    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
    018package org.apache.bcel.classfile;
    019
    020/**
    021 * Unknown (non-standard) attributes may be read via user-defined factory objects that can be registered with the
    022 * Attribute.addAttributeReader method. These factory objects should implement this interface.
    023 *
    024 * @see Attribute
    025 * @since 6.0
    026 */
    027public interface UnknownAttributeReader {
    028
    029    /**
    030     * When this attribute reader is added via the static method Attribute.addAttributeReader, an attribute name is
    031     * associated with it. As the class file parser parses attributes, it will call various AttributeReaders based on the
    032     * name of the attributes it is constructing.
    033     *
    034     * @param nameIndex An index into the constant pool, indexing a ConstantUtf8 that represents the name of the attribute.
    035     * @param length The length of the data contained in the attribute. This is written into the constant pool and should
    036     *        agree with what the factory expects the length to be.
    037     * @param file This is the data input that the factory needs to read its data from.
    038     * @param constantPool This is the constant pool associated with the Attribute that we are constructing.
    039     *
    040     * @return The user-defined AttributeReader should take this data and use it to construct an attribute. In the case of
    041     *         errors, a null can be returned which will cause the parsing of the class file to fail.
    042     *
    043     * @see Attribute#addAttributeReader(String, UnknownAttributeReader)
    044     */
    045    Attribute createAttribute(int nameIndex, int length, java.io.DataInput file, ConstantPool constantPool);
    046}