logfmt.ebnf

(*
 * Grammar for Apache's LogFormat as implemented by liblf
 * https://httpd.apache.org/docs/current/mod/mod_log_config.html#logformat
 * EBNF, ISO/IEC 14977:1996(E)
 * Terminals are uppercase, as defined per ABNF (RFC 5234 B.1 Core Rules)
 *)

logfmt = { literal | directive | "%%" }
	;

(* XXX: OCTET - ( "\" | "%" ) *)
literal =
	OCTET
	| "\t" | "\n" | "\'" | '\"' | "\\"
	;

(* XXX: OCTET - "}" *)
name = { OCTET }
	;

name-specifier = "C" | "e" | "i" | "n" | "o" | "^ti" | "^to"
	| custom-specifier
	;

nameless-specifier =
	"A" | "a" | "B" | "b" | "D" | "f" | "h" | "H" | "I" | "k" | "l" | "L"
	| "m" | "O" | "p" | "P" | "S" | "T" | "t" | "U" | "u" | "V" | "v" | "X"
	| custom-specifier
	;

custom-specifier =
	ALPHA
	;

directive =
	"%", [ predicate ], [ "<" | ">" ],
		( "{", name, "}", ( name-specifier )
		| nameless-specifier )
	;

status = DIGIT, { DIGIT } ;

predicate =
	[ "!" ], [ status, { ",", status } ]
	;