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
021     * {@link org.apache.tapestry.util.xml.RuleDirectedParser}'s rule stack. A rule
022     * is associated with an XML element. It is pushed onto the stack when the open
023     * tag for the rule is encountered. It is is popped off the stack after the
024     * end-tag is encountered. It is notified about any text it directly wraps
025     * around.
026     * <p>
027     * Rules should be stateless, because a rule instance may appear multiple times
028     * in the rule stack (if elements can be recusively nested).
029     * 
030     * @author Howard Lewis Ship
031     * @since 3.0
032     */
033    
034    public interface IRule
035    {
036    
037        /**
038         * Invoked just after the rule is pushed onto the rule stack. Typically, a
039         * Rule will use the information to create a new object and push it onto the
040         * object stack. If the rule needs to know about the element (rather than
041         * the attributes), it may obtain the URI, localName and qName from the
042         * parser.
043         */
044        void startElement(RuleDirectedParser parser, Attributes attributes);
045    
046        /**
047         * Invoked just after the rule is popped off the rule stack.
048         */
049        void endElement(RuleDirectedParser parser);
050    
051        /**
052         * Invoked when real content is found. The parser is responsible for
053         * aggregating all content provided by the underlying SAX parser into a
054         * single string.
055         */
056    
057        void content(RuleDirectedParser parser, String content);
058    }