Regulární výrazy

2011 Martin Bruchanov bruxy.regnet.cz

Metaznaky

% Sekce 3.2 Mastering regular expression

Základní; Rozšířené; Význam
dot, ^, $, [⋯], [^⋯];


\{min,max\}; {min,max}
\( \); ( ) 


. (tečka) -- libovolný znak
[···] -- množina znaků
[^···] -- negovaná množina znaků
( | ) -- možnosti
(A|B|C|D) -- množina znaků [ABCD], [A-D]
^ -- začátek řádku/řetězce
$ -- konec řádku/řetězce
\< \> -- začátek/konec slova
\1 \2 ... -- zpětná reference
\znak -- potlačí význam 

Kvantifikátory

Kvantifikátor	Počet opakování
?	minimálně 0krát, maximálně 1krát
*	minimálně 0krát (maximálně neomezeno)
+	minimálně 1krát (maximálně neomezeno)

*? líné
+? líné
{m,}? líné

{n}	právě nkrát
{m,n}	minimálně mkrát, maximálně nkrát
{m,}	minimálně mkrát (maximálně neomezeno)

(?=···) Positive lookahead.
(?!···) Negative lookahead.
(?<=···) Positive lookbehind.
(?<!···) Negative lookbehind.


[\b] Backspace
 
\f Form feed
\n Line feed
\r Carriage return
\t Tab
\v Vertical tab
 

Konverzní metaznaky

\E Terminate \L or \U conversion
\l Convert next character to lowercase
\L Convert all characters up to \E to lowercase
\u Convert next character to uppercase
\U Convert all characters up to \E to uppercase



POSIXové třídy znaků

\bTABLE
\bTABLEhead
POSIX 	Perl	ASCII 	Popis
\eTABLEhead
\bTABLEbody
	\bTR\eTD [:alnum:] 			[A-Za-z0-9] 	Alphanumeric characters
	\bTR\eTD [:word:] 	\w 	[A-Za-z0-9_] 	Alphanumeric characters plus "_"
	\bTR\eTD 		\W 	[^A-Za-z0-9_] 	Non-word characters
	\bTR\eTD [:alpha:] 			[A-Za-z] 	Alphabetic characters
	\bTR\eTD [:blank:] 			[ \t] 	Space and tab
	\bTR\eTD 		\b 	[(?<=\W)(?=\w)|(?<=\w)(?=\W)] 	Word boundaries
	\bTR\eTD [:cntrl:] 			[\x00-\x1F\x7F] 	Control characters
	\bTR\eTD [:digit:] 		\d 	[0-9] 	Digits
	\bTR\eTD 		\D 	[^0-9] 	Non-digits
	\bTR\eTD [:graph:] 			[\x21-\x7E] 	Visible characters
	\bTR\eTD [:lower:] 			[a-z] 	Lowercase letters
	\bTR\eTD [:print:] 			[\x20-\x7E] 	Visible characters and the space character
	\bTR\eTD [:punct:] 			[\]\[!"#$%&'()*+,./:;<=>?@\^_`{|}~-] 	Punctuation characters
	\bTR\eTD [:space:] 		\s 	[ \t\r\n\v\f] 	Whitespace characters
	\bTR\eTD 		\S 	[^ \t\r\n\v\f] 	Non-whitespace characters
	\bTR\eTD [:upper:] 			[A-Z] 	Uppercase letters
	\bTR\eTD [:xdigit:] 			[A-Fa-f0-9] 	Hexadecimal digits
\eTABLEbody

Unicode

\u2122
\x{2122}

\p{charClass} Matches a character that is in a specified Unicode
character class or block.
\P{charClass} Matches a character that is not in a specified Unicode
character class or
block.

awk


Grep

-E použije rozšířené regexpy
-G použije základní
-P perlovské

-v negace výrazu
-c zobrazí počet nálezů
-i ignoruje velikost písmen

Perl

m/pattern/ matches the specified pattern.
s/pattern/pattern/ performs a replace operation.
qr/pattern/ returns a Regex object that may be used later.
split() splits a string into substrings.



Příklady

"[^"]*" text v "uvozovkách"




\bTABLE\tfx
\bTABLEhead
\bTR\bTH POSIX \eTH\bTH Perl \eTH\bTH ASCII \eTH\bTH   Popis \eTH\eTR
\eTABLEhead
\bTABLEbody
\bTR\bTD \type{[:alnum:]} \eTD\bTD         \eTD\bTD \type{[A-Za-z0-9]}    \eTD\bTD Alphanumeric characters\eTD\eTR
\bTR\bTD \type{[:word:]}  \eTD\bTD\type{\w}\eTD\bTD \type{[A-Za-z0-9_]}   \eTD\bTD Alphanumeric characters plus "\_"\eTD\eTR
\bTR\bTD                  \eTD\bTD\type{\W}\eTD\bTD \type{[^A-Za-z0-9_]}  \eTD\bTD Non-word characters\eTD\eTR
\bTR\bTD \type{[:alpha:]} \eTD\bTD         \eTD\bTD \type{[A-Za-z]}       \eTD\bTD Alphabetic characters\eTD\eTR
\bTR\bTD \type{[:blank:]} \eTD\bTD         \eTD\bTD \type{[ \t]}          \eTD\bTD Space and tab\eTD\eTR
\bTR\bTD                  \eTD\bTD\type{\b}\eTD\bTD \type{[(?<=\W)(?=\w)|(?<=\w)(?=\W)]}  \eTD\bTD Word boundaries\eTD\eTR
\bTR\bTD \type{[:cntrl:]} \eTD\bTD         \eTD\bTD \type{[\x00-\x1F\x7F]} \eTD\bTD Control characters\eTD\eTR
\bTR\bTD \type{[:digit:]} \eTD\bTD\type{\d}\eTD\bTD \type{[0-9]}          \eTD\bTD Digits\eTD\eTR
\bTR\bTD                  \eTD\bTD\type{\D}\eTD\bTD \type{[^0-9]}         \eTD\bTD Non-digits\eTD\eTR
\bTR\bTD \type{[:graph:]} \eTD\bTD         \eTD\bTD \type{[\x21-\x7E]}    \eTD\bTD Visible characters\eTD\eTR
\bTR\bTD \type{[:lower:]} \eTD\bTD         \eTD\bTD \type{[a-z]}          \eTD\bTD Lowercase letters\eTD\eTR
\bTR\bTD \type{[:print:]} \eTD\bTD         \eTD\bTD \type{[\x20-\x7E]}    \eTD\bTD Visible characters and the space character\eTD\eTR
%\bTR\bTD \type{[:punct:]} \eTD\bTD         \eTD\bTD \type{[\]\[!"#$%&'()*+,./:;<=>?@\^_`{|}~-]}  \eTD\bTD Punctuation characters\eTD\eTR
\bTR\bTD \type{[:space:]} \eTD\bTD\type{\s}\eTD\bTD \type{[ \t\r\n\v\f]}  \eTD\bTD Whitespace characters\eTD\eTR
\bTR\bTD                  \eTD\bTD\type{\S}\eTD\bTD \type{[^ \t\r\n\v\f]} \eTD\bTD Non-whitespace characters\eTD\eTR
\bTR\bTD \type{[:upper:]} \eTD\bTD         \eTD\bTD \type{[A-Z]}          \eTD\bTD Uppercase letters\eTD\eTR
\bTR\bTD \type{[:xdigit:]}\eTD\bTD         \eTD\bTD \type{[A-Fa-f0-9]}    \eTD\bTD Hexadecimal digits\eTD\eTR
\eTABLEbody
\eTABLE