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Java > Open Source Codes > com > caucho > amber > expr > fun > LocateFunExpr


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  * Free Software Foundation, Inc.
23  * 59 Temple Place, Suite 330
24  * Boston, MA 02111-1307 USA
25  *
26  * @author Scott Ferguson
27  */
28
29 package com.caucho.amber.expr.fun;
30
31 import com.caucho.amber.expr.AmberExpr;
32 import com.caucho.amber.query.QueryParser;
33 import com.caucho.util.CharBuffer;
34 import com.caucho.util.L10N;
35
36 import java.util.ArrayList JavaDoc;
37
38
39 /**
40  * LOCATE function expression
41  */
42 public class LocateFunExpr extends FunExpr {
43   private static final L10N L = new L10N(LocateFunExpr.class);
44
45   /**
46    * Creates a new expression
47    */
48   protected LocateFunExpr(QueryParser parser,
49                           ArrayList JavaDoc<AmberExpr> args)
50   {
51     super(parser, "locate", args, false);
52   }
53
54   public static FunExpr create(QueryParser parser,
55                                ArrayList JavaDoc<AmberExpr> args)
56   {
57     return new LocateFunExpr(parser, args);
58   }
59
60   /**
61    * Generates the where expression.
62    */
63   public void generateWhere(CharBuffer cb)
64   {
65     generateInternalWhere(cb, true);
66   }
67
68   /**
69    * Generates the (update) where expression.
70    */
71   public void generateUpdateWhere(CharBuffer cb)
72   {
73     generateInternalWhere(cb, false);
74   }
75
76   //
77 // private/protected
78
79   void generateInternalWhere(CharBuffer cb,
80                              boolean select)
81   {
82     // Translate to => POSITION('word' in SUBSTRING(data,i,LENGTH(data)))+(i-1)
83
84     ArrayList JavaDoc<AmberExpr> args = getArgs();
85
86     int n = args.size();
87
88     // XXX:
89 // if (n < 2)
90 // throw _parser.error(L.l("expected at least 2 string arguments for LOCATE"));
91 //
92 // if (n > 3)
93 // throw _parser.error(L.l("expected at most 3 arguments for LOCATE"));
94
95     if (_parser.isDerbyDBMS()) {
96
97       // Derby.
98
99       cb.append("locate(");
100
101       if (select)
102         args.get(0).generateWhere(cb);
103       else
104         args.get(0).generateUpdateWhere(cb);
105
106       cb.append(',');
107
108       if (select)
109         args.get(1).generateWhere(cb);
110       else
111         args.get(1).generateUpdateWhere(cb);
112
113       cb.append(',');
114
115       if (n == 2) {
116         cb.append('1');
117       }
118       else {
119         AmberExpr expr = args.get(2);
120
121          if (select)
122           expr.generateWhere(cb);
123         else
124           expr.generateUpdateWhere(cb);
125       }
126
127       cb.append(')');
128
129       return;
130     }
131
132     // Postgres, MySql.
133
134     CharBuffer charBuffer = new CharBuffer();
135
136     charBuffer.append("position(");
137
138     if (select)
139       args.get(0).generateWhere(charBuffer);
140     else
141       args.get(0).generateUpdateWhere(charBuffer);
142
143     charBuffer.append(" in substring(");
144
145     if (select)
146       args.get(1).generateWhere(charBuffer);
147     else
148       args.get(1).generateUpdateWhere(charBuffer);
149
150     charBuffer.append(',');
151
152     int fromIndex = 1;
153
154     AmberExpr expr = null;
155
156     if (n == 2) {
157       charBuffer.append('1');
158     }
159     else {
160       expr = args.get(2);
161
162       try {
163         fromIndex = Integer.parseInt(expr.toString());
164       } catch (Exception JavaDoc ex) {
165         // XXX: this validation should be moved to QueryParser
166 // throw new QueryParseException(L.l("expected an integer for LOCATE 3rd argument"));
167 }
168
169       if (select)
170         expr.generateWhere(charBuffer);
171       else
172         expr.generateUpdateWhere(charBuffer);
173     }
174
175     charBuffer.append(",length(");
176
177     if (select)
178       args.get(1).generateWhere(charBuffer);
179     else
180       args.get(1).generateUpdateWhere(charBuffer);
181
182     charBuffer.append(")))");
183
184     cb.append("case when ");
185     cb.append(charBuffer);
186     cb.append(" <= 0 then 0 else ");
187     cb.append(charBuffer);
188
189     if (fromIndex > 1) {
190
191       cb.append('+');
192
193       cb.append(fromIndex-1);
194     }
195
196     cb.append(" end");
197   }
198 }
199
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