/*
// $Id: //open/mondrian-release/3.2/src/main/mondrian/olap/fun/LeadLagFunDef.java#1 $
// This software is subject to the terms of the Eclipse Public License v1.0
// Agreement, available at the following URL:
// http://www.eclipse.org/legal/epl-v10.html.
// Copyright (C) 2006-2009 Julian Hyde
// All Rights Reserved.
// You must accept the terms of that agreement to use this software.
*/
package mondrian.olap.fun;
import mondrian.olap.FunDef;
import mondrian.olap.Member;
import mondrian.olap.Evaluator;
import mondrian.calc.Calc;
import mondrian.calc.ExpCompiler;
import mondrian.calc.MemberCalc;
import mondrian.calc.IntegerCalc;
import mondrian.calc.impl.AbstractMemberCalc;
import mondrian.mdx.ResolvedFunCall;
/**
* Definition of the <code>Lead</code> and <code>Lag</code> MDX functions.
*
* @author jhyde
* @version $Id: //open/mondrian-release/3.2/src/main/mondrian/olap/fun/LeadLagFunDef.java#1 $
* @since Mar 23, 2006
*/
class LeadLagFunDef extends FunDefBase {
static final ReflectiveMultiResolver LagResolver =
new ReflectiveMultiResolver(
"Lag",
"<Member>.Lag(<Numeric Expression>)",
"Returns a member further along the specified member's dimension.",
new String[]{"mmmn"},
LeadLagFunDef.class);
static final ReflectiveMultiResolver LeadResolver =
new ReflectiveMultiResolver(
"Lead",
"<Member>.Lead(<Numeric Expression>)",
"Returns a member further along the specified member's dimension.",
new String[]{"mmmn"},
LeadLagFunDef.class);
public LeadLagFunDef(FunDef dummyFunDef) {
super(dummyFunDef);
}
public Calc compileCall(ResolvedFunCall call, ExpCompiler compiler) {
final MemberCalc memberCalc =
compiler.compileMember(call.getArg(0));
final IntegerCalc integerCalc =
compiler.compileInteger(call.getArg(1));
final boolean lag = call.getFunName().equals("Lag");
return new AbstractMemberCalc(
call,
new Calc[] {memberCalc, integerCalc})
{
public Member evaluateMember(Evaluator evaluator) {
Member member = memberCalc.evaluateMember(evaluator);
int n = integerCalc.evaluateInteger(evaluator);
if (lag) {
if (n == Integer.MIN_VALUE) {
// Bump up lagValue by one, otherwise -n (used
// in the getLeadMember call below) is out of
// range because Integer.MAX_VALUE ==
// -(Integer.MIN_VALUE + 1).
n += 1;
}
n = -n;
}
return evaluator.getSchemaReader().getLeadMember(member, n);
}
};
}
}
// End LeadLagFunDef.java