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/*
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 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
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package jdk.internal.org.objectweb.asm.commons;

import java.util.Collections;
import java.util.Comparator;

import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Opcodes;
import jdk.internal.org.objectweb.asm.tree.MethodNode;
import jdk.internal.org.objectweb.asm.tree.TryCatchBlockNode;

A MethodVisitor adapter to sort the exception handlers. The handlers are sorted in a method innermost-to-outermost. This allows the programmer to add handlers without worrying about ordering them correctly with respect to existing, in-code handlers. Behavior is only defined for properly-nested handlers. If any "try" blocks overlap (something that isn't possible in Java code) then this may not do what you want. In fact, this adapter just sorts by the length of the "try" block, taking advantage of the fact that a given try block must be larger than any block it contains).
Author:Adrian Sampson
/** * A {@link MethodVisitor} adapter to sort the exception handlers. The handlers * are sorted in a method innermost-to-outermost. This allows the programmer to * add handlers without worrying about ordering them correctly with respect to * existing, in-code handlers. * * Behavior is only defined for properly-nested handlers. If any "try" blocks * overlap (something that isn't possible in Java code) then this may not do * what you want. In fact, this adapter just sorts by the length of the "try" * block, taking advantage of the fact that a given try block must be larger * than any block it contains). * * @author Adrian Sampson */
public class TryCatchBlockSorter extends MethodNode { public TryCatchBlockSorter(final MethodVisitor mv, final int access, final String name, final String desc, final String signature, final String[] exceptions) { this(Opcodes.ASM6, mv, access, name, desc, signature, exceptions); } protected TryCatchBlockSorter(final int api, final MethodVisitor mv, final int access, final String name, final String desc, final String signature, final String[] exceptions) { super(api, access, name, desc, signature, exceptions); this.mv = mv; } @Override public void visitEnd() { // Compares TryCatchBlockNodes by the length of their "try" block. Comparator<TryCatchBlockNode> comp = new Comparator<TryCatchBlockNode>() { public int compare(TryCatchBlockNode t1, TryCatchBlockNode t2) { int len1 = blockLength(t1); int len2 = blockLength(t2); return len1 - len2; } private int blockLength(TryCatchBlockNode block) { int startidx = instructions.indexOf(block.start); int endidx = instructions.indexOf(block.end); return endidx - startidx; } }; Collections.sort(tryCatchBlocks, comp); // Updates the 'target' of each try catch block annotation. for (int i = 0; i < tryCatchBlocks.size(); ++i) { tryCatchBlocks.get(i).updateIndex(i); } if (mv != null) { accept(mv); } } }