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/*
 * This file is available under and governed by the GNU General Public
 * 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.
 *
 * 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. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * 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.
 */

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);
        }
    }
}