private double ReadNumber(SimpleParser parser)
{
var factor = parser.NextIs('-') ? -1 : 1;
parser.ConsumeAny('+', '-');
if (!double.TryParse(parser.ConsumeAny("0.123456789".ToCharArray()), NumberStyles.Any, CultureInfo.InvariantCulture, out var result))
{
return(double.NaN);
}
return(factor * result);
}
public double Eval()
{
var op_count = -1;
while (parser.HasNext)
{
if (Operations.Count > op_count)
{
op_count = Operations.Count;
}
else
{
break;
}
parser.ConsumeAny(' ');
if (parser.NextIs('('))
{
parser.Skip(1);
var exp = new Expression(parser)
{
MustConsumeClosingBracket = true
};
exp.Eval();
var op = new Operation {
Operator = "+", Expression = exp
};
Operations.Add(op);
}
else if (parser.NextIs("+-*^/%".ToCharArray()))
{
var op = new Operation()
{
Operator = parser.NextChar.ToString()
};
parser.Skip(1);
parser.ConsumeAny(' ');
if (parser.NextIs('('))
{
parser.Skip(1);
var exp = new Expression(parser);
exp.MustConsumeClosingBracket = true;
op.Expression = exp;
exp.Eval();
}
else
{
op.Expression = new Expression(ReadNumber(parser));
}
Operations.Add(op);
}
else if (parser.NextIs("0.123456789".ToCharArray()))
{
Operations.Add(new Operation {
Operator = "+", Expression = new Expression(ReadNumber(parser))
});
}
else if (parser.NextIs(')') && MustConsumeClosingBracket)
{
parser.Skip(1);
break;
}
}
if (!Operations.Any())
{
return(double.NaN);
}
var first_op = Operations.First();
if (string.IsNullOrEmpty(first_op.Operator))
{
first_op.Operator = "+";
}
else if (first_op.Operator == "-")
{
first_op.Operator = "+";
first_op.Expression.Value = (first_op.Expression.Value ?? Double.NaN) * (-1);
}
if (Operations.Count == 1)
{
var op = Operations[0];
var val = op.Expression.Value;
if (val == null)
{
return(double.NaN);
}
if (op.Operator == "-")
{
Value = (-1.0 * (val.Value));
}
else
{
Value = val;
}
}
else if (Operations.Count == 2)
{
Value = Operations[1].Apply(Operations[0].Apply(0));
}
else
{
if (Precedence(Operations[0].Operator) > 0)
{
return(double.NaN); // only + and minus may be first operator!
}
// repeated contraction by precedence
while (Operations.Count > 1)
{
var highest_op = Operations.Select(x => x.Operator).OrderByDescending(x => Precedence(x)).First();
if (Precedence(highest_op) == 0)
{
double sum = 0;
foreach (var op in Operations)
{
sum = op.Apply(sum);
}
return(sum);
}
var ops = new List <Operation>();
int i = 0;
foreach (var op in Operations)
{
if (op.Operator == highest_op)
{
var last_op = ops[ops.Count - 1];
last_op.Expression.Value = op.Apply(last_op.Expression.Value ?? double.NaN);
i++;
continue;
}
ops.Add(op);
i++;
}
Operations = ops;
}
return(Operations[0].Apply(0));
}
return(Value ?? double.NaN);
}