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use proc_macro2::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
use quote::ToTokens;
#[derive(Clone)]
pub(crate) struct Error {
message: String,
start: Span,
end: Span,
}
impl Error {
pub(crate) fn spanned(message: impl Into<String>, span: Span) -> Self {
Error {
message: message.into(),
start: span,
end: span,
}
}
}
impl ToTokens for Error {
fn to_tokens(&self, dst: &mut TokenStream) {
fn into_iter(token: impl Into<TokenTree>) -> impl Iterator<Item = TokenTree> {
let tree = token.into();
Some(tree).into_iter()
}
dst.extend(into_iter(Ident::new("compile_error", self.start)));
dst.extend(into_iter(Punct::new('!', Spacing::Alone)));
let mut message = TokenStream::new();
message.extend(into_iter(Literal::string(&self.message)));
let mut group = Group::new(Delimiter::Brace, message);
group.set_span(self.end);
dst.extend(into_iter(group));
}
}