Using Perl Regex to find & replace large chunks in code

jedikaiti has asked for the wisdom of the Perl Monks concerning the following question:

I have been asked to come up with a little something that could be used whenever we need to do a mass find-replace on large chunks of code. We're talking about CSTOL code that's edited in Emacs, and we need to swap out something like the below that shows up multiple times in anywhere from 1 - 10 (maybe more) different files.

; This code does something fancy
enable fancy_command
wait (fancy = true) or for $max_time
if $$error = $time out
    write "Oh crap, the fancy thing didn't work!"
    deal with not working
else
    do fancy_command
    write "fancy command done!"
endif
[download]

I figured this would be do-able with regular expressions in Perl, but I have no idea how, as I've never tried to match more than a single line at a time.

So I consulted my good friend Google and found this: http://noctilucent.org/blog/2003/12/replacing-large-chunks-of-text-with-perl.html

So I gave that solution a shot. It seems to spit out a chunk of reasonable-looking regex into sub.pl, but beyond that does nothing, and I'm really not sure how the sub.pl output is supposed to work. For my example "code" above, I get this in sub.pl:

;\s+This\s+code\s+does\s+something\s+fancy\s+
enable\s+fancy_command\s+
wait\s+\(fancy\s+=\s+true\)\s+or\s+for\s+\$max_time\s+
if\s+\$\$error\s+=\s+\$time\s+out\s+
    write\s+"Oh\s+crap,\s+the\s+fancy\s+thing\s+didn't\s+work!"\s+
    deal\s+with\s+not\s+working\s+
else\s+
    do\s+fancy_command\s+
    write\s+"fancy\s+command\s+done!"\s+
endif\s+%TESTING
%six
[download]

And, according to the web page, I can run that on my files (assuming similar file names) with this command: perl -p -0777 -i.bak sub.pl filename*.prc When I try that, nothing happens. My file doesn't get changed in any way (although the last modified date/time does get updated), but it does make a nice backup copy.

So, I'm lost. Can anyone help me find my way?

Kaiti
Swiss Army Nerd

Comment on Using Perl Regex to find & replace large chunks in code Select or Download Code

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Re: Using Perl Regex to find & replace large chunks in code by ikegami (Patriarch) on Mar 11, 2013 at 18:54 UTC
Actually, you should have gotten `s% ;\s+This\s+code\s+does\s+something\s+fancy\s+ enable\s+fancy_command\s+ wait\s+$fancy\s+=\s+true$\s+or\s+for\s+\$max_time\s+ if\s+\$\$error\s+=\s+\$time\s+out\s+ write\s+"Oh\s+crap,\s+the\s+fancy\s+thing\s+didn't\s+work!"\s+ deal\s+with\s+not\s+working\s+ else\s+ do\s+fancy_command\s+ write\s+"fancy\s+command\s+done!"\s+ endif\s+%TESTING %six` [download] which can be used as follows: `perl -i~ -0777p sub.pl .cstol` [download] `-0777` causes the whole file to loaded into `$_`. Update*: Oops, that command is the same as you gave. I've just tested it and it works. Perhaps you didn't have a newline after the last `endif`?	[reply] [d/l] [select]
Re^2: Using Perl Regex to find & replace large chunks in code by jedikaiti (Hermit) on Mar 11, 2013 at 21:55 UTC
I will make sure I have that newline, thanks! Kaiti Swiss Army Nerd	[reply]
Re: Using Perl Regex to find & replace large chunks in code by ikegami (Patriarch) on Mar 11, 2013 at 19:01 UTC
As a standalone script `local $/; my $search = <>; my $replace = <>; #local $^I = ''; # No backups. local $^I = '~'; # Make backups. while (<>) { s/\Q$search/$replace/g; print; }` [download] Usage: `$ script.pl - - .cstol search search search ^D replace replace replace ^D` [download] or `$ script.pl search.txt replace.txt .cstol` [download] You can tweak `$search`'s content as the linked node did if you so desire (but get rid of `\Q` if you do).	[reply] [d/l] [select]
Re: Using Perl Regex to find & replace large chunks in code by Anonymous Monk on Mar 11, 2013 at 19:57 UTC
See Re^2: Write to existing file with character insert, for slurping of file add local $/; before calling pie	[reply]
Re^2: Using Perl Regex to find & replace large chunks in code by jedikaiti (Hermit) on Mar 11, 2013 at 21:56 UTC
Thanks, both of you! I will play with that, too! Kaiti Swiss Army Nerd	[reply]


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