Regex BNF Grammar

Question

Is there any BNF grammar for regular expression?

Answer 1

You can see one for Perl regexp (displayed a little more in detail here, as posted by edg)

Answer 2

To post them on-site:

CMPT 384 Lecture Notes Robert D. Cameron November 29 - December 1, 1999

BNF Grammar of Regular Expressions  Following the precedence rules given previously, a BNF grammar for Perl-style regular expressions can be constructed as follows. <RE>    ::=     <union> | <simple-RE> <union>     ::= <RE> "|" <simple-RE> <simple-RE>     ::=     <concatenation> | <basic-RE> <concatenation>     ::= <simple-RE> <basic-RE> <basic-RE>  ::= <star> | <plus> | <elementary-RE> <star>  ::= <elementary-RE> "*" <plus>  ::= <elementary-RE> "+" <elementary-RE>     ::= <group> | <any> | <eos> | <char> | <set> <group>     ::=     "(" <RE> ")" <any>   ::=     "." <eos>   ::=     "$" <char>  ::=     any non metacharacter | "\" metacharacter <set>   ::=     <positive-set> | <negative-set> <positive-set>  ::=     "[" <set-items> "]" <negative-set>  ::=     "[^" <set-items> "]" <set-items>     ::=     <set-item> | <set-item> <set-items> <set-items>     ::=     <range> | <char> <range>     ::=     <char> "-" <char> 

via VonC.

--- Knud van Eeden --- 21 October 2003 - 03:22 am --------------------

PERL:Search/Replace:Regular Expression:Backus Naur Form:What is possible BNF for regular expression?

expression = term               term | expression  term = factor         factor term  factor = atom           atom metacharacter  atom = character         .         ( expression )         [ characterclass ]         [ ^ characterclass ]         { min }         { min ,  }         { min , max }  characterclass = characterrange                   characterrange characterclass  characterrange = begincharacter                   begincharacter - endcharacter  begincharacter = character  endcharacter = character  character =              anycharacterexceptmetacharacters              \ anycharacterexceptspecialcharacters  metacharacter = ?                  * {=0 or more, greedy}                  *? {=0 or more, non-greedy}                  + {=1 or more, greedy}                  +? {=1 or more, non-greedy}                  ^ {=begin of line character}                  $ {=end of line character}                  $` {=the characters to the left of the match}                  $' {=the characters to the right of the match}                  $& {=the characters that are matched}                  \t {=tab character}                  \n {=newline character}                  \r {=carriage return character}                  \f {=form feed character}                  \cX {=control character CTRL-X}                  \N {=the characters in Nth tag (if on match side)}                  $N{=the characters in Nth tag (if not on match side)}                  \NNN {=octal code for character NNN}                  \b {=match a 'word' boundary}                  \B {=match not a 'word' boundary}                  \d {=a digit, [0-9]}                  \D {=not a digit, [^0-9]}                  \s {=whitespace, [ \t\n\r\f]}                  \S {=not a whitespace, [^ \t\n\r\f]}                  \w {='word' character, [a-zA-Z0-9_]}                  \W {=not a 'word' character, [^a-zA-Z0-9_]}                  \Q {=put a quote (de-meta) on characters, until \E}                  \U {=change characters to uppercase, until \E}                  \L {=change characters to uppercase, until \E}  min = integer  max = integer  integer = digit            digit integer  anycharacter = ! " # $ % & ' ( ) * + , - . / :                ; < = > ? @ [ \ ] ^ _ ` { | } ~                0 1 2 3 4 5 6 7 8 9                A B C D E F G H I J K L M N O P Q R S T U V W X Y Z                a b c d e f g h i j k l m n o p q r s t u v w x y z  ---  [book: see also: Bucknall, Julian - the Tomes of Delphi: Algorithms  and Datastructures - p. 37 - 'Using regular expressions' -  http://www.amazon.com/exec/obidos/tg/detail/- /1556227361/qid=1065748783/sr=1-1/ref=sr_1_1/002-0122962-7851254? v=glance&s=books]  --- ---  Internet: see also:  ---  Compiler: Grammar: Expression: Regular: Which grammar defines set of  all regular expressions? [BNF] http://www.faqts.com/knowledge_base/view.phtml/aid/25950/fid/1263  ---  Perl Regular Expression: Quick Reference 1.05 http://www.erudil.com/preqr.pdf  ---  Top: Computers: Programming: Languages: Regular Expressions: Perl http://dmoz.org/Computers/Programming/Languages/Regular_Expressions/Per l/  ---  TSE: Search/Replace:Regular Expression:Backus Naur Form:What is  possible BNF for regular expression? http://www.faqts.com/knowledge_base/view.phtml/aid/25714/fid/1236  ---  Delphi: Search: Regular expression: Create: How to create a regular  expression parser in Delphi? http://www.faqts.com/knowledge_base/view.phtml/aid/25645/fid/175  ---  Delphi: Search: Regular expression: How to add regular expression  searching to Delphi? [Systools] http://www.faqts.com/knowledge_base/view.phtml/aid/25295/fid/175  ---------------------------------------------------------------------- 

via Ed Guinness.