org.compass.core.util.asm
Class Attribute

java.lang.Object
  extended by org.compass.core.util.asm.Attribute

public class Attribute
extends Object

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

Author:
Eric Bruneton, Eugene Kuleshov

Field Summary
(package private)  Attribute next
          The next attribute in this attribute list.
 String type
          The type of this attribute.
(package private)  byte[] value
          The raw value of this attribute, used only for unknown attributes.
 
Constructor Summary
protected Attribute(String type)
          Constructs a new empty attribute.
 
Method Summary
(package private)  int getCount()
          Returns the length of the attribute list that begins with this attribute.
protected  Label[] getLabels()
          Returns the labels corresponding to this attribute.
(package private)  int getSize(ClassWriter cw, byte[] code, int len, int maxStack, int maxLocals)
          Returns the size of all the attributes in this attribute list.
 boolean isCodeAttribute()
          Returns true if this type of attribute is a code attribute.
 boolean isUnknown()
          Returns true if this type of attribute is unknown.
(package private)  void put(ClassWriter cw, byte[] code, int len, int maxStack, int maxLocals, ByteVector out)
          Writes all the attributes of this attribute list in the given byte vector.
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.


value

byte[] value
The raw value of this attribute, used only for unknown attributes.


next

Attribute next
The next attribute in this attribute list. May be null.

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.

getCount

final int getCount()
Returns the length of the attribute list that begins with this attribute.

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

getSize

final int getSize(ClassWriter cw,
                  byte[] code,
                  int len,
                  int maxStack,
                  int maxLocals)
Returns the size of all the attributes in this attribute list.

Parameters:
cw - the class writer to be used to convert the attributes into byte arrays, with the write method.
code - the bytecode of the method corresponding to these code attributes, or null if these attributes are not code attributes.
len - the length of the bytecode of the method corresponding to these code attributes, or null if these attributes are not code attributes.
maxStack - the maximum stack size of the method corresponding to these code attributes, or -1 if these attributes are not code attributes.
maxLocals - the maximum number of local variables of the method corresponding to these code attributes, or -1 if these attributes are not code attributes.
Returns:
the size of all the attributes in this attribute list. This size includes the size of the attribute headers.

put

final void put(ClassWriter cw,
               byte[] code,
               int len,
               int maxStack,
               int maxLocals,
               ByteVector out)
Writes all the attributes of this attribute list in the given byte vector.

Parameters:
cw - the class writer to be used to convert the attributes into byte arrays, with the write method.
code - the bytecode of the method corresponding to these code attributes, or null if these attributes are not code attributes.
len - the length of the bytecode of the method corresponding to these code attributes, or null if these attributes are not code attributes.
maxStack - the maximum stack size of the method corresponding to these code attributes, or -1 if these attributes are not code attributes.
maxLocals - the maximum number of local variables of the method corresponding to these code attributes, or -1 if these attributes are not code attributes.
out - where the attributes must be written.


Copyright (c) 2004-2008 The Compass Project.