/*
* Copyright 2000-2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.bcel5_2_0.generic;
/**
* 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 386056 2006-03-15 11:31:56Z tcurdt $
* @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
*/
public final class BranchHandle extends InstructionHandle {
private BranchInstruction bi; // An alias in fact, but saves lots of casts
private BranchHandle(BranchInstruction i) {
super(i);
bi = i;
}
/** Factory methods.
*/
private static BranchHandle bh_list = null; // List of reusable handles
static final BranchHandle getBranchHandle( BranchInstruction i ) {
if (bh_list == null) {
return new BranchHandle(i);
}
BranchHandle bh = bh_list;
bh_list = (BranchHandle) bh.next;
bh.setInstruction(i);
return bh;
}
/** Handle adds itself to the list of resuable handles.
*/
protected void addHandle() {
next = bh_list;
bh_list = this;
}
/* 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.position;
}
void setPosition( int pos ) {
i_position = bi.position = pos;
}
protected int updatePosition( int offset, int max_offset ) {
int x = bi.updatePosition(offset, max_offset);
i_position = bi.position;
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);
if (!(i instanceof BranchInstruction)) {
throw new ClassGenException("Assigning " + i
+ " to branch handle which is not a branch instruction");
}
bi = (BranchInstruction) i;
}
}