Re: Regex Newbie Q: Non-Trivial Substitution and Modifying the Matched String
Veli-Pekka
You're implying that the music macro language is pos() sensitive.
That is a pretty severe problem in itself.
Can you output the macro language in a format that is not position
sensitive - do a global change - then process the macro language back
into original format?
I think I'd be more inclined to use a $noteindex{$note} = $pitch
hash table than a regex - then process the input one note at a time.
KenMc
On Oct 9, 2005, at 2:58 PM, Veli-Pekka Tätilä wrote:
Hi,
Yet another newbie question about regular expressions:
I'd like to find and replace bits of text as usual. However, rather
than replace all occurrences in one quick swoop using the s-
operator and the g-flag, the replacement is so complex that it
cannot be expressed as a straight substitution. So I would have to
find a piece of text, process it in a separate function, and
replace the matched text with the newly computed text. This goes on
for n interesting matches in the input.
Can I do this kind of thing in a simple loop, processing all
matches one by one? My understanding is that pos and some special
variables will tel me the character index of the mach in a string.
But if I then go and modify the string using substr to do the
substitution, wil it reset the search position to the beginning
when trying to match the next interesting bit? The replacement text
is by nature longer than the original so the input string needs to
grow on each substitution which might present a problem to the
matching operator. I took a look at perlop and some books I have on
Perl but didn't end up with a definitive answer of how I should
solve this problem.
That was the problem abstractly put, here's the specific instance:
I'm writing a program to convert notes given in the music macro
language to their equivalent pitches that are applied using markup
tags for speech synthesizers. I can match a note easily, and have
functions for computing the pitch and the tag in question. As the
note values don't depend on each other in any way, I'd like to
completely process one note at a time, doing the replacement, and
then continue matching the next note where it previously left off.
Naturally there are other tokens than just notes in the input so I
need to maintain the position of the note data in the input string.
If I modify a separate copy of the string, it will throw off the pos
() indeces because the substitutions will change the length of the
copy.
Any help appreciated as usual.
PS: If the problem statement is still a bit fuzzy or incomplete,
just ask and I'll try to provide more info.
--
With kind regards Veli-Pekka Tätilä ([EMAIL PROTECTED])
Accessibility, game music, synthesizers and programming:
http://www.student.oulu.fi/~vtatila/
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Re: filename sorting by last letter in the filename
Miha - Drop the extension. Split the name into an array, reverse the array and join it, put it into an array. Sort alphabetically the array (special subroutine that you can find online) -- then reverse the name, add the extension and print out. KenMc On Oct 10, 2005, at 5:16 AM, Miha Radej wrote: Hi! I have the following problem. As input data I have an array of filenames, ie: @files_a = qw(file1a.ext file1.ext file1m.ext file1g.ext) @files_b = qw(file2w.ext file2a.ext file2z.ext file2b.ext file2.ext file2x.ext file2y.ext file2c.ext) What I need to is sort the arrays by the versions (the files I have been presented with use alphabetical versioning, ie. no letter means original, then versions go as a, b, c, ...). That is not a problem. The problem I have is when instead of an array @files_a I get one like @files_v, which contains letters from the end of the alpahbet and the beginning, which should mean that the users ran out of letters and began from a, b, ... again. I am at a loss how to sort an array like @files_b without making it overly complicated (I have an idea in mind, with a few if's and else's and comparisons and stuff :) ). I have looked at some sort modules but I only have the out-of-the package ActivePerl installation to work with, with no option to install additional modules. The desired sort order would be something like: - first the file without the version letter, ie. ends with a number (if it exists) - then a-z In case of @files_b like arrays: - first the file without the version letter (if it exists) - then versions from the last part of the alphabet - versions from the first part of the alphabet The desired sort order of the @files_b array would be: file2.ext file2w.ext file2x.ext file2y.ext file2z.ext file2a.ext file2b.ext file2c.ext There can be holes in versions (ie. a, b, e, f) but not very likely. The versionless files often do not exist but I need to take them into consideration in case if they do. Before I go and implement my idea, I would like to ask you for any advice what to do in order to achieve what I need, where to find more information on sorting, etc. Thank you in advance, Miha ___ Perl-Win32-Users mailing list Perl-Win32-Users@listserv.ActiveState.com To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs ___ Perl-Win32-Users mailing list Perl-Win32-Users@listserv.ActiveState.com To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs
