001 /**
002 * =========================================
003 * LibFormula : a free Java formula library
004 * =========================================
005 *
006 * Project Info: http://reporting.pentaho.org/libformula/
007 *
008 * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors.
009 *
010 * This library is free software; you can redistribute it and/or modify it under the terms
011 * of the GNU Lesser General Public License as published by the Free Software Foundation;
012 * either version 2.1 of the License, or (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
015 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
016 * See the GNU Lesser General Public License for more details.
017 *
018 * You should have received a copy of the GNU Lesser General Public License along with this
019 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
020 * Boston, MA 02111-1307, USA.
021 *
022 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
023 * in the United States and other countries.]
024 *
025 *
026 * ------------
027 * $Id: ConcatOperator.java 2887 2007-06-06 17:07:52Z taqua $
028 * ------------
029 * (C) Copyright 2006-2007, by Pentaho Corporation.
030 */
031 package org.jfree.formula.operators;
032
033 import org.jfree.formula.EvaluationException;
034 import org.jfree.formula.FormulaContext;
035 import org.jfree.formula.LibFormulaErrorValue;
036 import org.jfree.formula.lvalues.TypeValuePair;
037 import org.jfree.formula.typing.TypeRegistry;
038 import org.jfree.formula.typing.coretypes.TextType;
039
040 /**
041 * Concats two strings operator.
042 *
043 * @author Thomas Morgner
044 */
045 public class ConcatOperator implements InfixOperator
046 {
047 public ConcatOperator()
048 {
049 }
050
051 public TypeValuePair evaluate(final FormulaContext context,
052 final TypeValuePair value1,
053 final TypeValuePair value2)
054 throws EvaluationException
055 {
056 final TypeRegistry typeRegistry = context.getTypeRegistry();
057
058 // Error or empty string, that's the question ..
059 final Object raw1 = value1.getValue();
060 final Object raw2 = value2.getValue();
061 if (raw1 == null || raw2 == null)
062 {
063 throw new EvaluationException(LibFormulaErrorValue.ERROR_NA_VALUE);
064 }
065
066 final String text1 = typeRegistry.convertToText(value1.getType(), raw1);
067 final String text2 = typeRegistry.convertToText(value2.getType(), raw2);
068 if (text1 == null && text2 == null)
069 {
070 throw new EvaluationException
071 (LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
072 }
073 if (text1 == null)
074 {
075 return new TypeValuePair(TextType.TYPE, text2);
076 }
077 if (text2 == null)
078 {
079 return new TypeValuePair(TextType.TYPE, text1);
080 }
081
082 return new TypeValuePair(TextType.TYPE, text1 + text2);
083 }
084
085 public int getLevel()
086 {
087 return 300;
088 }
089
090
091 public String toString()
092 {
093 return "&";
094 }
095
096 public boolean isLeftOperation()
097 {
098 return true;
099 }
100
101 /**
102 * Defines, whether the operation is associative. For associative operations,
103 * the evaluation order does not matter, if the operation appears more than
104 * once in an expression, and therefore we can optimize them a lot better than
105 * non-associative operations (ie. merge constant parts and precompute them
106 * once).
107 *
108 * @return true, if the operation is associative, false otherwise
109 */
110 public boolean isAssociative()
111 {
112 return false;
113 }
114
115 }