Expand description
Tokens representing Rust punctuation, keywords, and delimiters.
The type names in this module can be difficult to keep straight, so we
prefer to use the Token!
macro instead. This is a type-macro that
expands to the token type of the given token.
Example
The ItemStatic
syntax tree node is defined like this.
pub struct ItemStatic {
pub attrs: Vec<Attribute>,
pub vis: Visibility,
pub static_token: Token![static],
pub mutability: Option<Token![mut]>,
pub ident: Ident,
pub colon_token: Token![:],
pub ty: Box<Type>,
pub eq_token: Token![=],
pub expr: Box<Expr>,
pub semi_token: Token![;],
}
Parsing
Keywords and punctuation can be parsed through the ParseStream::parse
method. Delimiter tokens are parsed using the parenthesized!
,
bracketed!
and braced!
macros.
use syn::{Attribute, Result};
use syn::parse::{Parse, ParseStream};
// Parse the ItemStatic struct shown above.
impl Parse for ItemStatic {
fn parse(input: ParseStream) -> Result<Self> {
Ok(ItemStatic {
attrs: input.call(Attribute::parse_outer)?,
vis: input.parse()?,
static_token: input.parse()?,
mutability: input.parse()?,
ident: input.parse()?,
colon_token: input.parse()?,
ty: input.parse()?,
eq_token: input.parse()?,
expr: input.parse()?,
semi_token: input.parse()?,
})
}
}
Other operations
Every keyword and punctuation token supports the following operations.
Structs
abstract
+
+=
&
&&
&=
as
async
@
auto
await
!
become
box
{...}
[...]
break
^=
::
const
continue
crate
default
/
/=
do
.
..
...
..=
dyn
else
enum
=
==
extern
=>
final
fn
for
>=
None-delimited group
>
if
impl
in
<-
<=
let
loop
<
macro
match
mod
move
*=
mut
!=
|
|=
||
override
(...)
priv
pub
->
ref
%
%=
return
Self
self
;
<<
<<=
>>
>>=
*
static
struct
-
-=
super
trait
try
type
typeof
union
unsafe
unsized
use
virtual
where
while
yield
Traits
Marker trait for types that represent single tokens.