- package com.sun.org.apache.bcel.internal.generic;
-
- /* ====================================================================
- * The Apache Software License, Version 1.1
- *
- * Copyright (c) 2001 The Apache Software Foundation. All rights
- * reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. The end-user documentation included with the redistribution,
- * if any, must include the following acknowledgment:
- * "This product includes software developed by the
- * Apache Software Foundation (http://www.apache.org/)."
- * Alternately, this acknowledgment may appear in the software itself,
- * if and wherever such third-party acknowledgments normally appear.
- *
- * 4. The names "Apache" and "Apache Software Foundation" and
- * "Apache BCEL" must not be used to endorse or promote products
- * derived from this software without prior written permission. For
- * written permission, please contact apache@apache.org.
- *
- * 5. Products derived from this software may not be called "Apache",
- * "Apache BCEL", nor may "Apache" appear in their name, without
- * prior written permission of the Apache Software Foundation.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation. For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- */
-
- import com.sun.org.apache.bcel.internal.classfile.Utility;
- import java.util.HashSet;
- import java.util.Collection;
- import java.util.HashMap;
-
- /**
- * Instances of this class give users a handle to the instructions contained in
- * an InstructionList. Instruction objects may be used more than once within a
- * list, this is useful because it saves memory and may be much faster.
- *
- * Within an InstructionList an InstructionHandle object is wrapped
- * around all instructions, i.e., it implements a cell in a
- * doubly-linked list. From the outside only the next and the
- * previous instruction (handle) are accessible. One
- * can traverse the list via an Enumeration returned by
- * InstructionList.elements().
- *
- * @version $Id: InstructionHandle.java,v 1.1.1.1 2001/10/29 20:00:19 jvanzyl Exp $
- * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
- * @see Instruction
- * @see BranchHandle
- * @see InstructionList
- */
- public class InstructionHandle implements java.io.Serializable {
- InstructionHandle next, prev; // Will be set from the outside
- Instruction instruction;
- protected int i_position = -1; // byte code offset of instruction
- private HashSet targeters;
- private HashMap attributes;
-
- public final InstructionHandle getNext() { return next; }
- public final InstructionHandle getPrev() { return prev; }
- public final Instruction getInstruction() { return instruction; }
-
- /**
- * Replace current instruction contained in this handle.
- * Old instruction is disposed using Instruction.dispose().
- */
- public void setInstruction(Instruction i) { // Overridden in BranchHandle
- if(i == null)
- throw new ClassGenException("Assigning null to handle");
-
- if((this.getClass() != BranchHandle.class) && (i instanceof BranchInstruction))
- throw new ClassGenException("Assigning branch instruction " + i + " to plain handle");
-
- if(instruction != null)
- instruction.dispose();
-
- instruction = i;
- }
-
- /**
- * Temporarily swap the current instruction, without disturbing
- * anything. Meant to be used by a debugger, implementing
- * breakpoints. Current instruction is returned.
- */
- public Instruction swapInstruction(Instruction i) {
- Instruction oldInstruction = instruction;
- instruction = i;
- return oldInstruction;
- }
-
- /*private*/ protected InstructionHandle(Instruction i) {
- setInstruction(i);
- }
-
- private static InstructionHandle ih_list = null; // List of reusable handles
-
- /** Factory method.
- */
- static final InstructionHandle getInstructionHandle(Instruction i) {
- if(ih_list == null)
- return new InstructionHandle(i);
- else {
- InstructionHandle ih = ih_list;
- ih_list = ih.next;
-
- ih.setInstruction(i);
-
- return ih;
- }
- }
-
- /**
- * 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) {
- i_position += offset;
- return 0;
- }
-
- /** @return the position, i.e., the byte code offset of the contained
- * instruction. This is accurate only after
- * InstructionList.setPositions() has been called.
- */
- public int getPosition() { return i_position; }
-
- /** Set the position, i.e., the byte code offset of the contained
- * instruction.
- */
- void setPosition(int pos) { i_position = pos; }
-
- /** Overridden in BranchHandle
- */
- protected void addHandle() {
- next = ih_list;
- ih_list = this;
- }
-
- /**
- * Delete contents, i.e., remove user access and make handle reusable.
- */
- void dispose() {
- next = prev = null;
- instruction.dispose();
- instruction = null;
- i_position = -1;
- attributes = null;
- removeAllTargeters();
- addHandle();
- }
-
- /** Remove all targeters, if any.
- */
- public void removeAllTargeters() {
- if(targeters != null)
- targeters.clear();
- }
-
- /**
- * Denote this handle isn't referenced anymore by t.
- */
- public void removeTargeter(InstructionTargeter t) {
- targeters.remove(t);
- }
-
- /**
- * Denote this handle is being referenced by t.
- */
- public void addTargeter(InstructionTargeter t) {
- if(targeters == null)
- targeters = new HashSet();
-
- //if(!targeters.contains(t))
- targeters.add(t);
- }
-
- public boolean hasTargeters() {
- return (targeters != null) && (targeters.size() > 0);
- }
-
- /**
- * @return null, if there are no targeters
- */
- public InstructionTargeter[] getTargeters() {
- if(!hasTargeters())
- return null;
-
- InstructionTargeter[] t = new InstructionTargeter[targeters.size()];
- targeters.toArray(t);
- return t;
- }
-
- /** @return a (verbose) string representation of the contained instruction.
- */
- public String toString(boolean verbose) {
- return Utility.format(i_position, 4, false, ' ') + ": " + instruction.toString(verbose);
- }
-
- /** @return a string representation of the contained instruction.
- */
- public String toString() {
- return toString(true);
- }
-
- /** Add an attribute to an instruction handle.
- *
- * @param key the key object to store/retrieve the attribute
- * @param attr the attribute to associate with this handle
- */
- public void addAttribute(Object key, Object attr) {
- if(attributes == null)
- attributes = new HashMap(3);
-
- attributes.put(key, attr);
- }
-
- /** Delete an attribute of an instruction handle.
- *
- * @param key the key object to retrieve the attribute
- */
- public void removeAttribute(Object key) {
- if(attributes != null)
- attributes.remove(key);
- }
-
- /** Get attribute of an instruction handle.
- *
- * @param key the key object to store/retrieve the attribute
- */
- public Object getAttribute(Object key) {
- if(attributes != null)
- return attributes.get(key);
-
- return null;
- }
-
- /** @return all attributes associated with this handle
- */
- public Collection getAttributes() {
- return attributes.values();
- }
-
- /** Convenience method, simply calls accept() on the contained instruction.
- *
- * @param v Visitor object
- */
- public void accept(Visitor v) {
- instruction.accept(v);
- }
- }