https://github.com/dimitri/cl-abnf.git
git clone 'https://github.com/dimitri/cl-abnf.git'
(ql:quickload :cl-abnf)
This Common Lisp librairie implements a parser generator for the ABNF grammar format as described in RFC2234.
The generated parser is a regular expression scanner provided by the cl-ppcre lib, which means that we can't parse recursive grammar definition. One such definition is the ABNF definition as given by the RFC. Fortunately, as you have this lib, you most probably don't need to generate another parser to handle that particular ABNF grammar.
The system has been made Quicklisp ready.
$ cd ~/quicklisp/local-projects/
$ git clone https://github.com/dimitri/cl-abnf.git
* (ql:quickload "abnf")
Currently the ABNF system is maintained as part of the pgloader tool as a
central piece of its syslog message parser facility.
The parse-abnf-grammar function expects the grammar to be parsed as a
string, and also needs the top level rule name of the grammar you're
interested into, as a symbol or a string. You can also give a list of rule
names that you want to capture, they will be capture in the order in which
they are needed to expand the given top-level rule.
The parse-abnf-grammar function returns a cl-ppcre scanner.
~~~ {#example.lisp .commonlisp .numberLines} (defvar timestamp-abnf " TIMESTAMP = NILVALUE / FULL-DATE "T" FULL-TIME FULL-DATE = DATE-FULLYEAR "-" DATE-MONTH "-" DATE-MDAY DATE-FULLYEAR = 4DIGIT DATE-MONTH = 2DIGIT ; 01-12 DATE-MDAY = 2DIGIT ; 01-28, 01-29, 01-30, 01-31 based on ; month/year FULL-TIME = PARTIAL-TIME TIME-OFFSET PARTIAL-TIME = TIME-HOUR ":" TIME-MINUTE ":" TIME-SECOND [TIME-SECFRAC] TIME-HOUR = 2DIGIT ; 00-23 TIME-MINUTE = 2DIGIT ; 00-59 TIME-SECOND = 2DIGIT ; 00-59 TIME-SECFRAC = "." 1*6DIGIT TIME-OFFSET = "Z" / TIME-NUMOFFSET TIME-NUMOFFSET = ("+" / "-") TIME-HOUR ":" TIME-MINUTE
NILVALUE = \"-\" "
“A timestamp ABNF grammar.”)
(let ((scanner (abnf:parse-abnf-grammar timestamp-abnf :timestamp :registering-rules '(:full-date)))) (cl-ppcre:register-groups-bind (date) (scanner “2013-09-08T00:02:03.123456Z+02:00”) date)) ~~~
In the previous usage example the let block returns "2013-09-08".
This library supports the ABNF grammar as given in RFC 2234, with additional support for plain regular expressions.
Here's the RFC syntax:
rulelist = 1*( rule / (*c-wsp c-nl) )
rule = rulename defined-as elements c-nl
; continues if next line starts
; with white space
rulename = ALPHA *(ALPHA / DIGIT / "-")
defined-as = *c-wsp ("=" / "=/") *c-wsp
; basic rules definition and
; incremental alternatives
elements = alternation *c-wsp
c-wsp = WSP / (c-nl WSP)
c-nl = comment / CRLF
; comment or newline
comment = ";" *(WSP / VCHAR) CRLF
alternation = concatenation
*(*c-wsp "/" *c-wsp concatenation)
concatenation = repetition *(1*c-wsp repetition)
repetition = [repeat] element
repeat = 1*DIGIT / (*DIGIT "*" *DIGIT)
element = rulename / group / option /
char-val / num-val / prose-val / regex
; regex is an addition of this lib, see above
group = "(" *c-wsp alternation *c-wsp ")"
option = "[" *c-wsp alternation *c-wsp "]"
char-val = DQUOTE *(%x20-21 / %x23-7E) DQUOTE
; quoted string of SP and VCHAR
; without DQUOTE
num-val = "%" (bin-val / dec-val / hex-val)
bin-val = "b" 1*BIT
[ 1*("." 1*BIT) / ("-" 1*BIT) ]
; series of concatenated bit values
; or single ONEOF range
dec-val = "d" 1*DIGIT
[ 1*("." 1*DIGIT) / ("-" 1*DIGIT) ]
hex-val = "x" 1*HEXDIG
[ 1*("." 1*HEXDIG) / ("-" 1*HEXDIG) ]
prose-val = "<" *(%x20-3D / %x3F-7E) ">"
; bracketed string of SP and VCHAR
; without angles
; prose description, to be used as
; last resort
Those parts of the grammar are always provided, they are the defaults rules of the ABNF definition.
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
BIT = "0" / "1"
CHAR = %x01-7F
; any 7-bit US-ASCII character, excluding NUL
CR = %x0D
; carriage return
CRLF = CR LF
; Internet standard newline
CTL = %x00-1F / %x7F
; controls
DIGIT = %x30-39
; 0-9
DQUOTE = %x22
; " (Double Quote)
HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
HTAB = %x09
; horizontal tab
LF = %x0A
; linefeed
LWSP = *(WSP / CRLF WSP)
; linear white space (past newline)
OCTET = %x00-FF
; 8 bits of data
SP = %x20
We add support for plain regexp in the element rule. A regexp is expected
to follow the form:
regex = "~" delimiter expression delimiter
The expression shouldn't contain the delimiter of course, and the
allowed delimiters are ~//, ~[], ~{}, ~(), ~<>, ~"", ~'',
~|| and ~##. If you have to build a regexp with more than one of those
delimiters in it, you can just concatenate multiple parts together like in
this example:
complex-regex = ~/foo{bar}/ ~{baz/quux}
That will be used in exactly the same way as the following example:
complex-regex = ~<foo{bar}baz/quux>