jasm.attributes

Class Code

java.lang.Object

jasm.attributes.Code

All Implemented Interfaces:

BytecodeAttribute

public class Code
extends Object
implements BytecodeAttribute

This represents the Code attribute from the JVM Specification.

Author:

David J. Pearce

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Code.BytecodeMapAttribute Maps bytecodes to some kind of attribute.
static class	Code.Handler The exception handler class is used to store the necessary information about where control-flow is directed when an exception is raised.
static class	Code.Rewrite A rewrite defines a sequence of bytecodes that are to be rewritten as a (potentially) smaller sequence.

Nested classes/interfaces inherited from interface jasm.lang.BytecodeAttribute

BytecodeAttribute.Fn, BytecodeAttribute.Reader, BytecodeAttribute.Unknown

Field Summary

Fields

Modifier and Type	Field and Description
protected ArrayList<BytecodeAttribute>	attributes
protected ArrayList<Bytecode>	bytecodes
protected ArrayList<Code.Handler>	handlers
protected ClassFile.Method	method

Constructor Summary

Constructors

Constructor and Description
Code(Collection<Bytecode> bytecodes, Collection<Code.Handler> handlers, ClassFile.Method method)

Method Summary

Modifier and Type	Method and Description
void	addPoolItems(Set<Constant.Info> constantPool) When this method is called, the attribute must add all items that it needs to the constant pool.
void	apply(List<Code.Rewrite> rewrites) This method accepts a list of rewrites which should be applied.
<T extends BytecodeAttribute> T	attribute(Class<T> c)
List<BytecodeAttribute>	attributes()
List<Bytecode>	bytecodes()
List<Code.Handler>	handlers()
int	maxLocals() Determine the maximum number of local variable slots required for this method.
int	maxStack() Determine the maximum number of stack slots required for this method.
String	name()
void	print(PrintWriter output, Map<Constant.Info,Integer> constantPool) This method is used to print the contents of the attribute in human-readable form, similar to that produced by "javap".
void	validate(List<Code.Rewrite> rewrites) The purpose of this method is to validate a candidate list of rewrites.
void	write(BinaryOutputStream writer, Map<Constant.Info,Integer> constantPool) This method requires the attribute to write itself to the binary stream.

Methods inherited from class java.lang.Object

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

Field Detail

bytecodes

protected ArrayList<Bytecode> bytecodes

handlers

protected ArrayList<Code.Handler> handlers

attributes

protected ArrayList<BytecodeAttribute> attributes

method

protected ClassFile.Method method

Constructor Detail

Code

public Code(Collection<Bytecode> bytecodes,
            Collection<Code.Handler> handlers,
            ClassFile.Method method)

Method Detail

name

public String name()

Specified by:

name in interface BytecodeAttribute

attributes

public List<BytecodeAttribute> attributes()

attribute

public <T extends BytecodeAttribute> T attribute(Class<T> c)

maxLocals

public int maxLocals()

Determine the maximum number of local variable slots required for this method.

Returns:

maxStack

public int maxStack()

Determine the maximum number of stack slots required for this method.

Returns:

bytecodes

public List<Bytecode> bytecodes()

handlers

public List<Code.Handler> handlers()

addPoolItems

public void addPoolItems(Set<Constant.Info> constantPool)

Description copied from interface: BytecodeAttribute

When this method is called, the attribute must add all items that it needs to the constant pool.

Specified by:

addPoolItems in interface BytecodeAttribute

write

public void write(BinaryOutputStream writer,
                  Map<Constant.Info,Integer> constantPool)
           throws IOException

Description copied from interface: BytecodeAttribute

This method requires the attribute to write itself to the binary stream.

Specified by:

write in interface BytecodeAttribute

Parameters:

writer - Outputstream to which the attribute should be written.

constantPool - Map of CONSTANT_info items to their index in the constant pool.

Throws:

IOException

validate

public void validate(List<Code.Rewrite> rewrites)

The purpose of this method is to validate a candidate list of rewrites. More specifically, a rewrite is considered to be invalid if it crosses an exception handler boundary. Such rewrites are automatically removed from the list.

Parameters:

rewrites -

apply

public void apply(List<Code.Rewrite> rewrites)

This method accepts a list of rewrites which should be applied. For efficiency reasons, several constraints are made on the list:

1. The rewrites are ordered by their start location, such that the first rewrite has the lowest start location
2. The rewrites don't overlap. That is, we assume only one rewrite can be applied to any given region of bytecodes.

If the complete set of rewrites cannot be constructed according to these constraints, then it needs to be split up into several calls to this method.

Parameters:

rewrites -

print

public void print(PrintWriter output,
                  Map<Constant.Info,Integer> constantPool)

Description copied from interface: BytecodeAttribute

This method is used to print the contents of the attribute in human-readable form, similar to that produced by "javap".

Specified by:

print in interface BytecodeAttribute

Parameters:

output - Output writer to which the attribute is printed.

constantPool - Map of CONSTANT_info items to their index in the constant pool.