/***

  * ASM: a very small and fast Java bytecode manipulation framework

  * Copyright (c) 2000-2005 INRIA, France Telecom

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met:

  * 1. Redistributions of source code must retain the above copyright

  *    notice, this list of conditions and the following disclaimer.

  * 2. Redistributions in binary form must reproduce the above copyright

  *    notice, this list of conditions and the following disclaimer in the

  *    documentation and/or other materials provided with the distribution.

  * 3. Neither the name of the copyright holders nor the names of its

  *    contributors may be used to endorse or promote products derived from

  *    this software without specific prior written permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF

  * THE POSSIBILITY OF SUCH DAMAGE.

  */

 package clojure.asm;

 

 /**

  * A non standard class, field, method or code attribute.

  *

  * @author Eric Bruneton

  * @author Eugene Kuleshov

  */

 public class Attribute{

 

 /**

  * The type of this attribute.

  */

 public final String type;

 

 /**

  * The raw value of this attribute, used only for unknown attributes.

  */

 byte[] value;

 

 /**

  * The next attribute in this attribute list. May be <tt>null</tt>.

  */

 Attribute next;

 

 /**

  * Constructs a new empty attribute.

  *

  * @param type the type of the attribute.

  */

 protected Attribute(final String type){

 	this.type = type;

 }

 

 /**

  * Returns <tt>true</tt> if this type of attribute is unknown. The default

  * implementation of this method always returns <tt>true</tt>.

  *

  * @return <tt>true</tt> if this type of attribute is unknown.

  */

 public boolean isUnknown(){

 	return true;

 }

 

 /**

  * Returns <tt>true</tt> if this type of attribute is a code attribute.

  *

  * @return <tt>true</tt> if this type of attribute is a code attribute.

  */

 public boolean isCodeAttribute(){

 	return false;

 }

 

 /**

  * Returns the labels corresponding to this attribute.

  *

  * @return the labels corresponding to this attribute, or <tt>null</tt> if

  *         this attribute is not a code attribute that contains labels.

  */

 protected Label[] getLabels(){

 	return null;

 }

 

 /**

  * Reads a {@link #type type} attribute. This method must return a <i>new</i>

  * {@link Attribute} object, of type {@link #type type}, corresponding to

  * the <tt>len</tt> bytes starting at the given offset, in the given class

  * reader.

  *

  * @param cr      the class that contains the attribute to be read.

  * @param off     index of the first byte of the attribute's content in {@link

  *                ClassReader#b cr.b}. The 6 attribute header bytes, containing the

  *                type and the length of the attribute, are not taken into account

  *                here.

  * @param len     the length of the attribute's content.

  * @param buf     buffer to be used to call

  *                {@link ClassReader#readUTF8 readUTF8},

  *                {@link ClassReader#readClass(int,char[]) readClass} or

  *                {@link ClassReader#readConst readConst}.

  * @param codeOff index of the first byte of code's attribute content in

  *                {@link ClassReader#b cr.b}, or -1 if the attribute to be read is

  *                not a code attribute. The 6 attribute header bytes, containing the

  *                type and the length of the attribute, are not taken into account

  *                here.

  * @param labels  the labels of the method's code, or <tt>null</tt> if the

  *                attribute to be read is not a code attribute.

  * @return a <i>new</i> {@link Attribute} object corresponding to the given

  *         bytes.

  */

 protected Attribute read(

 		final ClassReader cr,

 		final int off,

 		final int len,

 		final char[] buf,

 		final int codeOff,

 		final Label[] labels){

 	Attribute attr = new Attribute(type);

 	attr.value = new byte[len];

 	System.arraycopy(cr.b, off, attr.value, 0, len);

 	return attr;

 }

 

 /**

  * Returns the byte array form of this attribute.

  *

  * @param cw        the class to which this attribute must be added. This parameter

  *                  can be used to add to the constant pool of this class the items

  *                  that corresponds to this attribute.

  * @param code      the bytecode of the method corresponding to this code

  *                  attribute, or <tt>null</tt> if this attribute is not a code

  *                  attributes.

  * @param len       the length of the bytecode of the method corresponding to this

  *                  code attribute, or <tt>null</tt> if this attribute is not a code

  *                  attribute.

  * @param maxStack  the maximum stack size of the method corresponding to

  *                  this code attribute, or -1 if this attribute is not a code

  *                  attribute.

  * @param maxLocals the maximum number of local variables of the method

  *                  corresponding to this code attribute, or -1 if this attribute is

  *                  not a code attribute.

  * @return the byte array form of this attribute.

  */

 protected ByteVector write(

 		final ClassWriter cw,

 		final byte[] code,

 		final int len,

 		final int maxStack,

 		final int maxLocals){

 	ByteVector v = new ByteVector();

 	v.data = value;

 	v.length = value.length;

 	return v;

 }

 

 /**

  * Returns the length of the attribute list that begins with this attribute.

  *

  * @return the length of the attribute list that begins with this attribute.

  */

 final int getCount(){

 	int count = 0;

 	Attribute attr = this;

 	while(attr != null)

 		{

 		count += 1;

 		attr = attr.next;

 		}

 	return count;

 }

 

 /**

  * Returns the size of all the attributes in this attribute list.

  *

  * @param cw        the class writer to be used to convert the attributes into byte

  *                  arrays, with the {@link #write write} method.

  * @param code      the bytecode of the method corresponding to these code

  *                  attributes, or <tt>null</tt> if these attributes are not code

  *                  attributes.

  * @param len       the length of the bytecode of the method corresponding to

  *                  these code attributes, or <tt>null</tt> if these attributes are

  *                  not code attributes.

  * @param maxStack  the maximum stack size of the method corresponding to

  *                  these code attributes, or -1 if these attributes are not code

  *                  attributes.

  * @param maxLocals the maximum number of local variables of the method

  *                  corresponding to these code attributes, or -1 if these attributes

  *                  are not code attributes.

  * @return the size of all the attributes in this attribute list. This size

  *         includes the size of the attribute headers.

  */

 final int getSize(

 		final ClassWriter cw,

 		final byte[] code,

 		final int len,

 		final int maxStack,

 		final int maxLocals){

 	Attribute attr = this;

 	int size = 0;

 	while(attr != null)

 		{

 		cw.newUTF8(attr.type);

 		size += attr.write(cw, code, len, maxStack, maxLocals).length + 6;

 		attr = attr.next;

 		}

 	return size;

 }

 

 /**

  * Writes all the attributes of this attribute list in the given byte

  * vector.

  *

  * @param cw        the class writer to be used to convert the attributes into byte

  *                  arrays, with the {@link #write write} method.

  * @param code      the bytecode of the method corresponding to these code

  *                  attributes, or <tt>null</tt> if these attributes are not code

  *                  attributes.

  * @param len       the length of the bytecode of the method corresponding to

  *                  these code attributes, or <tt>null</tt> if these attributes are

  *                  not code attributes.

  * @param maxStack  the maximum stack size of the method corresponding to

  *                  these code attributes, or -1 if these attributes are not code

  *                  attributes.

  * @param maxLocals the maximum number of local variables of the method

  *                  corresponding to these code attributes, or -1 if these attributes

  *                  are not code attributes.

  * @param out       where the attributes must be written.

  */

 final void put(

 		final ClassWriter cw,

 		final byte[] code,

 		final int len,

 		final int maxStack,

 		final int maxLocals,

 		final ByteVector out){

 	Attribute attr = this;

 	while(attr != null)

 		{

 		ByteVector b = attr.write(cw, code, len, maxStack, maxLocals);

 		out.putShort(cw.newUTF8(attr.type)).putInt(b.length);

 		out.putByteArray(b.data, 0, b.length);

 		attr = attr.next;

 		}

 }

 }