Re: lookahead ?

> 
   > Ok, now the line I'm trying to deal with is "some amount of whitespace,
   > then some text, then starting at column 48 a number, followed by a period,
   > followed by another number".  I want to capture the text (the "title"),
   > and the two numbers (major and minor versions):
   > 
   > line: title // <reject: $thiscolumn != 48> major \. minor
   > 
   > title: ??WHAT GOES HERE??
   > major: digits
   > minor: digits
   > 
   > digits: /\d+/
   > 
   > In a regex(p)?, I think I'd know what to do: positive lookahead on the
   > whitespace:
   > 
   > my ($title, $major, $minor) =
   >     $line =~ m/^\s*        # leading whitespace
   > 	      (.*?)        # the title
   >               (?:\s+(?=\d+\.\d+\s*$)) # the space preceeding the numbers
   >               (\d+)        # the major version number
   >               \.
   >               (\d+)        # the minor version number
   > 	      /x;
   > 
   > Can I accomplish this in a RD grammer without changing <skip:> ?

You really do want to use a regex here (to get the lookahead/backtracking
that RecDescent doesn't do).

   line: m/^(\s*        		# leading whitespace
   	      (.*?)        		# the title
              (?:\s+(?=\d+\.\d+\s*$)) 	# the space preceeding the numbers
	    )
            (\d+)        		# the major version number
            \.
            (\d+)        		# the minor version number
	 /x
	 <reject: length $1 != 47>
	 { @{$return}{title major minor)} = ($2,$3,$4) }


Damian