diff mbox series

[v2] rust: macros: update 'paste!' macro to accept string literals

Message ID 20231118013959.37384-1-tmgross@umich.edu
State New
Headers
Series [v2] rust: macros: update 'paste!' macro to accept string literals |

Commit Message

Trevor Gross Nov. 18, 2023, 1:39 a.m. UTC 
  Enable combining identifiers with literals in the 'paste!' macro. This
allows combining user-specified strings with affixes to create
namespaced identifiers.

This sample code:

    macro_rules! m {
        ($name:lit) => {
            paste!(struct [<_some_ $name _struct_>] {})
        }
    }

    m!("foo_bar");

Would previously cause a compilation error. It will now generate:

    struct _some_foo_bar_struct_ {}

Signed-off-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
---

Changes since v1: correct documentation and add an example. I added the
reviewed-bys since the only change is in documentation, not
functionality.

v1: https://lore.kernel.org/rust-for-linux/20231008094816.320424-1-tmgross@umich.edu/

 rust/macros/lib.rs   | 22 ++++++++++++++++++++--
 rust/macros/paste.rs | 10 +++++++++-
 2 files changed, 29 insertions(+), 3 deletions(-)

Comments

Alice Ryhl Nov. 27, 2023, 2:01 p.m. UTC | #1 
On Sat, Nov 18, 2023 at 2:41 AM Trevor Gross <tmgross@umich.edu> wrote:
>
> Enable combining identifiers with literals in the 'paste!' macro. This
> allows combining user-specified strings with affixes to create
> namespaced identifiers.
>
> This sample code:
>
>     macro_rules! m {
>         ($name:lit) => {
>             paste!(struct [<_some_ $name _struct_>] {})
>         }
>     }
>
>     m!("foo_bar");
>
> Would previously cause a compilation error. It will now generate:
>
>     struct _some_foo_bar_struct_ {}
>
> Signed-off-by: Trevor Gross <tmgross@umich.edu>
> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Reviewed-by: Benno Lossin <benno.lossin@proton.me>
> Reviewed-by: Gary Guo <gary@garyguo.net>

Since there are no other replies to this version, I'll confirm that
this still looks good to me.

Alice
Miguel Ojeda Dec. 13, 2023, 6:44 p.m. UTC | #2 
On Sat, Nov 18, 2023 at 2:43 AM Trevor Gross <tmgross@umich.edu> wrote:
>
> Enable combining identifiers with literals in the 'paste!' macro. This
> allows combining user-specified strings with affixes to create
> namespaced identifiers.
>
> This sample code:
>
>     macro_rules! m {
>         ($name:lit) => {
>             paste!(struct [<_some_ $name _struct_>] {})
>         }
>     }
>
>     m!("foo_bar");
>
> Would previously cause a compilation error. It will now generate:
>
>     struct _some_foo_bar_struct_ {}
>
> Signed-off-by: Trevor Gross <tmgross@umich.edu>
> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Reviewed-by: Benno Lossin <benno.lossin@proton.me>
> Reviewed-by: Gary Guo <gary@garyguo.net>

Applied to `rust-next` (with an added `:` before the example since
that is our usual convention).

Thanks everyone!

Cheers,
Miguel
diff mbox series

Patch

diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index c42105c2ff96..51d1f8836667 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -254,8 +254,8 @@  pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
 /// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
 /// single identifier.
 ///
-/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers
-/// (literals, lifetimes and documentation strings are not supported). There is a difference in
+/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
+/// literals (lifetimes and documentation strings are not supported). There is a difference in
 /// supported modifiers as well.
 ///
 /// # Example
@@ -337,6 +337,24 @@  pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
 /// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
 /// ```
 ///
+/// # Literals
+///
+/// Literals can also be concatenated with other identifiers
+///
+/// ```ignore
+/// macro_rules! create_numbered_fn {
+///     ($name:literal, $val:literal) => {
+///         kernel::macros::paste! {
+///             fn [<some_ $name _fn $val>]() -> u32 { $val }
+///         }
+///     };
+/// }
+///
+/// create_numbered_fn!("foo", 100);
+///
+/// assert_eq!(some_foo_fn100(), 100)
+/// ```
+///
 /// [`paste`]: https://docs.rs/paste/
 #[proc_macro]
 pub fn paste(input: TokenStream) -> TokenStream {
diff --git a/rust/macros/paste.rs b/rust/macros/paste.rs
index 385a78434224..f40d42b35b58 100644
--- a/rust/macros/paste.rs
+++ b/rust/macros/paste.rs
@@ -9,7 +9,15 @@  fn concat(tokens: &[TokenTree], group_span: Span) -> TokenTree {
     loop {
         match tokens.next() {
             None => break,
-            Some(TokenTree::Literal(lit)) => segments.push((lit.to_string(), lit.span())),
+            Some(TokenTree::Literal(lit)) => {
+                // Allow us to concat string literals by stripping quotes
+                let mut value = lit.to_string();
+                if value.starts_with('"') && value.ends_with('"') {
+                    value.remove(0);
+                    value.pop();
+                }
+                segments.push((value, lit.span()));
+            }
             Some(TokenTree::Ident(ident)) => {
                 let mut value = ident.to_string();
                 if value.starts_with("r#") {