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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * 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).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package org.openjdk.btrace.core.annotations;

/**
 * Allows specifying a probe handler instrumentation level matching expression.
 *
 * <p>See {@linkplain Level#value()} for the allowed expression syntax.
 *
 * @author Jaroslav Bachorik
 */
public @interface Level {
  /**
   * The level check expression.<br>
   * Allowed syntax is one of the following
   *
   * <ul>
   *   <li>{@code @Level("NUMBER")} - the same as {@code @Level(">=NUMBER")}
   *   <li>{@code @Level("=NUMBER")} - handler is enabled when instrumentation level equals
   *       <b>NUMBER</b>
   *   <li>{@code @Level(">NUMBER")} - handler is enabled when instrumentation level is greater than
   *       <b>NUMBER</b>
   *   <li>{@code @Level(">=NUMBER")} - handler is enabled when instrumentation level is greater
   *       than or equal to <b>NUMBER</b>
   *   <li>{@code @Level("<NUMBER")} - handler is enabled when instrumentation level is less than
   *       <b>NUMBER</b>
   *   <li>{@code @Level("<=NUMBER")} - handler is enabled when instrumentation level is less than
   *       or equal to <b>NUMBER</b>
   * </ul>
   *
   * <p>Where <b>NUMBER</b> is a non-negative integer number.
   *
   * @return the level
   */
  String value() default "";
}
