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1   /***
2    * Redistribution and use of this software and associated documentation
3    * ("Software"), with or without modification, are permitted provided
4    * that the following conditions are met:
5    *
6    * 1. Redistributions of source code must retain copyright
7    *    statements and notices.  Redistributions must also contain a
8    *    copy of this document.
9    *
10   * 2. Redistributions in binary form must reproduce the
11   *    above copyright notice, this list of conditions and the
12   *    following disclaimer in the documentation and/or other
13   *    materials provided with the distribution.
14   *
15   * 3. The name "Exolab" must not be used to endorse or promote
16   *    products derived from this Software without prior written
17   *    permission of Exoffice Technologies.  For written permission,
18   *    please contact info@exolab.org.
19   *
20   * 4. Products derived from this Software may not be called "Exolab"
21   *    nor may "Exolab" appear in their names without prior written
22   *    permission of Exoffice Technologies. Exolab is a registered
23   *    trademark of Exoffice Technologies.
24   *
25   * 5. Due credit should be given to the Exolab Project
26   *    (http://www.exolab.org/).
27   *
28   * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
29   * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30   * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31   * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
32   * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39   * OF THE POSSIBILITY OF SUCH DAMAGE.
40   *
41   * Copyright 2000-2001,2003 (C) Exoffice Technologies Inc. All Rights Reserved.
42   */
43  
44  package org.exolab.jms.selector.parser;
45  
46  import org.exolab.jms.selector.Identifiers;
47  import org.exolab.jms.selector.Type;
48  import org.exolab.jms.selector.TypeMismatchException;
49  
50  
51  /***
52   * Utility class for performing type checking
53   *
54   * @version     $Revision: 1.1 $ $Date: 2004/11/26 01:50:45 $
55   * @author      <a href="mailto:tma@netspace.net.au">Tim Anderson</a>
56   * @see         SelectorAST
57   * @see         SelectorTreeParser
58   * @see         Type
59   * @see         TypeMismatchException
60   */
61  final class TypeChecker {
62  
63      /***
64       * Private constructor
65       */
66      private TypeChecker() {
67      }
68  
69      /***
70       * Checks the return type of an expression against the expected type
71       *
72       * @param node the expression node
73       * @param expected the expected type of the expression
74       * @throws TypeMismatchException if the return type doesn't match that
75       * expected
76       */
77      public static void check(final SelectorAST node, final Type expected)
78          throws TypeMismatchException {
79  
80          Type type = node.getReturnType();
81          if (type != expected && type != Type.UNDEFINED) {
82              String msg = "expecting a " + expected + " expression, found a "
83                  + type;
84              throw new TypeMismatchException(node.getContext(), msg);
85          }
86      }
87  
88      /***
89       * Checks the return type of an expression against the expected type
90       *
91       * @param operator the expression operator
92       * @param node the expression node
93       * @param expected the expected type of the expression
94       * @throws TypeMismatchException if the return type doesn't match that
95       * expected
96       */
97      public static void check(final String operator, final SelectorAST node,
98                               final Type expected)
99          throws TypeMismatchException {
100 
101         Type type = node.getReturnType();
102         if (type != expected && type != Type.UNDEFINED) {
103             String msg = "expecting a " + expected
104                 + " expression for operator " + operator + ", found a " + type;
105             throw new TypeMismatchException(node.getContext(), msg);
106         }
107     }
108 
109     /***
110      * Checks the types of left and right hand sides of an expression against
111      * the expected type
112      *
113      * @param operator the expression operator
114      * @param left the left hand side of the expression
115      * @param right the right hand side of the expression
116      * @param expected the expected type of the expression
117      * @throws TypeMismatchException if a type doesn't match that expected
118      */
119     public static void check(final String operator, final SelectorAST left,
120                              final SelectorAST right, final Type expected)
121         throws TypeMismatchException {
122 
123         check(operator, left, expected);
124         check(operator, right, expected);
125     }
126 
127     /***
128      * Verifies if two expressions can be compared
129      *
130      * @param operator the comparison operator
131      * @param left the left hand side of the expression
132      * @param right the right hand side of the expression
133      * @throws TypeMismatchException if the expressions can't be compared
134      */
135     public static void checkComparison(final String operator,
136                                        final SelectorAST left,
137                                        final SelectorAST right)
138         throws TypeMismatchException {
139 
140         Type lhs = left.getReturnType();
141         Type rhs = right.getReturnType();
142 
143         if (lhs == Type.UNDEFINED || rhs == Type.UNDEFINED) {
144             // can't evaluate this at parse time.
145         } else if (lhs == Type.STRING && rhs == Type.STRING) {
146             checkStringComparison(operator, left, right);
147         } else if ((lhs == Type.STRING && rhs != Type.STRING)
148                    || (lhs == Type.BOOLEAN && rhs != Type.BOOLEAN)
149                    || (lhs == Type.NUMERIC && rhs != Type.NUMERIC)) {
150             String msg = "expecting a " + lhs + " expression for operator "
151                 + operator + ", found a " + rhs;
152             throw new TypeMismatchException(right.getContext(), msg);
153         }
154     }
155 
156     /***
157      * Verifies if two string expressions can be compared
158      *
159      * @param operator the comparison operator
160      * @param left the left hand side of the expression
161      * @param right the right hand side of the expression
162      * @throws TypeMismatchException if the expressions can't be compared
163      */
164     public static void checkStringComparison(final String operator,
165                                              final SelectorAST left,
166                                              final SelectorAST right)
167         throws TypeMismatchException {
168         if (left.getType() == SelectorTokenTypes.IDENT
169             && right.getType() == SelectorTokenTypes.STRING_LITERAL) {
170             checkIdentifierComparison(left, right);
171         } else if (left.getType() == SelectorTokenTypes.STRING_LITERAL
172                    && right.getType() == SelectorTokenTypes.IDENT) {
173             checkIdentifierComparison(right, left);
174         }
175     }
176 
177     /***
178      * Verifies that an identifier may be compared to a string literal
179      *
180      * @param identifier the identifier
181      * @param literal the string literal
182      * @throws TypeMismatchException if the expressions can't be compared
183      */
184     public static void checkIdentifierComparison(final SelectorAST identifier,
185                                                  final SelectorAST literal)
186         throws TypeMismatchException {
187         if (identifier.getText().equals(Identifiers.JMS_DELIVERY_MODE)) {
188             String value = literal.getText();
189             if (!value.equals(Identifiers.PERSISTENT)
190                 && !value.equals(Identifiers.NON_PERSISTENT)) {
191                 String msg = "Cannot compare JMSDeliveryMode with '"
192                     + value + "'";
193                 throw new TypeMismatchException(identifier.getContext(), msg);
194             }
195         }
196     }
197 
198 } //-- TypeChecker