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Java > Open Source Codes > mondrian > olap > fun > SubsetFunDef


1 /*
2 // $Id: //open/mondrian/src/main/mondrian/olap/fun/SubsetFunDef.java#1 $
3 // This software is subject to the terms of the Common Public License
4 // Agreement, available at the following URL:
5 // http://www.opensource.org/licenses/cpl.html.
6 // Copyright (C) 2006-2006 Julian Hyde
7 // All Rights Reserved.
8 // You must accept the terms of that agreement to use this software.
9 */
10 package mondrian.olap.fun;
11
12 import mondrian.olap.FunDef;
13 import mondrian.olap.Evaluator;
14 import mondrian.calc.Calc;
15 import mondrian.calc.ExpCompiler;
16 import mondrian.calc.ListCalc;
17 import mondrian.calc.IntegerCalc;
18 import mondrian.calc.impl.AbstractListCalc;
19 import mondrian.mdx.ResolvedFunCall;
20
21 import java.util.List JavaDoc;
22 import java.util.Collections JavaDoc;
23
24 /**
25  * Definition of the <code>Subset</code> MDX function.
26  *
27  * @author jhyde
28  * @version $Id: //open/mondrian/src/main/mondrian/olap/fun/SubsetFunDef.java#1 $
29  * @since Mar 23, 2006
30  */
31 class SubsetFunDef extends FunDefBase {
32     static final ReflectiveMultiResolver Resolver = new ReflectiveMultiResolver(
33             "Subset",
34             "Subset(<Set>, <Start>[, <Count>])",
35             "Returns a subset of elements from a set.",
36             new String JavaDoc[] {"fxxn", "fxxnn"},
37             SubsetFunDef.class);
38
39     public SubsetFunDef(FunDef dummyFunDef) {
40         super(dummyFunDef);
41     }
42
43     public Calc compileCall(ResolvedFunCall call, ExpCompiler compiler) {
44         final ListCalc listCalc =
45                 compiler.compileList(call.getArg(0));
46         final IntegerCalc startCalc =
47                 compiler.compileInteger(call.getArg(1));
48         final IntegerCalc countCalc =
49                 call.getArgCount() > 2 ?
50                 compiler.compileInteger(call.getArg(2)) :
51                 null;
52         return new AbstractListCalc(call, new Calc[] {listCalc, startCalc, countCalc}) {
53             public List JavaDoc evaluateList(Evaluator evaluator) {
54                 final List JavaDoc list =
55                         listCalc.evaluateList(evaluator);
56                 final int start =
57                         startCalc.evaluateInteger(evaluator);
58                 int end;
59                 if (countCalc != null) {
60                     final int count =
61                         countCalc.evaluateInteger(evaluator);
62                     end = start + count;
63                 } else {
64                     end = list.size();
65                 }
66                 if (end > list.size()) {
67                     end = list.size();
68                 }
69                 if (start >= end || start < 0) {
70                     return Collections.EMPTY_LIST;
71                 }
72                 assert 0 <= start;
73                 assert start < end;
74                 assert end <= list.size();
75                 if (start == 0 && end == list.size()) {
76                     return list;
77                 } else {
78                     return list.subList(start, end);
79                 }
80             }
81         };
82     }
83 }
84
85 // End SubsetFunDef.java
86
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