On Jun 29, David Arnold said:
>\backans{If $x=y^{2n}$ and $z=y^{3n}_{11}$, then we can substitute
> to find a solution.}
>
>I'd like to scan the file and replace all of these with this format:
>
>\begin{answer}
>If $x=y^{2n}$ and $z=y^{3n}_{11}$, then we can substitute
>to find a solution.
>\end{answer}
To match nested things, you probably want to use Regexp::Common, which
allows you to do that very easily:
use Regexp::Common;
$text =~ s<
\\ backans {
( $RE{balanced}{-parens=>'{}'} )
}
><\\begin{answer}\n$1\n\\end{answer}>xg;
The /x modifier is so that I can have extra whitespace, and the /g
modifier means "do it globally". The %RE hash is quite magical -- see the
Regexp::Common docs for an explanation. The module isn't standard,
though, so you'd have to download it from CPAN yourself.
If you want a stand-alone solution, you can have one if you make use of
some of Perl's special regex constructs:
my $rx; # must be declared first...
$rx = qr[
(?:
(?> [^{}\\]+ | \\. )
|
{ (??{ $rx }) }
)*
]xs;
$text =~ s/\\backans{($rx)}/\\begin{answer}\n$1\n\\end{answer}/g;
Its primary trick is the (??{ ... }) assertion, which evaluates its
contents as PART of the regex to match. Since its contents are $rx
itself, it basically creates an automatically deeply-enough nested regex
for you on the fly.
--
Jeff "japhy" Pinyan [EMAIL PROTECTED] http://www.pobox.com/~japhy/
RPI Acacia brother #734 http://www.perlmonks.org/ http://www.cpan.org/
CPAN ID: PINYAN [Need a programmer? If you like my work, let me know.]
<stu> what does y/// stand for? <tenderpuss> why, yansliterate of course.
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