- /* $Id: PluginRules.java,v 1.17 2004/05/10 06:44:13 skitching Exp $
- *
- * Copyright 2003-2004 The Apache Software Foundation.
- *
- * 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.apache.commons.digester.plugins;
-
- import java.util.ArrayList;
- import java.util.Iterator;
- import java.util.List;
- import java.util.ListIterator;
-
- import java.util.Map;
- import java.util.HashMap;
- import java.util.TreeMap;
- import java.util.Comparator;
-
- import org.apache.commons.digester.Digester;
- import org.apache.commons.digester.Rule;
- import org.apache.commons.digester.Rules;
- import org.apache.commons.digester.RulesBase;
- import org.apache.commons.logging.Log;
-
- /**
- * A custom digester Rules manager which must be used as the Rules object
- * when using the plugins module functionality.
- * <p>
- * During parsing, a linked list of PluginCreateRule instances develop, and
- * this list also acts like a stack. The original instance that was set before
- * the Digester started parsing is always at the tail of the list, and the
- * Digester always holds a reference to the instance at the head of the list
- * in the rules member. Initially, this list/stack holds just one instance,
- * ie head and tail are the same object.
- * <p>
- * When the start of an xml element causes a PluginCreateRule to fire, a new
- * PluginRules instance is created and inserted at the head of the list (ie
- * pushed onto the stack of Rules objects). Digester.getRules() therefore
- * returns this new Rules object, and any custom rules associated with that
- * plugin are added to that instance.
- * <p>
- * When the end of the xml element is encountered (and therefore the
- * PluginCreateRule end method fires), the stack of Rules objects is popped,
- * so that Digester.getRules returns the previous Rules object.
- *
- * @since 1.6
- */
-
- public class PluginRules implements Rules {
-
- /**
- * The Digester instance with which this Rules instance is associated.
- */
- protected Digester digester = null;
-
- /**
- * The rules implementation that we are "enhancing" with plugins
- * functionality, as per the Decorator pattern.
- */
- private Rules decoratedRules;
-
- /** Object which contains information about all known plugins. */
- private PluginManager pluginManager;
-
- /**
- * The path below which this rules object has responsibility.
- * For paths shorter than or equal the mountpoint, the parent's
- * match is called.
- */
- private String mountPoint = null;
-
- /**
- * The Rules object that holds rules applying "above" the mountpoint,
- * ie the next Rules object down in the stack.
- */
- private PluginRules parent = null;
-
- /**
- * A reference to the object that holds all data which should only
- * exist once per digester instance.
- */
- private PluginContext pluginContext = null;
-
- // ------------------------------------------------------------- Constructor
-
- /**
- * Constructor for top-level Rules objects. Exactly one of these must
- * be created and installed into the Digester instance as the Rules
- * object before parsing starts.
- */
- public PluginRules() {
- this(new RulesBase());
- }
-
- /**
- * Constructor for top-level Rules object which handles rule-matching
- * using the specified implementation.
- */
- public PluginRules(Rules decoratedRules) {
- this.decoratedRules = decoratedRules;
-
- pluginContext = new PluginContext();
- pluginManager = new PluginManager(pluginContext);
- }
-
- /**
- * Constructs a Rules instance which has a parent Rules object
- * (which is different from having a delegate rules object).
- * <p>
- * One of these is created each time a PluginCreateRule's begin method
- * fires, in order to manage the custom rules associated with whatever
- * concrete plugin class the user has specified.
- *
- * @param mountPoint is the digester match path for the element
- * matching a PluginCreateRule which caused this "nested parsing scope"
- * to begin.
- * @param parent must be non-null.
- */
- PluginRules(String mountPoint, PluginRules parent) {
- // no need to set digester or decoratedRules.digester,
- // because when Digester.setRules is called, the setDigester
- // method on this object will be called.
-
- decoratedRules = new RulesBase();
- pluginContext = parent.pluginContext;
- pluginManager = new PluginManager(parent.pluginManager);
-
- this.mountPoint = mountPoint;
- this.parent = parent;
- }
-
- // ------------------------------------------------------------- Properties
-
- /**
- * Return the parent Rules object.
- */
- public Rules getParent() {
- return parent;
- }
-
- /**
- * Return the Digester instance with which this instance is associated.
- */
- public Digester getDigester() {
- return digester;
- }
-
- /**
- * Set the Digester instance with which this Rules instance is associated.
- *
- * @param digester The newly associated Digester instance
- */
- public void setDigester(Digester digester) {
- this.digester = digester;
- decoratedRules.setDigester(digester);
- }
-
- /**
- * Return the namespace URI that will be applied to all subsequently
- * added <code>Rule</code> objects.
- */
- public String getNamespaceURI() {
- return decoratedRules.getNamespaceURI();
- }
-
- /**
- * Set the namespace URI that will be applied to all subsequently
- * added <code>Rule</code> objects.
- *
- * @param namespaceURI Namespace URI that must match on all
- * subsequently added rules, or <code>null</code> for matching
- * regardless of the current namespace URI
- */
- public void setNamespaceURI(String namespaceURI) {
- decoratedRules.setNamespaceURI(namespaceURI);
- }
-
- /**
- * Return the object which "knows" about all declared plugins.
- *
- * @return The pluginManager value
- */
- public PluginManager getPluginManager() {
- return pluginManager;
- }
-
- /**
- * See {@link PluginContext#getRuleFinders}.
- */
- public List getRuleFinders() {
- return pluginContext.getRuleFinders();
- }
-
- /**
- * See {@link PluginContext#setRuleFinders}.
- */
- public void setRuleFinders(List ruleFinders) {
- pluginContext.setRuleFinders(ruleFinders);
- }
-
- // --------------------------------------------------------- Public Methods
-
- /**
- * This package-scope method is used by the PluginCreateRule class to
- * get direct access to the rules that were dynamically added by the
- * plugin. No other class should need access to this object.
- */
- Rules getDecoratedRules() {
- return decoratedRules;
- }
-
- /**
- * Return the list of rules registered with this object, in the order
- * they were registered with this object.
- * <p>
- * Note that Rule objects stored in parent Rules objects are not
- * returned by this method.
- *
- * @return list of all Rule objects known to this Rules instance.
- */
- public List rules() {
- return decoratedRules.rules();
- }
-
- /**
- * Register a new Rule instance matching the specified pattern.
- *
- * @param pattern Nesting pattern to be matched for this Rule.
- * This parameter treats equally patterns that begin with and without
- * a leading slash ('/').
- * @param rule Rule instance to be registered
- */
- public void add(String pattern, Rule rule) {
- Log log = LogUtils.getLogger(digester);
- boolean debug = log.isDebugEnabled();
-
- if (debug) {
- log.debug("add entry" + ": mapping pattern [" + pattern + "]" +
- " to rule of type [" + rule.getClass().getName() + "]");
- }
-
- // allow patterns with a leading slash character
- if (pattern.startsWith("/"))
- {
- pattern = pattern.substring(1);
- }
-
- if (mountPoint != null) {
- if (!pattern.equals(mountPoint)
- && !pattern.startsWith(mountPoint + "/")) {
- // This can only occur if a plugin attempts to add a
- // rule with a pattern that doesn't start with the
- // prefix passed to the addRules method. Plugins mustn't
- // add rules outside the scope of the tag they were specified
- // on, so refuse this.
-
- // alas, can't throw exception
- log.warn(
- "An attempt was made to add a rule with a pattern that"
- + "is not at or below the mountpoint of the current"
- + " PluginRules object."
- + " Rule pattern: " + pattern
- + ", mountpoint: " + mountPoint
- + ", rule type: " + rule.getClass().getName());
- return;
- }
- }
-
- decoratedRules.add(pattern, rule);
-
- if (rule instanceof InitializableRule) {
- try {
- ((InitializableRule)rule).postRegisterInit(pattern);
- } catch (PluginConfigurationException e) {
- // Currently, Digester doesn't handle exceptions well
- // from the add method. The workaround is for the
- // initialisable rule to remember that its initialisation
- // failed, and to throw the exception when begin is
- // called for the first time.
- if (debug) {
- log.debug("Rule initialisation failed", e);
- }
- // throw e; -- alas, can't do this
- return;
- }
- }
-
- if (debug) {
- log.debug("add exit" + ": mapped pattern [" + pattern + "]" +
- " to rule of type [" + rule.getClass().getName() + "]");
- }
- }
-
- /**
- * Clear all rules.
- */
- public void clear() {
- decoratedRules.clear();
- }
-
- /**
- * Return a List of all registered Rule instances that match the specified
- * nesting pattern, or a zero-length List if there are no matches. If more
- * than one Rule instance matches, they <strong>must</strong> be returned
- * in the order originally registered through the <code>add()</code>
- * method.
- *
- * @param path the path to the xml nodes to be matched.
- *
- * @deprecated Call match(namespaceURI,pattern) instead.
- */
- public List match(String path) {
- return (match(null, path));
- }
-
- /**
- * Return a List of all registered Rule instances that match the specified
- * nodepath, or a zero-length List if there are no matches. If more
- * than one Rule instance matches, they <strong>must</strong> be returned
- * in the order originally registered through the <code>add()</code>
- * method.
- * <p>
- * @param namespaceURI Namespace URI for which to select matching rules,
- * or <code>null</code> to match regardless of namespace URI
- * @param path the path to the xml nodes to be matched.
- */
- public List match(String namespaceURI, String path) {
- Log log = LogUtils.getLogger(digester);
- boolean debug = log.isDebugEnabled();
-
- if (debug) {
- log.debug(
- "Matching path [" + path +
- "] on rules object " + this.toString());
- }
-
- List matches;
- if ((mountPoint != null) &&
- (path.length() <= mountPoint.length())) {
- if (debug) {
- log.debug(
- "Path [" + path + "] delegated to parent.");
- }
-
- matches = parent.match(namespaceURI, path);
-
- // Note that in the case where path equals mountPoint,
- // we deliberately return only the rules from the parent,
- // even though this object may hold some rules matching
- // this same path. See PluginCreateRule's begin, body and end
- // methods for the reason.
- } else {
- matches = decoratedRules.match(namespaceURI, path);
- }
-
- return matches;
- }
-
- /** See {@link PluginContext#setPluginClassAttribute}. */
- public void setPluginClassAttribute(String namespaceUri,
- String attrName) {
- pluginContext.setPluginClassAttribute(namespaceUri, attrName);
- }
-
- /** See {@link PluginContext#setPluginIdAttribute}. */
- public void setPluginIdAttribute(String namespaceUri,
- String attrName) {
- pluginContext.setPluginIdAttribute(namespaceUri, attrName);
- }
-
- /** See {@link PluginContext#getPluginClassAttrNs}. */
- public String getPluginClassAttrNs() {
- return pluginContext.getPluginClassAttrNs();
- }
-
- /** See {@link PluginContext#getPluginClassAttr}. */
- public String getPluginClassAttr() {
- return pluginContext.getPluginClassAttr();
- }
-
- /** See {@link PluginContext#getPluginIdAttrNs}. */
- public String getPluginIdAttrNs() {
- return pluginContext.getPluginIdAttrNs();
- }
-
- /** See {@link PluginContext#getPluginIdAttr}. */
- public String getPluginIdAttr() {
- return pluginContext.getPluginIdAttr();
- }
- }