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Java > Open Source Codes > org > apache > derby > impl > sql > compile > MaterializeSubqueryNode


1 /*
2
3    Derby - Class org.apache.derby.impl.sql.compile.MaterializeSubqueryNode
4
5    Licensed to the Apache Software Foundation (ASF) under one or more
6    contributor license agreements. See the NOTICE file distributed with
7    this work for additional information regarding copyright ownership.
8    The ASF licenses this file to you under the Apache License, Version 2.0
9    (the "License"); you may not use this file except in compliance with
10    the License. You may obtain a copy of the License at
11
12       http://www.apache.org/licenses/LICENSE-2.0
13
14    Unless required by applicable law or agreed to in writing, software
15    distributed under the License is distributed on an "AS IS" BASIS,
16    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17    See the License for the specific language governing permissions and
18    limitations under the License.
19
20  */
21
22 package org.apache.derby.impl.sql.compile;
23
24 import org.apache.derby.iapi.services.compiler.MethodBuilder;
25 import org.apache.derby.iapi.services.compiler.LocalField;
26 import org.apache.derby.iapi.error.StandardException;
27 import org.apache.derby.iapi.reference.ClassName;
28 import org.apache.derby.iapi.services.classfile.VMOpcode;
29
30 import org.apache.derby.impl.sql.compile.ActivationClassBuilder;
31
32 /**
33  * A MaterializeSubqueryNode is used to replace the nodes for a subquery, to facilitate
34  * code generation for materialization if possible. See beetle 4373 for details.
35  *
36  * @author Tingjian Ge
37  */
38 class MaterializeSubqueryNode extends ResultSetNode
39 {
40
41     private LocalField lf;
42
43     public MaterializeSubqueryNode(LocalField lf)
44     {
45         this.lf = lf;
46     }
47
48     public void generate(ActivationClassBuilder acb,
49                          MethodBuilder mb)
50         throws StandardException
51     {
52         acb.pushThisAsActivation(mb);
53         mb.getField(lf);
54         mb.callMethod(VMOpcode.INVOKEVIRTUAL, ClassName.BaseActivation, "materializeResultSetIfPossible", ClassName.NoPutResultSet, 1);
55     }
56
57     void decrementLevel(int decrement)
58     {
59     }
60 }
61
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