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org.apache.commons.jexl.ExpressionImpl |
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1 | /* |
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2 | * Copyright 2002-2006 The Apache Software Foundation. |
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3 | * |
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4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
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5 | * you may not use this file except in compliance with the License. |
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6 | * You may obtain a copy of the License at |
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7 | * |
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8 | * http://www.apache.org/licenses/LICENSE-2.0 |
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9 | * |
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10 | * Unless required by applicable law or agreed to in writing, software |
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11 | * distributed under the License is distributed on an "AS IS" BASIS, |
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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13 | * See the License for the specific language governing permissions and |
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14 | * limitations under the License. |
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15 | */ |
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16 | ||
17 | package org.apache.commons.jexl; |
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18 | ||
19 | import java.util.ArrayList; |
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20 | import java.util.List; |
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21 | ||
22 | import org.apache.commons.jexl.parser.SimpleNode; |
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23 | ||
24 | /** |
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25 | * Instances of ExpressionImpl are created by the {@link ExpressionFactory}, |
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26 | * and this is the default implementation of the {@link Expression} interface. |
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27 | * |
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28 | * @since 1.0 |
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29 | * @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a> |
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30 | * @version $Id: ExpressionImpl.java 397111 2006-04-26 06:47:52Z dion $ |
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31 | */ |
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32 | class ExpressionImpl implements Expression { |
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33 | ||
34 | /** resolvers called before expression evaluation. */ |
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35 | protected List preResolvers; |
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36 | ||
37 | /** resolvers called after expression evaluation. */ |
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38 | protected List postResolvers; |
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39 | ||
40 | /** |
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41 | * Original expression. This is just a 'snippet', not a valid statement |
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42 | * (i.e. foo.bar() vs foo.bar(); |
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43 | */ |
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44 | protected String expression; |
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45 | ||
46 | /** |
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47 | * The resulting AST we can call value() on. |
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48 | */ |
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49 | protected SimpleNode node; |
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50 | ||
51 | /** |
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52 | * do not let this be generally instantiated with a 'new'. |
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53 | * |
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54 | * @param expr the expression. |
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55 | * @param ref the parsed expression. |
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56 | */ |
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57 | 271 | ExpressionImpl(String expr, SimpleNode ref) { |
58 | 271 | expression = expr; |
59 | 271 | node = ref; |
60 | 271 | } |
61 | ||
62 | /** |
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63 | * {@inheritDoc} |
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64 | */ |
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65 | public Object evaluate(JexlContext context) throws Exception { |
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66 | 272 | Object val = null; |
67 | ||
68 | /* |
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69 | * if we have pre resolvers, give them a wack |
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70 | */ |
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71 | 272 | if (preResolvers != null) { |
72 | 3 | val = tryResolver(preResolvers, context); |
73 | ||
74 | 3 | if (val != JexlExprResolver.NO_VALUE) { |
75 | 2 | return val; |
76 | } |
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77 | } |
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78 | ||
79 | 270 | val = node.value(context); |
80 | ||
81 | /* |
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82 | * if null, call post resolvers |
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83 | */ |
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84 | 269 | if (val == null && postResolvers != class="keyword">null) { |
85 | 0 | val = tryResolver(postResolvers, context); |
86 | ||
87 | 0 | if (val != JexlExprResolver.NO_VALUE) { |
88 | 0 | return val; |
89 | } |
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90 | } |
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91 | ||
92 | 269 | return val; |
93 | } |
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94 | ||
95 | /** |
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96 | * Tries the resolvers in the given resolverlist against the context. |
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97 | * |
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98 | * @param resolverList list of JexlExprResolvers |
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99 | * @param context JexlContext to use for evauluation |
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100 | * @return value (including null) or JexlExprResolver.NO_VALUE |
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101 | */ |
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102 | protected Object tryResolver(List resolverList, JexlContext context) { |
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103 | 3 | Object val = JexlExprResolver.NO_VALUE; |
104 | 3 | String expr = getExpression(); |
105 | ||
106 | 4 | for (int i = 0; i < resolverList.size(); i++) { |
107 | 3 | JexlExprResolver jer = (JexlExprResolver) resolverList.get(i); |
108 | ||
109 | 3 | val = jer.evaluate(context, expr); |
110 | ||
111 | /* |
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112 | * as long as it's not NO_VALUE, return it |
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113 | */ |
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114 | 3 | if (val != JexlExprResolver.NO_VALUE) { |
115 | 2 | return val; |
116 | } |
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117 | } |
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118 | ||
119 | 1 | return val; |
120 | } |
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121 | ||
122 | /** |
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123 | * {@inheritDoc} |
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124 | */ |
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125 | public String getExpression() { |
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126 | 4 | return expression; |
127 | } |
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128 | ||
129 | /** |
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130 | * {@inheritDoc} |
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131 | */ |
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132 | public void addPreResolver(JexlExprResolver resolver) { |
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133 | 3 | if (preResolvers == null) { |
134 | 3 | preResolvers = new ArrayList(); |
135 | } |
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136 | 3 | preResolvers.add(resolver); |
137 | 3 | } |
138 | ||
139 | /** |
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140 | * {@inheritDoc} |
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141 | */ |
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142 | public void addPostResolver(JexlExprResolver resolver) { |
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143 | 1 | if (postResolvers == null) { |
144 | 1 | postResolvers = new ArrayList(); |
145 | } |
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146 | 1 | postResolvers.add(resolver); |
147 | 1 | } |
148 | ||
149 | /** |
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150 | * Provide a string representation of the expression. |
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151 | * |
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152 | * @return the expression or blank if it's null. |
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153 | */ |
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154 | public String toString() { |
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155 | 1 | String expr = getExpression(); |
156 | 1 | return expr == null ? "" : expr; |
157 | } |
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158 | ||
159 | } |
This report is generated by jcoverage, Maven and Maven JCoverage Plugin. |