Re: [PATCH v3 01/13] rust: macros: add `quote!` macro

From: Andreas Hindborg
Date: Thu Mar 30 2023 - 07:45:15 EST



y86-dev@xxxxxxxxxxxxxx writes:

> From: Gary Guo <gary@xxxxxxxxxxx>
>
> Add the `quote!` macro for creating `TokenStream`s directly via the
> given Rust tokens. It also supports repetitions using iterators.
>
> It will be used by the pin-init API proc-macros to generate code.
>
> Signed-off-by: Gary Guo <gary@xxxxxxxxxxx>
> Signed-off-by: Benno Lossin <y86-dev@xxxxxxxxxxxxxx>
> ---
> rust/macros/lib.rs | 2 +
> rust/macros/quote.rs | 145 +++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 147 insertions(+)
> create mode 100644 rust/macros/quote.rs
>
> diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
> index c1d385e345b9..82b520f024dd 100644
> --- a/rust/macros/lib.rs
> +++ b/rust/macros/lib.rs
> @@ -2,6 +2,8 @@
>
> //! Crate for all kernel procedural macros.
>
> +#[macro_use]
> +mod quote;
> mod concat_idents;
> mod helpers;
> mod module;
> diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs
> new file mode 100644
> index 000000000000..7efb009c25a9
> --- /dev/null
> +++ b/rust/macros/quote.rs
> @@ -0,0 +1,145 @@
> +// SPDX-License-Identifier: Apache-2.0 OR MIT
> +
> +use proc_macro::{TokenStream, TokenTree};
> +
> +pub(crate) trait ToTokens {
> + fn to_tokens(&self, tokens: &mut TokenStream);
> +}
> +
> +impl<T: ToTokens> ToTokens for Option<T> {
> + fn to_tokens(&self, tokens: &mut TokenStream) {
> + if let Some(v) = self {
> + v.to_tokens(tokens);
> + }
> + }
> +}
> +
> +impl ToTokens for proc_macro::Group {
> + fn to_tokens(&self, tokens: &mut TokenStream) {
> + tokens.extend([TokenTree::from(self.clone())]);
> + }
> +}
> +
> +impl ToTokens for TokenTree {
> + fn to_tokens(&self, tokens: &mut TokenStream) {
> + tokens.extend([self.clone()]);
> + }
> +}
> +
> +impl ToTokens for TokenStream {
> + fn to_tokens(&self, tokens: &mut TokenStream) {
> + tokens.extend(self.clone());
> + }
> +}
> +
> +/// Converts tokens into [`proc_macro::TokenStream`] and performs variable interpolations with
> +/// the given span.
> +///
> +/// This is a similar to the
> +/// [`quote_spanned!`](https://docs.rs/quote/latest/quote/macro.quote_spanned.html) macro from the
> +/// `quote` crate but provides only just enough functionality needed by the current `macros` crate.
> +#[allow(unused_macros)]
> +macro_rules! quote_spanned {
> + ($span:expr => $($tt:tt)*) => {
> + #[allow(clippy::vec_init_then_push)]
> + {
> + let mut tokens = Vec::new();
> + let span = $span;
> + quote_spanned!(@proc tokens span $($tt)*);
> + proc_macro::TokenStream::from_iter(tokens)

Should this be `::alloc::vec::Vec` and
`::proc_macro::TokenStream::from_iter` ?

Best regards,
Andreas

> + }};
> + (@proc $v:ident $span:ident) => {};
> + (@proc $v:ident $span:ident #$id:ident $($tt:tt)*) => {
> + let mut ts = proc_macro::TokenStream::new();
> + crate::quote::ToTokens::to_tokens(&$id, &mut ts);
> + $v.extend(ts.into_iter());
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident #(#$id:ident)* $($tt:tt)*) => {
> + for token in $id {
> + let mut ts = proc_macro::TokenStream::new();
> + crate::quote::ToTokens::to_tokens(&token, &mut ts);
> + $v.extend(ts.into_iter());
> + }
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident ( $($inner:tt)* ) $($tt:tt)*) => {
> + let mut tokens = Vec::new();
> + quote_spanned!(@proc tokens $span $($inner)*);
> + $v.push(proc_macro::TokenTree::Group(proc_macro::Group::new(
> + proc_macro::Delimiter::Parenthesis,
> + proc_macro::TokenStream::from_iter(tokens)
> + )));
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident [ $($inner:tt)* ] $($tt:tt)*) => {
> + let mut tokens = Vec::new();
> + quote_spanned!(@proc tokens $span $($inner)*);
> + $v.push(proc_macro::TokenTree::Group(proc_macro::Group::new(
> + proc_macro::Delimiter::Bracket,
> + proc_macro::TokenStream::from_iter(tokens)
> + )));
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident { $($inner:tt)* } $($tt:tt)*) => {
> + let mut tokens = Vec::new();
> + quote_spanned!(@proc tokens $span $($inner)*);
> + $v.push(proc_macro::TokenTree::Group(proc_macro::Group::new(
> + proc_macro::Delimiter::Brace,
> + proc_macro::TokenStream::from_iter(tokens)
> + )));
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident :: $($tt:tt)*) => {
> + $v.push(
> + proc_macro::TokenTree::Punct(proc_macro::Punct::new(':', proc_macro::Spacing::Joint))
> + );
> + $v.push(
> + proc_macro::TokenTree::Punct(proc_macro::Punct::new(':', proc_macro::Spacing::Alone))
> + );
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident : $($tt:tt)*) => {
> + $v.push(
> + proc_macro::TokenTree::Punct(proc_macro::Punct::new(':', proc_macro::Spacing::Alone))
> + );
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident , $($tt:tt)*) => {
> + $v.push(
> + proc_macro::TokenTree::Punct(proc_macro::Punct::new(',', proc_macro::Spacing::Alone))
> + );
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident @ $($tt:tt)*) => {
> + $v.push(
> + proc_macro::TokenTree::Punct(proc_macro::Punct::new('@', proc_macro::Spacing::Alone))
> + );
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident ! $($tt:tt)*) => {
> + $v.push(
> + proc_macro::TokenTree::Punct(proc_macro::Punct::new('!', proc_macro::Spacing::Alone))
> + );
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> + (@proc $v:ident $span:ident $id:ident $($tt:tt)*) => {
> + $v.push(proc_macro::TokenTree::Ident(proc_macro::Ident::new(stringify!($id), $span)));
> + quote_spanned!(@proc $v $span $($tt)*);
> + };
> +}
> +
> +/// Converts tokens into [`proc_macro::TokenStream`] and performs variable interpolations with
> +/// mixed site span ([`Span::mixed_site()`]).
> +///
> +/// This is a similar to the [`quote!`](https://docs.rs/quote/latest/quote/macro.quote.html) macro
> +/// from the `quote` crate but provides only just enough functionality needed by the current
> +/// `macros` crate.
> +///
> +/// [`Span::mixed_site()`]: https://doc.rust-lang.org/proc_macro/struct.Span.html#method.mixed_site
> +#[allow(unused_macros)]
> +macro_rules! quote {
> + ($($tt:tt)*) => {
> + quote_spanned!(proc_macro::Span::mixed_site() => $($tt)*)
> + }
> +}