Lexical Conventions

1 Lexical Conventions

Blanks

The following characters are considered as blanks: space, newline and horizontal tabulation. Blanks separate adjacent identifiers, literals and keywords that would be otherwise confused as a single identifier, literal or keyword. Apart from that, they are ignored.

Comments

Comments are C-like comments. They start with the characters /* and end with the characters */. C++ comments style can also be used; all characters from the two characters // until the end of the line are considered as part of a comment. Comments are treated as blanks.

Special lexeme

There are several kinds of identifiers :

ident which defines identifier (for variables, functions, branches and service name)
headerId which defines SIP header in the RFC fashion, which means, with a colon at the end of the header name
eventIdent which defines SIP event in the RFC fashion, which means, an alphanumeric sequence of characters with possibly some '.' inside when template event packages are used
uriScheme which is defined as scheme in the RFC 3261

They use common definitions of letter and digit.

letter	::=	A..Z \| a..z
digit	::=	0..9

Identifiers

Identifiers are a sequence of letters, digits and _ (the underscore character) starting with a letter or an underscore. A letter can be any of the 52 lowercase and uppercase letters from the ASCII set. The current implementation places no limit on the number of characters of an identifier.

ident

::=

(letter | _) (letter | digit | _)^*

Header names

Header names are a sequence of letters, digits and - (the minus character) starting with a letter and ending with a colon. A letter can be any of the 52 lowercase and uppercase letters from the ASCII set. The current implementation places no limit on the number of characters of a header name.

headerId

::=

#letter (letter | digit | _ | ! | % | * | - | + | ' | ` | ~)^* :

Event identifiers

Event identifiers are a sequence of letters, digits and special characters as defined in RFC 3265. A letter can be any of the 52 lowercase and uppercase letters from the ASCII set. The current implementation places no limit on the number of characters of an event identifier.

eventIdent	::=	event-package (. event-template)^*
event-package	::=	token-nodot
event-template	::=	token-nodot
token-nodot	::=	(letter \| digit \| _ \| ! \| % \| * \| - \| + \| ' \| ` \| ~)⁺

URI Scheme

URI scheme are defined as in RFC 3261

uriScheme

::=

letter (letter | digit | - | + | .)^*

Integer Literals

An integer literal is a sequence of one or more digits. Integer literals are in decimal (radix 10).

integer

::=

0 | (1..9 digit^*)

Prefix and Infix Operator

The following tokens are the SPL operators:

=	+	-	*	/	&&
==	!=	<	>	>=	\|\|
<=	!	match	notmatch

Keywords

The identifiers below are reserved keywords:

BODY	bool	branch	break	bye
cancel	case	continue	default	deploy
dialog	else	event	false	FIFO
foreach	forward	http	https	if
in	incoming	int	LIFO	local
mailto	match	notmatch	outgoing	parallel
pop	processing	push	reason	registration
remote	request	requestURI	response	return
select	service	sip	sips	string
time	true	type	undeploy	uninvite
unregister	unsubscribe	uri	void	when
with

The following character sequences are also reserved.

{	}	[	]	(	)	<	>	\|
=	:	,	;	.

Besides the above mentioned keywords, all sipHeader, responseKind and SIPmethod are also keywords and are written in uppercase.

Ambiguities

Lexical ambiguities are resolved according to the “longest match” rule: when a character sequence can be decomposed into tokens in several different ways, the resulting decomposition is the one with the longest first token.