RE: [PHP] comment followed by ?> fails to parse

-----Original Message----- > From: Thalis A. Kalfigopoulos [mailto:thalis@cs.pitt.edu] > Sent: Wednesday, May 29, 2002 1:40 PM > To: Jonathan Rosenberg > Cc: php-general@lists.php.net > Subject: RE: [PHP] comment followed by ?> fails to parse > On Wed, 29 May 2002, Jonathan Rosenberg wrote: > > You need to brush up on your parsing theory. If the > > PHP parser can balance parentheses, it can balance comments, > > also. > From what I remember from my compilers theory, > "regexpr" is one thing, but "grammar" is another. The > parsing phase uses a grammar which is more powerful > (every regexpr has equivalent grammar but not the > other way around). But the comments are usually > detected and dropped thereof in the scanning phase > (prior to parsing). If I remember correctly, scanning typically uses a finite state machine (equivalent to regular expressions), while parsing using a pushdown automaton (or equivalent). You are also correct that many (most?) compilers throw out comments during scanning. > Of course you could keep comments > around and do the "balanced parenthesis matching" in > the parsing phase. Some languages support nested comments & do just this. > Any fallacies in my memory recollection? Nope. I think you're correct & I retract my previous criticism. > cheers, > thalis