Class StackMap

java.lang.Object

javassist.bytecode.AttributeInfo

javassist.bytecode.StackMap

public class StackMap
extends AttributeInfo

Another stack_map attribute defined in CLDC 1.1 for J2ME.

This is an entry in the attributes table of a Code attribute. It was introduced by J2ME CLDC 1.1 (JSR 139) for pre-verification.

According to the CLDC specification, the sizes of some fields are not 16bit but 32bit if the code size is more than 64K or the number of the local variables is more than 64K. However, for the J2ME CLDC technology, they are always 16bit. The implementation of the StackMap class assumes they are 16bit.

Since:

3.12

See Also:

• MethodInfo.doPreverify
• StackMapTable

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	StackMap.Walker	A code walker for a StackMap attribute.
static class	StackMap.Writer	Internal use only.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DOUBLE	Double_variable_info.tag.
static final int	FLOAT	Float_variable_info.tag.
static final int	INTEGER	Integer_variable_info.tag.
static final int	LONG	Long_variable_info.tag.
static final int	NULL	Null_variable_info.tag.
static final int	OBJECT	Object_variable_info.tag.
static final String	tag	The name of this attribute "StackMap".
static final int	THIS	UninitializedThis_variable_info.tag.
static final int	TOP	Top_variable_info.tag.
static final int	UNINIT	Uninitialized_variable_info.tag.

Method Summary

Modifier and Type	Method	Description
AttributeInfo	copy(ConstPool newCp, Map<String,String> classnames)	Makes a copy.
void	insertLocal(int index, int tag, int classInfo)	Updates this stack map table when a new local variable is inserted for a new parameter.
int	numOfEntries()	Returns number_of_entries.
void	print(PrintWriter out)	Prints this stack map.
void	removeNew(int where)	Undocumented method.

Methods inherited from class AttributeInfo

get, getConstPool, getName, length, set, setMaxAttributeLength

Methods inherited from class Object

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

Field Details

tag

public static final String tag

The name of this attribute "StackMap".

See Also:

• Constant Field Values

TOP

public static final int TOP

Top_variable_info.tag.

See Also:

• Constant Field Values

INTEGER

public static final int INTEGER

Integer_variable_info.tag.

See Also:

• Constant Field Values

FLOAT

public static final int FLOAT

Float_variable_info.tag.

See Also:

• Constant Field Values

DOUBLE

public static final int DOUBLE

Double_variable_info.tag.

See Also:

• Constant Field Values

LONG

public static final int LONG

Long_variable_info.tag.

See Also:

• Constant Field Values

NULL

public static final int NULL

Null_variable_info.tag.

See Also:

• Constant Field Values

THIS

public static final int THIS

UninitializedThis_variable_info.tag.

See Also:

• Constant Field Values

OBJECT

public static final int OBJECT

Object_variable_info.tag.

See Also:

• Constant Field Values

UNINIT

public static final int UNINIT

Uninitialized_variable_info.tag.

See Also:

• Constant Field Values

Method Details

numOfEntries

public int numOfEntries()

Returns number_of_entries.

copy

public AttributeInfo copy(ConstPool newCp,
 Map<String,String> classnames)

Makes a copy.

Overrides:

copy in class AttributeInfo

Parameters:

newCp - the constant pool table used by the new copy.

classnames - pairs of replaced and substituted class names.

insertLocal

public void insertLocal(int index,
 int tag,
 int classInfo)
                 throws BadBytecode

Updates this stack map table when a new local variable is inserted for a new parameter.

Parameters:

index - the index of the added local variable.

tag - the type tag of that local variable. It is available by StackMapTable.typeTagOf(char).

classInfo - the index of the CONSTANT_Class_info structure in a constant pool table. This should be zero unless the tag is ITEM_Object.

Throws:

BadBytecode

See Also:

• CtBehavior.addParameter(javassist.CtClass)
• StackMapTable.typeTagOf(char)
• ConstPool

removeNew

public void removeNew(int where)
               throws CannotCompileException

Undocumented method. Do not use; internal-use only.

This method is for javassist.convert.TransformNew. It is called to update the stack map when the NEW opcode (and the following DUP) is removed.

Parameters:

where - the position of the removed NEW opcode.

Throws:

CannotCompileException

print

public void print(PrintWriter out)

Prints this stack map.