public static bool IsAtomToken(LexerToken token)
{
return
token is TokenString ||
token is TokenInteger ||
token is TokenIdentifier;
}
SExp CreateAtom(LexerToken token)
{
SExp atom = null;
if (token is TokenLeftParen)
{
atom = new __LeftParen();
}
else if (token is TokenInteger)
{
int n = 0;
int.TryParse(token.Value, out n);
atom = new Integer(n);
}
else if (token is TokenString)
{
atom = new String(token.Value);
}
else if (token is TokenIdentifier)
{
atom = new Identifier(token.Value);
}
else
{
string msg =
string.Format("failed to create atom from token '{0}'.", token.Value);
throw new ParserException(msg);
}
return atom;
}