KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > objectweb > medor > expression > lib > Substring


1 /**
2  * MEDOR: Middleware Enabling Distributed Object Requests
3  *
4  * Copyright (C) 2001-2003 France Telecom R&D
5  * Contact: alexandre.lefebvre@rd.francetelecom.com
6  *
7  * This library is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * This library is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with this library; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  *
21  * Initial developers: M. Alia, A. Lefebvre
22  */
23 package org.objectweb.medor.expression.lib;
24
25 import org.objectweb.jorm.type.api.PType;
26 import org.objectweb.jorm.type.api.PTypeSpace;
27 import org.objectweb.medor.expression.api.Expression;
28 import org.objectweb.medor.expression.api.ExpressionException;
29 import org.objectweb.medor.expression.api.MalformedExpressionException;
30 import org.objectweb.medor.expression.api.Operand;
31 import org.objectweb.medor.expression.api.Operator;
32 import org.objectweb.medor.expression.api.ParameterOperand;
33 import org.objectweb.medor.expression.api.TypingException;
34
35 /**
36  * Operator representing the substring extraction given a String, a first
37  * integer to start from and a second integer indicating the length of the
38  * required substring.
39  */
40 public class Substring extends BasicOperator {
41
42     /**
43      * Constructs the operator
44      * @param inputString is the String from which to extract the substing
45      * @param start is the index of the first character in the String to start
46      * with. It is expected that 1 is the first character in the string (and
47      * not 0 like in Java).
48      * @param length is the size of the requested substring
49      */
50     public Substring(Expression inputString, Expression start,
51                      Expression length) {
52         super(PTypeSpace.STRING, new Expression[]{inputString, start, length});
53     }
54
55     public Substring() {
56         super(PTypeSpace.STRING);
57     }
58
59     public Operand evaluate(ParameterOperand[] pos, Object JavaDoc o)
60         throws ExpressionException {
61         try {
62             result.setValue(
63                     evaluate(
64                             getExpression(0).evaluate(pos, o).getString(),
65                             getExpression(1).evaluate(pos, o).getInt(),
66                             getExpression(2).evaluate(pos, o).getInt()));
67         }
68         catch (NullPointerException JavaDoc e) {
69             // result == null or missing children objects
70 throw new ExpressionException("Unevaluable Expression: May not be compiled");
71         }
72         return result;
73     }
74
75
76     public Operand compileExpression()
77             throws ExpressionException, MalformedExpressionException {
78         if ((getExpression(0) != null) && (getExpression(1) != null) && (getExpression(2) != null)) {
79             getExpression(0).compileExpression();
80             getExpression(1).compileExpression();
81             getExpression(2).compileExpression();
82             if ((getExpression(0).getType().getTypeCode() ==
83                     PType.TYPECODE_STRING) &&
84                     (getExpression(1).getType().isa(PTypeSpace.STRING)) &&
85                     (getExpression(2).getType().isa(PTypeSpace.INT))) {
86                 result = new BasicVariableOperand(type);
87                 verified = true;
88             } else
89             //it is not a boolean type
90 throw new TypingException("Attempt Arg Types: String, int , int");
91         } else
92         //Operands not yet assigned
93 throw new MalformedExpressionException("Null children value");
94         return result;
95     }
96
97     public String JavaDoc evaluate(String JavaDoc op, int start, int length) {
98         return op.substring(start-1, length + start-1);
99     }
100
101     public String JavaDoc getOperatorString() {
102         return Operator.SUBSTRING;
103     }
104 }
105
Popular Tags