001 /*
002 // $Id: //open/mondrian/src/main/mondrian/calc/impl/TupleValueCalc.java#7 $
003 // This software is subject to the terms of the Common Public License
004 // Agreement, available at the following URL:
005 // http://www.opensource.org/licenses/cpl.html.
006 // Copyright (C) 2006-2007 Julian Hyde
007 // All Rights Reserved.
008 // You must accept the terms of that agreement to use this software.
009 */
010 package mondrian.calc.impl;
011
012 import mondrian.olap.*;
013 import mondrian.olap.fun.TupleFunDef;
014 import mondrian.olap.type.TupleType;
015 import mondrian.olap.type.Type;
016 import mondrian.calc.TupleCalc;
017 import mondrian.calc.Calc;
018 import mondrian.calc.DummyExp;
019
020 /**
021 * Expression which evaluates a tuple expression,
022 * sets the dimensional context to the result of that expression,
023 * then yields the value of the current measure in the current
024 * dimensional context.
025 *
026 * <p>The evaluator's context is preserved.
027 *
028 * @see mondrian.calc.impl.ValueCalc
029 * @see mondrian.calc.impl.MemberValueCalc
030 *
031 * @author jhyde
032 * @version $Id: //open/mondrian/src/main/mondrian/calc/impl/TupleValueCalc.java#7 $
033 * @since Sep 27, 2005
034 */
035 public class TupleValueCalc extends GenericCalc {
036 private final TupleCalc tupleCalc;
037
038 public TupleValueCalc(Exp exp, TupleCalc tupleCalc) {
039 super(exp);
040 this.tupleCalc = tupleCalc;
041 }
042
043 public Object evaluate(Evaluator evaluator) {
044 final Member[] members = tupleCalc.evaluateTuple(evaluator);
045 if (members == null) {
046 return null;
047 }
048
049 final boolean needToReturnNull =
050 evaluator.needToReturnNullForUnrelatedDimension(members);
051 if (needToReturnNull) {
052 return null;
053 }
054
055 Member [] savedMembers = new Member[members.length];
056 for (int i = 0; i < members.length; i++) {
057 savedMembers[i] = evaluator.setContext(members[i]);
058 }
059 Object result = evaluator.evaluateCurrent();
060 evaluator.setContext(savedMembers);
061 return result;
062 }
063
064 public Calc[] getCalcs() {
065 return new Calc[] {tupleCalc};
066 }
067
068 public boolean dependsOn(Dimension dimension) {
069 if (super.dependsOn(dimension)) {
070 return true;
071 }
072 for (Type type : ((TupleType) tupleCalc.getType()).elementTypes) {
073 // If the expression definitely includes the dimension (in this
074 // case, that means it is a member of that dimension) then we
075 // do not depend on the dimension. For example, the scalar value of
076 // ([Store].[USA], [Gender].[F])
077 // does not depend on [Store].
078 //
079 // If the dimensionality of the expression is unknown, then the
080 // expression MIGHT include the dimension, so to be safe we have to
081 // say that it depends on the given dimension. For example,
082 // (Dimensions(3).CurrentMember.Parent, [Gender].[F])
083 // may depend on [Store].
084 if (type.usesDimension(dimension, true)) {
085 return false;
086 }
087 }
088 return true;
089 }
090
091 /**
092 * Optimizes the scalar evaluation of a tuple. It evaluates the members
093 * of the tuple, sets the context to these members, and evaluates the
094 * scalar result in one step, without generating a tuple.<p/>
095 *
096 * This is useful when evaluating calculated members:<blockquote><code>
097 *
098 * <pre>WITH MEMBER [Measures].[Sales last quarter]
099 * AS ' ([Measures].[Unit Sales], [Time].PreviousMember '</pre>
100 *
101 * </code></blockquote>
102 *
103 * @return optimized expression
104 */
105 public Calc optimize() {
106 if (tupleCalc instanceof TupleFunDef.CalcImpl) {
107 TupleFunDef.CalcImpl calc = (TupleFunDef.CalcImpl) tupleCalc;
108 return new MemberValueCalc(
109 new DummyExp(type), calc.getMemberCalcs());
110 }
111 return this;
112 }
113 }
114
115 // End TupleValueCalc.java