org.jacoco.core/src/org/jacoco/core/internal/flow/MethodProbesVisitor.java

/*******************************************************************************
 * Copyright (c) 2009, 2017 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:
 *    Marc R. Hoffmann - initial API and implementation
 *    
 *******************************************************************************/
package org.jacoco.core.internal.flow;

import org.jacoco.core.internal.instr.InstrSupport;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.tree.MethodNode;

/**
 * A {@link MethodVisitor} with additional methods to get probe insertion
 * information.
 */
public abstract class MethodProbesVisitor extends MethodVisitor {

	/**
	 * New visitor instance without delegate visitor.
	 */
	public MethodProbesVisitor() {
		this(null);
	}

	/**
	 * New visitor instance that delegates to the given visitor.
	 * 
	 * @param mv
	 *            optional next visitor in chain
	 */
	public MethodProbesVisitor(final MethodVisitor mv) {
		super(InstrSupport.ASM_API_VERSION, mv);
	}

	/**
	 * Visits an unconditional probe that should be inserted at the current
	 * position.
	 * 
	 * @param probeId
	 *            id of the probe to insert
	 */
	@SuppressWarnings("unused")
	public void visitProbe(final int probeId) {
	}

	/**
	 * Visits a jump instruction. A probe with the given id should be inserted
	 * in a way that it is executed only when the jump to the given label is
	 * executed.
	 * 
	 * @param opcode
	 *            the opcode of the type instruction to be visited. This opcode
	 *            is either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, IF_ICMPEQ,
	 *            IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE,
	 *            IF_ACMPEQ, IF_ACMPNE, GOTO, IFNULL or IFNONNULL.
	 * @param label
	 *            the operand of the instruction to be visited. This operand is
	 *            a label that designates the instruction to which the jump
	 *            instruction may jump.
	 * @param probeId
	 *            id of the probe
	 * @param frame
	 *            stackmap frame status after the execution of the jump
	 *            instruction. The instance is only valid with the call of this
	 *            method.
	 * @see MethodVisitor#visitJumpInsn(int, Label)
	 */
	@SuppressWarnings("unused")
	public void visitJumpInsnWithProbe(final int opcode, final Label label,
			final int probeId, final IFrame frame) {
	}

	/**
	 * Visits a zero operand instruction with a probe. This event is used only
	 * for instructions that terminate the method. Therefore the probe must be
	 * inserted before the actual instruction.
	 * 
	 * @param opcode
	 *            the opcode of the instruction to be visited. This opcode is
	 *            either IRETURN, LRETURN, FRETURN, DRETURN, ARETURN, RETURN or
	 *            ATHROW.
	 * @param probeId
	 *            id of the probe
	 * @see MethodVisitor#visitInsn(int)
	 */
	@SuppressWarnings("unused")
	public void visitInsnWithProbe(final int opcode, final int probeId) {
	}

	/**
	 * Visits a TABLESWITCH instruction with optional probes for each target
	 * label. Implementations can be optimized based on the fact that the same
	 * target labels will always have the same probe id within a call to this
	 * method. The probe id for each label can be obtained with
	 * {@link LabelInfo#getProbeId(Label)}.
	 * 
	 * @param min
	 *            the minimum key value.
	 * @param max
	 *            the maximum key value.
	 * @param dflt
	 *            beginning of the default handler block.
	 * @param labels
	 *            beginnings of the handler blocks. <code>labels[i]</code> is
	 *            the beginning of the handler block for the
	 *            <code>min + i</code> key.
	 * @param frame
	 *            stackmap frame status after the execution of the switch
	 *            instruction. The instance is only valid with the call of this
	 *            method.
	 * @see MethodVisitor#visitTableSwitchInsn(int, int, Label, Label[])
	 */
	@SuppressWarnings("unused")
	public void visitTableSwitchInsnWithProbes(final int min, final int max,
			final Label dflt, final Label[] labels, final IFrame frame) {
	}

	/**
	 * Visits a LOOKUPSWITCH instruction with optional probes for each target
	 * label. Implementations can be optimized based on the fact that the same
	 * target labels will always have the same probe id within a call to this
	 * method. The probe id for each label can be obtained with
	 * {@link LabelInfo#getProbeId(Label)}.
	 * 
	 * @param dflt
	 *            beginning of the default handler block.
	 * @param keys
	 *            the values of the keys.
	 * @param labels
	 *            beginnings of the handler blocks. <code>labels[i]</code> is
	 *            the beginning of the handler block for the
	 *            <code>keys[i]</code> key.
	 * @param frame
	 *            stackmap frame status after the execution of the switch
	 *            instruction. The instance is only valid with the call of this
	 *            method.
	 * @see MethodVisitor#visitLookupSwitchInsn(Label, int[], Label[])
	 */
	@SuppressWarnings("unused")
	public void visitLookupSwitchInsnWithProbes(final Label dflt,
			final int[] keys, final Label[] labels, final IFrame frame) {
	}

	/**
	 * This method can be overwritten to hook into the process of emitting the
	 * instructions of this method as <code>visitX()</code> events.
	 *
	 * @param methodNode
	 *            the content to emit
	 * @param methodVisitor
	 *            A visitor to emit the content to. Note that this is not
	 *            necessarily this visitor instance but some wrapper which
	 *            calculates the probes.
	 */
	public void accept(final MethodNode methodNode,
			final MethodVisitor methodVisitor) {
		methodNode.accept(methodVisitor);
	}

}