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


1 /*
2 // $Id: //open/mondrian/src/main/mondrian/olap/fun/CoalesceEmptyFunDef.java#10 $
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) 2004-2006 Julian Hyde and others
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.*;
13 import mondrian.calc.*;
14 import mondrian.calc.impl.GenericCalc;
15 import mondrian.mdx.ResolvedFunCall;
16
17 /**
18  * Definition of the <code>CoalesceEmpty</code> MDX function.
19  *
20  * <p>It evaluates each of the arguments to the function, returning the
21  * first such argument that does not return a null value.
22  *
23  * @author gjohnson
24  * @version $Id: //open/mondrian/src/main/mondrian/olap/fun/CoalesceEmptyFunDef.java#10 $
25  */
26 public class CoalesceEmptyFunDef extends FunDefBase {
27     static final ResolverBase Resolver = new ResolverImpl();
28
29     public CoalesceEmptyFunDef(ResolverBase resolverBase, int type, int[] types) {
30         super(resolverBase, type, types);
31     }
32
33     public Calc compileCall(ResolvedFunCall call, ExpCompiler compiler) {
34         final Exp[] args = call.getArgs();
35         final Calc[] calcs = new Calc[args.length];
36         for (int i = 0; i < args.length; i++) {
37             calcs[i] = compiler.compileScalar(args[i], true);
38         }
39         return new GenericCalc(call) {
40             public Object JavaDoc evaluate(Evaluator evaluator) {
41                 for (Calc calc : calcs) {
42                     final Object JavaDoc o = calc.evaluate(evaluator);
43                     if (o != null) {
44                         return o;
45                     }
46                 }
47                 return null;
48             }
49
50             public Calc[] getCalcs() {
51                 return calcs;
52             }
53         };
54     }
55
56     private static class ResolverImpl extends ResolverBase {
57         public ResolverImpl() {
58             super(
59                     "CoalesceEmpty",
60                     "CoalesceEmpty(<Value Expression>[, <Value Expression>...])",
61                     "Coalesces an empty cell value to a different value. All of the expressions must be of the same type (number or string).",
62                     Syntax.Function);
63         }
64
65         public FunDef resolve(
66                 Exp[] args, Validator validator, int[] conversionCount) {
67             if (args.length < 1) {
68                 return null;
69             }
70             final int[] types = {Category.Numeric, Category.String};
71             final int[] argTypes = new int[args.length];
72             for (int type : types) {
73                 int matchingArgs = 0;
74                 conversionCount[0] = 0;
75                 for (int i = 0; i < args.length; i++) {
76                     if (validator.canConvert(args[i], type, conversionCount)) {
77                         matchingArgs++;
78                     }
79                     argTypes[i] = type;
80                 }
81                 if (matchingArgs == args.length) {
82                     return new CoalesceEmptyFunDef(this, type, argTypes);
83                 }
84             }
85             return null;
86         }
87
88         public boolean requiresExpression(int k) {
89             return true;
90         }
91     }
92 }
93
94 // End CoalesceEmptyFunDef.java
95
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