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1
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.ConstantCalc;
19 import mondrian.calc.impl.AbstractListCalc;
20 import mondrian.mdx.ResolvedFunCall;
21
22 import java.util.List  ;
23 import java.util.Collections ;
24
25
33 class HeadTailFunDef extends FunDefBase {
34 static final Resolver TailResolver = new ReflectiveMultiResolver(
35 "Tail",
36 "Tail(<Set>[, <Count>])",
37 "Returns a subset from the end of a set.",
38 new String [] {"fxx", "fxxn"},
39 HeadTailFunDef.class);
40
41 static final Resolver HeadResolver = new ReflectiveMultiResolver(
42 "Head",
43 "Head(<Set>[, < Numeric Expression >])",
44 "Returns the first specified number of elements in a set.",
45 new String [] {"fxx", "fxxn"},
46 HeadTailFunDef.class);
47
48 private final boolean head;
49
50 public HeadTailFunDef(FunDef dummyFunDef) {
51 super(dummyFunDef);
52 head = dummyFunDef.getName().equals("Head");
53 }
54
55 public Calc compileCall(ResolvedFunCall call, ExpCompiler compiler) {
56 final ListCalc listCalc =
57 compiler.compileList(call.getArg(0));
58 final IntegerCalc integerCalc =
59 call.getArgCount() > 1 ?
60 compiler.compileInteger(call.getArg(1)) :
61 ConstantCalc.constantInteger(1);
62 if (head) {
63 return new AbstractListCalc(call, new Calc[] {listCalc, integerCalc}) {
64 public List evaluateList(Evaluator evaluator) {
65 List list = listCalc.evaluateList(evaluator);
66 int count = integerCalc.evaluateInteger(evaluator);
67 return head(count, list);
68 }
69 };
70 } else {
71 return new AbstractListCalc(call, new Calc[] {listCalc, integerCalc}) {
72
73 public List evaluateList(Evaluator evaluator) {
74 List list = listCalc.evaluateList(evaluator);
75 int count = integerCalc.evaluateInteger(evaluator);
76 return tail(count, list);
77 }
78 };
79 }
80 }
81
82 static List tail(final int count, List members) {
83 assert members != null;
84 final int memberCount = members.size();
85 if (count >= memberCount) {
86 return members;
87 }
88 if (count <= 0) {
89 return Collections.EMPTY_LIST;
90 }
91 return members.subList(memberCount - count, memberCount);
92 }
93
94 static List head(final int count, List members) {
95 assert members != null;
96 if (count >= members.size()) {
97 return members;
98 }
99 if (count <= 0) {
100 return Collections.EMPTY_LIST;
101 }
102 return members.subList(0, count);
103 }
104 }
105
106 |
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