SelectItemExpression


1   /*
2    * Copyright 2004-2005 Gary Bentley 
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License"); you may 
5    * not use this file except in compliance with the License. 
6    * You may obtain a copy of the License at 
7    *    http://www.apache.org/licenses/LICENSE-2.0 
8    *
9    * Unless required by applicable law or agreed to in writing, software 
10   * distributed under the License is distributed on an "AS IS" BASIS, 
11   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
12   * See the License for the specific language governing permissions and 
13   * limitations under the License.
14   */
15  package org.josql.expressions;
16  
17  import java.util.Map  ;
18  import java.util.Collection  ;
19  
20  import org.josql.Query;
21  import org.josql.QueryExecutionException;
22  import org.josql.QueryParseException;
23  
24  import org.josql.internal.Utilities;
25  
26  public class SelectItemExpression extends Expression
27  {
28  
29      public static final String   KEY = "key";
30      public static final String   VALUE = "value";
31  
32      private Expression exp = null;
33      private boolean fixedResult = false;
34      private Class   addItemsType = null;
35      private String   addItemsMapType = null;
36      private String   alias = null;
37  
38      public String   getAlias ()
39      {
40  
41      return this.alias;
42  
43      }
44  
45      public void setAlias (String   a)
46      {
47  
48      this.alias = Utilities.stripQuotes (a);
49  
50      }
51  
52      public boolean hasFixedResult (Query q)
53      {
54  
55      return this.fixedResult;
56  
57      }
58  
59      public Class   getExpectedReturnType (Query  q)
60                                      throws QueryParseException
61      {
62  
63      return this.exp.getExpectedReturnType (q);
64  
65      }
66  
67      public void init (Query  q)
68                    throws QueryParseException
69      {
70  
71      this.exp.init (q);
72  
73      this.fixedResult = this.exp.hasFixedResult (q);
74  
75      /*
76      if (this.isAddItemsFromCollectionOrMap ())
77      {
78  
79          // Get the expected return type.
80          Class expC = this.getExpectedReturnType (q);
81  
82          if (expC.getName ().equals (Object.class.getName ()))
83          {
84  
85          // Defer until later.
86          return;
87  
88          }
89  
90          if (!this.addItemsType.isAssignableFrom (expC))
91          {
92  
93          throw new QueryParseException ("Expected return type from select clause column will be: " +
94                             expC.getName () +
95                             ", however expecting to add items to results from type: " +
96                             this.addItemsType.getName ());
97  
98          }
99  
100     }
101     */
102 
103     }
104 
105     public void setAddMapType (String   t)
106     {
107 
108     this.addItemsMapType = t;
109 
110     }
111 
112     public Collection   getAddItems (Object   v)
113     {
114 
115     if (Map  .class.isAssignableFrom (this.addItemsType))
116     {
117 
118         boolean k = this.addItemsMapType.equals (SelectItemExpression.KEY);
119 
120         Map   m = (Map  ) v;
121 
122         if (k)
123         {
124 
125         return m.keySet ();
126 
127         }
128 
129         return m.values ();
130 
131     }
132 
133     if (v instanceof Collection  )
134     {
135 
136         return (Collection  ) v;
137 
138     }
139 
140     // This is a nasty hack but is "ok" for now, fix in a later version...
141     java.util.List   l = new java.util.ArrayList   ();
142     l.add (v);
143 
144     return l;
145 
146     }
147 
148     public boolean isAddItemsFromCollectionOrMap ()
149     {
150 
151     return this.addItemsType != null;
152 
153     }
154 
155     public void setAddItemsType (Class   c)
156     {
157 
158     this.addItemsType = c;
159 
160     }
161 
162     public Expression getExpression ()
163     {
164 
165     return this.exp;
166 
167     }
168 
169     public void setExpression (Expression exp)
170     {
171 
172     this.exp = exp;
173 
174     }
175 
176     public boolean isTrue (Object   o,
177                Query  q)
178                        throws QueryExecutionException
179     {
180 
181     return this.exp.isTrue (o,
182                 q);
183 
184     }
185 
186     public Object   getValue (Object   o,
187                 Query  q)
188                         throws QueryExecutionException
189     {
190 
191     return this.exp.getValue (o,
192                   q);
193 
194     }
195 
196     public String   toString ()
197     {
198 
199     StringBuffer   b = new StringBuffer   ();
200 
201     if (this.isAddItemsFromCollectionOrMap ())
202     {
203 
204         b.append ("[*");
205 
206         if (this.addItemsMapType != null)
207         {
208 
209         b.append (", ");
210         b.append (this.addItemsMapType);
211 
212         }
213 
214         b.append ("] ");
215 
216     }
217 
218     b.append (this.exp);
219 
220     if (this.alias != null)
221     {
222 
223         b.append (" ");
224         b.append (this.alias);
225 
226     }
227 
228     return b.toString ();
229 
230     }
231 
232 }
233
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