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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. |