org.aspectj/bcel-builder/src/main/java/org/aspectj/apache/bcel/generic/BranchHandle.java

package org.aspectj.apache.bcel.generic;

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/**
 * BranchHandle is returned by specialized InstructionList.append() whenever a BranchInstruction is appended. This is useful when
 * the target of this instruction is not known at time of creation and must be set later via setTarget().
 *
 * @see InstructionHandle
 * @see Instruction
 * @see InstructionList
 * @version $Id: BranchHandle.java,v 1.5 2009/10/05 17:35:36 aclement Exp $
 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 */
public final class BranchHandle extends InstructionHandle {
	private InstructionBranch bi; // An alias in fact, but saves lots of casts

	private BranchHandle(InstructionBranch i) {
		super(i);
		bi = i;
	}

	static final BranchHandle getBranchHandle(InstructionBranch i) {
		return new BranchHandle(i);
	}

	/*
	 * Override InstructionHandle methods: delegate to branch instruction. Through this overriding all access to the private
	 * i_position field should be prevented.
	 */
	public int getPosition() {
		return bi.positionOfThisInstruction;
	}

	void setPosition(int pos) {
		this.pos = bi.positionOfThisInstruction = pos;
	}

	/**
	 * 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
	 */
	protected int updatePosition(int offset, int max_offset) {
		int x = bi.updatePosition(offset, max_offset);
		pos = bi.positionOfThisInstruction;
		return x;
	}

	/**
	 * Pass new target to instruction.
	 */
	public void setTarget(InstructionHandle ih) {
		bi.setTarget(ih);
	}

	/**
	 * Update target of instruction.
	 */
	public void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih) {
		bi.updateTarget(old_ih, new_ih);
	}

	/**
	 * @return target of instruction.
	 */
	public InstructionHandle getTarget() {
		return bi.getTarget();
	}

	/**
	 * Set new contents. Old instruction is disposed and may not be used anymore.
	 */
	public void setInstruction(Instruction i) {
		super.setInstruction(i);
		bi = (InstructionBranch) i;
	}
}