public DragonToken Scan()
{
try
{
for (; ; ReadChar())
{
if (Peek == ' ' || Peek == '\t')
{
continue;
}
else if (Peek == '\n')
{
Line = Line + 1;
}
else
{
break;
}
}
switch (Peek)
{
case '&':
if (ReadChar('&'))
{
return(DragonWord.and);
}
else
{
return(new DragonToken('&'));
}
case '|':
if (ReadChar('|'))
{
return(DragonWord.or);
}
else
{
return(new DragonToken('|'));
}
case '=':
if (ReadChar('='))
{
return(DragonWord.eq);
}
else
{
return(new DragonToken('='));
}
case '!':
if (ReadChar('='))
{
return(DragonWord.ne);
}
else
{
return(new DragonToken('!'));
}
case '<':
if (ReadChar('='))
{
return(DragonWord.le);
}
else
{
return(new DragonToken('<'));
}
case '>':
if (ReadChar('='))
{
return(DragonWord.ge);
}
else
{
return(new DragonToken('>'));
}
}
if (Char.IsDigit(Peek))
{
int v = 0;
do
{
v *= 10;
v += Convert.ToInt16(Peek);
ReadChar();
}while (Char.IsDigit(Peek));
if (Peek != '.')
{
return(new DragonNumber(v));
}
float x = v;
float d = 10;
for (; ;)
{
ReadChar();
if (!Char.IsDigit(Peek))
{
break;
}
x += Convert.ToInt16(Peek);
x /= d;
d *= 10;
}
return(new DragonReal(x));
}
if (Char.IsLetter(Peek))
{
StringBuilder Sb = new StringBuilder();
do
{
Sb.Append(Peek);
ReadChar();
}while (Char.IsLetterOrDigit(Peek));
string s = Sb.ToString();
DragonWord w = (DragonWord)Words[s];
if (w != null)
{
return(w);
}
w = new DragonWord(s, DragonTag.ID);
Words.Add(s, w);
return(w);
}
DragonToken tok = new DragonToken(Peek);
Peek = ' ';
return(tok);
}
catch
{
throw new IOException();
}
}
void Reserve(DragonWord w)
{
Words.Add(w.LexElement, w);
}
