from : Identifiers - The Rust Reference
it is saying
RAW_IDENTIFIER → r# IDENTIFIER_OR_KEYWORD
and
NON_KEYWORD_IDENTIFIER → IDENTIFIER_OR_KEYWORDexcept a strict or reserved keyword
i am not sure why it is repeating the same thing here
IDENTIFIER → NON_KEYWORD_IDENTIFIER | RAW_IDENTIFIER
and what does it mean by
except _, RAW_IDENTIFIER, or $crate
Oh… there’s a really confusing phrasing here. It looks to me like the line of
ident: an IDENTIFIER_OR_KEYWORD except_, RAW_IDENTIFIER, or$crate
is supposed to be read
ident: an ((IDENTIFIER_OR_KEYWORD except_)), [or a] ((RAW_IDENTIFIER)), or (($crate))
but it’s easy to instead see
ident: an IDENTIFIER_OR_KEYWORD except ((_, RAW_IDENTIFIER, or$crate))
thanks for the comment but what about the graph ? i don't understand a piece of
it
NON_KEYWORD_IDENTIFIER is the regular identifier, things like a but not for. RAW_IDENTIFIER is r# followed by any word, like r#a or r#for. Another way to put it is:
KEYWORD_IDENTIFIER -> r# a strict or reserved keyword
NON_KEYWORD_IDENTIFIER -> [r#] IDENTIFIER_OR_KEYWORD except a strict or reserved keyword
IDENTIFIER -> KEYWORD_IDENTIFIER | NON_KEYWORD_IDENTIFIER
That is, r# + a keyword, or a non-keyword with or without r#.
Just checking, since everyone needs to learn “common knowledge” at some point — have you heard of Backus-Naur form? That’s more-or-less what the graph is.
