org.apache.bcel.verifier.structurals
Class Subroutines

java.lang.Object
  |
  +--org.apache.bcel.verifier.structurals.Subroutines

public class Subroutines

extends java.lang.Object

Instances of this class contain information about the subroutines found in a code array of a method. This implementation considers the top-level (the instructions reachable without a JSR or JSR_W starting off from the first instruction in a code array of a method) being a special subroutine; see getTopLevel() for that. Please note that the definition of subroutines in the Java Virtual Machine Specification, Second Edition is somewhat incomplete. Therefore, JustIce uses an own, more rigid notion. Basically, a subroutine is a piece of code that starts at the target of a JSR of JSR_W instruction and ends at a corresponding RET instruction. Note also that the control flow of a subroutine may be complex and non-linear; and that subroutines may be nested. JustIce also mandates subroutines not to be protected by exception handling code (for the sake of control flow predictability). To understand JustIce's notion of subroutines, please read TODO: refer to the paper.

Version:

$Id: Subroutines.java,v 1.1.1.1 2001/10/29 20:00:42 jvanzyl Exp $

Author:

Enver Haase

See Also:

getTopLevel()

Field Summary

Subroutine

TOPLEVEL This is referring to a special subroutine, namely the top level.

Constructor Summary

Subroutines(MethodGen mg)
Constructor.

Method Summary

Subroutine	getSubroutine(InstructionHandle leader) Returns the Subroutine object associated with the given leader (that is, the first instruction of the subroutine).
Subroutine	getTopLevel() For easy handling, the piece of code that is not a subroutine, the top-level, is also modeled as a Subroutine object.
Subroutine	subroutineOf(InstructionHandle any) Returns the subroutine object associated with the given instruction.
java.lang.String	toString() Returns a String representation of this object; merely for debugging puposes.

Methods inherited from class java.lang.Object

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

Field Detail

TOPLEVEL

public final Subroutine TOPLEVEL

This is referring to a special subroutine, namely the top level. This is not really a subroutine but we use it to distinguish between top level instructions and unreachable instructions.

Constructor Detail

Subroutines

public Subroutines(MethodGen mg)

Constructor.

Parameters:

il - A MethodGen object representing method to create the Subroutine objects of.

Method Detail

getSubroutine

public Subroutine getSubroutine(InstructionHandle leader)

Returns the Subroutine object associated with the given leader (that is, the first instruction of the subroutine). You must not use this to get the top-level instructions modeled as a Subroutine object.

See Also:

getTopLevel()

subroutineOf

public Subroutine subroutineOf(InstructionHandle any)

Returns the subroutine object associated with the given instruction. This is a costly operation, you should consider using getSubroutine(InstructionHandle). Returns 'null' if the given InstructionHandle lies in so-called 'dead code', i.e. code that can never be executed.

See Also:

getSubroutine(InstructionHandle), getTopLevel()

getTopLevel

public Subroutine getTopLevel()

For easy handling, the piece of code that is not a subroutine, the top-level, is also modeled as a Subroutine object. It is a special Subroutine object where you must not invoke getEnteringJsrInstructions() or getLeavingRET().

See Also:

Subroutine.getEnteringJsrInstructions(), Subroutine.getLeavingRET()

toString

public java.lang.String toString()

Returns a String representation of this object; merely for debugging puposes.

Overrides:

toString in class java.lang.Object