/*******************************************************************************
 * Copyright (c) 2009, 2018 Mountainminds GmbH & Co. KG and Contributors
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Evgeny Mandrikov - initial API and implementation
 *
 *******************************************************************************/
package org.jacoco.core.internal.analysis.filter;

import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.MethodNode;

/**
 * Filters private empty constructors that do not have arguments.
 */
public final class PrivateEmptyNoArgConstructorFilter implements IFilter {

	private static final String CONSTRUCTOR_NAME = "<init>";
	private static final String CONSTRUCTOR_DESC = "()V";

	public void filter(final String className, final String superClassName,
			final MethodNode methodNode, final IFilterOutput output) {
		if ((methodNode.access & Opcodes.ACC_PRIVATE) != 0
				&& CONSTRUCTOR_NAME.equals(methodNode.name)
				&& CONSTRUCTOR_DESC.equals(methodNode.desc)
				&& new Matcher().match(methodNode, superClassName)) {
			output.ignore(methodNode.instructions.getFirst(),
					methodNode.instructions.getLast());
		}
	}

	private static class Matcher extends AbstractMatcher {
		private boolean match(final MethodNode methodNode,
				final String superClassName) {
			firstIsALoad0(methodNode);
			nextIsInvokeSuper(superClassName, CONSTRUCTOR_DESC);
			nextIs(Opcodes.RETURN);
			return cursor != null;
		}
	}

}
