1 | use crate::ToTokens; |
2 | use proc_macro2::extra::DelimSpan; |
3 | use proc_macro2::{Span, TokenStream}; |
4 | |
5 | // Not public API other than via the syn crate. Use syn::spanned::Spanned. |
6 | pub trait Spanned: private::Sealed { |
7 | fn __span(&self) -> Span; |
8 | } |
9 | |
10 | impl Spanned for Span { |
11 | fn __span(&self) -> Span { |
12 | *self |
13 | } |
14 | } |
15 | |
16 | impl Spanned for DelimSpan { |
17 | fn __span(&self) -> Span { |
18 | self.join() |
19 | } |
20 | } |
21 | |
22 | impl<T: ?Sized + ToTokens> Spanned for T { |
23 | fn __span(&self) -> Span { |
24 | join_spans(self.into_token_stream()) |
25 | } |
26 | } |
27 | |
28 | fn join_spans(tokens: TokenStream) -> Span { |
29 | let mut iter = tokens.into_iter().map(|tt| tt.span()); |
30 | |
31 | let first = match iter.next() { |
32 | Some(span) => span, |
33 | None => return Span::call_site(), |
34 | }; |
35 | |
36 | iter.fold(None, |_prev, next| Some(next)) |
37 | .and_then(|last| first.join(last)) |
38 | .unwrap_or(first) |
39 | } |
40 | |
41 | mod private { |
42 | use crate::ToTokens; |
43 | use proc_macro2::extra::DelimSpan; |
44 | use proc_macro2::Span; |
45 | |
46 | pub trait Sealed {} |
47 | impl Sealed for Span {} |
48 | impl Sealed for DelimSpan {} |
49 | impl<T: ?Sized + ToTokens> Sealed for T {} |
50 | } |
51 | |