Notation

Grammar

The following notations are used by the Lexer and Syntax grammar snippets:

Notation	Examples	Meaning
CAPITAL	KW_IF, INTEGER_LITERAL	A token produced by the lexer
ItalicCamelCase	LetStatement, Item	A syntactical production
string	x, while, *	The exact character(s)
\x	\n, \r, \t, \0	The character represented by this escape
x?	pub?	An optional item
x*	OuterAttribute*	0 or more of x
x+	MacroMatch+	1 or more of x
xa..b	HEX_DIGIT1..6	a to b repetitions of x
|	u8 | u16, Block | Item	Either one or another
[ ]	[b B]	Any of the characters listed
[ - ]	[a-z]	Any of the characters in the range
~[ ]	~[b B]	Any characters, except those listed
~string	~\n, ~*/	Any characters, except this sequence
( )	(, Parameter)?	Groups items

String table productions

Some rules in the grammar — notably unary operators, binary operators, and keywords — are given in a simplified form: as a listing of printable strings. These cases form a subset of the rules regarding the token rule, and are assumed to be the result of a lexical-analysis phase feeding the parser, driven by a DFA, operating over the disjunction of all such string table entries.

When such a string in monospace font occurs inside the grammar, it is an implicit reference to a single member of such a string table production. See tokens for more information.