Construct a REGEX by selected substitution

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

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Re: Construct a REGEX by selected substitution by planetscape (Chancellor) on Sep 29, 2007 at 09:01 UTC
In addition to the Pattern Matching, Regular Expressions, and Parsing section of our very fine Tutorials, you may also find the following helpful: Mastering Regular Expressions perlrequick perlretut perlre YAPE::Regex::Explain GraphViz::Regex The Regex Coach (Win32 only, IIRC) HTH, planetscape	[reply]
Re: Construct a REGEX by selected substitution by jeanluca (Deacon) on Sep 29, 2007 at 08:11 UTC
Have a look at perlre which helps me all the time! Especially the part Extended Patterns (which I've used here) is very interesting! For the string you submitted the following will do `$str =~ s/(?<=\s)TXT/FOO/g ;` [download] CHeers LuCa UPDATE: this one might be easier `$str =~ s/ TXT/ FOO/g ;` [download]	[reply] [d/l] [select]
Re^2: Construct a REGEX by selected substitution by pysome (Scribe) on Sep 29, 2007 at 08:37 UTC
How to deal if the $str is : `'<a code=" TXT"> abc =" TXT </a> <text code= TXT> efg =" TXT </text> < +input s=" TXT"> hig =" TXT</input>';` [download] Thanks,	[reply] [d/l]
Re^3: Construct a REGEX by selected substitution by GrandFather (Saint) on Sep 29, 2007 at 09:07 UTC
It looks like what you really need to do is parse some HTML and manipulate some of the elements of the parsed text. However it's not clear just what you want to be able to manipulate, particularly as the sample you've given isn't a well formed fragment of HTML - you seem to have mismatched quote characters. It doesn't help that it's not clear just which TXT instances in the sample ought to be replaced. For modest sized documents HTML::TreeParser may be the most appropriate tool for the job. Perl is environmentally friendly - it saves trees	[reply]
Re^3: Construct a REGEX by selected substitution by jeanluca (Deacon) on Sep 29, 2007 at 09:02 UTC
Did you read the perlre documentation ? It contains the answer to your question! Show us what you've tried or tell us whats unclear about the documentation! LuCa	[reply]
Re: Construct a REGEX by selected substitution by sanPerl (Friar) on Sep 29, 2007 at 17:21 UTC
This will help you. I always use this technique. `my $str = '<a code=TXT> abc TXT </a> <text code=TXT> efg TXT </text> < +input s=TXT> hig TXT</input>'; print "Before: ",$str,"\n#########\n"; $str =~ s{(>)(.*?)(<)} { my ($tag_ends, $mydata, $tag_starts) = ($1,$2,$3); $mydata =~ s/TXT/FOO/gs; "$tag_ends$mydata$tag_starts" }exgs; print "After: ",$str,"\n#########\n";` [download] Let me know if you need any more help.	[reply] [d/l]
Re^2: Construct a REGEX by selected substitution by pysome (Scribe) on Sep 30, 2007 at 02:11 UTC
Thank you very much. Although it is verbose by modifier :/ex.	[reply]
Re: Construct a REGEX by selected substitution by Anonymous Monk on Sep 29, 2007 at 06:28 UTC
How to compose the regex?? Have you ever composed a regex?	[reply]
Re: Construct a REGEX by selected substitution by pysome (Scribe) on Sep 29, 2007 at 10:12 UTC
Is it really a challenge?	[reply]