001 /*
002 * PatternElement.java - transducer class
003 *
004 * Copyright (c) 1995-2010, The University of Sheffield. See the file
005 * COPYRIGHT.txt in the software or at http://gate.ac.uk/gate/COPYRIGHT.txt
006 *
007 * This file is part of GATE (see http://gate.ac.uk/), and is free
008 * software, licenced under the GNU Library General Public License,
009 * Version 2, June 1991 (in the distribution as file licence.html,
010 * and also available at http://gate.ac.uk/gate/licence.html).
011 *
012 * Hamish Cunningham, 24/07/98
013 *
014 * $Id: PatternElement.java 12006 2009-12-01 17:24:28Z thomas_heitz $
015 */
016
017
018 package gate.jape;
019
020 import java.util.Stack;
021
022 import gate.AnnotationSet;
023
024
025 /**
026 * Superclass of the various types of pattern element, and of
027 * ConstraintGroup. Inherits from Matcher, providing matches and reset.
028 * Provides access to the annotations that are cached by subclasses, and
029 * multilevel rollback of those caches. Stores the match history.
030 */
031 abstract public class PatternElement implements Cloneable,
032 JapeConstants, java.io.Serializable
033 {
034 /** Debug flag */
035 private static final boolean DEBUG = false;
036
037 /** Match history stack, for use in rollback. In BasicPatternElements
038 * the objects on the stack are Integers giving the number of annots that
039 * were cached at that point in the history. In ComplexPatternElements
040 * the objects are Integers giving the number of times the component
041 * ConstraintGroup was successfully matched. In ConstraintGroups the
042 * elements are arrays representing conjunctions of PatternElement that
043 * succeeded at that point in the history.
044 */
045 protected Stack matchHistory;
046
047 /** Anonymous construction. */
048 public PatternElement() {
049 matchHistory = new Stack();
050 } // Anonymous constructor.
051
052 /** Cloning for processing of macro references. Note that it doesn't
053 * really clone the match history, just set it to a new Stack. This is
054 * because a) JGL doesn't have real clone methods and b) we don't
055 * actually need it anywhere but during parsing the .jape, where there
056 * is no match history yet.
057 */
058 public Object clone() {
059 try {
060 PatternElement newPE = (PatternElement) super.clone();
061 newPE.matchHistory = new Stack();
062 return newPE;
063 } catch(CloneNotSupportedException e) {
064 throw(new InternalError(e.toString()));
065 }
066 } // clone
067
068
069 /**
070 * Finishes the JAPE language parsing, building all the in-memory structures
071 * required.
072 */
073 public abstract void finish();
074 /** Create a string representation of the object with padding. */
075 abstract public String toString(String pad);
076
077 } // class PatternElement
078
079
080 // $Log$
081 // Revision 1.7 2005/01/11 13:51:36 ian
082 // Updating copyrights to 1998-2005 in preparation for v3.0
083 //
084 // Revision 1.6 2004/07/21 17:10:08 akshay
085 // Changed copyright from 1998-2001 to 1998-2004
086 //
087 // Revision 1.5 2004/03/25 13:01:14 valyt
088 // Imports optimisation throughout the Java sources
089 // (to get rid of annoying warnings in Eclipse)
090 //
091 // Revision 1.4 2000/11/08 16:35:03 hamish
092 // formatting
093 //
094 // Revision 1.3 2000/10/16 16:44:34 oana
095 // Changed the comment of DEBUG variable
096 //
097 // Revision 1.2 2000/10/10 15:36:36 oana
098 // Changed System.out in Out and System.err in Err;
099 // Added the DEBUG variable seted on false;
100 // Added in the header the licence;
101 //
102 // Revision 1.1 2000/02/23 13:46:09 hamish
103 // added
104 //
105 // Revision 1.1.1.1 1999/02/03 16:23:02 hamish
106 // added gate2
107 //
108 // Revision 1.8 1998/11/03 19:06:49 hamish
109 // java stack, not jgl stack for matchHistory
110 //
111 // Revision 1.7 1998/11/01 23:18:44 hamish
112 // use new instead of clear on containers
113 //
114 // Revision 1.6 1998/09/26 09:19:18 hamish
115 // added cloning of PE macros
116 //
117 // Revision 1.5 1998/08/12 15:39:41 hamish
118 // added padding toString methods
119 //
120 // Revision 1.4 1998/08/03 19:51:24 hamish
121 // rollback added
122 //
123 // Revision 1.3 1998/07/30 11:05:22 hamish
124 // more jape
125 //
126 // Revision 1.2 1998/07/29 11:07:06 hamish
127 // first compiling version
128 //
129 // Revision 1.1.1.1 1998/07/28 16:37:46 hamish
130 // gate2 lives
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