Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||||||
BooleanFunction |
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1 | /* |
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2 | * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/BooleanFunction.java,v 1.16 2005/06/28 13:44:45 elharo Exp $ |
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3 | * $Revision: 1.16 $ |
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4 | * $Date: 2005/06/28 13:44:45 $ |
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5 | * |
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6 | * ==================================================================== |
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7 | * |
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8 | * Copyright (C) 2000-2002 bob mcwhirter & James Strachan. |
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9 | * All rights reserved. |
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10 | * |
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11 | * Redistribution and use in source and binary forms, with or without |
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12 | * modification, are permitted provided that the following conditions |
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13 | * are met: |
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14 | * |
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15 | * 1. Redistributions of source code must retain the above copyright |
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16 | * notice, this list of conditions, and the following disclaimer. |
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17 | * |
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18 | * 2. Redistributions in binary form must reproduce the above copyright |
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19 | * notice, this list of conditions, and the disclaimer that follows |
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20 | * these conditions in the documentation and/or other materials |
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21 | * provided with the distribution. |
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22 | * |
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23 | * 3. The name "Jaxen" must not be used to endorse or promote products |
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24 | * derived from this software without prior written permission. For |
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25 | * written permission, please contact license@jaxen.org. |
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26 | * |
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27 | * 4. Products derived from this software may not be called "Jaxen", nor |
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28 | * may "Jaxen" appear in their name, without prior written permission |
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29 | * from the Jaxen Project Management (pm@jaxen.org). |
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30 | * |
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31 | * In addition, we request (but do not require) that you include in the |
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32 | * end-user documentation provided with the redistribution and/or in the |
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33 | * software itself an acknowledgement equivalent to the following: |
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34 | * "This product includes software developed by the |
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35 | * Jaxen Project <http://www.jaxen.org/>." |
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36 | * Alternatively, the acknowledgment may be graphical using the logos |
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37 | * available at http://www.jaxen.org/ |
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38 | * |
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39 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
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40 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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41 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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42 | * DISCLAIMED. IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT |
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43 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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44 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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45 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
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46 | * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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47 | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
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48 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
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49 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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50 | * SUCH DAMAGE. |
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51 | * |
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52 | * ==================================================================== |
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53 | * This software consists of voluntary contributions made by many |
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54 | * individuals on behalf of the Jaxen Project and was originally |
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55 | * created by bob mcwhirter <bob@werken.com> and |
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56 | * James Strachan <jstrachan@apache.org>. For more information on the |
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57 | * Jaxen Project, please see <http://www.jaxen.org/>. |
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58 | * |
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59 | * $Id: BooleanFunction.java,v 1.16 2005/06/28 13:44:45 elharo Exp $ |
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60 | */ |
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61 | ||
62 | ||
63 | package org.jaxen.function; |
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64 | ||
65 | import java.util.List; |
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66 | ||
67 | import org.jaxen.Context; |
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68 | import org.jaxen.Function; |
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69 | import org.jaxen.FunctionCallException; |
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70 | import org.jaxen.Navigator; |
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71 | ||
72 | /** |
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73 | * <p> |
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74 | * <b>4.3</b> <code><i>boolean</i> boolean(<i>object</i>)</code> |
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75 | * </p> |
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76 | * |
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77 | * <blockquote |
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78 | * src="http://www.w3.org/TR/xpath#section-Boolean-Functions"> |
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79 | * <p> |
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80 | * The <b><a href="http://www.w3.org/TR/xpath#function-boolean" target="_top">boolean</a></b> |
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81 | * function converts its argument to a boolean as follows: |
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82 | * </p> |
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83 | * |
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84 | * <ul> |
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85 | * |
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86 | * <li> |
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87 | * <p> |
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88 | * a number is true if and only if it is neither positive or negative |
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89 | * zero nor NaN |
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90 | * </p> |
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91 | * </li> |
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92 | * |
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93 | * <li> |
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94 | * <p> |
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95 | * a node-set is true if and only if it is non-empty |
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96 | * </p> |
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97 | * </li> |
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98 | * |
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99 | * <li> |
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100 | * <p> |
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101 | * a string is true if and only if its length is non-zero |
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102 | * </p> |
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103 | * </li> |
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104 | * |
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105 | * <li> |
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106 | * |
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107 | * <p> |
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108 | * an object of a type other than the four basic types is converted to a |
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109 | * boolean in a way that is dependent on that type |
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110 | * </p></li></ul> |
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111 | * </blockquote> |
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112 | * |
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113 | * @author bob mcwhirter (bob @ werken.com) |
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114 | * @see <a href="http://www.w3.org/TR/xpath#function-boolean">Section 4.3 of the XPath Specification</a> |
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115 | */ |
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116 | public class BooleanFunction implements Function |
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117 | { |
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118 | ||
119 | ||
120 | /** |
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121 | * Create a new <code>BooleanFunction</code> object. |
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122 | */ |
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123 | 294 | public BooleanFunction() {} |
124 | ||
125 | /** Convert the argument to a <code>Boolean</code> |
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126 | * |
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127 | * @param context the context at the point in the |
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128 | * expression when the function is called |
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129 | * @param args a list with exactly one item which will be converted to a |
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130 | * <code>Boolean</code> |
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131 | * |
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132 | * @return the result of evaluating the function; |
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133 | * <code>Boolean.TRUE</code> or <code>Boolean.FALSE</code> |
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134 | * |
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135 | * @throws FunctionCallException if <code>args</code> has more or less than one item |
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136 | */ |
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137 | public Object call(Context context, |
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138 | List args) throws FunctionCallException |
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139 | { |
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140 | 48 | if ( args.size() == 1 ) |
141 | { |
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142 | 36 | return evaluate( args.get(0), context.getNavigator() ); |
143 | } |
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144 | ||
145 | 12 | throw new FunctionCallException("boolean() requires one argument"); |
146 | } |
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147 | ||
148 | /** |
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149 | * <p>Convert the argument <code>obj</code> to a <code>Boolean</code> |
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150 | * according to the following rules:</p> |
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151 | * |
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152 | * <ul> |
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153 | * <li>Lists are false if they're empty; true if they're not.</li> |
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154 | * <li>Booleans are false if they're false; true if they're true.</li> |
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155 | * <li>Strings are false if they're empty; true if they're not.</li> |
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156 | * <li>Numbers are false if they're 0 or NaN; true if they're not.</li> |
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157 | * <li>All other objects are true.</li> |
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158 | * </ul> |
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159 | * |
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160 | * @param obj the object to convert to a boolean |
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161 | * @param nav ignored |
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162 | * |
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163 | * @return <code>Boolean.TRUE</code> or <code>Boolean.FALSE</code> |
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164 | */ |
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165 | public static Boolean evaluate(Object obj, Navigator nav) |
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166 | { |
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167 | 21486 | if ( obj instanceof List ) |
168 | { |
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169 | 1302 | List list = (List) obj; |
170 | ||
171 | // if it's an empty list, then we have a null node-set -> false |
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172 | 1302 | if (list.size() == 0) |
173 | { |
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174 | 18 | return Boolean.FALSE; |
175 | } |
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176 | ||
177 | // otherwise, unwrap the list and check the primitive |
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178 | 1284 | obj = list.get(0); |
179 | } |
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180 | ||
181 | // now check for primitive types |
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182 | // otherwise a non-empty node-set is true |
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183 | ||
184 | // if it's a Boolean, let it decide |
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185 | 21468 | if ( obj instanceof Boolean ) |
186 | { |
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187 | 19956 | return (Boolean) obj; |
188 | } |
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189 | // if it's a Number, != 0 -> true |
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190 | 1512 | else if ( obj instanceof Number ) |
191 | { |
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192 | 222 | double d = ((Number) obj).doubleValue(); |
193 | 222 | if ( d == 0 || Double.isNaN(d) ) |
194 | { |
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195 | 48 | return Boolean.FALSE; |
196 | } |
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197 | 174 | return Boolean.TRUE; |
198 | } |
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199 | // if it's a String, "" -> false |
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200 | 1290 | else if ( obj instanceof String ) |
201 | { |
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202 | 24 | return ( ((String)obj).length() > 0 |
203 | ? Boolean.TRUE |
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204 | : Boolean.FALSE ); |
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205 | } |
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206 | else |
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207 | { |
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208 | // assume it's a node so that this node-set is non-empty |
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209 | // and so it's true |
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210 | 1266 | return ( obj != null ) ? Boolean.TRUE : Boolean.FALSE; |
211 | } |
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212 | ||
213 | } |
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214 | } |