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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package com.oracle.truffle.api.instrument;

import com.oracle.truffle.api.nodes.*;

/**
 * Methods for inserting a {@link Probe} at a Truffle AST node.
 * <p>
 * This interface is guest language agnostic, but current extensions are language-specific. This
 * will be revisited.
 * <p>
 * <strong>Disclaimer:</strong> experimental interface under development. Really!
 */
public interface ASTNodeProber {

    /**
     * Optionally applies <em>instrumentation</em> at a Truffle AST node, depending on guest
     * language characteristics and use-case policy.
     * <ul>
     * <li>if no instrumentation is to be applied, returns the AST node unmodified;</li>
     * <li>if an AST node is to be instrumented, then returns a newly created {@link Wrapper} that
     * <em>decorates</em> the AST node and notifies an associated {@link Probe} of all
     * {@link ExecutionEvents} at the wrapped AST node.</li>
     * <li>if the argument is itself a {@link Wrapper}, i.e. if the AST node at this site has
     * already been wrapped, then the wrapper is returned (with the possible addition of a
     * {@linkplain SyntaxTag tag}).</li>
     * </ul>
     *
     * @param astNode an AST node to which instrumentation might be applied
     * @param tag an optional category directing how the node, if instrumented, should be perceived
     *            by tool users
     * @param args additional arguments for instrumentation specific to a particular guest language
     * @return if no instrumentation should be applied or if the node is a {@link Wrapper} then the
     *         unmodified node; otherwise a newly created {@link Wrapper} (whose child
     *         {@code astNode}) with an associated {@link Probe} .
     */

    Node probeAs(Node astNode, SyntaxTag tag, Object... args);
}