SubTime.java

/*****************************************************************************
      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.util.Calendar;
import java.sql.*;

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 SubTime extends PostfixCommand {
	final public int getNumberOfParameters() {
		return 2;
	}
	
	/**
	 * Calculates the result of applying the "+" operator to the arguments from
	 * the stack and pushes it back on the stack.
	 */
	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 java.util.Date subTime(Comparable<?>  param1, Comparable<?>  param2, Calendar cal) throws ParseException {
		if (param1 == null || param2 == null) {
			return null;
		}
		if ((param1 instanceof Time || param1 instanceof Timestamp) && param2 instanceof Time) {
			java.util.Date d1 = (java.util.Date)param1;
			java.util.Date d2 = (java.util.Date)param2;
			cal.setTimeInMillis(d2.getTime());
			int h = cal.get(HOUR_OF_DAY);
			int m = cal.get(MINUTE);
			int s = cal.get(SECOND);
			cal.setTimeInMillis(d1.getTime());
			cal.add(SECOND, -s);
			cal.add(MINUTE, -m);
			cal.roll(HOUR_OF_DAY, -h);
			return (param1 instanceof Time) ? new Time(cal.getTimeInMillis()) : new Timestamp(cal.getTimeInMillis());
		} else {
			throw new ParseException(WRONG_TYPE+"  subtime("+param1.getClass()+","+param2.getClass()+")");
		}
	}

	public Comparable<?> getResult(Comparable<?>... comparables)
			throws ParseException {
		return subTime(comparables[0],comparables[1],JepRuntime.getCalendar());
	}
}