pin_init_internal/
pin_data.rs

1// SPDX-License-Identifier: Apache-2.0 OR MIT
2
3#[cfg(not(kernel))]
4use proc_macro2 as proc_macro;
5
6use crate::helpers::{parse_generics, Generics};
7use proc_macro::{Group, Punct, Spacing, TokenStream, TokenTree};
8
9pub(crate) fn pin_data(args: TokenStream, input: TokenStream) -> TokenStream {
10    // This proc-macro only does some pre-parsing and then delegates the actual parsing to
11    // `pin_init::__pin_data!`.
12
13    let (
14        Generics {
15            impl_generics,
16            decl_generics,
17            ty_generics,
18        },
19        rest,
20    ) = parse_generics(input);
21    // The struct definition might contain the `Self` type. Since `__pin_data!` will define a new
22    // type with the same generics and bounds, this poses a problem, since `Self` will refer to the
23    // new type as opposed to this struct definition. Therefore we have to replace `Self` with the
24    // concrete name.
25
26    // Errors that occur when replacing `Self` with `struct_name`.
27    let mut errs = TokenStream::new();
28    // The name of the struct with ty_generics.
29    let struct_name = rest
30        .iter()
31        .skip_while(|tt| !matches!(tt, TokenTree::Ident(i) if i.to_string() == "struct"))
32        .nth(1)
33        .and_then(|tt| match tt {
34            TokenTree::Ident(_) => {
35                let tt = tt.clone();
36                let mut res = vec![tt];
37                if !ty_generics.is_empty() {
38                    // We add this, so it is maximally compatible with e.g. `Self::CONST` which
39                    // will be replaced by `StructName::<$generics>::CONST`.
40                    res.push(TokenTree::Punct(Punct::new(':', Spacing::Joint)));
41                    res.push(TokenTree::Punct(Punct::new(':', Spacing::Alone)));
42                    res.push(TokenTree::Punct(Punct::new('<', Spacing::Alone)));
43                    res.extend(ty_generics.iter().cloned());
44                    res.push(TokenTree::Punct(Punct::new('>', Spacing::Alone)));
45                }
46                Some(res)
47            }
48            _ => None,
49        })
50        .unwrap_or_else(|| {
51            // If we did not find the name of the struct then we will use `Self` as the replacement
52            // and add a compile error to ensure it does not compile.
53            errs.extend(
54                "::core::compile_error!(\"Could not locate type name.\");"
55                    .parse::<TokenStream>()
56                    .unwrap(),
57            );
58            "Self".parse::<TokenStream>().unwrap().into_iter().collect()
59        });
60    let impl_generics = impl_generics
61        .into_iter()
62        .flat_map(|tt| replace_self_and_deny_type_defs(&struct_name, tt, &mut errs))
63        .collect::<Vec<_>>();
64    let mut rest = rest
65        .into_iter()
66        .flat_map(|tt| {
67            // We ignore top level `struct` tokens, since they would emit a compile error.
68            if matches!(&tt, TokenTree::Ident(i) if i.to_string() == "struct") {
69                vec![tt]
70            } else {
71                replace_self_and_deny_type_defs(&struct_name, tt, &mut errs)
72            }
73        })
74        .collect::<Vec<_>>();
75    // This should be the body of the struct `{...}`.
76    let last = rest.pop();
77    let mut quoted = quote!(::pin_init::__pin_data! {
78        parse_input:
79        @args(#args),
80        @sig(#(#rest)*),
81        @impl_generics(#(#impl_generics)*),
82        @ty_generics(#(#ty_generics)*),
83        @decl_generics(#(#decl_generics)*),
84        @body(#last),
85    });
86    quoted.extend(errs);
87    quoted
88}
89
90/// Replaces `Self` with `struct_name` and errors on `enum`, `trait`, `struct` `union` and `impl`
91/// keywords.
92///
93/// The error is appended to `errs` to allow normal parsing to continue.
94fn replace_self_and_deny_type_defs(
95    struct_name: &Vec<TokenTree>,
96    tt: TokenTree,
97    errs: &mut TokenStream,
98) -> Vec<TokenTree> {
99    match tt {
100        TokenTree::Ident(ref i)
101            if i.to_string() == "enum"
102                || i.to_string() == "trait"
103                || i.to_string() == "struct"
104                || i.to_string() == "union"
105                || i.to_string() == "impl" =>
106        {
107            errs.extend(
108                format!(
109                    "::core::compile_error!(\"Cannot use `{i}` inside of struct definition with \
110                        `#[pin_data]`.\");"
111                )
112                .parse::<TokenStream>()
113                .unwrap()
114                .into_iter()
115                .map(|mut tok| {
116                    tok.set_span(tt.span());
117                    tok
118                }),
119            );
120            vec![tt]
121        }
122        TokenTree::Ident(i) if i.to_string() == "Self" => struct_name.clone(),
123        TokenTree::Literal(_) | TokenTree::Punct(_) | TokenTree::Ident(_) => vec![tt],
124        TokenTree::Group(g) => vec![TokenTree::Group(Group::new(
125            g.delimiter(),
126            g.stream()
127                .into_iter()
128                .flat_map(|tt| replace_self_and_deny_type_defs(struct_name, tt, errs))
129                .collect(),
130        ))],
131    }
132}
pin_init_internal/pin_data.rs

pin_init_internal/
pin_data.rs
