# spanned.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/quote-1.0.9/src/spanned.rs`.
Keywords: rust, rustlang, rust-lang

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    use crate::ToTokens;
    use proc_macro2::{Span, TokenStream};

    pub trait Spanned {
        fn __span(&self) -> Span;
    }

    impl Spanned for Span {
        fn __span(&self) -> Span {
            *self
        }
    }

    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().filter_map(|tt| {
            // FIXME: This shouldn't be required, since optimally spans should
            // never be invalid. This filter_map can probably be removed when
            // https://github.com/rust-lang/rust/issues/43081 is resolved.
            let span = tt.span();
            let debug = format!("{:?}", span);
            if debug.ends_with("bytes(0..0)") {
                None
            } else {
                Some(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)
    }