1 package org.drools.semantics.java;
2
3 /*
4 $Id: Expr.java,v 1.6 2002/08/19 04:30:49 bob Exp $
5
6 Copyright 2002 (C) The Werken Company. All Rights Reserved.
7
8 Redistribution and use of this software and associated documentation
9 ("Software"), with or without modification, are permitted provided
10 that the following conditions are met:
11
12 1. Redistributions of source code must retain copyright
13 statements and notices. Redistributions must also contain a
14 copy of this document.
15
16 2. Redistributions in binary form must reproduce the
17 above copyright notice, this list of conditions and the
18 following disclaimer in the documentation and/or other
19 materials provided with the distribution.
20
21 3. The name "drools" must not be used to endorse or promote
22 products derived from this Software without prior written
23 permission of The Werken Company. For written permission,
24 please contact bob@werken.com.
25
26 4. Products derived from this Software may not be called "drools"
27 nor may "drools" appear in their names without prior written
28 permission of The Werken Company. "drools" is a registered
29 trademark of The Werken Company.
30
31 5. Due credit should be given to The Werken Company.
32 (http://drools.werken.com/).
33
34 THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS
35 ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
36 NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
37 FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
38 THE WERKEN COMPANY OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
39 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
40 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
41 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
42 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
43 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
44 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
45 OF THE POSSIBILITY OF SUCH DAMAGE.
46
47 */
48
49 import org.drools.rule.Declaration;
50 import org.drools.smf.ConfigurationException;
51
52 /*** Base class for expression-based Java semantic components.
53 *
54 * @see ExprCondition
55 * @see ExprExtractor
56 *
57 * @author <a href="mailto:bob@eng.werken.com">bob mcwhirter</a>
58 *
59 * @version $Id: Expr.java,v 1.6 2002/08/19 04:30:49 bob Exp $
60 */
61 public class Expr extends Interp
62 {
63 // ------------------------------------------------------------
64 // Constants
65 // ------------------------------------------------------------
66
67 /*** Empty declaration array. */
68 private static final Declaration[] EMPTY_DECLS = new Declaration[0];
69
70 // ------------------------------------------------------------
71 // Instance members
72 // ------------------------------------------------------------
73
74 /*** Required declarations. */
75 private Declaration[] requiredDecls;
76
77 // ------------------------------------------------------------
78 // Constants
79 // ------------------------------------------------------------
80
81 /*** Construct.
82 */
83 protected Expr()
84 {
85 this.requiredDecls = EMPTY_DECLS;
86 }
87
88 /*** Construct.
89 *
90 * @param expr The expression.
91 * @param availDecls The available declarations.
92 *
93 * @throws ConfigurationException If an error occurs while
94 * attempting to perform configuration.
95 */
96 protected Expr(String expr,
97 Declaration[] availDecls) throws ConfigurationException
98 {
99 configure( expr,
100 availDecls );
101 }
102
103 // ------------------------------------------------------------
104 // Constants
105 // ------------------------------------------------------------
106
107 /*** Retrieve the expression.
108 *
109 * @return The expression.
110 */
111 public String getExpression()
112 {
113 return getText();
114 }
115
116 /*** Set the expression.
117 *
118 * @param expr The expression.
119 */
120 protected void setExpression(String expr)
121 {
122 setText( expr );
123 }
124
125 /*** Configure/parse the expression.
126 *
127 * @param expr The expression.
128 * @param decls All available declarations.
129 *
130 * @throws ConfigurationException If an error occurs while
131 * attempting to configure/parse the expression.
132 */
133 public void configure(String expr,
134 Declaration[] decls) throws ConfigurationException
135 {
136 ExprAnalyzer analyzer = new ExprAnalyzer();
137
138 try
139 {
140 this.requiredDecls = analyzer.analyze( expr,
141 decls );
142 }
143 catch (Exception e)
144 {
145 throw new ConfigurationException( e );
146 }
147
148 setExpression( expr );
149 }
150
151 /*** Retrieve the <code>Declaration</code>s required for
152 * evaluating the expression.
153 *
154 * @return The required declarations.
155 */
156 public Declaration[] getRequiredTupleMembers()
157 {
158 return this.requiredDecls;
159 }
160 }
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