| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.drill.exec.compile; |
| |
| import org.objectweb.asm.ClassVisitor; |
| |
| /** |
| * An ASM ClassVisitor that allows for a late-bound delegate. |
| * |
| * <p>The ClassVisitor constructor takes an optional ClassVisitor argument |
| * to which all calls will be delegated. However, in some circumstances, ClassVisitor |
| * derivatives may not be able to specify the delegate until after they have called |
| * the ClassVisitor constructor themselves. In other words, they may not be able to |
| * specify the delegate until *after* they have called super(). This version of the |
| * ClassVisitor will support that via the use of the {@link #setDelegate} method. |
| */ |
| public class RetargetableClassVisitor extends ClassVisitor { |
| private boolean started; |
| |
| /** |
| * See {@link org.objectweb.asm.ClassVisitor#ClassVisitor(int)}. |
| */ |
| public RetargetableClassVisitor(final int api) { |
| super(api); |
| } |
| |
| /** |
| * See {@link org.objectweb.asm.ClassVisitor#ClassVisitor(int, ClassVisitor)}. |
| */ |
| public RetargetableClassVisitor(final int api, final ClassVisitor cv) { |
| super(api, cv); |
| } |
| |
| /** |
| * Set the delegate for this ClassVisitor. Must be called before the visitor is |
| * used (i.e., before any other methods are called), and only once. |
| * @param cv the ClassVisitor to delegate calls to |
| */ |
| protected void setDelegate(final ClassVisitor cv) { |
| if (started) { |
| throw new IllegalStateException("can't change delegate after visitor has been used"); |
| } |
| |
| // This member was only protected, so we can take advantage of that to set it here. |
| this.cv = cv; |
| } |
| } |