/*
 * $Header: /cvshome/build/org.osgi.framework/src/org/osgi/framework/Filter.java,v 1.16 2007/02/21 16:49:05 hargrave Exp $
 * 
 * Copyright (c) OSGi Alliance (2000, 2007). All Rights Reserved.
 * 
 * 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.osgi.framework;

import java.util.Dictionary;

/**
 * An RFC 1960-based Filter.
 * <p>
 * <code>Filter</code> objects can be created by calling
 * {@link BundleContext#createFilter} with the chosen filter string.
 * <p>
 * A <code>Filter</code> object can be used numerous times to determine if the
 * match argument matches the filter string that was used to create the
 * <code>Filter</code> object.
 * <p>
 * Some examples of LDAP filters are:
 * 
 * <pre>
 *  &quot;(cn=Babs Jensen)&quot;
 *  &quot;(!(cn=Tim Howes))&quot;
 *  &quot;(&amp;(&quot; + Constants.OBJECTCLASS + &quot;=Person)(|(sn=Jensen)(cn=Babs J*)))&quot;
 *  &quot;(o=univ*of*mich*)&quot;
 * </pre>
 * 
 * @since 1.1
 * @see "Core Specification, section 5.5, for a description of the filter string
 *      syntax."
 * @ThreadSafe
 * @version $Revision: 1.16 $
 */
public interface Filter {
	/**
	 * Filter using a service's properties.
	 * <p>
	 * The filter is executed using the keys and values of the referenced
	 * service's properties. The keys are case insensitively matched with the
	 * filter.
	 * 
	 * @param reference The reference to the service whose properties are used
	 *        in the match.
	 * 
	 * @return <code>true</code> if the service's properties match this
	 *         filter; <code>false</code> otherwise.
	 */
	public boolean match(ServiceReference reference);

	/**
	 * Filter using a <code>Dictionary</code> object. The Filter is executed
	 * using the <code>Dictionary</code> object's keys and values. The keys
	 * are case insensitively matched with the filter.
	 * 
	 * @param dictionary The <code>Dictionary</code> object whose keys are
	 *        used in the match.
	 * 
	 * @return <code>true</code> if the <code>Dictionary</code> object's
	 *         keys and values match this filter; <code>false</code>
	 *         otherwise.
	 * 
	 * @throws IllegalArgumentException If <code>dictionary</code> contains
	 *         case variants of the same key name.
	 */
	public boolean match(Dictionary dictionary);

	/**
	 * Returns this <code>Filter</code> object's filter string.
	 * <p>
	 * The filter string is normalized by removing whitespace which does not
	 * affect the meaning of the filter.
	 * 
	 * @return Filter string.
	 */
	public String toString();

	/**
	 * Compares this <code>Filter</code> object to another object.
	 * 
	 * @param obj The object to compare against this <code>Filter</code>
	 *        object.
	 * 
	 * @return If the other object is a <code>Filter</code> object, then
	 *         returns <code>this.toString().equals(obj.toString()</code>;<code>false</code>
	 *         otherwise.
	 */
	public boolean equals(Object obj);

	/**
	 * Returns the hashCode for this <code>Filter</code> object.
	 * 
	 * @return The hashCode of the filter string; that is,
	 *         <code>this.toString().hashCode()</code>.
	 */
	public int hashCode();

	/**
	 * Filter with case sensitivity using a <code>Dictionary</code> object.
	 * The Filter is executed using the <code>Dictionary</code> object's keys
	 * and values. The keys are case sensitively matched with the filter.
	 * 
	 * @param dictionary The <code>Dictionary</code> object whose keys are
	 *        used in the match.
	 * 
	 * @return <code>true</code> if the <code>Dictionary</code> object's
	 *         keys and values match this filter; <code>false</code>
	 *         otherwise.
	 * 
	 * @since 1.3
	 */
	public boolean matchCase(Dictionary dictionary);
}