private Token NextToken()
{
clutter = current;
nl = Skip();
while (true)
{
payload = current;
Debug.Assert(current <= limit);
if (current == limit)
{
return(Token(TK.Eof));
}
switch (Current)
{
case '"':
return(String());
case '\'':
return(Char());
case '(':
current += 1;
return(Token(TK.LParen));
case ')':
current += 1;
return(Token(TK.RParen));
case '[':
current += 1;
return(Token(TK.LSquare));
case ']':
current += 1;
return(Token(TK.RSquare));
case '{':
current += 1;
return(Token(TK.LBrace));
case '}':
current += 1;
return(Token(TK.RBrace));
case ',':
current += 1;
return(Token(TK.Comma));
case '~':
current += 1;
return(Token(TK.Tilde));
case ':':
current += 1;
return(Token(TK.Colon));
case ';':
current += 1;
return(Token(TK.Semi));
case '?':
current += 1;
return(Token(TK.Question));
case '|':
current += 1;
return(Token(TK.Pipe));
case '^':
current += 1;
return(Token(TK.Hat));
case '&':
current += 1;
return(Token(TK.Amper));
case '.':
current += 1;
if (current < limit)
{
if (Current == '>')
{
current += 1;
return(Token(TK.Chain));
}
if (Current == '.' && current + 1 < limit && Next == '.')
{
current += 2;
return(Token(TK.Ellipsis));
}
}
return(Token(TK.Dot));
case '@':
current += 1;
if (current < limit && Current == '{')
{
current += 1;
return(Token(TK.AtLBrace));
}
return(Token(TK.At));
case '+':
current += 1;
return(Token(TK.Plus));
case '-':
current += 1;
if (current < limit)
{
if (Current == '>')
{
current += 1;
return(Token(TK.Arrow));
}
}
return(Token(TK.Minus));
case '/':
current += 1;
return(Token(TK.Divide));
case '*':
current += 1;
return(Token(TK.Multiply));
case '%':
current += 1;
if (current < limit)
{
if (Current == '%')
{
current += 1;
return(Token(TK.Mod));
}
}
return(Token(TK.Rem));
case '=':
current += 1;
if (current < limit)
{
if (Current == '>')
{
current += 1;
return(Token(TK.DblArrow));
}
else if (Current == '=')
{
current += 1;
return(Token(TK.Eq));
}
}
return(Token(TK.Assign));
case '!':
current += 1;
if (current < limit)
{
if (Current == '=')
{
current += 1;
return(Token(TK.Ne));
}
}
return(Token(TK.Exclamation));
case '<':
current += 1;
if (current < limit)
{
if (Current == ':')
{
current += 1;
return(Token(TK.Subtype));
}
if (Current == '=')
{
current += 1;
return(Token(TK.Le));
}
if (Current == '<')
{
current += 1;
return(Token(TK.LShift));
}
}
return(Token(TK.Lt));
case '>':
current += 1;
if (current < limit)
{
if (Current == '=')
{
current += 1;
return(Token(TK.Ge));
}
}
return(Token(TK.Gt));
default:
if (Current.IsLetterOrUnderscore())
{
return(IdentifierOrKeyword());
}
if (Current.IsDigit())
{
return(Number());
}
break;
}
Errors.AtOffset(ErrNo.Lex001, Source, current, $"unknown character ``{CharRep.InText(Current)}´´ in source stream");
current += 1;
nl = Skip() || nl;
}
}