org.apache.bcel.generic
Class BranchInstruction

java.lang.Object
  extended by org.apache.bcel.generic.Instruction
      extended by org.apache.bcel.generic.BranchInstruction
All Implemented Interfaces:
java.io.Serializable, java.lang.Cloneable, InstructionTargeter
Direct Known Subclasses:
GotoInstruction, IfInstruction, JsrInstruction, Select

public abstract class BranchInstruction
extends Instruction
implements InstructionTargeter

Abstract super class for branching instructions like GOTO, IFEQ, etc.. Branch instructions may have a variable length, namely GOTO, JSR, LOOKUPSWITCH and TABLESWITCH.

Version:
$Id: BranchInstruction.java 386056 2006-03-15 11:31:56Z tcurdt $
Author:
M. Dahm
See Also:
InstructionList, Serialized Form

Field Summary
protected  int index
           
protected  int position
           
protected  InstructionHandle target
           
 
Fields inherited from class org.apache.bcel.generic.Instruction
length, opcode
 
Constructor Summary
(package private) BranchInstruction()
          Empty constructor needed for the Class.newInstance() statement in Instruction.readInstruction().
protected BranchInstruction(short opcode, InstructionHandle target)
          Common super constructor
 
Method Summary
 boolean containsTarget(InstructionHandle ih)
           
(package private)  void dispose()
          Inform target that it's not targeted anymore.
 void dump(java.io.DataOutputStream out)
          Dump instruction as byte code to stream out.
 int getIndex()
           
 InstructionHandle getTarget()
           
protected  int getTargetOffset()
           
protected  int getTargetOffset(InstructionHandle _target)
           
protected  void initFromFile(ByteSequence bytes, boolean wide)
          Read needed data (e.g.
(package private) static void notifyTarget(InstructionHandle old_ih, InstructionHandle new_ih, InstructionTargeter t)
          Used by BranchInstruction, LocalVariableGen, CodeExceptionGen
 void setTarget(InstructionHandle target)
          Set branch target
 java.lang.String toString(boolean verbose)
          Long output format: <position in byte code> <name of opcode> "["<opcode number>"]" "("<length of instruction>")" "<"<target instruction>">" "@"<branch target offset>
protected  int updatePosition(int offset, int max_offset)
          Called by InstructionList.setPositions when setting the position for every instruction.
 void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih)
           
 
Methods inherited from class org.apache.bcel.generic.Instruction
accept, consumeStack, copy, equals, getComparator, getLength, getName, getOpcode, produceStack, readInstruction, setComparator, toString, toString
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

index

protected int index

target

protected InstructionHandle target

position

protected int position
Constructor Detail

BranchInstruction

BranchInstruction()
Empty constructor needed for the Class.newInstance() statement in Instruction.readInstruction(). Not to be used otherwise.


BranchInstruction

protected BranchInstruction(short opcode,
                            InstructionHandle target)
Common super constructor

Parameters:
opcode - Instruction opcode
target - instruction to branch to
Method Detail

dump

public void dump(java.io.DataOutputStream out)
          throws java.io.IOException
Dump instruction as byte code to stream out.

Overrides:
dump in class Instruction
Parameters:
out - Output stream
Throws:
java.io.IOException

getTargetOffset

protected int getTargetOffset(InstructionHandle _target)
Parameters:
_target - branch target
Returns:
the offset to `target' relative to this instruction

getTargetOffset

protected int getTargetOffset()
Returns:
the offset to this instruction's target

updatePosition

protected int updatePosition(int offset,
                             int max_offset)
Called by InstructionList.setPositions when setting the position for every instruction. In the presence of variable length instructions `setPositions' performs multiple passes over the instruction list to calculate the correct (byte) positions and offsets by calling this function.

Parameters:
offset - additional offset caused by preceding (variable length) instructions
max_offset - the maximum offset that may be caused by these instructions
Returns:
additional offset caused by possible change of this instruction's length

toString

public java.lang.String toString(boolean verbose)
Long output format: <position in byte code> <name of opcode> "["<opcode number>"]" "("<length of instruction>")" "<"<target instruction>">" "@"<branch target offset>

Overrides:
toString in class Instruction
Parameters:
verbose - long/short format switch
Returns:
mnemonic for instruction

initFromFile

protected void initFromFile(ByteSequence bytes,
                            boolean wide)
                     throws java.io.IOException
Read needed data (e.g. index) from file. Conversion to a InstructionHandle is done in InstructionList(byte[]).

Overrides:
initFromFile in class Instruction
Parameters:
bytes - input stream
wide - wide prefix?
Throws:
java.io.IOException
See Also:
InstructionList

getIndex

public final int getIndex()
Returns:
target offset in byte code

getTarget

public InstructionHandle getTarget()
Returns:
target of branch instruction

setTarget

public void setTarget(InstructionHandle target)
Set branch target

Parameters:
target - branch target

notifyTarget

static final void notifyTarget(InstructionHandle old_ih,
                               InstructionHandle new_ih,
                               InstructionTargeter t)
Used by BranchInstruction, LocalVariableGen, CodeExceptionGen


updateTarget

public void updateTarget(InstructionHandle old_ih,
                         InstructionHandle new_ih)
Specified by:
updateTarget in interface InstructionTargeter
Parameters:
old_ih - old target
new_ih - new target

containsTarget

public boolean containsTarget(InstructionHandle ih)
Specified by:
containsTarget in interface InstructionTargeter
Returns:
true, if ih is target of this instruction

dispose

void dispose()
Inform target that it's not targeted anymore.

Overrides:
dispose in class Instruction