content: /*******************************************************************************
   * Copyright (c) 2009, 2019 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 java.util.HashSet;
  import java.util.Set;
  
  import org.objectweb.asm.Opcodes;
  import org.objectweb.asm.Type;
  import org.objectweb.asm.tree.AbstractInsnNode;
  import org.objectweb.asm.tree.JumpInsnNode;
  import org.objectweb.asm.tree.MethodNode;
  import org.objectweb.asm.tree.VarInsnNode;
  
  /**
   * Filters branches that Kotlin compiler generates for default arguments.
   * 
   * For each default argument Kotlin compiler generates following bytecode to
   * determine if it should be used or not:
   * 
   * <pre>
   * ILOAD maskVar
   * ICONST_x, BIPUSH, SIPUSH, LDC or LDC_W
   * IAND
   * IFEQ label
   * default argument
   * label:
   * </pre>
   * 
   * Where <code>maskVar</code> is penultimate argument of synthetic method with
   * suffix "$default". And its value can't be zero - invocation with all
   * arguments uses original non synthetic method, thus <code>IFEQ</code>
   * instructions should be ignored.
   */
  public final class KotlinDefaultArgumentsFilter implements IFilter {
  
  	static boolean isDefaultArgumentsMethodName(final String methodName) {
  		return methodName.endsWith("$default");
  	}
  
  	public void filter(final MethodNode methodNode,
  			final IFilterContext context, final IFilterOutput output) {
  		if ((methodNode.access & Opcodes.ACC_SYNTHETIC) == 0) {
  			return;
  		}
  		if (!isDefaultArgumentsMethodName(methodNode.name)) {
  			return;
  		}
  		if (!KotlinGeneratedFilter.isKotlinClass(context)) {
  			return;
  		}
  
  		new Matcher().match(methodNode, output);
  	}
  
  	private static class Matcher extends AbstractMatcher {
  		public void match(final MethodNode methodNode,
  				final IFilterOutput output) {
  			cursor = methodNode.instructions.getFirst();
  
  			final Set<AbstractInsnNode> ignore = new HashSet<AbstractInsnNode>();
  			final int maskVar = Type.getMethodType(methodNode.desc)
  					.getArgumentTypes().length - 2;
  			while (true) {
  				if (cursor.getOpcode() != Opcodes.ILOAD) {
  					break;
  				}
  				if (((VarInsnNode) cursor).var != maskVar) {
  					break;
  				}
  				next();
  				nextIs(Opcodes.IAND);
  				nextIs(Opcodes.IFEQ);
  				if (cursor == null) {
  					return;
  				}
  				ignore.add(cursor);
  				cursor = ((JumpInsnNode) cursor).label;
  				skipNonOpcodes();
  			}
  
  			for (AbstractInsnNode i : ignore) {
  				output.ignore(i, i);
  			}
  		}
  	}
  
  }
  