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1 package org.apache.bcel.generic; 2 3 /* ==================================================================== 4 * The Apache Software License, Version 1.1 5 * 6 * Copyright (c) 2001 The Apache Software Foundation. All rights 7 * reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in 18 * the documentation and/or other materials provided with the 19 * distribution. 20 * 21 * 3. The end-user documentation included with the redistribution, 22 * if any, must include the following acknowledgment: 23 * "This product includes software developed by the 24 * Apache Software Foundation (http://www.apache.org/)." 25 * Alternately, this acknowledgment may appear in the software itself, 26 * if and wherever such third-party acknowledgments normally appear. 27 * 28 * 4. The names "Apache" and "Apache Software Foundation" and 29 * "Apache BCEL" must not be used to endorse or promote products 30 * derived from this software without prior written permission. For 31 * written permission, please contact apache@apache.org. 32 * 33 * 5. Products derived from this software may not be called "Apache", 34 * "Apache BCEL", nor may "Apache" appear in their name, without 35 * prior written permission of the Apache Software Foundation. 36 * 37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR 41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 48 * SUCH DAMAGE. 49 * ==================================================================== 50 * 51 * This software consists of voluntary contributions made by many 52 * individuals on behalf of the Apache Software Foundation. For more 53 * information on the Apache Software Foundation, please see 54 * <http://www.apache.org/>;. 55 */ 56 57 /*** 58 * BranchHandle is returned by specialized InstructionList.append() whenever a 59 * BranchInstruction is appended. This is useful when the target of this 60 * instruction is not known at time of creation and must be set later 61 * via setTarget(). 62 * 63 * @see InstructionHandle 64 * @see Instruction 65 * @see InstructionList 66 * @version $Id: BranchHandle.java,v 1.1.1.1 2001/10/29 20:00:06 jvanzyl Exp $ 67 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A> 68 */ 69 public final class BranchHandle extends InstructionHandle { 70 private BranchInstruction bi; // An alias in fact, but saves lots of casts 71 72 private BranchHandle(BranchInstruction i) { 73 super(i); 74 bi = i; 75 } 76 77 /*** Factory methods. 78 */ 79 private static BranchHandle bh_list = null; // List of reusable handles 80 81 static final BranchHandle getBranchHandle(BranchInstruction i) { 82 if(bh_list == null) 83 return new BranchHandle(i); 84 else { 85 BranchHandle bh = bh_list; 86 bh_list = (BranchHandle)bh.next; 87 88 bh.setInstruction(i); 89 90 return bh; 91 } 92 } 93 94 /*** Handle adds itself to the list of resuable handles. 95 */ 96 protected void addHandle() { 97 next = bh_list; 98 bh_list = this; 99 } 100 101 /* Override InstructionHandle methods: delegate to branch instruction. 102 * Through this overriding all access to the private i_position field should 103 * be prevented. 104 */ 105 public int getPosition() { return bi.position; } 106 107 void setPosition(int pos) { 108 i_position = bi.position = pos; 109 } 110 111 protected int updatePosition(int offset, int max_offset) { 112 int x = bi.updatePosition(offset, max_offset); 113 i_position = bi.position; 114 return x; 115 } 116 117 /*** 118 * Pass new target to instruction. 119 */ 120 public void setTarget(InstructionHandle ih) { 121 bi.setTarget(ih); 122 } 123 124 /*** 125 * Update target of instruction. 126 */ 127 public void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih) { 128 bi.updateTarget(old_ih, new_ih); 129 } 130 131 /*** 132 * @return target of instruction. 133 */ 134 public InstructionHandle getTarget() { 135 return bi.getTarget(); 136 } 137 138 /*** 139 * Set new contents. Old instruction is disposed and may not be used anymore. 140 */ 141 public void setInstruction(Instruction i) { 142 super.setInstruction(i); 143 144 if(!(i instanceof BranchInstruction)) 145 throw new ClassGenException("Assigning " + i + 146 " to branch handle which is not a branch instruction"); 147 148 bi = (BranchInstruction)i; 149 } 150 } 151

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