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use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};
use std::iter::FromIterator;
pub fn wrap(output: TokenStream) -> TokenStream {
let mut hasher = DefaultHasher::default();
output.to_string().hash(&mut hasher);
let mangled_name = format!("_paste_{}", hasher.finish());
let ident = Ident::new(&mangled_name, Span::call_site());
// #[derive(paste::EnumHack)]
// enum #ident {
// Value = (stringify! {
// #output
// }, 0).1,
// }
TokenStream::from_iter(vec![
TokenTree::Punct(Punct::new('#', Spacing::Alone)),
TokenTree::Group(Group::new(
Delimiter::Bracket,
TokenStream::from_iter(vec![
TokenTree::Ident(Ident::new("derive", Span::call_site())),
TokenTree::Group(Group::new(
Delimiter::Parenthesis,
TokenStream::from_iter(vec![
TokenTree::Ident(Ident::new("paste", Span::call_site())),
TokenTree::Punct(Punct::new(':', Spacing::Joint)),
TokenTree::Punct(Punct::new(':', Spacing::Alone)),
TokenTree::Ident(Ident::new("EnumHack", Span::call_site())),
]),
)),
]),
)),
TokenTree::Ident(Ident::new("enum", Span::call_site())),
TokenTree::Ident(ident),
TokenTree::Group(Group::new(
Delimiter::Brace,
TokenStream::from_iter(vec![
TokenTree::Ident(Ident::new("Value", Span::call_site())),
TokenTree::Punct(Punct::new('=', Spacing::Alone)),
TokenTree::Group(Group::new(
Delimiter::Parenthesis,
TokenStream::from_iter(vec![
TokenTree::Ident(Ident::new("stringify", Span::call_site())),
TokenTree::Punct(Punct::new('!', Spacing::Alone)),
TokenTree::Group(Group::new(Delimiter::Brace, output)),
TokenTree::Punct(Punct::new(',', Spacing::Alone)),
TokenTree::Literal(Literal::usize_unsuffixed(0)),
]),
)),
TokenTree::Punct(Punct::new('.', Spacing::Alone)),
TokenTree::Literal(Literal::usize_unsuffixed(1)),
TokenTree::Punct(Punct::new(',', Spacing::Alone)),
]),
)),
])
}
pub fn extract(input: TokenStream) -> TokenStream {
let mut tokens = input.into_iter();
let _ = tokens.next().expect("enum");
let _ = tokens.next().expect("#ident");
let mut braces = match tokens.next().expect("{...}") {
TokenTree::Group(group) => group.stream().into_iter(),
_ => unreachable!("{...}"),
};
let _ = braces.next().expect("Value");
let _ = braces.next().expect("=");
let mut parens = match braces.next().expect("(...)") {
TokenTree::Group(group) => group.stream().into_iter(),
_ => unreachable!("(...)"),
};
let _ = parens.next().expect("stringify");
let _ = parens.next().expect("!");
let token_stream = match parens.next().expect("{...}") {
TokenTree::Group(group) => group.stream(),
_ => unreachable!("{...}"),
};
let _ = parens.next().expect(",");
let _ = parens.next().expect("0");
let _ = braces.next().expect(".");
let _ = braces.next().expect("1");
let _ = braces.next().expect(",");
token_stream
}
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