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Library for use in Java components of Vespa. Shared code which do not fit anywhere else.

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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.yolean.trace;

/**
 * This class is an abstract visitor of {@link TraceNode}. See {@link TraceNode#accept(TraceVisitor)}.
 *
 * @author bratseth
 * @since 5.1.15
 */
public abstract class TraceVisitor {

    /**
     * Visits a {@link TraceNode}. Called by {@link TraceNode#accept(TraceVisitor)}, before visiting its
     * children.
     *
     * @param node the TraceNode being visited
     * @see TraceNode#accept(TraceVisitor)
     */
    public abstract void visit(TraceNode node);

    /**
     * Enters a {@link TraceNode}. This method is called after {@link #visit(TraceNode)}, but before visiting its
     * children. Note that this method is NOT called if a TraceNode has zero children.
     * The default implementation of this method does nothing.
     *
     * @param node the TraceNode being entered
     * @see #leaving(TraceNode)
     */
    @SuppressWarnings("UnusedParameters")
    public void entering(TraceNode node) {
        // empty
    }

    /**
     * Leaves a {@link TraceNode}. This method is called after {@link #entering(TraceNode)}, and after visiting its
     * children. Note that this method is NOT called if a TraceNode has zero children.
     * The default implementation of this method does nothing.
     *
     * @param node the TraceNode being left
     */
    @SuppressWarnings("UnusedParameters")
    public void leaving(TraceNode node) {
        // empty
    }
}