[Raleigh-talk] [Perl help] - Multiple substitutions in a file

[Matt Nash]

Of course, you want actual spaces (not '\s') in the replace string, but you
knew that.

On Tue, Feb 22, 2011 at 9:56 PM, Matt Nash <mattnashbrowns at gmail.com> wrote:

> Hi John,
>
> You are reading the entire file into an array of lines, then processing
> that array using a C-style for loop and interpolating the index var into the
> search string... and that is the LEAST crazy thing. :)  It works, of course,
> because it turns out that there are infinitely many ways to do it.
>
> For your immediate problem of the search-and-replace, I recommend reading
> the  whole file into a single string, newlines and all, then using the /gc
> modifiers in the regex.  Maybe put your colorChange stuff into an array that
> you loop through, checking the regex for the nth match:
>
> @changes = ($change1, $change2, $change3);
>
> foreach $change (@changes) {
>     $wholefile =~
> s|08\s00\s00\s1C\s\d\d\s\d\d\s\d\d\s\d\d|08\s00\s00\s1C\s$change|gc;
> }
>
> see http://perldoc.perl.org/perlre.html and
> http://perldoc.perl.org/perlretut.htm<http://perldoc.perl.org/perlretut.html#Using-regular-expressions-in-Perl> for
> lots of details, but the upshot of the modifiers is: g makes it keep looking
> for matches; c tells it to remember where it last matched, and start from
> there on the next match.  You don't have to care what n is, because you are
> matching your search string exactly as many times as you have changes to
> make.
>
> ...but this project sounds ripe for refactoring, if I may be so bold.
>  Could it be that what you really need is a templating system?
>
> Thanks for bringing some much-needed questions to this list!
>
> Matt
>
> On Tue, Feb 22, 2011 at 8:31 PM, John Ricker <sephtin+pm-talk at gmail.com>wrote:
>
>> Received so much help with the last question (which seems to be
>> functioning great, btw.. thanks all)... thought I'd try again.  ;)
>>
>> Have a script that was recently migrated to Perl from shell/bash, and am
>> wondering if there's an easy way in Perl to do the following-
>>
>> File(s) being modified are hex, and look something like:
>> ---x---
>> ...
>> 08 00 00 00 FF FF FF FF FF FF FF FF 1B 00 00 00 02 01 10 00 28 01 00 00 09
>> 00 00 00 FF FF FF FF FF FF FF FF 1C 00 00 00 14 00 14 00 0D 00 00 00 00 00
>> 0D 00 18 00 00 00 11 00 00 00 FF FF FF FF 08 00 00 05 02 0E 00 00 18 00 00
>> 00 0E 00 00 00 FF FF FF FF 08 00 00 1C 00 00 00 FF 18 00 00 00 09 00 00 00
>> FF FF FF FF 08 00 00 11 10 00 00 00 18 00 00 00 0F 00 00 00 FF FF FF FF 08
>> 00 00 01 11 02 02 01 18 00 00 00 03 00 00 00 FF FF FF FF 08 00 00 01 05 00
>> 08 01 18 00 00 00 10 00 00 00 FF FF FF FF 08 00 00 05 01 0F 00 00 18 00 00
>> 00 05 00 00 00 FF FF FF FF 08 00 00 05 01 0F 00 00 18 00 00
>> ...
>> ---x---
>> File(s) contain several occurrences of "08 00 00 1c ## ## ## ##" or more
>> appropriately for this list: "08\s00\s00\s1C\s\d\d\s\d\d\s\d\d\s\d\d"
>>
>>  Now on to the good stuff...  I would like to replace the ## ## ## ## with
>> my chosen colors, that are being provided by vars... Example:
>> colorChange1="FF 00 00 FF"
>> colorChange2="FF FF 00 FF"
>> colorChange3="FF 00 FF FF"
>> ...
>>
>> I'm wondering how it might be possible, to replace the FIRST occurrence
>> (in the file, NOT in a line) of "08 00 00 1C ## ## ## ##" with "08 00 00 1C
>> $colorChange1", the second with "08 00 00 1C $colorChange2", etc.
>>
>> More info:
>> --Script modifies files to theme them, in this case, I'm taking a BINARY
>> (compiled XML) file, converting it to HEX via xxd, and then changing the
>> text color for a theme via substitution.
>> --I originally thought it could be done similar to what sed does... with
>> s|(08\s00\s00\s1C)\s\d\d\s\d\d\s\d\d\s\d\d|$1$colorChange1|1  (note last
>> digit...), but testing has shown that this doesn't work as expected.
>> --Not really related, but in the binary, the colors are actually
>> backwards, so color - FF AB CD EF becomes binary - EF CD AB FF, but that's
>> an easy change.
>> --CURRENTLY in my script, I'm doing this via a sub, passing an array of
>> the colors, the file, and the file location (directory), and pulling the
>> file, making the changes, and saving it back out via loop... BUT, because I
>> couldn't figure out how to just do the multiple replaces... I cheated and
>> made template files that contain "08 00 00 1C 11 11 11 11" and "08 00 00 1C
>> 22 22 22 22", so when I iterate through the loop, I just change like so:
>> for ( $i = 1 ; $i <= $COUNT ; $i++ ) {
>> ...
>>     $line =~ s|08\s00\s00\s1c\s$i$i\s$i$i\s$i$i\s$i$i\s|08 00 00 1c
>> $array_ref[$i]|;
>> ...
>> }
>>
>> Code works, but I'd much rather be able to pull native files straight out
>> of the .zip, and change them that way... :P
>>
>> Anyway, again, if there are specifics I missed, happy to provide them.
>> I keep thinking there should be an easy way to do this... but my google-fu
>> is failing me..
>>
>> Thanks again for the help with the previous problem, and in advance for
>> any assistance on this one.  :)
>> At the very least, I guess I can provide some chatter to the group.
>>
>> -John (sephtin @gmail)
>>
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>>
>>
>
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