package org.matheclipse.core.reflection.system;

import org.matheclipse.core.eval.exception.Validate;
import org.matheclipse.core.eval.exception.WrongNumberOfArguments;
import org.matheclipse.core.eval.interfaces.AbstractFunctionEvaluator;
import org.matheclipse.core.expression.F;
import org.matheclipse.core.interfaces.IAST;
import org.matheclipse.core.interfaces.IExpr;

/**
 * Compares the first expression with the second expression for order. Returns 1, 0, -1 as this expression is canonical less than,
 * equal to, or greater than the specified expression. 

 * 

 * (Implementation note: see the different results in the IExpr#compareTo(IExpr) method)
 * 
 * @see org.matheclipse.core.interfaces.IExpr#compareTo(IExpr)
 */
public class Order extends AbstractFunctionEvaluator {

	public Order() {
	}

	@Override
	public IExpr evaluate(final IAST ast) {
		Validate.checkSize(ast, 3);

		final int cp = ast.arg1().compareTo(ast.get(2));
		if (cp < 0) {
			return F.C1;
		} else if (cp > 0) {
			return F.CN1;
		}
		return F.C0;
	}

}