org.objectweb.asm

Class Attribute

Known Direct Subclasses:
StackMapAttribute

public class Attribute
extends Object

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

Authors:
Eric Bruneton
Eugene Kuleshov

Field Summary

String
type
The type of this attribute.

Constructor Summary

Attribute(String type)
Constructs a new empty attribute.

Method Summary

protected Label[]
getLabels()
Returns the labels corresponding to this attribute.
boolean
isCodeAttribute()
Returns true if this type of attribute is a code attribute.
boolean
isUnknown()
Returns true if this type of attribute is unknown.
protected Attribute
read(ClassReader cr, int off, int len, char[] buf, int codeOff, Label labels)
Reads a type attribute.
protected ByteVector
write(ClassWriter cw, byte[] code, int len, int maxStack, int maxLocals)
Returns the byte array form of this attribute.

Field Details

type

public final String type
The type of this attribute.

Constructor Details

Attribute

protected Attribute(String type)
Constructs a new empty attribute.

Parameters:
type - the type of the attribute.

Method Details

getLabels

protected Label[] getLabels()
Returns the labels corresponding to this attribute.

Returns:
the labels corresponding to this attribute, or null if this attribute is not a code attribute that contains labels.


isCodeAttribute

public boolean isCodeAttribute()
Returns true if this type of attribute is a code attribute.

Returns:
true if this type of attribute is a code attribute.


isUnknown

public boolean isUnknown()
Returns true if this type of attribute is unknown. The default implementation of this method always returns true.

Returns:
true if this type of attribute is unknown.


read

protected Attribute read(ClassReader cr,
                         int off,
                         int len,
                         char[] buf,
                         int codeOff,
                         Label labels)
Reads a type attribute. This method must return a new Attribute object, of type type, corresponding to the len bytes starting at the given offset, in the given class reader. readClass or readConst. 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.

Parameters:
cr - the class that contains the attribute to be read.
off - index of the first byte of the attribute's content in cr.b. The 6 attribute header bytes, containing the type and the length of the attribute, are not taken into account here.
len - the length of the attribute's content.
buf - buffer to be used to call readUTF8,
codeOff - index of the first byte of code's attribute content in
labels - the labels of the method's code, or null if the attribute to be read is not a code attribute.

Returns:
a new Attribute object corresponding to the given bytes.


write

protected ByteVector write(ClassWriter cw,
                           byte[] code,
                           int len,
                           int maxStack,
                           int maxLocals)
Returns the byte array form of this attribute.

Parameters:
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.
code - the bytecode of the method corresponding to this code attribute, or null if this attribute is not a code attributes.
len - the length of the bytecode of the method corresponding to this code attribute, or null if this attribute is not a code attribute.
maxStack - the maximum stack size of the method corresponding to this code attribute, or -1 if this attribute is not a code attribute.
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.

Returns:
the byte array form of this attribute.