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ANNIE is a general purpose information extraction system that provides the building blocks of many other GATE applications.

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/* 
 *  PatternElement.java - transducer class
 *
 *  Copyright (c) 1995-2012, The University of Sheffield. See the file
 *  COPYRIGHT.txt in the software or at http://gate.ac.uk/gate/COPYRIGHT.txt
 *
 *  This file is part of GATE (see http://gate.ac.uk/), and is free
 *  software, licenced under the GNU Library General Public License,
 *  Version 2, June 1991 (in the distribution as file licence.html,
 *  and also available at http://gate.ac.uk/gate/licence.html).
 *
 *  Hamish Cunningham, 24/07/98
 *
 *  $Id: PatternElement.java 17599 2014-03-08 16:30:42Z markagreenwood $
 */


package gate.jape;

import java.io.Serializable;
import java.util.Stack;


/**
  * Superclass of the various types of pattern element, and of
  * ConstraintGroup. Inherits from Matcher, providing matches and reset.
  * Provides access to the annotations that are cached by subclasses, and
  * multilevel rollback of those caches. Stores the match history.
  */
abstract public class PatternElement implements Cloneable, 
		      JapeConstants, Serializable
{
  private static final long serialVersionUID = -3721781489731606247L;

  /** Match history stack, for use in rollback. In BasicPatternElements
    * the objects on the stack are Integers giving the number of annots that
    * were cached at that point in the history. In ComplexPatternElements
    * the objects are Integers giving the number of times the component
    * ConstraintGroup was successfully matched. In ConstraintGroups the
    * elements are arrays representing conjunctions of PatternElement that
    * succeeded at that point in the history.
    */
  protected Stack