Messages in this thread Patch in this message | | | From | Trevor Gross <> | Subject | [PATCH v2] rust: macros: update 'paste!' macro to accept string literals | Date | Fri, 17 Nov 2023 20:39:59 -0500 |
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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_ $name _struct_>] {}) } }
m!("foo_bar");
Would previously cause a compilation error. It will now generate:
struct _some_foo_bar_struct_ {}
Signed-off-by: Trevor Gross <tmgross@umich.edu> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Gary Guo <gary@garyguo.net> ---
Changes since v1: correct documentation and add an example. I added the reviewed-bys since the only change is in documentation, not functionality.
v1: https://lore.kernel.org/rust-for-linux/20231008094816.320424-1-tmgross@umich.edu/
rust/macros/lib.rs | 22 ++++++++++++++++++++-- rust/macros/paste.rs | 10 +++++++++- 2 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index c42105c2ff96..51d1f8836667 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -254,8 +254,8 @@ pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { /// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a /// single identifier. /// -/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers -/// (literals, lifetimes and documentation strings are not supported). There is a difference in +/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and +/// literals (lifetimes and documentation strings are not supported). There is a difference in /// supported modifiers as well. /// /// # Example @@ -337,6 +337,24 @@ pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { /// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK); /// ``` /// +/// # Literals +/// +/// Literals can also be concatenated with other identifiers +/// +/// ```ignore +/// macro_rules! create_numbered_fn { +/// ($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#") { -- 2.34.1
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