private static void ParseRule(UnsafeReader reader, int min, int max)
{
if (ParseListItem(reader, min, max))
{
for (; reader.MoveNextIf(',') && ParseListItem(reader, min, max);)
{
;
}
}
}
private static unsafe NaiveRule ParseRule(UnsafeReader reader, int min, int max)
{
var values = new HashSet <int>();
if (ParseListItem(reader, min, max, values))
{
for (; reader.MoveNextIf(',') && ParseListItem(reader, min, max, values);)
{
;
}
}
return(new NaiveRule(values));
}
private static bool WhiteSpaceAtLeastOnce(UnsafeReader s)
{
if (s.IsEmpty)
{
return(false);
}
var retval = false;
while (s.MoveNextIf(' '))
{
retval = true;
}
return(retval);
}
private static bool ParseListItem(UnsafeReader reader, int min, int max)
{
// ?
// *[/step]
// from[-to][/step]
int start, stop = -1, step;
// ? does not support steps
if (reader.MoveNextIf('?'))
{
return(true);
}
// *
if (reader.MoveNextIf('*'))
{
start = min;
stop = max;
}
else
{
// min[-max]
if (!TryReadInt(reader, out start) ||
start < min ||
start > max)
{
return(false);
}
// [-max]
if (reader.MoveNextIf('-'))
{
if (!TryReadInt(reader, out stop) ||
stop > max ||
stop < start)
{
// syntax error
return(false);
}
}
}
if (reader.MoveNextIf('/'))
{
if (!TryReadInt(reader, out step))
{
// syntax error
return(false);
}
if (stop == -1)
{
stop = max;
}
}
else
{
// short-circuit for simple scalar
if (stop == -1)
{
return(true);
}
step = 1;
}
return(true);
}