static ReElement ParseRepitition(ReElement element, ReParseContext context)
{
var min = ParseInt(context) ?? 0;
if (context.Current == ',')
{
if (!context.MoveNext())
{
ThrowUnexpectedEnd();
}
var max = ParseInt(context);
return(ReFactory.NewRepetition(element, min, max));
}
else
{
return(ReFactory.NewRepetition(element, min, min));
}
}
static ReElement ParseSequence(ReParseContext context)
{
var choice = new List <ReElement>();
var sequence = new List <ReElement>();
var abort = false;
while (!context.End && !abort)
{
switch (context.Current)
{
case '[':
if (!context.MoveNext())
{
ThrowUnexpectedEnd();
}
sequence.Add(ParseCharSet(context));
if (context.End)
{
ThrowUnexpectedEnd();
}
if (context.Current != ']')
{
ThrowUnexpectedChar(context);
}
context.MoveNext();
break;
case '(':
if (!context.MoveNext())
{
ThrowUnexpectedEnd();
}
sequence.Add(ParseSequence(context));
if (context.End)
{
ThrowUnexpectedEnd();
}
if (context.Current != ')')
{
ThrowUnexpectedChar(context);
}
context.MoveNext();
break;
case ')':
abort = true;
break;
case '|':
choice.Add(ReFactory.NewConcatenation(sequence));
sequence.Clear();
context.MoveNext();
break;
case '.':
sequence.Add(ReFactory.NewSingleton(CharSet.LineBody));
context.MoveNext();
break;
case '?':
if (sequence.Count == 0)
{
ThrowUnexpectedChar(context);
}
sequence[sequence.Count - 1] = ReFactory.NewRepetition(sequence[sequence.Count - 1], 0, 1);
context.MoveNext();
break;
case '+':
if (sequence.Count == 0)
{
ThrowUnexpectedChar(context);
}
sequence[sequence.Count - 1] = ReFactory.NewRepetition(sequence[sequence.Count - 1], 1, null);
context.MoveNext();
break;
case '*':
if (sequence.Count == 0)
{
ThrowUnexpectedChar(context);
}
sequence[sequence.Count - 1] = ReFactory.NewRepetition(sequence[sequence.Count - 1], 0, null);
context.MoveNext();
break;
case '{':
if (sequence.Count == 0)
{
ThrowUnexpectedChar(context);
}
if (!context.MoveNext())
{
ThrowUnexpectedEnd();
}
sequence[sequence.Count - 1] = ParseRepitition(sequence[sequence.Count - 1], context);
if (context.Current != '}')
{
ThrowUnexpectedChar(context);
}
context.MoveNext();
break;
case '\\':
if (!context.MoveNext())
{
ThrowUnexpectedEnd();
}
sequence.Add(ReFactory.NewSingleton(CharSet.New(ParseEscapeSequence(context))));
break;
default:
sequence.Add(ReFactory.NewSingleton(CharSet.New(context.Current)));
context.MoveNext();
break;
}
}
choice.Add(ReFactory.NewConcatenation(sequence));
return(ReFactory.NewUnion(choice));
}