Converting comma delimeter string into a table

It would be nice to split the incoming comma delimeter string into a table and returns a table back to the caller.

For example, you would like to turn 'A,B' into a table.

select *
from dbo.fn_to_table ('''A'',''B''')

select count(*)
from dbo.fn_to_table ('''A'',''B''')

create function dbo.fn_to_table (@str nvarchar(max))
returns  @tb table (code nvarchar(50)) 
as
begin

declare 
  @pos int,
  @prev_pos int,
  @s nvarchar(50)

select @pos = charindex(',', @str)
select @prev_pos = 0

if ((len(@str) > 0) and (@pos = 0))
 insert into @tb (code)  
 select replace(@str, '''','');

while @pos > 0
begin
 select @s = replace( substring(@str, @prev_pos, 
                 @pos - @prev_pos), '''','');
 -- select @prev_pos, @pos, @s
 insert into @tb (code)
 select @s

 select @prev_pos = @pos + 1;
 select @pos = charindex(',', @str, @pos + 1);
end

if ((@prev_pos > 0) and (@pos = 0))
begin
 insert into @tb (code)
 select  replace( substring(@str, @prev_pos, 
             len(@str) - @prev_pos), '''','');
end

return 

end