001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.util.xml;
016    
017    import org.xml.sax.Attributes;
018    
019    /**
020     * A rule that may be pushed onto the {@link org.apache.tapestry.util.xml.RuleDirectedParser}'s
021     * rule stack.  A rule is associated with an XML element.  It is pushed onto the stack when the
022     * open tag for the rule is encountered.  It is is popped off the stack after the end-tag is
023     * encountered.  It is notified about any text it directly wraps around.
024     * 
025     * <p>Rules should be stateless, because a rule instance may appear multiple times in the
026     * rule stack (if elements can be recusively nested).
027     *
028     * @author Howard Lewis Ship
029     * @since 3.0
030     **/
031    
032    public interface IRule
033    {
034            /**
035             * Invoked just after the rule is pushed onto the rule stack.  Typically, a Rule will
036             *  use the information to create a new object and push it onto the object stack.
037             *  If the rule needs to know about the element (rather than the attributes), it
038             *  may obtain the URI, localName and qName from the parser.
039             * 
040             */
041            public void startElement(RuleDirectedParser parser, Attributes attributes);
042            
043            /**
044             * Invoked just after the rule is popped off the rule stack.
045             */
046            public void endElement(RuleDirectedParser parser);
047            
048            
049            /**
050             * Invoked when real content is found.  The parser is responsible for aggregating
051             * all content provided by the underlying SAX parser into a single string.
052             */
053            
054            public void content(RuleDirectedParser parser, String content);
055    }