Identifier


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5    *
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7    * 1.1 (the "License"); you may not use this file except in compliance with the
8    * License.  You may obtain a copy of the License at
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15   *
16   * The Original Code is "MantaRay" (TM).
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18   * The Initial Developer of the Original Code is Coridan.
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33   * of this file under either the MPL or the GNU LESSER GENERAL PUBLIC LICENSE.
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46  package org.mr.api.jms.selector.syntax;
47  
48  import javax.jms.DeliveryMode  ;
49  import javax.jms.JMSException  ;
50  import javax.jms.Message  ;
51  
52  
53  /**
54   * This class implements an identifier. When evaluated, this returns
55   * the value of named header identifier or property, or null if the
56   * identifier is null or the property does not exist.
57   *
58   */
59  class Identifier implements Expression {
60  
61      /**
62       * The identifier name
63       */
64      private final String   name;
65  
66      /**
67       * If true the identifier is a header identifier, otherwise it is an user
68       * identifier
69       */
70      private final boolean headerField;
71  
72      /**
73       * Persistent delivery mode
74       */
75      private static final MantaString PERSISTENT = new MantaString(Identifiers.PERSISTENT);
76  
77      /**
78       * Non-persistent delivery mode
79       */
80      private static final MantaString NON_PERSISTENT = new MantaString(Identifiers.NON_PERSISTENT);
81  
82  
83      /**
84       * Construct a new <code>Identifier</code>
85       *
86       * @param name the identifier name
87       * @throws SelectorException if the identifier cannot be queried by
88       * selectors
89       */
90      public Identifier(final String   name) throws SelectorException {
91          this.name = name;
92  
93          if (Identifiers.isJMSIdentifier(name)) {
94              if (!Identifiers.isQueryableJMSIdentifier(name)) {
95                  throw new SelectorException("Invalid header field: " + name);
96              }//if
97              headerField = true;
98          }//if 
99          else {
100             headerField = false;
101         }//else
102     }//Identifier
103 
104     /**
105      * Evaluate the expression
106      *
107      * @param msg the message to use to obtain any header identifier and property values
108      * @return the evaluated result, or <code>null</code> if the value of the expression is unknown
109      */
110     public final MantaObject evaluate(final Message   msg) {
111 
112         MantaObject value = null;
113         try {
114             if (headerField) {
115                 if (name.equals(Identifiers.JMS_DELIVERY_MODE)) {
116                     value = deliveryMode(msg.getJMSDeliveryMode());
117                 }//if 
118                 else if (name.equals(Identifiers.JMS_PRIORITY)) {
119                     value = new MantaLong(msg.getJMSPriority());
120                 }//elseif
121                 else if (name.equals(Identifiers.JMS_TIMESTAMP)) {
122                     value = new MantaLong(msg.getJMSTimestamp());
123                 }//elseif
124                 else if (name.equals(Identifiers.JMS_MESSAGE_ID)) {
125                     String   id = msg.getJMSMessageID();
126                     if (id != null) {
127                         value = new MantaString(id);
128                     }//if
129                 } //elseif
130                 else if (name.equals(Identifiers.JMS_CORRELATION_ID)) {
131                     String   id = msg.getJMSCorrelationID();
132                     if (id != null) {
133                         value = new MantaString(id);
134                     }//if
135                 } //elseif
136                 else if (name.equals(Identifiers.JMS_TYPE)) {
137                     String   type = msg.getJMSType();
138                     if (type != null) {
139                         value = new MantaString(type);
140                     }//if
141                 }//elseif
142             }//if 
143             else {
144                 value = MantaObjectFactory.create(msg.getObjectProperty(name));
145             }////else
146         }//try 
147         catch (JMSException   ignore) {
148             // do nothing
149         }//catch
150         return value;
151     }//evaluate
152     
153 
154     /**
155      * Return a string representation of this expression.
156      *
157      * @return a string representation of this expression
158      */
159     public final String   toString() {
160         return name;
161     }//toString
162     
163 
164     /**
165      * Converts the delivery mode to a string
166      *
167      * @param mode the delivery mode. One of
168      * <code>DeliveryMode.PERSISTENT</code> or
169      * <code>DeliveryMode.NON_PERSISTENT</code>
170      * @return the stringified representation of the delivery mode
171      */
172     private MantaString deliveryMode(final int mode) {
173         MantaString result = PERSISTENT;
174         if (mode == DeliveryMode.NON_PERSISTENT) {
175             result = NON_PERSISTENT;
176         }//if
177         return result;
178     }//deliveryMode
179 }//Identifier
180
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