WARNING merlyn wrote BAD CODE

[Ovid]

Okay, the title is kind of a joke. It's just a good-natured tweak at merlyn for the brouhaha over his WARNING t0mas wrote BAD CODE node that generated so much flak. No offense intended :)

merlyn's code was bugging me, but I couldn't quite put my finger on it. My problem was that the dot metacharacter is so indiscriminating that it will match anything. However, I simply assumed that if merlyn posted the code, it must work. His code is great if you're checking for C-style comments that begin and end in something like /* comment here */ or "? comment here ?". But if you read my post, that's not what we were checking for:

What happens if you were trying to extract questions in quotes without the trailing question mark?

I mentioned embedded question marks (my idea was that we might have more than one question in a quote), but I never mentioned embedded quotes. I just wanted one set of quotes and my original post bears that out. Here's merlyn's code and my correction:

#!/usr/bin/perl -w

$myvar = q{ abc"def"g"hi?"jkl };

# This regex is from merlyn

print "matched <$1>\n" if
$myvar =~ /"            # First quote
            (           # Capture text to $1
             (?:        # Non-backreferencing parentheses
                (?!\?") # not question quote?
                .       # ok to inch along
             )*         # Zero or more
            )           # End capture
          \?"/sx;       # Followed by a question mark and quote

# This regex is from Ovid

print "matched <$1>\n" if 
$myvar =~ /"            # First quote
            (           # Capture text to $1
             (?:        # Non-backreferencing parentheses
               [^?"]    # Not a question mark or parentheses
               |        # or
               \?(?!")  # A question mark not followed by a quote
             )*         # Zero or more
            )           # End Capture
          \?"/sx;       # Followed by a question mark and quote

The first regex will print matched <def"g"hi>. The second will print matched <hi>.

No disrespect is intended towards Randal as he was right in pointing out that my first regex was broken.

Cheers,
Ovid

[merlyn]

I misunderstood the goal, but I knew that yours wouldn't solve the goal. :)

-- Randal L. Schwartz, Perl hacker