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use crate::ToTokens;
use proc_macro2::extra::DelimSpan;
use proc_macro2::{Span, TokenStream};
// Not public API other than via the syn crate. Use syn::spanned::Spanned.
pub trait Spanned: private::Sealed {
fn __span(&self) -> Span;
}
impl Spanned for Span {
fn __span(&self) -> Span {
*self
}
}
impl Spanned for DelimSpan {
fn __span(&self) -> Span {
self.join()
}
}
impl<T: ?Sized + ToTokens> Spanned for T {
fn __span(&self) -> Span {
join_spans(self.into_token_stream())
}
}
fn join_spans(tokens: TokenStream) -> Span {
let mut iter = tokens.into_iter().map(|tt| tt.span());
let first = match iter.next() {
Some(span) => span,
None => return Span::call_site(),
};
iter.fold(None, |_prev, next| Some(next))
.and_then(|last| first.join(last))
.unwrap_or(first)
}
mod private {
use crate::ToTokens;
use proc_macro2::extra::DelimSpan;
use proc_macro2::Span;
pub trait Sealed {}
impl Sealed for Span {}
impl Sealed for DelimSpan {}
impl<T: ?Sized + ToTokens> Sealed for T {}
}