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Summary: Nested Field Constr Method Detail: Field Constr Method

org.apache.bcel.verifier.structurals

Class Subroutines

public class Subroutines extends 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 386056 2006-03-15 11:31:56Z tcurdt $

Author: Enver Haase

See Also: getTopLevel

Nested Class Summary
classSubroutines.SubroutineImpl
This inner class implements the Subroutine interface.
Field Summary
static IntegerBLACK
static IntegerGRAY
Hashtablesubroutines
The Hashtable containing the subroutines found.
SubroutineTOPLEVEL
This is referring to a special subroutine, namely the top level.
static IntegerWHITE
Constructor Summary
Subroutines(MethodGen mg)
Constructor.
Method Summary
SubroutinegetSubroutine(InstructionHandle leader)
Returns the Subroutine object associated with the given leader (that is, the first instruction of the subroutine).
static InstructionHandle[]getSuccessors(InstructionHandle instruction)
A utility method that calculates the successors of a given InstructionHandle in the same subroutine.
SubroutinegetTopLevel()
For easy handling, the piece of code that is not a subroutine, the top-level, is also modeled as a Subroutine object.
voidnoRecursiveCalls(Subroutine sub, Set set)
This (recursive) utility method makes sure that no subroutine is calling a subroutine that uses the same local variable for the RET as themselves (recursively).
SubroutinesubroutineOf(InstructionHandle any)
Returns the subroutine object associated with the given instruction.
StringtoString()
Returns a String representation of this object; merely for debugging puposes.

Field Detail

BLACK

private static final Integer BLACK

GRAY

private static final Integer GRAY

subroutines

private Hashtable subroutines
The Hashtable containing the subroutines found. Key: InstructionHandle of the leader of the subroutine. Elements: SubroutineImpl objects.

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.

WHITE

private static final Integer WHITE

Constructor Detail

Subroutines

public Subroutines(MethodGen mg)
Constructor.

Parameters: mg 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

getSuccessors

private static InstructionHandle[] getSuccessors(InstructionHandle instruction)
A utility method that calculates the successors of a given InstructionHandle in the same subroutine. That means, a RET does not have any successors as defined here. A JsrInstruction has its physical successor as its successor (opposed to its target) as defined here.

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: getEnteringJsrInstructions getLeavingRET

noRecursiveCalls

private void noRecursiveCalls(Subroutine sub, Set set)
This (recursive) utility method makes sure that no subroutine is calling a subroutine that uses the same local variable for the RET as themselves (recursively). This includes that subroutines may not call themselves recursively, even not through intermediate calls to other subroutines.

Throws: StructuralCodeConstraintException if the above constraint is not satisfied.

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 getTopLevel

toString

public String toString()
Returns a String representation of this object; merely for debugging puposes.

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Summary: Nested Field Constr Method Detail: Field Constr Method