80 lines
2.9 KiB
Rust
80 lines
2.9 KiB
Rust
// SPDX-License-Identifier: Apache-2.0 OR MIT
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use proc_macro::{Punct, Spacing, TokenStream, TokenTree};
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pub(crate) fn pin_data(args: TokenStream, input: TokenStream) -> TokenStream {
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// This proc-macro only does some pre-parsing and then delegates the actual parsing to
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// `kernel::__pin_data!`.
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//
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// In here we only collect the generics, since parsing them in declarative macros is very
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// elaborate. We also do not need to analyse their structure, we only need to collect them.
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// `impl_generics`, the declared generics with their bounds.
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let mut impl_generics = vec![];
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// Only the names of the generics, without any bounds.
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let mut ty_generics = vec![];
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// Tokens not related to the generics e.g. the `impl` token.
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let mut rest = vec![];
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// The current level of `<`.
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let mut nesting = 0;
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let mut toks = input.into_iter();
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// If we are at the beginning of a generic parameter.
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let mut at_start = true;
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for tt in &mut toks {
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match tt.clone() {
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TokenTree::Punct(p) if p.as_char() == '<' => {
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if nesting >= 1 {
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impl_generics.push(tt);
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}
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nesting += 1;
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}
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TokenTree::Punct(p) if p.as_char() == '>' => {
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if nesting == 0 {
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break;
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} else {
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nesting -= 1;
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if nesting >= 1 {
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impl_generics.push(tt);
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}
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if nesting == 0 {
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break;
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}
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}
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}
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tt => {
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if nesting == 1 {
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match &tt {
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TokenTree::Ident(i) if i.to_string() == "const" => {}
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TokenTree::Ident(_) if at_start => {
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ty_generics.push(tt.clone());
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ty_generics.push(TokenTree::Punct(Punct::new(',', Spacing::Alone)));
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at_start = false;
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}
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TokenTree::Punct(p) if p.as_char() == ',' => at_start = true,
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TokenTree::Punct(p) if p.as_char() == '\'' && at_start => {
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ty_generics.push(tt.clone());
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}
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_ => {}
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}
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}
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if nesting >= 1 {
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impl_generics.push(tt);
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} else if nesting == 0 {
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rest.push(tt);
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}
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}
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}
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}
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rest.extend(toks);
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// This should be the body of the struct `{...}`.
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let last = rest.pop();
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quote!(::kernel::__pin_data! {
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parse_input:
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@args(#args),
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@sig(#(#rest)*),
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@impl_generics(#(#impl_generics)*),
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@ty_generics(#(#ty_generics)*),
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@body(#last),
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})
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}
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