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jeremybenn |
/***
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* ASM: a very small and fast Java bytecode manipulation framework
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* Copyright (c) 2000-2005 INRIA, France Telecom
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package org.objectweb.asm;
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/**
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* A non standard class, field, method or code attribute.
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*
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* @author Eric Bruneton
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* @author Eugene Kuleshov
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*/
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public class Attribute {
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/**
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* The type of this attribute.
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*/
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public final String type;
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/**
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* The raw value of this attribute, used only for unknown attributes.
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*/
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byte[] value;
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/**
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* The next attribute in this attribute list. May be <tt>null</tt>.
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*/
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Attribute next;
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/**
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* Constructs a new empty attribute.
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*
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* @param type the type of the attribute.
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*/
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protected Attribute(final String type) {
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this.type = type;
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}
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/**
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* Returns <tt>true</tt> if this type of attribute is unknown. The default
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* implementation of this method always returns <tt>true</tt>.
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*
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* @return <tt>true</tt> if this type of attribute is unknown.
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*/
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public boolean isUnknown() {
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return true;
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}
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/**
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* Returns <tt>true</tt> if this type of attribute is a code attribute.
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*
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* @return <tt>true</tt> if this type of attribute is a code attribute.
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*/
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public boolean isCodeAttribute() {
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return false;
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}
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/**
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* Returns the labels corresponding to this attribute.
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*
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* @return the labels corresponding to this attribute, or <tt>null</tt> if
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* this attribute is not a code attribute that contains labels.
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*/
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protected Label[] getLabels() {
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return null;
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}
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/**
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* Reads a {@link #type type} attribute. This method must return a <i>new</i>
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* {@link Attribute} object, of type {@link #type type}, corresponding to
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* the <tt>len</tt> bytes starting at the given offset, in the given class
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* reader.
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*
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* @param cr the class that contains the attribute to be read.
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* @param off index of the first byte of the attribute's content in {@link
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* ClassReader#b cr.b}. The 6 attribute header bytes, containing the
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* type and the length of the attribute, are not taken into account
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* here.
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* @param len the length of the attribute's content.
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* @param buf buffer to be used to call
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* {@link ClassReader#readUTF8 readUTF8},
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* {@link ClassReader#readClass(int,char[]) readClass} or
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* {@link ClassReader#readConst readConst}.
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* @param codeOff index of the first byte of code's attribute content in
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* {@link ClassReader#b cr.b}, or -1 if the attribute to be read is
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* not a code attribute. The 6 attribute header bytes, containing the
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* type and the length of the attribute, are not taken into account
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* here.
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* @param labels the labels of the method's code, or <tt>null</tt> if the
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* attribute to be read is not a code attribute.
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* @return a <i>new</i> {@link Attribute} object corresponding to the given
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* bytes.
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*/
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protected Attribute read(
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ClassReader cr,
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int off,
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int len,
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char[] buf,
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int codeOff,
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Label[] labels)
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{
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Attribute attr = new Attribute(type);
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attr.value = new byte[len];
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System.arraycopy(cr.b, off, attr.value, 0, len);
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return attr;
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}
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/**
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* Returns the byte array form of this attribute.
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*
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* @param cw the class to which this attribute must be added. This parameter
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* can be used to add to the constant pool of this class the items
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* that corresponds to this attribute.
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* @param code the bytecode of the method corresponding to this code
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* attribute, or <tt>null</tt> if this attribute is not a code
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* attributes.
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* @param len the length of the bytecode of the method corresponding to this
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* code attribute, or <tt>null</tt> if this attribute is not a code
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* attribute.
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* @param maxStack the maximum stack size of the method corresponding to
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* this code attribute, or -1 if this attribute is not a code
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* attribute.
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* @param maxLocals the maximum number of local variables of the method
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* corresponding to this code attribute, or -1 if this attribute is
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* not a code attribute.
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* @return the byte array form of this attribute.
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*/
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protected ByteVector write(
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ClassWriter cw,
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byte[] code,
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int len,
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int maxStack,
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int maxLocals)
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{
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ByteVector v = new ByteVector();
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v.data = value;
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v.length = value.length;
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return v;
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}
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/**
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* Returns the length of the attribute list that begins with this attribute.
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*
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* @return the length of the attribute list that begins with this attribute.
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*/
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final int getCount() {
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int count = 0;
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Attribute attr = this;
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while (attr != null) {
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count += 1;
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attr = attr.next;
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}
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return count;
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}
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/**
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* Returns the size of all the attributes in this attribute list.
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*
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* @param cw the class writer to be used to convert the attributes into byte
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* arrays, with the {@link #write write} method.
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* @param code the bytecode of the method corresponding to these code
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* attributes, or <tt>null</tt> if these attributes are not code
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* attributes.
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* @param len the length of the bytecode of the method corresponding to
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* these code attributes, or <tt>null</tt> if these attributes are
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* not code attributes.
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* @param maxStack the maximum stack size of the method corresponding to
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* these code attributes, or -1 if these attributes are not code
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* attributes.
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* @param maxLocals the maximum number of local variables of the method
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* corresponding to these code attributes, or -1 if these attributes
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* are not code attributes.
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* @return the size of all the attributes in this attribute list. This size
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* includes the size of the attribute headers.
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*/
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final int getSize(
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final ClassWriter cw,
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final byte[] code,
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final int len,
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final int maxStack,
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final int maxLocals)
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{
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Attribute attr = this;
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int size = 0;
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while (attr != null) {
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cw.newUTF8(attr.type);
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size += attr.write(cw, code, len, maxStack, maxLocals).length + 6;
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attr = attr.next;
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}
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return size;
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}
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/**
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* Writes all the attributes of this attribute list in the given byte
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* vector.
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*
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* @param cw the class writer to be used to convert the attributes into byte
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* arrays, with the {@link #write write} method.
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* @param code the bytecode of the method corresponding to these code
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* attributes, or <tt>null</tt> if these attributes are not code
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* attributes.
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* @param len the length of the bytecode of the method corresponding to
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* these code attributes, or <tt>null</tt> if these attributes are
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* not code attributes.
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* @param maxStack the maximum stack size of the method corresponding to
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* these code attributes, or -1 if these attributes are not code
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* attributes.
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* @param maxLocals the maximum number of local variables of the method
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* corresponding to these code attributes, or -1 if these attributes
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* are not code attributes.
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* @param out where the attributes must be written.
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*/
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final void put(
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final ClassWriter cw,
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final byte[] code,
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final int len,
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final int maxStack,
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final int maxLocals,
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final ByteVector out)
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{
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Attribute attr = this;
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while (attr != null) {
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ByteVector b = attr.write(cw, code, len, maxStack, maxLocals);
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out.putShort(cw.newUTF8(attr.type)).putInt(b.length);
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out.putByteArray(b.data, 0, b.length);
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attr = attr.next;
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}
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}
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}
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