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use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
use std::iter::FromIterator;
pub struct Error {
span: Span,
msg: String,
}
impl Error {
pub fn new(span: Span, msg: impl Into<String>) -> Self {
Error {
span,
msg: msg.into(),
}
}
}
pub fn compile_error(err: Error) -> TokenStream {
// compile_error!($msg)
TokenStream::from_iter(vec![
TokenTree::Ident(Ident::new("compile_error", err.span)),
TokenTree::Punct({
let mut punct = Punct::new('!', Spacing::Alone);
punct.set_span(err.span);
punct
}),
TokenTree::Group({
let mut group = Group::new(Delimiter::Brace, {
TokenStream::from_iter(vec![TokenTree::Literal({
let mut string = Literal::string(&err.msg);
string.set_span(err.span);
string
})])
});
group.set_span(err.span);
group
}),
])
}
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