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.instr;
  
  import org.jacoco.core.runtime.IExecutionDataAccessorGenerator;
  import org.objectweb.asm.ClassVisitor;
  import org.objectweb.asm.Label;
  import org.objectweb.asm.MethodVisitor;
  import org.objectweb.asm.Opcodes;
  
  /**
   * This strategy for Java 8 interfaces adds a static method requesting the probe
   * array from the runtime, a static field to hold the probe array and adds code
   * for its initialization into interface initialization method.
   */
  class InterfaceFieldProbeArrayStrategy implements IProbeArrayStrategy {
  
  	/**
  	 * Frame stack with a single boolean array.
  	 */
  	private static final Object[] FRAME_STACK_ARRZ = new Object[] { InstrSupport.DATAFIELD_DESC };
  
  	/**
  	 * Empty frame locals.
  	 */
  	private static final Object[] FRAME_LOCALS_EMPTY = new Object[0];
  
  	private final String className;
  	private final long classId;
  	private final int probeCount;
  	private final IExecutionDataAccessorGenerator accessorGenerator;
  
  	private boolean seenClinit = false;
  
  	InterfaceFieldProbeArrayStrategy(final String className, final long classId,
  			final int probeCount,
  			final IExecutionDataAccessorGenerator accessorGenerator) {
  		this.className = className;
  		this.classId = classId;
  		this.probeCount = probeCount;
  		this.accessorGenerator = accessorGenerator;
  	}
  
  	public int storeInstance(final MethodVisitor mv, final boolean clinit,
  			final int variable) {
  		if (clinit) {
  			final int maxStack = accessorGenerator.generateDataAccessor(classId,
  					className, probeCount, mv);
  
  			// Stack[0]: [Z
  
  			mv.visitInsn(Opcodes.DUP);
  
  			// Stack[1]: [Z
  			// Stack[0]: [Z
  
  			mv.visitFieldInsn(Opcodes.PUTSTATIC, className,
  					InstrSupport.DATAFIELD_NAME, InstrSupport.DATAFIELD_DESC);
  
  			// Stack[0]: [Z
  
  			mv.visitVarInsn(Opcodes.ASTORE, variable);
  
  			seenClinit = true;
  			return Math.max(maxStack, 2);
  		} else {
  			mv.visitMethodInsn(Opcodes.INVOKESTATIC, className,
  					InstrSupport.INITMETHOD_NAME, InstrSupport.INITMETHOD_DESC,
  					true);
  			mv.visitVarInsn(Opcodes.ASTORE, variable);
  			return 1;
  		}
  	}
  
  	public void addMembers(final ClassVisitor cv, final int probeCount) {
  		createDataField(cv);
  		createInitMethod(cv, probeCount);
  		if (!seenClinit) {
  			createClinitMethod(cv, probeCount);
  		}
  	}
  
  	private void createDataField(final ClassVisitor cv) {
  		cv.visitField(InstrSupport.DATAFIELD_INTF_ACC,
  				InstrSupport.DATAFIELD_NAME, InstrSupport.DATAFIELD_DESC, null,
  				null);
  	}
  
  	private void createInitMethod(final ClassVisitor cv, final int probeCount) {
  		final MethodVisitor mv = cv.visitMethod(InstrSupport.INITMETHOD_ACC,
  				InstrSupport.INITMETHOD_NAME, InstrSupport.INITMETHOD_DESC,
  				null, null);
  		mv.visitCode();
  
  		// Load the value of the static data field:
  		mv.visitFieldInsn(Opcodes.GETSTATIC, className,
  				InstrSupport.DATAFIELD_NAME, InstrSupport.DATAFIELD_DESC);
  		mv.visitInsn(Opcodes.DUP);
  
  		// Stack[1]: [Z
  		// Stack[0]: [Z
  
  		// Skip initialization when we already have a data array:
  		final Label alreadyInitialized = new Label();
  		mv.visitJumpInsn(Opcodes.IFNONNULL, alreadyInitialized);
  
  		// Stack[0]: [Z
  
  		mv.visitInsn(Opcodes.POP);
  		final int size = accessorGenerator.generateDataAccessor(classId,
  				className, probeCount, mv);
  
  		// Stack[0]: [Z
  
  		// Return the class' probe array:
  		mv.visitFrame(Opcodes.F_NEW, 0, FRAME_LOCALS_EMPTY, 1,
  				FRAME_STACK_ARRZ);
  		mv.visitLabel(alreadyInitialized);
  		mv.visitInsn(Opcodes.ARETURN);
  
  		mv.visitMaxs(Math.max(size, 2), 0); // Maximum local stack size is 2
  		mv.visitEnd();
  	}
  
  	private void createClinitMethod(final ClassVisitor cv,
  			final int probeCount) {
  		final MethodVisitor mv = cv.visitMethod(InstrSupport.CLINIT_ACC,
  				InstrSupport.CLINIT_NAME, InstrSupport.CLINIT_DESC, null, null);
  		mv.visitCode();
  
  		final int maxStack = accessorGenerator.generateDataAccessor(classId,
  				className, probeCount, mv);
  
  		// Stack[0]: [Z
  
  		mv.visitFieldInsn(Opcodes.PUTSTATIC, className,
  				InstrSupport.DATAFIELD_NAME, InstrSupport.DATAFIELD_DESC);
  
  		mv.visitInsn(Opcodes.RETURN);
  
  		mv.visitMaxs(maxStack, 0);
  		mv.visitEnd();
  	}
  
  }
  