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
015package org.apache.tapestry.util.xml;
016
017import 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
032public 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}