001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     *  Unless required by applicable law or agreed to in writing, software
012     *  distributed under the License is distributed on an "AS IS" BASIS,
013     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     *  See the License for the specific language governing permissions and
015     *  limitations under the License.
016     *
017     */
018    package org.apache.bcel.classfile;
019    
020    /**
021     * Unknown (non-standard) attributes may be read via user-defined factory
022     * objects that can be registered with the Attribute.addAttributeReader
023     * method. These factory objects should implement this interface.
024    
025     * @see Attribute
026     * @version $Id: AttributeReader.java 1158060 2011-08-15 23:17:19Z dbrosius $
027     * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
028     */
029    public interface AttributeReader {
030    
031        /**
032         When this attribute reader is added via the static method
033         Attribute.addAttributeReader, an attribute name is associated with it.
034         As the class file parser parses attributes, it will call various
035         AttributeReaders based on the name of the attributes it is
036         constructing.
037    
038         @param name_index An index into the constant pool, indexing a
039         ConstantUtf8 that represents the name of the attribute.
040    
041         @param length The length of the data contained in the attribute.  This
042         is written into the constant pool and should agree with what the
043         factory expects the length to be.
044    
045         @param file This is the data input stream that the factory needs to read
046         its data from.
047    
048         @param constant_pool This is the constant pool associated with the
049         Attribute that we are constructing.
050    
051         @return The user-defined AttributeReader should take this data and use
052         it to construct an attribute.  In the case of errors, a null can be
053         returned which will cause the parsing of the class file to fail.
054    
055         @see Attribute#addAttributeReader( String, AttributeReader )
056         */
057        Attribute createAttribute( int name_index, int length, java.io.DataInputStream file,
058                ConstantPool constant_pool );
059    }