| 1 | use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree}; |
|---|---|
| 2 | use std::fmt::Display; |
| 3 | use std::iter::FromIterator; |
| 4 | |
| 5 | pub type Result<T, E = Error> = std::result::Result<T, E>; |
| 6 | |
| 7 | pub struct Error { |
| 8 | begin: Span, |
| 9 | end: Span, |
| 10 | msg: String, |
| 11 | } |
| 12 | |
| 13 | impl Error { |
| 14 | pub fn new(span: Span, msg: impl Display) -> Self { |
| 15 | Self::new2(span, span, msg) |
| 16 | } |
| 17 | |
| 18 | pub fn new2(begin: Span, end: Span, msg: impl Display) -> Self { |
| 19 | Error { |
| 20 | begin, |
| 21 | end, |
| 22 | msg: msg.to_string(), |
| 23 | } |
| 24 | } |
| 25 | |
| 26 | pub fn group(group: Group, msg: impl Display) -> Self { |
| 27 | let mut iter = group.stream().into_iter(); |
| 28 | let delimiter = group.span(); |
| 29 | let begin = iter.next().map_or(delimiter, |t| t.span()); |
| 30 | let end = iter.last().map_or(begin, |t| t.span()); |
| 31 | Self::new2(begin, end, msg) |
| 32 | } |
| 33 | |
| 34 | pub fn into_compile_error(self) -> TokenStream { |
| 35 | // compile_error! { $msg } |
| 36 | TokenStream::from_iter(vec![ |
| 37 | TokenTree::Ident(Ident::new("compile_error", self.begin)), |
| 38 | TokenTree::Punct({ |
| 39 | let mut punct = Punct::new('!', Spacing::Alone); |
| 40 | punct.set_span(self.begin); |
| 41 | punct |
| 42 | }), |
| 43 | TokenTree::Group({ |
| 44 | let mut group = Group::new(Delimiter::Brace, { |
| 45 | TokenStream::from_iter(vec![TokenTree::Literal({ |
| 46 | let mut string = Literal::string(&self.msg); |
| 47 | string.set_span(self.end); |
| 48 | string |
| 49 | })]) |
| 50 | }); |
| 51 | group.set_span(self.end); |
| 52 | group |
| 53 | }), |
| 54 | ]) |
| 55 | } |
| 56 | } |
| 57 |