File	Doc	Category	Size	Date	Package
BranchInstruction.java	API Doc	Java SE 5 API	8182	Fri Aug 26 14:55:18 BST 2005	com.sun.org.apache.bcel.internal.generic

BranchInstruction

• java.lang.Object
  • com.sun.org.apache.bcel.internal.generic.Instruction

Fields Summary
protected int	index
protected InstructionHandle	target
protected int	position

Constructors Summary
BranchInstruction() Empty constructor needed for the Class.newInstance() statement in Instruction.readInstruction(). Not to be used otherwise.
protected BranchInstruction(short opcode, InstructionHandle target) Common super constructor param opcodee Instruction opcode param target instruction to branch to super(opcode, (short)3); setTarget(target);

Methods Summary
public boolean	containsTarget(com.sun.org.apache.bcel.internal.generic.InstructionHandle ih) return true, if ih is target of this instruction return (target == ih);
void	dispose() Inform target that it's not targeted anymore. setTarget(null); index=-1; position=-1;
public void	dump(java.io.DataOutputStream out) Dump instruction as byte code to stream out. param out Output stream out.writeByte(opcode); index = getTargetOffset(); if(Math.abs(index) >= 32767) // too large for short throw new ClassGenException("Branch target offset too large for short"); out.writeShort(index); // May be negative, i.e., point backwards
public final int	getIndex() return target offset in byte code return index;
public com.sun.org.apache.bcel.internal.generic.InstructionHandle	getTarget() return target of branch instruction return target;
protected int	getTargetOffset(com.sun.org.apache.bcel.internal.generic.InstructionHandle target) param target branch target return the offset to `target' relative to this instruction if(target == null) throw new ClassGenException("Target of " + super.toString(true) + " is invalid null handle"); int t = target.getPosition(); if(t < 0) throw new ClassGenException("Invalid branch target position offset for " + super.toString(true) + ":" + t + ":" + target); return t - position;
protected int	getTargetOffset() return the offset to this instruction's target return getTargetOffset(target);
protected void	initFromFile(com.sun.org.apache.bcel.internal.util.ByteSequence bytes, boolean wide) Read needed data (e.g. index) from file. Conversion to a InstructionHandle is done in InstructionList(byte[]). param bytes input stream param wide wide prefix? see InstructionList length = 3; index = bytes.readShort();
static final void	notifyTarget(com.sun.org.apache.bcel.internal.generic.InstructionHandle old_ih, com.sun.org.apache.bcel.internal.generic.InstructionHandle new_ih, com.sun.org.apache.bcel.internal.generic.InstructionTargeter t) Used by BranchInstruction, LocalVariableGen, CodeExceptionGen if(old_ih != null) old_ih.removeTargeter(t); if(new_ih != null) new_ih.addTargeter(t);
public void	setTarget(com.sun.org.apache.bcel.internal.generic.InstructionHandle target) Set branch target param target branch target notifyTarget(this.target, target, this); this.target = target;
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> param verbose long/short format switch return mnemonic for instruction String s = super.toString(verbose); String t = "null"; if(verbose) { if(target != null) { if(target.getInstruction() == this) t = "<points to itself>"; else if(target.getInstruction() == null) t = "<null instruction!!!?>"; else t = target.getInstruction().toString(false); // Avoid circles } } else { if(target != null) { index = getTargetOffset(); t = "" + (index + position); } } return s + " -> " + t;
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. param offset additional offset caused by preceding (variable length) instructions param max_offset the maximum offset that may be caused by these instructions return additional offset caused by possible change of this instruction's length position += offset; return 0;
public void	updateTarget(com.sun.org.apache.bcel.internal.generic.InstructionHandle old_ih, com.sun.org.apache.bcel.internal.generic.InstructionHandle new_ih) param old_ih old target param new_ih new target if(target == old_ih) setTarget(new_ih); else throw new ClassGenException("Not targeting " + old_ih + ", but " + target);