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// 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
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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package aj.org.objectweb.asm.commons;
import java.util.Collections;
import java.util.Comparator;
import aj.org.objectweb.asm.MethodVisitor;
import aj.org.objectweb.asm.Opcodes;
import aj.org.objectweb.asm.tree.MethodNode;
import aj.org.objectweb.asm.tree.TryCatchBlockNode;
/**
* 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 {
/**
* Constructs a new {@link TryCatchBlockSorter}.
*
* @param methodVisitor the method visitor to which this visitor must delegate method calls. May
* be {@literal null}.
* @param access the method's access flags (see {@link Opcodes}). This parameter also indicates if
* the method is synthetic and/or deprecated.
* @param name the method's name.
* @param descriptor the method's descriptor (see {@link aj.org.objectweb.asm.Type}).
* @param signature the method's signature. May be {@literal null} if the method parameters,
* return type and exceptions do not use generic types.
* @param exceptions the internal names of the method's exception classes (see {@link
* aj.org.objectweb.asm.Type#getInternalName()}). May be {@literal null}.
*/
public TryCatchBlockSorter(
final MethodVisitor methodVisitor,
final int access,
final String name,
final String descriptor,
final String signature,
final String[] exceptions) {
this(
/* latest api = */ Opcodes.ASM9,
methodVisitor,
access,
name,
descriptor,
signature,
exceptions);
if (getClass() != TryCatchBlockSorter.class) {
throw new IllegalStateException();
}
}
protected TryCatchBlockSorter(
final int api,
final MethodVisitor methodVisitor,
final int access,
final String name,
final String descriptor,
final String signature,
final String[] exceptions) {
super(api, access, name, descriptor, signature, exceptions);
this.mv = methodVisitor;
}
@Override
public void visitEnd() {
// Sort the TryCatchBlockNode elements by the length of their "try" block.
Collections.sort(
tryCatchBlocks,
new Comparator() {
@Override
public int compare(
final TryCatchBlockNode tryCatchBlockNode1,
final TryCatchBlockNode tryCatchBlockNode2) {
return blockLength(tryCatchBlockNode1) - blockLength(tryCatchBlockNode2);
}
private int blockLength(final TryCatchBlockNode tryCatchBlockNode) {
int startIndex = instructions.indexOf(tryCatchBlockNode.start);
int endIndex = instructions.indexOf(tryCatchBlockNode.end);
return endIndex - startIndex;
}
});
// Update 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);
}
}
}