001    // This file is part of the Attempto Java Packages.
002    // Copyright 2008, Attempto Group, University of Zurich (see http://attempto.ifi.uzh.ch).
003    //
004    // The Attempto Java Packages is free software: you can redistribute it and/or modify it under the
005    // terms of the GNU Lesser General Public License as published by the Free Software Foundation,
006    // either version 3 of the License, or (at your option) any later version.
007    //
008    // The Attempto Java Packages is distributed in the hope that it will be useful, but WITHOUT ANY
009    // WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
010    // PURPOSE. See the GNU Lesser General Public License for more details.
011    //
012    // You should have received a copy of the GNU Lesser General Public License along with the Attempto
013    // Java Packages. If not, see http://www.gnu.org/licenses/.
014    
015    package ch.uzh.ifi.attempto.chartparser;
016    
017    /**
018     * This class represents a string object that can unify with other string objects.
019     * 
020     * @author Tobias Kuhn
021     */
022    public class StringRef {
023            
024            private StringEntity stringEntity;
025            
026            /**
027             * Creates a new string object with null as value.
028             */
029            public StringRef() {
030                    this((String) null);
031            }
032            
033            /**
034             * Creates a new string object with the given value.
035             * 
036             * @param string The value of the new string object.
037             */
038            public StringRef(String string) {
039                    stringEntity = new StringEntity(string);
040                    stringEntity.addReference(this);
041            }
042            
043            StringRef(StringEntity stringEntity) {
044                    this.stringEntity = stringEntity;
045                    stringEntity.addReference(this);
046            }
047            
048            void setStringEntity(StringEntity stringEntity) {
049                    this.stringEntity = stringEntity;
050            }
051            
052            /**
053             * Unifies this string object with another string object. If unification is not possible,
054             * an exception is thrown.
055             * 
056             * @param stringObj The string object to be unified with this string object.
057             * @throws UnificationFailedException If unification fails.
058             */
059            public void unify(StringRef stringObj) throws UnificationFailedException {
060                    stringEntity.unify(stringObj.stringEntity);
061            }
062            
063            /**
064             * Returns the value of this string object.
065             * 
066             * @return The value of this string object.
067             */
068            public String getString() {
069                    return stringEntity.getString();
070            }
071            
072            int getID() {
073                    return stringEntity.getID();
074            }
075            
076            StringEntity getStringEntity() {
077                    return stringEntity;
078            }
079    
080    }