Augmented Backus-Naur Form
Augmented Backus-Naur Form, aka Augmented Backus-Naur Form, is an actively used grammar language created in 2008. In computer science, augmented Backus–Naur form (ABNF) is a metalanguage based on Backus–Naur form (BNF), but consisting of its own syntax and derivation rules. The motive principle for ABNF is to describe a formal system of a language to be used as a bidirectional communications protocol. It is defined by Internet Standard 68 ("STD 68", type case sic), which as of December 2010 is RFC 5234, and it often serves as the definition language for IETF communication protocols. Read more on Wikipedia...
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- Augmented Backus-Naur Form ranks in the top 20% of languages
- the Augmented Backus-Naur Form wikipedia page
- Augmented Backus-Naur Form first appeared in 2008
- file extensions for Augmented Backus-Naur Form include abnf
- See also: regex
- I have 31 facts about Augmented Backus-Naur Form. what would you like to know? email me and let me know how I can help.
Example code from Linguist:
; Source: https://github.com/toml-lang/toml
; License: MIT
;; This is an attempt to define TOML in ABNF according to the grammar defined
;; in RFC 4234 (http://www.ietf.org/rfc/rfc4234.txt).
;; TOML
toml = expression *( newline expression )
expression = (
ws /
ws comment /
ws keyval ws [ comment ] /
ws table ws [ comment ]
)
;; Newline
newline = (
%x0A / ; LF
%x0D.0A ; CRLF
)
newlines = 1*newline
;; Whitespace
ws = *(
%x20 / ; Space
%x09 ; Horizontal tab
)
;; Comment
comment-start-symbol = %x23 ; #
non-eol = %x09 / %x20-10FFFF
comment = comment-start-symbol *non-eol
;; Key-Value pairs
keyval-sep = ws %x3D ws ; =
keyval = key keyval-sep val
key = unquoted-key / quoted-key
unquoted-key = 1*( ALPHA / DIGIT / %x2D / %x5F ) ; A-Z / a-z / 0-9 / - / _
quoted-key = quotation-mark 1*basic-char quotation-mark ; See Basic Strings
val = integer / float / string / boolean / date-time / array / inline-table
;; Table
table = std-table / array-table
;; Standard Table
std-table-open = %x5B ws ; [ Left square bracket
std-table-close = ws %x5D ; ] Right square bracket
table-key-sep = ws %x2E ws ; . Period
std-table = std-table-open key *( table-key-sep key) std-table-close
;; Array Table
array-table-open = %x5B.5B ws ; [[ Double left square bracket
array-table-close = ws %x5D.5D ; ]] Double right square bracket
array-table = array-table-open key *( table-key-sep key) array-table-close
;; Integer
integer = [ minus / plus ] int
minus = %x2D ; -
plus = %x2B ; +
digit1-9 = %x31-39 ; 1-9
underscore = %x5F ; _
int = DIGIT / digit1-9 1*( DIGIT / underscore DIGIT )
;; Float
float = integer ( frac / frac exp / exp )
zero-prefixable-int = DIGIT *( DIGIT / underscore DIGIT )
frac = decimal-point zero-prefixable-int
decimal-point = %x2E ; .
exp = e integer
e = %x65 / %x45 ; e E
;; String
string = basic-string / ml-basic-string / literal-string / ml-literal-string
;; Basic String
basic-string = quotation-mark *basic-char quotation-mark
quotation-mark = %x22 ; "
basic-char = basic-unescaped / escaped
escaped = escape ( %x22 / ; " quotation mark U+0022
%x5C / ; \ reverse solidus U+005C
%x2F / ; / solidus U+002F
%x62 / ; b backspace U+0008
%x66 / ; f form feed U+000C
%x6E / ; n line feed U+000A
%x72 / ; r carriage return U+000D
%x74 / ; t tab U+0009
%x75 4HEXDIG / ; uXXXX U+XXXX
%x55 8HEXDIG ) ; UXXXXXXXX U+XXXXXXXX
basic-unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
escape = %x5C ; \
;; Multiline Basic String
ml-basic-string-delim = quotation-mark quotation-mark quotation-mark
ml-basic-string = ml-basic-string-delim ml-basic-body ml-basic-string-delim
ml-basic-body = *( ml-basic-char / newline / ( escape newline ))
ml-basic-char = ml-basic-unescaped / escaped
ml-basic-unescaped = %x20-5B / %x5D-10FFFF
;; Literal String
literal-string = apostraphe *literal-char apostraphe
apostraphe = %x27 ; ' Apostrophe
literal-char = %x09 / %x20-26 / %x28-10FFFF
;; Multiline Literal String
ml-literal-string-delim = apostraphe apostraphe apostraphe
ml-literal-string = ml-literal-string-delim ml-literal-body ml-literal-string-delim
ml-literal-body = *( ml-literal-char / newline )
ml-literal-char = %x09 / %x20-10FFFF
;; Boolean
boolean = true / false
true = %x74.72.75.65 ; true
false = %x66.61.6C.73.65 ; false
;; Datetime (as defined in RFC 3339)
date-fullyear = 4DIGIT
date-month = 2DIGIT ; 01-12
date-mday = 2DIGIT ; 01-28, 01-29, 01-30, 01-31 based on month/year
time-hour = 2DIGIT ; 00-23
time-minute = 2DIGIT ; 00-59
time-second = 2DIGIT ; 00-58, 00-59, 00-60 based on leap second rules
time-secfrac = "." 1*DIGIT
time-numoffset = ( "+" / "-" ) time-hour ":" time-minute
time-offset = "Z" / time-numoffset
partial-time = time-hour ":" time-minute ":" time-second [time-secfrac]
full-date = date-fullyear "-" date-month "-" date-mday
full-time = partial-time time-offset
date-time = full-date "T" full-time
;; Array
array-open = %x5B ws ; [
array-close = ws %x5D ; ]
array = array-open array-values array-close
array-values = [ val [ array-sep ] [ ( comment newlines) / newlines ] /
val array-sep [ ( comment newlines) / newlines ] array-values ]
array-sep = ws %x2C ws ; , Comma
;; Inline Table
inline-table-open = %x7B ws ; {
inline-table-close = ws %x7D ; }
inline-table-sep = ws %x2C ws ; , Comma
inline-table = inline-table-open inline-table-keyvals inline-table-close
inline-table-keyvals = [ inline-table-keyvals-non-empty ]
inline-table-keyvals-non-empty = key keyval-sep val /
key keyval-sep val inline-table-sep inline-table-keyvals-non-empty
;; Built-in ABNF terms, reproduced here for clarity
; ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
; DIGIT = %x30-39 ; 0-9
; HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
Example code from Wikipedia:
postal-address = name-part street zip-part
name-part = *(personal-part SP) last-name [SP suffix] CRLF
name-part =/ personal-part CRLF
personal-part = first-name / (initial ".")
first-name = *ALPHA
initial = ALPHA
last-name = *ALPHA
suffix = ("Jr." / "Sr." / 1*("I" / "V" / "X"))
street = [apt SP] house-num SP street-name CRLF
apt = 1*4DIGIT
house-num = 1*8(DIGIT / ALPHA)
street-name = 1*VCHAR
zip-part = town-name "," SP state 1*2SP zip-code CRLF
town-name = 1*(ALPHA / SP)
state = 2ALPHA
zip-code = 5DIGIT ["-" 4DIGIT]
Last updated August 22nd, 2019