private static void ConsumeToken(Stack <TOKEN> stack, TOKEN.Ttype ttype, string errmsg)
{
if (stack.Count == 0 || stack.Peek().ttype != ttype)
{
throw new ParseException(errmsg);
}
stack.Pop();
}
private static BigInteger Parse(Stack <TOKEN> stack, Priority priority)
{
BigInteger v = 0;
if (stack.Count == 0)
{
throw new ParseException("empty stack");
}
TOKEN t = stack.Pop();
// Parse prefix operators
switch (t.ttype)
{
case TOKEN.Ttype.MINUS:
v = -Parse(stack, Priority.SIGN);
break;
case TOKEN.Ttype.PLUS:
v = Parse(stack, Priority.SIGN);
break;
case TOKEN.Ttype.INTEGER:
v = t.integer;
break;
case TOKEN.Ttype.BRACKETOPEN:
v = Parse(stack, Priority.ALL);
ConsumeToken(stack, TOKEN.Ttype.BRACKETCLOSE, "closing bracket expected");
break;
case TOKEN.Ttype.FUNCTION:
FunctionInfo fi = prefixFunctions[t.function];
v = fi.function(ParseArguments(stack, fi.numargs));
break;
default:
throw new ParseException("unexpected prefix");
}
// Parse infix operators
while (stack.Count != 0)
{
TOKEN.Ttype ttype = stack.Peek().ttype;
if (ttype == TOKEN.Ttype.BRACKETCLOSE || ttype == TOKEN.Ttype.COMMA)
{
break;
}
OperatorInfo io = infixOperators[ttype];
if ((priority > io.priority) || (priority == io.priority && io.left_associative))
{
return(v);
}
stack.Pop();
BigInteger b = (io.numargs == 2) ? Parse(stack, io.priority) : 0;
v = io.function(v, b);
}
return(v);
}
