private static void SkipWhiteSpace(this InputReader input)
{
while (input.HasNext() && char.IsWhiteSpace(input.PeekNext()))
{
input.Next();
}
}
public IExpression?Parse(InputReader input)
{
if (input.NextIs(_beginSymbol))
{
input.Next();
var expression = Start.Parse(input);
if (!input.NextIs(_endSymbol))
{
throw new BadInputFormat(input.Text, input.Index);
}
input.Next();
return(_expressionFactory.Invoke(expression));
}
return(_next.Parse(input));
}
internal static string TakeIf(this InputReader input, params char[] anyOf)
{
input.SkipWhiteSpace();
if (input.NextIs(anyOf))
{
return(input.Next().ToString());
}
return("");
}
internal static string TakeWhile(this InputReader input, Func <char, bool> predicate)
{
input.SkipWhiteSpace();
string token = "";
while (input.HasNext() && predicate(input.PeekNext()))
{
token += input.Next();
}
return(token);
}
public IExpression?Parse(InputReader input)
{
var left = ParseNextExpression(input);
while (input.NextIs(_supportedOperators.Keys.ToArray()))
{
var symbol = input.Next();
var right = ParseNextExpression(input);
left = _supportedOperators[symbol]?.Invoke(left, right);
}
return(left);
}