001 /*
002 // $Id: //open/mondrian/src/main/mondrian/calc/impl/MemberValueCalc.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.calc.Calc;
013 import mondrian.calc.MemberCalc;
014 import mondrian.olap.Dimension;
015 import mondrian.olap.Evaluator;
016 import mondrian.olap.Exp;
017 import mondrian.olap.Member;
018 import mondrian.olap.type.ScalarType;
019 import mondrian.olap.type.Type;
020
021 /**
022 * Expression which evaluates a few member expressions,
023 * sets the dimensional context to the result of those expressions,
024 * then yields the value of the current measure in the current
025 * dimensional context.
026 *
027 * <p>The evaluator's context is preserved.
028 *
029 * <p>Note that a MemberValueCalc with 0 member expressions is equivalent to a
030 * {@link mondrian.calc.impl.ValueCalc}; see also {@link mondrian.calc.impl.TupleValueCalc}.
031 *
032 * @author jhyde
033 * @version $Id: //open/mondrian/src/main/mondrian/calc/impl/MemberValueCalc.java#7 $
034 * @since Sep 27, 2005
035 */
036 public class MemberValueCalc extends GenericCalc {
037 private final MemberCalc[] memberCalcs;
038 private final Member[] savedMembers;
039
040 public MemberValueCalc(Exp exp, MemberCalc[] memberCalcs) {
041 super(exp);
042 final Type type = exp.getType();
043 assert type instanceof ScalarType : exp;
044 this.memberCalcs = memberCalcs;
045 this.savedMembers = new Member[memberCalcs.length];
046 }
047
048 public Object evaluate(Evaluator evaluator) {
049 Member[] members = new Member[memberCalcs.length];
050 for (int i = 0; i < memberCalcs.length; i++) {
051 MemberCalc memberCalc = memberCalcs[i];
052 final Member member = memberCalc.evaluateMember(evaluator);
053 if (member == null ||
054 member.isNull()) {
055 // This method needs to leave the evaluator in the same state
056 // it found it.
057 for (int j = 0; j < i; j++) {
058 evaluator.setContext(savedMembers[j]);
059 }
060 return null;
061 }
062 savedMembers[i] = evaluator.setContext(member);
063 members[i] = member;
064 }
065 final boolean needToReturnNull =
066 evaluator.needToReturnNullForUnrelatedDimension(members);
067 if (needToReturnNull) {
068 evaluator.setContext(savedMembers);
069 return null;
070 }
071
072 final Object result = evaluator.evaluateCurrent();
073 evaluator.setContext(savedMembers);
074 return result;
075 }
076
077 public Calc[] getCalcs() {
078 return memberCalcs;
079 }
080
081 public boolean dependsOn(Dimension dimension) {
082 if (super.dependsOn(dimension)) {
083 return true;
084 }
085 for (MemberCalc memberCalc : memberCalcs) {
086 // If the expression definitely includes the dimension (in this
087 // case, that means it is a member of that dimension) then we
088 // do not depend on the dimension. For example, the scalar value of
089 // [Store].[USA]
090 // does not depend on [Store].
091 //
092 // If the dimensionality of the expression is unknown, then the
093 // expression MIGHT include the dimension, so to be safe we have to
094 // say that it depends on the given dimension. For example,
095 // Dimensions(3).CurrentMember.Parent
096 // may depend on [Store].
097 if (memberCalc.getType().usesDimension(dimension, true)) {
098 return false;
099 }
100 }
101 return true;
102 }
103 }
104
105 // End MemberValueCalc.java