org.datanucleus.asm

Class Attribute

java.lang.Object

org.datanucleus.asm.Attribute

public class Attribute
extends Object

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

Author:

Eric Bruneton, Eugene Kuleshov

Field Summary

Fields

Modifier and Type	Field and Description
String	type The type of this attribute.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Attribute(String type) Constructs a new empty attribute.

Method Summary

Methods

Modifier and Type	Method and Description
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.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

type

public final String type

The type of this attribute.

Constructor Detail

Attribute

protected Attribute(String type)

Constructs a new empty attribute.

Parameters:

type - the type of the attribute.

Method Detail

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.

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.

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.

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.

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, readClass or readConst.

codeOff - index of the first byte of code's attribute content in 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.

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.