package org.apache.bcel.classfile;

/* ====================================================================
 * The Apache Software License, Version 1.1
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 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
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 *    notice, this list of conditions and the following disclaimer.
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 *    distribution.
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 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 *    "Apache BCEL" must not be used to endorse or promote products
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

/**
 * Unknown (non-standard) attributes may be read via user-defined factory
 * objects that can be registered with the Attribute.addAttributeReader
 * method. These factory objects should implement this interface.

 * @see Attribute
 * @version $Id: AttributeReader.java,v 1.3 2002/07/11 19:39:04 mdahm Exp $
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 */
public interface AttributeReader {
  /**
     When this attribute reader is added via the static method
     Attribute.addAttributeReader, an attribute name is associated with it.
     As the class file parser parses attributes, it will call various
     AttributeReaders based on the name of the attributes it is
     constructing.

     @param name_index An index into the constant pool, indexing a
     ConstantUtf8 that represents the name of the attribute.

     @param length The length of the data contained in the attribute.  This
     is written into the constant pool and should agree with what the
     factory expects the length to be.

     @param file This is the data input stream that the factory needs to read
     its data from.

     @param constant_pool This is the constant pool associated with the
     Attribute that we are constructing.

     @return The user-defined AttributeReader should take this data and use
     it to construct an attribute.  In the case of errors, a null can be
     returned which will cause the parsing of the class file to fail.

     @see Attribute#addAttributeReader( String, AttributeReader )
  */
  public Attribute createAttribute(int name_index, 
				   int length,
				   java.io.DataInputStream file,
				   ConstantPool constant_pool);
}