/* Arithmetic evaluation, in Jsish */
function evalArithmeticExp(s) {
    s = s.replace(/\s/g,'').replace(/^\+/,'');
    var rePara = /\([^\(\)]*\)/;
    var exp;

    function evalExp(s) {
        s = s.replace(/[\(\)]/g,'');
        var reMD = /[0-9]+\.?[0-9]*\s*[\*\/]\s*[+-]?[0-9]+\.?[0-9]*/;
        var reM = /\*/;
        var reAS = /-?[0-9]+\.?[0-9]*\s*[\+-]\s*[+-]?[0-9]+\.?[0-9]*/;
        var reA    = /[0-9]\+/;
        var exp;

        function multiply(s, b=0) {
            b = s.split('*');
            return b[0] * b[1];
        }

        function divide(s, b=0) {
            b = s.split('/');
            return b[0] / b[1];
        }

        function add(s, b=0) {
            s = s.replace(/^\+/,'').replace(/\++/,'+');
            b = s.split('+');
            return Number(b[0]) + Number(b[1]);
        }

        function subtract(s, b=0) {
            s = s.replace(/\+-|-\+/g,'-');

            if (s.match(/--/)) {
                return add(s.replace(/--/,'+'));
            }
            b = s.split('-');
            return b.length == 3 ? -1 * b[1] - b[2] : b[0] - b[1];
        }

        while (exp = s.match(reMD)) {
            s = exp[0].match(reM) ? s.replace(exp[0], multiply(exp[0]).toString()) : s.replace(exp[0], divide(exp[0]).toString());
        }

        while (exp = s.match(reAS)) {
            s = exp[0].match(reA)? s.replace(exp[0], add(exp[0]).toString()) : s.replace(exp[0], subtract(exp[0]).toString());
        }

        return '' + s;
    }

    while (exp = s.match(rePara)) {
        s = s.replace(exp[0], evalExp(exp[0]));
    }

    return evalExp(s);
}

if (Interp.conf('unitTest')) {
;    evalArithmeticExp('2+3');
;    evalArithmeticExp('2+3/4');
;    evalArithmeticExp('2*3-4');
;    evalArithmeticExp('2*(3+4)+5/6');
;    evalArithmeticExp('2 * (3 + (4 * 5 + (6 * 7) * 8) - 9) * 10');
;    evalArithmeticExp('2*-3--4+-0.25');
}

/*
=!EXPECTSTART!=
evalArithmeticExp('2+3') ==> 5
evalArithmeticExp('2+3/4') ==> 2.75
evalArithmeticExp('2*3-4') ==> 2
evalArithmeticExp('2*(3+4)+5/6') ==> 14.8333333333333
evalArithmeticExp('2 * (3 + (4 * 5 + (6 * 7) * 8) - 9) * 10') ==> 7000
evalArithmeticExp('2*-3--4+-0.25') ==> -2.25
=!EXPECTEND!=
*/