1 // ASM: a very small and fast Java bytecode manipulation framework 2 // Copyright (c) 2000-2011 INRIA, France Telecom 3 // All rights reserved. 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions 7 // are met: 8 // 1. Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // 2. Redistributions in binary form must reproduce the above copyright 11 // notice, this list of conditions and the following disclaimer in the 12 // documentation and/or other materials provided with the distribution. 13 // 3. Neither the name of the copyright holders nor the names of its 14 // contributors may be used to endorse or promote products derived from 15 // this software without specific prior written permission. 16 // 17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 18 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 21 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 22 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 23 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 25 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 26 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 27 // THE POSSIBILITY OF SUCH DAMAGE. 28 29 package org.objectweb.asm.commons; 30 31 import java.util.Collections; 32 import java.util.Comparator; 33 import org.objectweb.asm.MethodVisitor; 34 import org.objectweb.asm.Opcodes; 35 import org.objectweb.asm.tree.MethodNode; 36 import org.objectweb.asm.tree.TryCatchBlockNode; 37 38 /** 39 * A {@link MethodVisitor} adapter to sort the exception handlers. The handlers are sorted in a 40 * method innermost-to-outermost. This allows the programmer to add handlers without worrying about 41 * ordering them correctly with respect to existing, in-code handlers. 42 * 43 * <p>Behavior is only defined for properly-nested handlers. If any "try" blocks overlap (something 44 * that isn't possible in Java code) then this may not do what you want. In fact, this adapter just 45 * sorts by the length of the "try" block, taking advantage of the fact that a given try block must 46 * be larger than any block it contains). 47 * 48 * @author Adrian Sampson 49 */ 50 public class TryCatchBlockSorter extends MethodNode { 51 52 /** 53 * Constructs a new {@link TryCatchBlockSorter}. 54 * 55 * @param methodVisitor the method visitor to which this visitor must delegate method calls. May 56 * be {@literal null}. 57 * @param access the method's access flags (see {@link Opcodes}). This parameter also indicates if 58 * the method is synthetic and/or deprecated. 59 * @param name the method's name. 60 * @param descriptor the method's descriptor (see {@link org.objectweb.asm.Type}). 61 * @param signature the method's signature. May be {@literal null} if the method parameters, 62 * return type and exceptions do not use generic types. 63 * @param exceptions the internal names of the method's exception classes (see {@link 64 * org.objectweb.asm.Type#getInternalName()}). May be {@literal null}. 65 */ TryCatchBlockSorter( final MethodVisitor methodVisitor, final int access, final String name, final String descriptor, final String signature, final String[] exceptions)66 public TryCatchBlockSorter( 67 final MethodVisitor methodVisitor, 68 final int access, 69 final String name, 70 final String descriptor, 71 final String signature, 72 final String[] exceptions) { 73 this( 74 /* latest api = */ Opcodes.ASM9, 75 methodVisitor, 76 access, 77 name, 78 descriptor, 79 signature, 80 exceptions); 81 if (getClass() != TryCatchBlockSorter.class) { 82 throw new IllegalStateException(); 83 } 84 } 85 TryCatchBlockSorter( final int api, final MethodVisitor methodVisitor, final int access, final String name, final String descriptor, final String signature, final String[] exceptions)86 protected TryCatchBlockSorter( 87 final int api, 88 final MethodVisitor methodVisitor, 89 final int access, 90 final String name, 91 final String descriptor, 92 final String signature, 93 final String[] exceptions) { 94 super(api, access, name, descriptor, signature, exceptions); 95 this.mv = methodVisitor; 96 } 97 98 @Override visitEnd()99 public void visitEnd() { 100 // Sort the TryCatchBlockNode elements by the length of their "try" block. 101 Collections.sort( 102 tryCatchBlocks, 103 new Comparator<TryCatchBlockNode>() { 104 105 @Override 106 public int compare( 107 final TryCatchBlockNode tryCatchBlockNode1, 108 final TryCatchBlockNode tryCatchBlockNode2) { 109 return blockLength(tryCatchBlockNode1) - blockLength(tryCatchBlockNode2); 110 } 111 112 private int blockLength(final TryCatchBlockNode tryCatchBlockNode) { 113 int startIndex = instructions.indexOf(tryCatchBlockNode.start); 114 int endIndex = instructions.indexOf(tryCatchBlockNode.end); 115 return endIndex - startIndex; 116 } 117 }); 118 // Update the 'target' of each try catch block annotation. 119 for (int i = 0; i < tryCatchBlocks.size(); ++i) { 120 tryCatchBlocks.get(i).updateIndex(i); 121 } 122 if (mv != null) { 123 accept(mv); 124 } 125 } 126 } 127