/*****************************************************************************
SQLJEP - Java SQL Expression Parser 0.2
November 1 2006
(c) Copyright 2006, Alexey Gaidukov
SQLJEP Author: Alexey Gaidukov
SQLJEP is based on JEP 2.24 (http://www.singularsys.com/jep/)
(c) Copyright 2002, Nathan Funk
See LICENSE.txt for license information.
*****************************************************************************/
package com.meidusa.amoeba.sqljep.function;
import java.sql.*;
import java.math.BigDecimal;
import java.util.Calendar;
import static java.util.Calendar.*;
import com.meidusa.amoeba.sqljep.function.PostfixCommand;
import com.meidusa.amoeba.sqljep.ASTFunNode;
import com.meidusa.amoeba.sqljep.JepRuntime;
import com.meidusa.amoeba.sqljep.ParseException;
public class MonthsBetween extends PostfixCommand {
private final static BigDecimal DAYS_IN_MONTH = new BigDecimal(31);
final public int getNumberOfParameters() {
return 2;
}
public Comparable<?>[] evaluate(ASTFunNode node, JepRuntime runtime) throws ParseException {
node.childrenAccept(runtime.ev, null);
Comparable<?> param2 = runtime.stack.pop();
Comparable<?> param1 = runtime.stack.pop();
return new Comparable<?>[]{param1,param2};
}
public static BigDecimal monthsBetween(Comparable<?> param1, Comparable<?> param2, Calendar cal) throws ParseException {
if (param1 == null && param2 == null) {
return null;
}
try {
if (param1 instanceof java.util.Date && param2 instanceof java.util.Date) {
if (param1 instanceof Time || param2 instanceof Time) {
throw new ParseException();
}
java.util.Date d1 = (java.util.Date)param1;
java.util.Date d2 = (java.util.Date)param2;
cal.setTimeInMillis(d1.getTime());
int y1 = cal.get(YEAR);
int m1 = cal.get(MONTH);
int dt1 = cal.get(DATE);
cal.setTimeInMillis(d2.getTime());
int y2 = cal.get(YEAR);
int m2 = cal.get(MONTH);
int dt2 = cal.get(DATE);
BigDecimal m = new BigDecimal((y1-y2)*12+(m1-m2));
BigDecimal d = new BigDecimal(dt1-dt2);
d = d.divide(DAYS_IN_MONTH, 40, BigDecimal.ROUND_HALF_UP);
return m.add(d);
} else {
throw new ParseException();
}
} catch (ParseException e) {
throw new ParseException(WRONG_TYPE+" month_between("+param1.getClass()+","+param2.getClass()+")");
}
}
public Comparable<?> getResult(Comparable<?>... comparables)
throws ParseException {
return monthsBetween(comparables[0], comparables[1], JepRuntime.getCalendar());
}
}