	 * Filter these attributes to those matching the filter type
	 */
	private Collection filter(Collection coll, Class filter) {
		if (filter == null) {
			return coll;
		}

		List matches = new LinkedList();
		for (Iterator it = coll.iterator(); it.hasNext(); ) {
			Object next = it.next();
			if (filter.isInstance(next)) {
				matches.add(next);
			}
		}
		return matches;
	}

	/**
	 * @see org.springframework.metadata.Attributes#getAttributes(java.lang.reflect.Method, java.lang.Class)
	 */
	public final Collection getAttributes(Method targetMethod, Class filter) {
		return filter(getAttributes(targetMethod), filter);
	}

	/**
	 * @see org.springframework.metadata.Attributes#getAttributes(java.lang.reflect.Field, java.lang.Class)
	 */
	public final Collection getAttributes(Field targetField, Class filter) {
		return filter(getAttributes(targetField), filter);
	}

}