From e45f50b55e2bcc64909d2a22698060a6eb6c2f5f Mon Sep 17 00:00:00 2001
From: Rainer Gerhards
C-like comments (/* some c
Below is the formal definition of expression format (in ABNF, RFC 2234):
-
if_stmt := "if" expr "then" # an aid, not part of expression itself+
expr := e_and *("or" e_and)
e_and := e_cmp *("and" e_cmp)
e_cmp := val 0*1(cmp_op val)
val := term *(("+" / "-") term)
term := factor *(("*" / "/" / "%") factor)
factor := ["not"] ["-"] terminal
terminal := var / constant / function / ( "(" expr ")" )
function := name "(" *("," expr) ")"
var := "$" varname
varname := msgvar / sysvar
msgvar := name
sysvar := "$" name
name := alpha *(alnum)
constant := string / number
string := simpstr / tplstr ; tplstr will be implemented in next phase
simpstr := "'" *char "'" ; use your imagination for char ;)
tplstr := '"' template '"' ; not initially implemented
number := ["-"] 1*digit ; 0nn = octal, 0xnn = hex, nn = decimal
cmp_op := "==" / "!=" / "<>" / "<" / ">" / "<=" / ">=" / "contains" / "startswith"
digit := %x30-39
alpha := "a" ... "z" # all letters
alnum :* alpha / digit / "_"
; The stuff immediately below here is a quick shot at how the config
; file ABNF *at whole* may look like. That is not really related to
; expressions, but for the time being I put it here. It will later be
; moved to a more appropriate place. -- rgerhards, 2008-02-22
if_stmt := "if" expr "then"
; and now the actual expression
expr := e_and *("or" e_and)
e_and := e_cmp *("and" e_cmp)
e_cmp := val 0*1(cmp_op val)
val := term *(("+" / "-") term)
term := factor *(("*" / "/" / "%") factor)
factor := ["not"] ["-"] terminal
terminal := var / constant / function / ( "(" expr ")" )
function := name "(" *("," expr) ")"
var := "$" varname
varname := msgvar / sysvar
msgvar := name
sysvar := "$" name
name := alpha *(alnum)
constant := string / number
string := simpstr / tplstr ; tplstr will be implemented in next phase
simpstr := "'" *char "'" ; use your imagination for char ;)
tplstr := '"' template '"' ; not initially implemented
number := ["-"] 1*digit ; 0nn = octal, 0xnn = hex, nn = decimal
cmp_op := "==" / "!=" / "<>" / "<" / ">" / "<=" / ">=" / "contains" / "startswith"
digit := %x30-39
alpha := "a" ... "z" # all letters
alnum :* alpha / digit / "_"
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