public static bool Rewind(this ISource source, string pattern)
{
var codes = new LinkedList <int>();
foreach (var ch in pattern)
{
var code = source.Peek();
if (code == -1 || ch != (char)code)
{
codes.ForEach(x => source.Buffer(x));
return(false);
}
codes.AddFirst(source.Read());
}
return(true);
}
public ClDouble Read(ISource source)
{
if (!TryReadAtLeastOneNumber(source, out var significand))
{
return(null);
}
if (!source.Rewind("."))
{
significand.Reverse().ForEach(ch => source.Buffer(ch));
return(null);
}
if (!TryReadAtLeastOneNumber(source, out var mantissa))
{
throw new SyntaxError($"Invalid format of the {nameof(ClDouble)} literal");
}
var number = double.Parse($"{significand}.{mantissa}", NumberStyles.Float,
CultureInfo.InvariantCulture);
return(new ClDouble(number));
}
public static bool RewindSpaces(this ISource source)
{
bool loop(bool atLeastOne = false)
{
if (source.Eof())
{
return(atLeastOne);
}
var code = source.Read();
if (char.IsWhiteSpace((char)code))
{
return(loop(true));
}
source.Buffer(code);
return(atLeastOne);
}
return(loop());
}