|
1
18 package org.apache.activemq.filter;
19
20 import javax.jms.JMSException  ;
21
22
27 public abstract class ArithmeticExpression extends BinaryExpression {
28
29 protected static final int INTEGER = 1;
30 protected static final int LONG = 2;
31 protected static final int DOUBLE = 3;
32
33
37 public ArithmeticExpression(Expression left, Expression right) {
38 super(left, right);
39 }
40
41 public static Expression createPlus(Expression left, Expression right) {
42 return new ArithmeticExpression(left, right) {
43 protected Object evaluate(Object lvalue, Object rvalue) {
44 if (lvalue instanceof String ) {
45 String text = (String ) lvalue;
46 String answer = text + rvalue;
47 return answer;
48 }
49 else if (lvalue instanceof Number ) {
50 return plus((Number ) lvalue, asNumber(rvalue));
51 }
52 throw new RuntimeException ("Cannot call plus operation on: " + lvalue + " and: " + rvalue);
53 }
54
55 public String getExpressionSymbol() {
56 return "+";
57 }
58 };
59 }
60
61 public static Expression createMinus(Expression left, Expression right) {
62 return new ArithmeticExpression(left, right) {
63 protected Object evaluate(Object lvalue, Object rvalue) {
64 if (lvalue instanceof Number ) {
65 return minus((Number ) lvalue, asNumber(rvalue));
66 }
67 throw new RuntimeException ("Cannot call minus operation on: " + lvalue + " and: " + rvalue);
68 }
69
70 public String getExpressionSymbol() {
71 return "-";
72 }
73 };
74 }
75
76 public static Expression createMultiply(Expression left, Expression right) {
77 return new ArithmeticExpression(left, right) {
78
79 protected Object evaluate(Object lvalue, Object rvalue) {
80 if (lvalue instanceof Number ) {
81 return multiply((Number ) lvalue, asNumber(rvalue));
82 }
83 throw new RuntimeException ("Cannot call multiply operation on: " + lvalue + " and: " + rvalue);
84 }
85
86 public String getExpressionSymbol() {
87 return "*";
88 }
89 };
90 }
91
92 public static Expression createDivide(Expression left, Expression right) {
93 return new ArithmeticExpression(left, right) {
94
95 protected Object evaluate(Object lvalue, Object rvalue) {
96 if (lvalue instanceof Number ) {
97 return divide((Number ) lvalue, asNumber(rvalue));
98 }
99 throw new RuntimeException ("Cannot call divide operation on: " + lvalue + " and: " + rvalue);
100 }
101
102 public String getExpressionSymbol() {
103 return "/";
104 }
105 };
106 }
107
108 public static Expression createMod(Expression left, Expression right) {
109 return new ArithmeticExpression(left, right) {
110
111 protected Object evaluate(Object lvalue, Object rvalue) {
112 if (lvalue instanceof Number ) {
113 return mod((Number ) lvalue, asNumber(rvalue));
114 }
115 throw new RuntimeException ("Cannot call mod operation on: " + lvalue + " and: " + rvalue);
116 }
117
118 public String getExpressionSymbol() {
119 return "%";
120 }
121 };
122 }
123
124 protected Number plus(Number left, Number right) {
125 switch (numberType(left, right)) {
126 case INTEGER:
127 return new Integer (left.intValue() + right.intValue());
128 case LONG:
129 return new Long (left.longValue() + right.longValue());
130 default:
131 return new Double (left.doubleValue() + right.doubleValue());
132 }
133 }
134
135 protected Number minus(Number left, Number right) {
136 switch (numberType(left, right)) {
137 case INTEGER:
138 return new Integer (left.intValue() - right.intValue());
139 case LONG:
140 return new Long (left.longValue() - right.longValue());
141 default:
142 return new Double (left.doubleValue() - right.doubleValue());
143 }
144 }
145
146 protected Number multiply(Number left, Number right) {
147 switch (numberType(left, right)) {
148 case INTEGER:
149 return new Integer (left.intValue() * right.intValue());
150 case LONG:
151 return new Long (left.longValue() * right.longValue());
152 default:
153 return new Double (left.doubleValue() * right.doubleValue());
154 }
155 }
156
157 protected Number divide(Number left, Number right) {
158 return new Double (left.doubleValue() / right.doubleValue());
159 }
160
161 protected Number mod(Number left, Number right) {
162 return new Double (left.doubleValue() % right.doubleValue());
163 }
164
165 private int numberType(Number left, Number right) {
166 if (isDouble(left) || isDouble(right)) {
167 return DOUBLE;
168 }
169 else if (left instanceof Long || right instanceof Long ) {
170 return LONG;
171 }
172 else {
173 return INTEGER;
174 }
175 }
176
177 private boolean isDouble(Number n) {
178 return n instanceof Float || n instanceof Double ;
179 }
180
181 protected Number asNumber(Object value) {
182 if (value instanceof Number ) {
183 return (Number ) value;
184 }
185 else {
186 throw new RuntimeException ("Cannot convert value: " + value + " into a number");
187 }
188 }
189
190 public Object evaluate(MessageEvaluationContext message) throws JMSException {
191 Object lvalue = left.evaluate(message);
192 if (lvalue == null) {
193 return null;
194 }
195 Object rvalue = right.evaluate(message);
196 if (rvalue == null) {
197 return null;
198 }
199 return evaluate(lvalue, rvalue);
200 }
201
202
203
208 abstract protected Object evaluate(Object lvalue, Object rvalue);
209
210 }
211 |
Popular Tags |
Java API By Example, From Geeks To Geeks.