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Regular Expression

Regular Expression. Veloxsoft Member Education 2005-04-08 작성 , 발표 : 개발 5 팀 김기용. Introduction. 일반적인 문자열 비교 함수들 C : strcmp(s1, s2) Java : s1.equals(s2) JavaScript : (s1 == s2) Perl : (s1 eq s2) VB : (s1 = s2) 확장된 문자열 비교 / 검색 ( 겨우 이정도 ?) Ignore case: [C] strcmpi

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Regular Expression

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  1. Regular Expression Veloxsoft Member Education 2005-04-08 작성, 발표: 개발 5팀 김기용

  2. Introduction • 일반적인 문자열 비교 함수들 • C : strcmp(s1, s2) • Java : s1.equals(s2) • JavaScript : (s1 == s2) • Perl : (s1 eq s2) • VB : (s1 = s2) • 확장된 문자열 비교/검색 (겨우 이정도?) • Ignore case: [C] strcmpi • Inclusion: [C] strchr, strstr • 좀 더 다양한 문자열 검색/치환 필요

  3. Where to use • 전통적인 unix commands • grep / sed / awk • Text editors • vi / emacs / MSDEV / EditPlus / UltraEdit / … • Languages • JavaScript / Perl / Python / VB.net / Java / … • Libraries • CRegExp in MFC … • PCRE in many languages

  4. 기본 문법 • 대개 / (slash) 로 시작하여 / 로 끝남. • 두 / 사이에 찾고자 하는 문자열을 넣으면 간단한 정규식이 만들어진다. • 아래 정규식은 velox 라는 문자열을 찾는다.

  5. Wildcard • . : Match any character /bb.om/ =~ “bbbom”, “bbcom”, “bbdom”, … • [] : Character class /bb[abc]om/ =~ "bbaom", "bbbom", "bbcom", … !~ "bbdom", "bb.om", … /bb[a-z]om/ =~ "bbaom", "bbbom", … , "bbzom“ !~ "bbAom", "bb.om", "bb!om", … /bb[a-ckA-C0-8]om/ =~ "bbaom", "bbkom", "bbAom", "bb7om", … !~ "bbdom", "bbDom", "bb9om", … /bb[^ag-k]om/ =~ "bbbom", "bbcom", … !~ "bbaom", "bbgom", …, "bbkom"

  6. Perl / JavaScript 에서 가장 잘 지원 PHP 에서도 PCRE (Perl Compatible Regular Expression) 을 사용할 수 있음 Tool 마다 지원하는 Set 가 다름 Escaped wildcard

  7. Quantifier • {min, max} /bbc{2}om/ =~ "bbccom" !~ "bbcbbcom" /bb[abc]{2}om/ =~ "bbabom", "bbbbom", “bbcaom” !~ "bbcom", “bbabcom” /bb[a-z]{3,7}om/ =~ "bbcomom", "bbcomcomom", “bbscgyongom” !~ "bbabom", "bbbluekissom"

  8. Short Quantifier /bbc?om/ =~ “bbom”, “bbcom” /bbc+om/ =~ “bbcom”, “bbccom”, “bbcccom”, … !~ “bbom” /bbc*om/ =~ “bbom”, “bbcom”, “bbccom”, …

  9. Grouping • () : group /b(bco)*m/ =~ "bm", "bbcom", “bbcobcom” /bb([a-z]o)+m/ =~ "bbcom", "bbzom", “bbaobocodoeom” !~ "bbm", "bbazm"

  10. Boundary • ^ : Match the beginning of the line • $ : Match the end of the line /bbcom/ =~ “my bbcomm” /^bbcom/ =~ “bbcomm” !~ “my bbcomm” /bbcom$/ =~ “my bbcom” !~ “bbcomm” /\bbbcom\b/ =~ “bbcom good” !~ “bbcomm”

  11. Selection • Using vertical bar /bb(com|micro)soft/ =~ "bbcomsoft", “bbmicrosoft” !~ "bbsoft"

  12. Substitution • Format /search pattern/replacement text/ • perl $str = "The microsoft conquers the market"; $str =~ s/micro/velox/; • sed # cat text.txt The microsoft conquers the market # cat text.txt | sed 's/microsoft/veloxsoft/' The veloxsoft conquers the market #

  13. Back reference Example

  14. Maximal / Minimal matching • Greedy str = "bbcommunication"; $str =~ s/bbcom*/babo/; # str becomes: "babounication"; • Which * ? $str = "bbcommunication"; $str =~ s/(bbcom*)(m*uni)/\1_\2/; # str -> "bbcomm_unication" • Minimal $str = "bbcommunication"; $str =~ s/(bbcom*?)(m*uni)/\1_\2/; # str -> "bbco_mmunication"

  15. Search Options • i : ignore case • g : global search /bbcom/i =~ "BbCom " $str = "BbCom"; $str =~ s/b/Bee/gi; # str -> "BeeBeeCom“

  16. MSDEV Replace Example • Find: ^\([0-9A-Za-z\.]+\) \(.+\)$ • Replace: <TR><TH><A HREF="http://\1">\1</A></TH><TD>\2</TD>

  17. 응용예 1 • Replace in Files (bash & sed) $ for file in *.h *.cpp; do sed 's/TCmdWindow/TFrame/g' < $file > tmp; mv tmp $file; done • 텍스트  HTML 포매팅 • 문서 coloring (용문객잔 / PERL) • http://scgyong.new21.net/study/misc/yongmun/ • 주소록 txt  HTML table (MSDEV)

  18. 응용예 2 – 로그 파일 분석 • Log 에 현재 시각을 출력하는 루틴 작성 class Debug { public static void logTimeStamp(String str) { System.out.println("<" + str + “:" + System.currentTimeMillis() + “>"); } } • 프로그램에서 특정 키워드와 함께 시각을 출력 class AEmergencyCarlet extends Carlet { public void start() { Debug.logTimeStamp("Carlet.Acn.Start"); dial(); } public void connected() { Debug.logTimeStamp("Carlet.Acn.Connected"); } } • Log 분석기에서 특정 키워드의 시각을 출력하거나 키워드 사이 값을 계산 next unless (($key, $time) = ($l =~ /^<(\S+):(\d+)>\s*$/));

  19. 응용예 3 – 만화 다운 받기 #!/usr/bin/perl $wget = '/usr/bin/wget'; $rfmt = 'http://ntamin.paran.com/webToon/web_toon/toon_view.asp?page=%d&cartoon_num=1'; $lfmt = 'page_%03d.html'; for ($page = 1; ; $page++) { $url = sprintf($rfmt, $page); $loc = sprintf($lfmt, $page); $cmd = "$wget -c -O $loc '$url'"; print "$cmd\n"; `$cmd`; last if ($? == 256); checkFile(); } sub checkFile { open(FILE, $loc) or die $!; while (<FILE>) { if (/^\s*<option value="(\d+)" selected >\d+\1<\/option>\s*$/) { exit if ($page != $1); } if (/^\s*<td>등록일\s*:\s*(\d{4}\.\d{2}\.\d{2})<\/td>\s*$/) { $date = $1; $date =~ s/\./_/g; } if (/^\s*<td\s+align="center"><img\s+src=".+UPLOAD\/Cartoon\/([^"]+)"\s*border="0"/) { $file = $1; downloadFile(); } } close(FILE); } sub downloadFile { $remote = "http://ntafile.paran.com/UPLOAD/Cartoon/$file"; $local = sprintf('1001_%03d_%s.jpg', $page, $date); $cmd = "$wget -c -O $local $remote"; print"$cmd\n"; `$cmd`; last if ($? == 256); }

  20. Reference • The C Programming Language • PerlDOC Regular Expression $ perldoc perlre $ perldoc –T perlre | less -r • http://scgyong.new21.net/study/re/

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