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/***
* 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 org.objectweb.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(
ClassReader cr,
int off,
int len,
char[] buf,
int codeOff,
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(
ClassWriter cw,
byte[] code,
int len,
int maxStack,
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;
}
}
}
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