Lexical conventions

2 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 two characters /* and end with the characters */. C++ comments style can also be used; all characters from the two characters // till the end of the line are considered as comments too. Comments are treated as blanks.

Identifiers

Identifiers are a sequence of letters, digits and _ (the underscore character) starting with a letter. 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 \| _)^*
letter	::=	A..Z \| a..z
digit	::=	0..9

Integer literals

An integer literal is a sequence of one or more digits, optionally preceded by a minus sign. By default, integers literals are in decimal (radix 10).

integer-literal	::=	(0..9)⁺
	\|	0x (0..9 \| A..F \| a..f)⁺
	\|	0o (0..7)⁺

The following prefixes select a different radix:

Prefix	Radix
0x	hexadecimal (radix 16)
0o	octal (radix 8)

Note that the initial 0 is digit zero and the o for octal is letter o.

Boolean literals

The boolean type has two possible values, represented by the literals true and false. A boolean literal is always of type boolean.

boolean-literal	::=	true
	\|	false

Bit literals

Bit literals are delimited by ' (single quote) characters.

bits-literal	::=	' (bit)⁺ '
bit	::=	0 \| 1 \| * \| .

Prefix and infix operators

The following tokens are the Devil operators :

@	..	.	=>	<=	<=>
=	#
+	-	*	/
==	!=	<	>	>=
&&	\|\|	!

Note that sequences of ``operator characters'', such as != or <=> are read as a single token.

Keywords

The identifiers below are reserved keywords:

as	bit	bool	const	device	else
except	false	for	if	int	mask
port	post	pre	private	read	register
serialized	set	structure	trigger	true	type
unused	variable	volatile	write

The following character sequences are also reserved:

{	}	[	]	(	)
:	,	=	;

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.