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Java > Open Source Codes > org > objectstyle > cayenne > exp > parser > ASTNegate


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
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6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
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10  * modification, are permitted provided that the following conditions
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24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
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26  * if and wherever such third-party acknowlegements normally appear.
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54  * <http://objectstyle.org/>.
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56
57 package org.objectstyle.cayenne.exp.parser;
58
59 import java.io.PrintWriter JavaDoc;
60 import java.math.BigDecimal JavaDoc;
61
62 import org.objectstyle.cayenne.exp.Expression;
63 import org.objectstyle.cayenne.util.ConversionUtil;
64
65 /**
66  * "Negate" expression.
67  *
68  * @since 1.1
69  * @author Andrei Adamchik
70  */

71 public class ASTNegate extends SimpleNode {
72     ASTNegate(int id) {
73         super(id);
74     }
75
76     public ASTNegate() {
77         super(ExpressionParserTreeConstants.JJTNEGATE);
78     }
79
80     public ASTNegate(Object JavaDoc node) {
81         super(ExpressionParserTreeConstants.JJTNEGATE);
82         jjtAddChild(wrapChild(node), 0);
83     }
84
85     /**
86      * Creates a copy of this expression node, without copying children.
87      */

88     public Expression shallowCopy() {
89         return new ASTNegate(id);
90     }
91
92     protected Object JavaDoc evaluateNode(Object JavaDoc o) throws Exception JavaDoc {
93         int len = jjtGetNumChildren();
94         if (len == 0) {
95             return null;
96         }
97
98         BigDecimal JavaDoc result = ConversionUtil.toBigDecimal(evaluateChild(0, o));
99         return result != null ? result.negate() : null;
100     }
101
102     public void encodeAsString(PrintWriter JavaDoc pw) {
103         if ((children != null) && (children.length > 0)) {
104             pw.print("-");
105
106             SimpleNode child = (SimpleNode) children[0];
107
108             // don't call super - we have our own parenthesis policy
109
boolean useParen =
110                 parent != null
111                     && !((child instanceof ASTScalar) || (child instanceof ASTPath));
112             if (useParen) {
113                 pw.print("(");
114             }
115
116             child.encodeAsString(pw);
117
118             if (useParen) {
119                 pw.print(')');
120             }
121         }
122     }
123
124     protected String JavaDoc getExpressionOperator(int index) {
125         throw new UnsupportedOperationException JavaDoc(
126             "No operator for '" + ExpressionParserTreeConstants.jjtNodeName[id] + "'");
127     }
128
129     public int getType() {
130         return Expression.NEGATIVE;
131     }
132
133     public int getOperandCount() {
134         return 1;
135     }
136 }
137
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