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 |
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.