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package org.apache.tomcat.util.digester;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* <p><code>Rules</code> <em>Decorator</em> that returns default rules
* when no matches are returned by the wrapped implementation.</p>
*
* <p>This allows default <code>Rule</code> instances to be added to any
* existing <code>Rules</code> implementation. These default <code>Rule</code>
* instances will be returned for any match for which the wrapped
* implementation does not return any matches.</p>
* <p> For example,
* <pre>
* Rule alpha;
* ...
* WithDefaultsRulesWrapper rules = new WithDefaultsRulesWrapper(new BaseRules());
* rules.addDefault(alpha);
* ...
* digester.setRules(rules);
* ...
* </pre>
* when a pattern does not match any other rule, then rule alpha will be called.
* </p>
* <p><code>WithDefaultsRulesWrapper</code> follows the <em>Decorator</em> pattern.</p>
*
* @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<Rule> defaultRules = new ArrayList<Rule>();
/** All rules (preserves order in which they were originally added) */
private List<Rule> allRules = new ArrayList<Rule>();
// --------------------------------------------------------- Constructor
/**
* Base constructor.
*
* @param wrappedRules the wrapped <code>Rules</code> implementation, not null
* @throws IllegalArgumentException when <code>wrappedRules</code> 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 */
public Digester getDigester() {
return wrappedRules.getDigester();
}
/** Sets digeseter using these Rules */
public void setDigester(Digester digester) {
wrappedRules.setDigester(digester);
Iterator<Rule> it = defaultRules.iterator();
while (it.hasNext()) {
Rule rule = it.next();
rule.setDigester(digester);
}
}
/** Gets namespace to apply to Rule's added */
public String getNamespaceURI() {
return wrappedRules.getNamespaceURI();
}
/** Sets namespace to apply to Rule's added subsequently */
public void setNamespaceURI(String namespaceURI) {
wrappedRules.setNamespaceURI(namespaceURI);
}
/** Gets Rule's which will be fired when the wrapped implementation returns no matches */
public List<Rule> getDefaults() {
return defaultRules;
}
// --------------------------------------------------------- Public Methods
/**
* Return list of rules matching given pattern.
* If wrapped implementation returns any matches return those.
* Otherwise, return default matches.
*/
public List<Rule> match(String namespaceURI, String pattern) {
List<Rule> matches = wrappedRules.match(namespaceURI, pattern);
if (matches == null || matches.isEmpty()) {
// a little bit of defensive programming
return new ArrayList<Rule>(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 */
public List<Rule> rules() {
return allRules;
}
/** Clears all Rule's */
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.
*/
public void add(String pattern, Rule rule) {
wrappedRules.add(pattern, rule);
allRules.add(rule);
}
}