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Full Discussion: Regex learning.
Top Forums Shell Programming and Scripting Regex learning. Post 303044737 by RavinderSingh13 on Tuesday 3rd of March 2020 12:09:53 AM
Old 03-03-2020
Hello All,

Learnt an example of Lazy match in Regex in Perl, so thought to share here.
Let's say following is Input_file.

Code:
cat Input_file
abcdtest123^ DUMMYtestabcd12234 DUMMY bla blabla12231311313blabla bla.....,,,,,bla
test132131 ^ DUMMY blabla1213 121313_ 131y7351eg1eub wdfwfknfidh28e7ty;;;

Now we would like to have data between first occurrence of ^ to DUMMY , then we could use Lazy match like as follows:

Code:
perl -pe 's|(\^.*?DUMMY\s+)(.*)| new_text_here.... \2|'  Input_file

Output will be as follows for mentioned sample:
Code:
abcdtest123 new_text_here.... bla blabla12231311313blabla bla.....,,,,,bla
test132131  new_text_here.... blabla1213 121313_ 131y7351eg1eub wdfwfknfidh28e7ty;;;

Why is Lazy match Good here? Because .* is a GREEDY match and matches anything till last occurrence of any mentioned character etc but using Lazy match .*?DUMMY\s+ it matches very first occurrence of string DUMMY followed with space starting from ^

Tested and written this in PERL, thought/views/improvements are most welcome here.

Thanks,
R. Singh
This User Gave Thanks to RavinderSingh13 For This Post:
 

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Jcode(3pm)						User Contributed Perl Documentation						Jcode(3pm)

NAME
Jcode - Japanese Charset Handler SYNOPSIS
use Jcode; # # traditional Jcode::convert($str, $ocode, $icode, "z"); # or OOP! print Jcode->new($str)->h2z->tr($from, $to)->utf8; DESCRIPTION
<Japanese document is now available as Jcode::Nihongo. > Jcode.pm supports both object and traditional approach. With object approach, you can go like; $iso_2022_jp = Jcode->new($str)->h2z->jis; Which is more elegant than: $iso_2022_jp = $str; &jcode::convert($iso_2022_jp, 'jis', &jcode::getcode($str), "z"); For those unfamiliar with objects, Jcode.pm still supports "getcode()" and "convert()." If the perl version is 5.8.1, Jcode acts as a wrapper to Encode, the standard charset handler module for Perl 5.8 or later. Methods Methods mentioned here all return Jcode object unless otherwise mentioned. Constructors $j = Jcode->new($str [, $icode]) Creates Jcode object $j from $str. Input code is automatically checked unless you explicitly set $icode. For available charset, see get- code below. For perl 5.8.1 or better, $icode can be any encoding name that Encode understands. $j = Jcode->new($european, 'iso-latin1'); When the object is stringified, it returns the EUC-converted string so you can <print $j> instead of <print $j->euc>. Passing Reference Instead of scalar value, You can use reference as Jcode->new($str); This saves time a little bit. In exchange of the value of $str being converted. (In a way, $str is now "tied" to jcode object). $j->set($str [, $icode]) Sets $j's internal string to $str. Handy when you use Jcode object repeatedly (saves time and memory to create object). # converts mailbox to SJIS format my $jconv = new Jcode; $/ = 00; while(&lt;&gt;){ print $jconv->set($_)->mime_decode->sjis; } $j->append($str [, $icode]); Appends $str to $j's internal string. $j = jcode($str [, $icode]); shortcut for Jcode->new() so you can go like; Encoded Strings In general, you can retrieve encoded string as $j->encoded. $sjis = jcode($str)->sjis $euc = $j->euc $jis = $j->jis $sjis = $j->sjis $ucs2 = $j->ucs2 $utf8 = $j->utf8 What you code is what you get :) $iso_2022_jp = $j->iso_2022_jp Same as "$j->h2z->jis". Hankaku Kanas are forcibly converted to Zenkaku. For perl 5.8.1 and better, you can also use any encoding names and aliases that Encode supports. For example: $european = $j->iso_latin1; # replace '-' with '_' for names. FYI: Encode::Encoder uses similar trick. $j->fallback($fallback) For perl is 5.8.1 or better, Jcode stores the internal string in UTF-8. Any character that does not map to ->encoding are replaced with a '?', which is Encode standard. my $unistr = "x{262f}"; # YIN YANG my $j = jcode($unistr); # $j->euc is '?' You can change this behavior by specifying fallback like Encode. Values are the same as Encode. "Jcode::FB_PERLQQ", "Jcode::FB_XML- CREF", "Jcode::FB_HTMLCREF" are aliased to those of Encode for convenice. print $j->fallback(Jcode::FB_PERLQQ)->euc; # 'x{262f}' print $j->fallback(Jcode::FB_XMLCREF)->euc; # '&#x262f;' print $j->fallback(Jcode::FB_HTMLCREF)->euc; # '&#9775;' The global variable $Jcode::FALLBACK stores the default fallback so you can override that by assigning the value. $Jcode::FALLBACK = Jcode::FB_PERLQQ; # set default fallback scheme [@lines =] $jcode->jfold([$width, $newline_str, $kref]) folds lines in jcode string every $width (default: 72) where $width is the number of "halfwidth" character. Fullwidth Characters are counted as two. with a newline string spefied by $newline_str (default: " "). Rudimentary kinsoku suppport is now available for Perl 5.8.1 and better. $length = $jcode->jlength(); returns character length properly, rather than byte length. Methods that use MIME::Base64 To use methods below, you need MIME::Base64. To install, simply perl -MCPAN -e 'CPAN::Shell->install("MIME::Base64")' If your perl is 5.6 or better, there is no need since MIME::Base64 is bundled. $mime_header = $j->mime_encode([$lf, $bpl]) Converts $str to MIME-Header documented in RFC1522. When $lf is specified, it uses $lf to fold line (default: ). When $bpl is speci- fied, it uses $bpl for the number of bytes (default: 76; this number must be smaller than 76). For Perl 5.8.1 or better, you can also encode MIME Header as: $mime_header = $j->MIME_Header; In which case the resulting $mime_header is MIME-B-encoded UTF-8 whereas "$j->mime_encode()" returnes MIME-B-encoded ISO-2022-JP. Most modern MUAs support both. $j->mime_decode; Decodes MIME-Header in Jcode object. For perl 5.8.1 or better, you can also do the same as: Jcode->new($str, 'MIME-Header') Hankaku vs. Zenkaku $j->h2z([$keep_dakuten]) Converts X201 kana (Hankaku) to X208 kana (Zenkaku). When $keep_dakuten is set, it leaves dakuten as is (That is, "ka + dakuten" is left as is instead of being converted to "ga") You can retrieve the number of matches via $j->nmatch; $j->z2h Converts X208 kana (Zenkaku) to X201 kana (Hankaku). You can retrieve the number of matches via $j->nmatch; Regexp emulators To use "->m()" and "->s()", you need perl 5.8.1 or better. $j->tr($from, $to, $opt); Applies "tr/$from/$to/" on Jcode object where $from and $to are EUC-JP strings. On perl 5.8.1 or better, $from and $to can also be flagged UTF-8 strings. If $opt is set, "tr/$from/$to/$opt" is applied. $opt must be 'c', 'd' or the combination thereof. You can retrieve the number of matches via $j->nmatch; The following methods are available only for perl 5.8.1 or better. $j->s($patter, $replace, $opt); Applies "s/$pattern/$replace/$opt". $pattern and "replace" must be in EUC-JP or flagged UTF-8. $opt are the same as regexp options. See perlre for regexp options. Like "$j->tr()", "$j->s()" returns the object itself so you can nest the operation as follows; $j->tr("a-z", "A-Z")->s("foo", "bar"); [@match = ] $j->m($pattern, $opt); Applies "m/$patter/$opt". Note that this method DOES NOT RETURN AN OBJECT so you can't chain the method like "$j->s()". Instance Variables If you need to access instance variables of Jcode object, use access methods below instead of directly accessing them (That's what OOP is all about) FYI, Jcode uses a ref to array instead of ref to hash (common way) to optimize speed (Actually you don't have to know as long as you use access methods instead; Once again, that's OOP) $j->r_str Reference to the EUC-coded String. $j->icode Input charcode in recent operation. $j->nmatch Number of matches (Used in $j->tr, etc.) Subroutines ($code, [$nmatch]) = getcode($str) Returns char code of $str. Return codes are as follows ascii Ascii (Contains no Japanese Code) binary Binary (Not Text File) euc EUC-JP sjis SHIFT_JIS jis JIS (ISO-2022-JP) ucs2 UCS2 (Raw Unicode) utf8 UTF8 When array context is used instead of scaler, it also returns how many character codes are found. As mentioned above, $str can be $str instead. jcode.pl Users: This function is 100% upper-conpatible with jcode::getcode() -- well, almost; * When its return value is an array, the order is the opposite; jcode::getcode() returns $nmatch first. * jcode::getcode() returns 'undef' when the number of EUC characters is equal to that of SJIS. Jcode::getcode() returns EUC. for Jcode.pm there is no in-betweens. Jcode::convert($str, [$ocode, $icode, $opt]) Converts $str to char code specified by $ocode. When $icode is specified also, it assumes $icode for input string instead of the one checked by getcode(). As mentioned above, $str can be $str instead. jcode.pl Users: This function is 100% upper-conpatible with jcode::convert() ! BUGS
For perl is 5.8.1 or later, Jcode acts as a wrapper to Encode. Meaning Jcode is subject to bugs therein. ACKNOWLEDGEMENTS
This package owes a lot in motivation, design, and code, to the jcode.pl for Perl4 by Kazumasa Utashiro <utashiro@iij.ad.jp>. Hiroki Ohzaki <ohzaki@iod.ricoh.co.jp> has helped me polish regexp from the very first stage of development. JEncode by makamaka@donzoko.net has inspired me to integrate Encode to Jcode. He has also contributed Japanese POD. And folks at Jcode Mailing list <jcode5@ring.gr.jp>. Without them, I couldn't have coded this far. SEE ALSO
Encode Jcode::Nihongo <http://www.iana.org/assignments/character-sets> COPYRIGHT
Copyright 1999-2005 Dan Kogai <dankogai@dan.co.jp> This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.8.8 2005-02-19 Jcode(3pm)
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