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.

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.