001/* $Id: AbstractRulesImpl.java 471661 2006-11-06 08:09:25Z skitching $
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one or more
004 * contributor license agreements.  See the NOTICE file distributed with
005 * this work for additional information regarding copyright ownership.
006 * The ASF licenses this file to You under the Apache License, Version 2.0
007 * (the "License"); you may not use this file except in compliance with
008 * the License.  You may obtain a copy of the License at
009 * 
010 *      http://www.apache.org/licenses/LICENSE-2.0
011 * 
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */ 
018
019
020package org.apache.commons.digester;
021
022
023import java.util.List;
024
025
026/**
027 * <p><code>AbstractRuleImpl</code> provides basic services for <code>Rules</code> implementations.
028 * Extending this class should make it easier to create a <code>Rules</code> implementation.</p>
029 * 
030 * <p><code>AbstractRuleImpl</code> manages the <code>Digester</code> 
031 * and <code>namespaceUri</code> properties.
032 * If the subclass overrides {@link #registerRule} (rather than {@link #add}),
033 * then the <code>Digester</code> and <code>namespaceURI</code> of the <code>Rule</code>
034 * will be set correctly before it is passed to <code>registerRule</code>.
035 * The subclass can then perform whatever it needs to do to register the rule.</p>
036 *
037 * @since 1.5
038 */
039
040abstract public class AbstractRulesImpl implements Rules {
041
042    // ------------------------------------------------------------- Fields
043    
044    /** Digester using this <code>Rules</code> implementation */
045    private Digester digester;
046    /** Namespace uri to assoicate with subsequent <code>Rule</code>'s */
047    private String namespaceURI;
048    
049    // ------------------------------------------------------------- Properties
050
051    /**
052     * Return the Digester instance with which this Rules instance is
053     * associated.
054     */
055    public Digester getDigester() {
056        return digester;
057    }
058
059    /**
060     * Set the Digester instance with which this Rules instance is associated.
061     *
062     * @param digester The newly associated Digester instance
063     */
064    public void setDigester(Digester digester) {
065        this.digester = digester;
066    }
067
068    /**
069     * Return the namespace URI that will be applied to all subsequently
070     * added <code>Rule</code> objects.
071     */
072    public String getNamespaceURI() {
073        return namespaceURI;
074    }
075
076    /**
077     * Set the namespace URI that will be applied to all subsequently
078     * added <code>Rule</code> objects.
079     *
080     * @param namespaceURI Namespace URI that must match on all
081     *  subsequently added rules, or <code>null</code> for matching
082     *  regardless of the current namespace URI
083     */
084    public void setNamespaceURI(String namespaceURI) {
085        this.namespaceURI = namespaceURI;
086    }
087
088    // --------------------------------------------------------- Public Methods
089
090    /**
091     * Registers a new Rule instance matching the specified pattern.
092     * This implementation sets the <code>Digester</code> and the
093     * <code>namespaceURI</code> on the <code>Rule</code> before calling {@link #registerRule}.
094     *
095     * @param pattern Nesting pattern to be matched for this Rule
096     * @param rule Rule instance to be registered
097     */
098    public void add(String pattern, Rule rule) {
099        // set up rule
100        if (this.digester != null) {
101            rule.setDigester(this.digester);
102        }
103        
104        if (this.namespaceURI != null) {
105            rule.setNamespaceURI(this.namespaceURI);
106        }
107        
108        registerRule(pattern, rule);
109        
110    }
111    
112    /** 
113     * Register rule at given pattern.
114     * The the Digester and namespaceURI properties of the given <code>Rule</code>
115     * can be assumed to have been set properly before this method is called.
116     *
117     * @param pattern Nesting pattern to be matched for this Rule
118     * @param rule Rule instance to be registered
119     */ 
120    abstract protected void registerRule(String pattern, Rule rule);
121
122    /**
123     * Clear all existing Rule instance registrations.
124     */
125    abstract public void clear();
126
127
128    /**
129     * Return a List of all registered Rule instances that match the specified
130     * nesting pattern, or a zero-length List if there are no matches.  If more
131     * than one Rule instance matches, they <strong>must</strong> be returned
132     * in the order originally registered through the <code>add()</code>
133     * method.
134     *
135     * @param pattern Nesting pattern to be matched
136     *
137     * @deprecated Call match(namespaceURI,pattern) instead.
138     */
139    public List match(String pattern) {
140        return match(namespaceURI, pattern);
141    }
142
143
144    /**
145     * Return a List of all registered Rule instances that match the specified
146     * nesting pattern, or a zero-length List if there are no matches.  If more
147     * than one Rule instance matches, they <strong>must</strong> be returned
148     * in the order originally registered through the <code>add()</code>
149     * method.
150     *
151     * @param namespaceURI Namespace URI for which to select matching rules,
152     *  or <code>null</code> to match regardless of namespace URI
153     * @param pattern Nesting pattern to be matched
154     */
155    abstract public List match(String namespaceURI, String pattern);
156
157
158    /**
159     * Return a List of all registered Rule instances, or a zero-length List
160     * if there are no registered Rule instances.  If more than one Rule
161     * instance has been registered, they <strong>must</strong> be returned
162     * in the order originally registered through the <code>add()</code>
163     * method.
164     */
165    abstract public List rules();
166
167}