/*****************************************************************************

 JEP 2.4.1, Extensions 1.1.1
      April 30 2007
      (c) Copyright 2007, Nathan Funk and Richard Morris
      See LICENSE-*.txt for license information.

 *****************************************************************************/

package weasel.jep.function;


import java.util.Stack;
import java.util.Vector;

import weasel.jep.ParseException;


/**
 * The list function. Returns a Vector comprising all the children.
 * 
 * @author Rich Morris Created on 29-Feb-2004
 */
public class Range extends PostfixMathCommand {
	public Range() {
		numberOfParameters = -1;
	}

	/**
	 * Generates a range [low,low+inc,...,low+inc*(steps-1)]
	 * 
	 * @param low
	 * @param inc
	 * @param steps
	 * @return a Vector
	 */
	public Object genRange(double low, double inc, int steps) {
		Vector res = new Vector(steps);
		res.setSize(steps);
		for (int i = 0; i < steps; ++i)
			res.set(i, new Double(low + inc * i));
		return res;
	}

	@Override
	public void run(Stack inStack) throws ParseException {
		checkStack(inStack); // check the stack
		if (curNumberOfParameters < 1) throw new ParseException("Empty list");

		Object res;
		if (curNumberOfParameters == 2) {
			Object lastObj = inStack.pop();
			Object firstObj = inStack.pop();
			double last = ((Number) lastObj).doubleValue();
			double first = ((Number) firstObj).doubleValue();
			double diff = last - first;
			int steps = 1 + (int) diff;
			res = genRange(first, 1.0, steps);
		} else if (curNumberOfParameters == 3) {
			Object incObj = inStack.pop();
			Object lastObj = inStack.pop();
			Object firstObj = inStack.pop();
			double inc = ((Number) incObj).doubleValue();
			double last = ((Number) lastObj).doubleValue();
			double first = ((Number) firstObj).doubleValue();
			double diff = (last - first) / inc;
			int steps = 1 + (int) diff;
			res = genRange(first, inc, steps);
		} else if (curNumberOfParameters == 4) {
			Object stepsObj = inStack.pop();
			Object lastObj = inStack.pop();
			Object firstObj = inStack.pop();
			int steps = ((Number) stepsObj).intValue();
			double last = ((Number) lastObj).doubleValue();
			double first = ((Number) firstObj).doubleValue();
			double inc = (last - first) / (steps - 1);
			res = genRange(first, inc, steps);
		} else
			throw new ParseException("Range:only a maximum of four arguments can be specified");
		inStack.push(res);
		return;
	}
}
