1use proc_macro::*;
2
3#[proc_macro]
4pub fn alloc_impl_proc(item: TokenStream) -> TokenStream {
5 let mut item = item.into_iter();
6 let Some(TokenTree::Group(krate)) = item.next() else { panic!() };
7 let krate = krate.stream();
8 let stack = match item.next() {
9 Some(TokenTree::Group(stack)) => {
10 let mut stack = stack.stream().into_iter();
11 _ = stack.next();
12 let Some(TokenTree::Ident(stack)) = stack.next() else { panic!() };
13 stack
14 },
15 Some(_) => {
16 let Some(TokenTree::Ident(stack)) = item.next() else { panic!() };
17 stack
18 },
19
20 _ => panic!(),
21 };
22 let Some(TokenTree::Group(block)) = item.next() else { panic!() };
23
24 let mut tokens = Vec::new();
25
26 tokens.extend([
27 TokenTree::Ident(Ident::new("let", Span::call_site())),
28 TokenTree::Ident(stack.clone()),
29 TokenTree::Punct(Punct::new('=', Spacing::Alone)),
30 TokenTree::Ident(stack.clone()),
31 TokenTree::Punct(Punct::new(';', Spacing::Alone)),
32 ]);
33
34 let mut cur_stmt = vec![TokenTree::Ident(stack.clone())];
35 for token in block.stream().into_iter() {
36 match token {
37 TokenTree::Punct(p) if p.as_char() == ';' => {
38 tokens.extend(krate.clone().into_iter().chain([
39 TokenTree::Punct(Punct::new(':', Spacing::Joint)),
40 TokenTree::Punct(Punct::new(':', Spacing::Alone)),
41 TokenTree::Ident(Ident::new("alloc_impl_rules", Span::call_site())),
42 TokenTree::Punct(Punct::new('!', Spacing::Alone)),
43 TokenTree::Group(Group::new(Delimiter::Parenthesis, TokenStream::from_iter(cur_stmt))),
44 TokenTree::Punct(Punct::new(';', Spacing::Alone)),
45 ]));
46
47 cur_stmt = vec![TokenTree::Ident(stack.clone())];
48 },
49 token => cur_stmt.push(token),
50 }
51 }
52
53 tokens.extend([
54 TokenTree::Ident(Ident::new("let", Span::call_site())),
55 TokenTree::Ident(Ident::new("_", Span::call_site())),
56 TokenTree::Punct(Punct::new('=', Spacing::Alone)),
57 TokenTree::Ident(stack.clone()),
58 TokenTree::Punct(Punct::new(';', Spacing::Alone)),
59 ]);
60
61 TokenStream::from_iter(tokens)
62}