org.biojava.utils.bytecode
Class Label

java.lang.Object
  org.biojava.utils.bytecode.Label

All Implemented Interfaces:

CodeGenerator

public class Label
extends java.lang.Object
implements CodeGenerator

A Label used to mark a position in byte code.

Labels are used as the targets for jumps, and for exception handlers. Labels can be named. They implement CodeGenerator, which allows them to be added to things like an InstructionVector. The writeCode method takes care of marking the label with the context.

Author:

Thomas Down, Matthew Pocock

Field Summary

java.lang.String

name

Constructor Summary

Label()

Label(java.lang.String name)

Method Summary

int	stackDelta() Return the change in the stack dept this generator will cause.
int	stackDepth() Return the total depth of the stack required by this CodeGenerator.
java.lang.String	toString()
void	writeCode(CodeContext ctx) Write the byte or bytes for this CodeGenerator to a CodeContext.

Methods inherited from class java.lang.Object

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

Field Detail

name

public java.lang.String name

Constructor Detail

Label

public Label()

Label

public Label(java.lang.String name)

Method Detail

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

writeCode

public void writeCode(CodeContext ctx)
               throws CodeException

Description copied from interface: CodeGenerator

Write the byte or bytes for this CodeGenerator to a CodeContext.

Specified by:

writeCode in interface CodeGenerator

Parameters:

ctx - a CodeContext to write to

Throws:

CodeException - if there was some failure in writing to the context

stackDepth

public int stackDepth()

Description copied from interface: CodeGenerator

Return the total depth of the stack required by this CodeGenerator.

For single byte-code instructions, this will be the same as stackDelta() if stackDelta() is positive, zero otherwise. For a compound instruction, this will be the maximum stack depth required to execute all sub-instructions.

Specified by:

stackDepth in interface CodeGenerator

Returns:

the stack depth needed

stackDelta

public int stackDelta()

Description copied from interface: CodeGenerator

Return the change in the stack dept this generator will cause.

In the case of an instruction that adds items to the stack, stackDelta will be positive. For instructions that removes items from the stack, this will be negative.

Specified by:

stackDelta in interface CodeGenerator

Returns:

the change between stack depth before and after execution of this code