org.apache.tomcat.util.digester.WithDefaultsRulesWrapper Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.tomcat.util.digester;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* Rules Decorator that returns default rules
* when no matches are returned by the wrapped implementation.
*
* This allows default Rule instances to be added to any
* existing Rules implementation. These default Rule
* instances will be returned for any match for which the wrapped
* implementation does not return any matches.
* For example,
*
* Rule alpha;
* ...
* WithDefaultsRulesWrapper rules = new WithDefaultsRulesWrapper(new BaseRules());
* rules.addDefault(alpha);
* ...
* digester.setRules(rules);
* ...
*
* when a pattern does not match any other rule, then rule alpha will be called.
*
* WithDefaultsRulesWrapper follows the Decorator pattern.
*
* @since 1.6
*/
public class WithDefaultsRulesWrapper implements Rules {
// --------------------------------------------------------- Fields
/** The Rules implementation that this class wraps. */
private Rules wrappedRules;
/** Rules to be fired when the wrapped implementations returns none. */
private List defaultRules = new ArrayList();
/** All rules (preserves order in which they were originally added) */
private List allRules = new ArrayList();
// --------------------------------------------------------- Constructor
/**
* Base constructor.
*
* @param wrappedRules the wrapped Rules implementation, not null
* @throws IllegalArgumentException when wrappedRules is null
*/
public WithDefaultsRulesWrapper(Rules wrappedRules) {
if (wrappedRules == null) {
throw new IllegalArgumentException("Wrapped rules must not be null");
}
this.wrappedRules = wrappedRules;
}
// --------------------------------------------------------- Properties
/** Gets digester using these Rules */
@Override
public Digester getDigester() {
return wrappedRules.getDigester();
}
/** Sets digester using these Rules */
@Override
public void setDigester(Digester digester) {
wrappedRules.setDigester(digester);
Iterator it = defaultRules.iterator();
while (it.hasNext()) {
Rule rule = it.next();
rule.setDigester(digester);
}
}
/** Gets namespace to apply to Rule's added */
@Override
public String getNamespaceURI() {
return wrappedRules.getNamespaceURI();
}
/** Sets namespace to apply to Rule's added subsequently */
@Override
public void setNamespaceURI(String namespaceURI) {
wrappedRules.setNamespaceURI(namespaceURI);
}
/** Gets Rule's which will be fired when the wrapped implementation returns no matches */
public List getDefaults() {
return defaultRules;
}
// --------------------------------------------------------- Public Methods
/**
* Return list of rules matching given pattern.
* If wrapped implementation returns any matches return those.
* Otherwise, return default matches.
*/
@Override
public List match(String namespaceURI, String pattern) {
List matches = wrappedRules.match(namespaceURI, pattern);
if (matches == null || matches.isEmpty()) {
// a little bit of defensive programming
return new ArrayList(defaultRules);
}
// otherwise
return matches;
}
/** Adds a rule to be fired when wrapped implementation returns no matches */
public void addDefault(Rule rule) {
// set up rule
if (wrappedRules.getDigester() != null) {
rule.setDigester(wrappedRules.getDigester());
}
if (wrappedRules.getNamespaceURI() != null) {
rule.setNamespaceURI(wrappedRules.getNamespaceURI());
}
defaultRules.add(rule);
allRules.add(rule);
}
/** Gets all rules */
@Override
public List rules() {
return allRules;
}
/** Clears all Rule's */
@Override
public void clear() {
wrappedRules.clear();
allRules.clear();
defaultRules.clear();
}
/**
* Adds a Rule to be fired on given pattern.
* Pattern matching is delegated to wrapped implementation.
*/
@Override
public void add(String pattern, Rule rule) {
wrappedRules.add(pattern, rule);
allRules.add(rule);
}
}