##### Coverage Report - org.apache.commons.configuration.interpol.ConfigurationInterpolator

Classes in this File | Line Coverage | Branch Coverage | Complexity
ConfigurationInterpolator |
98% | 45/46
100% | 11/11
| 2.272727272727273;2,273

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     /*
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      * Licensed to the Apache Software Foundation (ASF) under one or more
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      * contributor license agreements.  See the NOTICE file distributed with
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      * this work for additional information regarding copyright ownership.
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      * The ASF licenses this file to You under the Apache License, Version 2.0
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      * (the "License"); you may not use this file except in compliance with
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      * the License.  You may obtain a copy of the License at
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      *
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      *     http://www.apache.org/licenses/LICENSE-2.0
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      *
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      * Unless required by applicable law or agreed to in writing, software
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      * distributed under the License is distributed on an "AS IS" BASIS,
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      * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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      * See the License for the specific language governing permissions and
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      * limitations under the License.
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      */
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     package org.apache.commons.configuration.interpol;
18 |  |
19 |  |
     import java.util.HashMap;
20 |  |
     import java.util.Map;
21 |  |
     import java.util.Set;
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23 |  |
     import org.apache.commons.lang.text.StrLookup;
24 |  |
25 |  |
     /**
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      * <p>
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      * A class that handles interpolation (variable substitution) for configuration
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      * objects.
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      * </p>
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      * <p>
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      * Each instance of <code>AbstractConfiguration</code> is associated with an
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      * object of this class. All interpolation tasks are delegated to this object.
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      * </p>
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      * <p>
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      * <code>ConfigurationInterpolator</code> works together with the
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      * <code>StrSubstitutor</code> class from <a
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      * href="http://commons.apache.org/lang">Commons Lang</a>. By extending
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      * <code>StrLookup</code> it is able to provide values for variables that
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      * appear in expressions.
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      * </p>
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      * <p>
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      * The basic idea of this class is that it can maintain a set of primitive
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      * <code>StrLookup</code> objects, each of which is identified by a special
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      * prefix. The variables to be processed have the form
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      * <code>${prefix:name}</code>. <code>ConfigurationInterpolator</code> will
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      * extract the prefix and determine, which primitive lookup object is registered
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      * for it. Then the name of the variable is passed to this object to obtain the
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      * actual value. It is also possible to define a default lookup object, which
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      * will be used for variables that do not have a prefix or that cannot be
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      * resolved by their associated lookup object.
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      * </p>
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      * <p>
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      * When a new instance of this class is created it is initialized with a default
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      * set of primitive lookup objects. This set can be customized using the static
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      * methods <code>registerGlobalLookup()</code> and
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      * <code>deregisterGlobalLookup()</code>. Per default it contains the
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      * following standard lookup objects:
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      * </p>
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      * <p>
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      * <table border="1">
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      * <tr>
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      * <th>Prefix</th>
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      * <th>Lookup object</th>
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      * </tr>
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      * <tr>
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      * <td valign="top">sys</td>
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      * <td>With this prefix a lookup object is associated that is able to resolve
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      * system properties.</td>
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      * </tr>
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      * <tr>
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      * <td valign="top">const</td>
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      * <td>The <code>const</code> prefix indicates that a variable is to be
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      * interpreted as a constant member field of a class (i.e. a field with the
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      * <b>static final</b> modifiers). The name of the variable must be of the form
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      * <code>&lt;full qualified class name&gt;.&lt;field name&gt;</code>, e.g.
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      * <code>org.apache.commons.configuration.interpol.ConfigurationInterpolator.PREFIX_CONSTANTS
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      * </code>.</td>
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      * </tr>
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      * </table>
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      * </p>
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      * <p>
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      * After an instance has been created the current set of lookup objects can be
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      * modified using the <code>registerLookup()</code> and
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      * <code>deregisterLookup()</code> methods. The default lookup object (that is
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      * invoked for variables without a prefix) can be set with the
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      * <code>setDefaultLookup()</code> method. (If a
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      * <code>ConfigurationInterpolator</code> instance is created by a
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      * configuration object, this lookup points to the configuration itself, so that
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      * variables are resolved using the configuration's properties. This ensures
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      * backward compatibility to earlier version of Commons Configuration.)
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      * </p>
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      * <p>
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      * Implementation node: Instances of this class are not thread-safe related to
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      * modifications of their current set of registered lookup objects. It is
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      * intended that each instance is associated with a single
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      * <code>Configuration</code> object and used for its interpolation tasks.
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      * </p>
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      *
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      * @version $Id: ConfigurationInterpolator.java 561230 2007-07-31 04:17:09Z rahul $
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      * @since 1.4
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      * @author <a
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      * href="http://commons.apache.org/configuration/team-list.html">Commons
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      * Configuration team</a>
104 |  |
      */
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     public class ConfigurationInterpolator extends StrLookup
106 |  |
     {
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         /**
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          * Constant for the prefix of the standard lookup object for resolving
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          * system properties.
110 |  |
          */
111 |  |
         public static final String PREFIX_SYSPROPERTIES = "sys";
112 |  |
113 |  |
         /**
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          * Constant for the prefix of the standard lookup object for resolving
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          * constant values.
116 |  |
          */
117 |  |
         public static final String PREFIX_CONSTANTS = "const";
118 |  |
119 |  |
         /** Constant for the prefix separator. */
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         private static final char PREFIX_SEPARATOR = ':';
121 |  |
122 |  |
         /** A map with the globally registered lookup objects. */
123 |  |
         private static Map globalLookups;
124 |  |
125 |  |
         /** A map with the locally registered lookup objects. */
126 |  |
         private Map localLookups;
127 |  |
128 |  |
         /** Stores the default lookup object. */
129 |  |
         private StrLookup defaultLookup;
130 |  |
131 |  |
         /**
132 |  |
          * Creates a new instance of <code>ConfigurationInterpolator</code>.
133 |  |
          */
134 |  |
         public ConfigurationInterpolator()
135 | 746 |
         {
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             synchronized (globalLookups)
137 |  |
             {
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                 localLookups = new HashMap(globalLookups);
139 | 746 |
             }
140 | 746 |
         }
141 |  |
142 |  |
         /**
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          * Registers the given lookup object for the specified prefix globally. This
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          * means that all instances that are created later will use this lookup
145 |  |
          * object for this prefix. If for this prefix a lookup object is already
146 |  |
          * registered, the new lookup object will replace the old one. Note that the
147 |  |
          * lookup objects registered here will be shared between multiple clients.
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          * So they should be thread-safe.
149 |  |
          *
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          * @param prefix the variable prefix (must not be <b>null</b>)
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          * @param lookup the lookup object to be used for this prefix (must not be
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          * <b>null</b>)
153 |  |
          */
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         public static void registerGlobalLookup(String prefix, StrLookup lookup)
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         {
156 | 5 |
             if (prefix == null)
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             {
158 | 1 |
                 throw new IllegalArgumentException(
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                         "Prefix for lookup object must not be null!");
160 |  |
             }
161 | 4 |
             if (lookup == null)
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             {
163 | 1 |
                 throw new IllegalArgumentException(
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                         "Lookup object must not be null!");
165 |  |
             }
166 | 3 |
             synchronized (globalLookups)
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             {
168 | 3 |
                 globalLookups.put(prefix, lookup);
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             }
170 | 3 |
         }
171 |  |
172 |  |
         /**
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          * Deregisters the global lookup object for the specified prefix. This means
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          * that this lookup object won't be available for later created instances
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          * any more. For already existing instances this operation does not have any
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          * impact.
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          *
178 |  |
          * @param prefix the variable prefix
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          * @return a flag whether for this prefix a lookup object had been
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          * registered
181 |  |
          */
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         public static boolean deregisterGlobalLookup(String prefix)
183 |  |
         {
184 | 24 |
             synchronized (globalLookups)
185 |  |
             {
186 | 24 |
                 return globalLookups.remove(prefix) != null;
187 | 0 |
             }
188 |  |
         }
189 |  |
190 |  |
         /**
191 |  |
          * Registers the given lookup object for the specified prefix at this
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          * instance. From now on this lookup object will be used for variables that
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          * have the specified prefix.
194 |  |
          *
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          * @param prefix the variable prefix (must not be <b>null</b>)
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          * @param lookup the lookup object to be used for this prefix (must not be
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          * <b>null</b>)
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          */
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         public void registerLookup(String prefix, StrLookup lookup)
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         {
201 | 11 |
             if (prefix == null)
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             {
203 | 1 |
                 throw new IllegalArgumentException(
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                         "Prefix for lookup object must not be null!");
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             }
206 | 10 |
             if (lookup == null)
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             {
208 | 1 |
                 throw new IllegalArgumentException(
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                         "Lookup object must not be null!");
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             }
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             localLookups.put(prefix, lookup);
212 | 9 |
         }
213 |  |
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         /**
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          * Deregisters the lookup object for the specified prefix at this instance.
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          * It will be removed from this instance.
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          *
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          * @param prefix the variable prefix
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          * @return a flag whether for this prefix a lookup object had been
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          * registered
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          */
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         public boolean deregisterLookup(String prefix)
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         {
224 | 2 |
             return localLookups.remove(prefix) != null;
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         }
226 |  |
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         /**
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          * Returns a set with the prefixes, for which lookup objects are registered
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          * at this instance. This means that variables with these prefixes can be
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          * processed.
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          *
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          * @return a set with the registered variable prefixes
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          */
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         public Set prefixSet()
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         {
236 | 9 |
             return localLookups.keySet();
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         }
238 |  |
239 |  |
         /**
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          * Returns the default lookup object.
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          *
242 |  |
          * @return the default lookup object
243 |  |
          */
244 |  |
         public StrLookup getDefaultLookup()
245 |  |
         {
246 | 4764 |
             return defaultLookup;
247 |  |
         }
248 |  |
249 |  |
         /**
250 |  |
          * Sets the default lookup object. This lookup object will be used for all
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          * variables without a special prefix. If it is set to <b>null</b>, such
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          * variables won't be processed.
253 |  |
          *
254 |  |
          * @param defaultLookup the new default lookup object
255 |  |
          */
256 |  |
         public void setDefaultLookup(StrLookup defaultLookup)
257 |  |
         {
258 | 724 |
             this.defaultLookup = defaultLookup;
259 | 724 |
         }
260 |  |
261 |  |
         /**
262 |  |
          * Resolves the specified variable. This implementation will try to extract
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          * a variable prefix from the given variable name (the first colon (':') is
264 |  |
          * used as prefix separator). It then passes the name of the variable with
265 |  |
          * the prefix stripped to the lookup object registered for this prefix. If
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          * no prefix can be found or if the associated lookup object cannot resolve
267 |  |
          * this variable, the default lookup object will be used.
268 |  |
          *
269 |  |
          * @param var the name of the variable whose value is to be looked up
270 |  |
          * @return the value of this variable or <b>null</b> if it cannot be
271 |  |
          * resolved
272 |  |
          */
273 |  |
         public String lookup(String var)
274 |  |
         {
275 | 2483 |
             if (var == null)
276 |  |
             {
277 | 1 |
                 return null;
278 |  |
             }
279 |  |
280 | 2482 |
             int prefixPos = var.indexOf(PREFIX_SEPARATOR);
281 | 2482 |
             if (prefixPos >= 0)
282 |  |
             {
283 | 104 |
                 String prefix = var.substring(0, prefixPos);
284 | 104 |
                 String name = var.substring(prefixPos + 1);
285 | 104 |
                 String value = fetchLookupForPrefix(prefix).lookup(name);
286 | 104 |
                 if (value != null)
287 |  |
                 {
288 | 99 |
                     return value;
289 |  |
                 }
290 |  |
             }
291 | 2383 |
             return fetchNoPrefixLookup().lookup(var);
292 |  |
         }
293 |  |
294 |  |
         /**
295 |  |
          * Returns the lookup object to be used for variables without a prefix. This
296 |  |
          * implementation will check whether a default lookup object was set. If
297 |  |
          * this is the case, it will be returned. Otherwise a <b>null</b> lookup
298 |  |
          * object will be returned.
299 |  |
          *
300 |  |
          * @return the lookup object to be used for variables without a prefix
301 |  |
          */
302 |  |
         protected StrLookup fetchNoPrefixLookup()
303 |  |
         {
304 | 2383 |
             return (getDefaultLookup() != null) ? getDefaultLookup() : StrLookup.noneLookup();
305 |  |
         }
306 |  |
307 |  |
         /**
308 |  |
          * Obtains the lookup object for the specified prefix. This method is called
309 |  |
          * by the <code>lookup()</code> method. This implementation will check
310 |  |
          * whether a lookup object is registered for the given prefix. If not, a
311 |  |
          * <b>null</b> lookup object will be returned.
312 |  |
          *
313 |  |
          * @param prefix the prefix
314 |  |
          * @return the lookup object to be used for this prefix
315 |  |
          */
316 |  |
         protected StrLookup fetchLookupForPrefix(String prefix)
317 |  |
         {
318 | 104 |
             StrLookup lookup = (StrLookup) localLookups.get(prefix);
319 | 104 |
             if (lookup == null)
320 |  |
             {
321 | 4 |
                 lookup = StrLookup.noneLookup();
322 |  |
             }
323 | 104 |
             return lookup;
324 |  |
         }
325 |  |
326 |  |
         // static initializer, sets up the map with the standard lookups
327 |  |
         static
328 |  |
         {
329 | 55 |
             globalLookups = new HashMap();
330 | 55 |
             globalLookups.put(PREFIX_SYSPROPERTIES, StrLookup.systemPropertiesLookup());
331 | 55 |
             globalLookups.put(PREFIX_CONSTANTS, new ConstantLookup());
332 | 55 |
         }
333 |  |
     }