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_ $name _struct_>] {})
}
}
m!("foo_bar");
Would previously cause a compilation error. It will now generate:
struct _some_foo_bar_struct_ {}
Signed-off-by: Trevor Gross <[email protected]>
Reviewed-by: Martin Rodriguez Reboredo <[email protected]>
Reviewed-by: Vincenzo Palazzo <[email protected]>
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
Reviewed-by: Gary Guo <[email protected]>
---
Changes since v1: correct documentation and add an example. I added the
reviewed-bys since the only change is in documentation, not
functionality.
v1: https://lore.kernel.org/rust-for-linux/[email protected]/
rust/macros/lib.rs | 22 ++++++++++++++++++++--
rust/macros/paste.rs | 10 +++++++++-
2 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index c42105c2ff96..51d1f8836667 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -254,8 +254,8 @@ pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
/// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
/// single identifier.
///
-/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers
-/// (literals, lifetimes and documentation strings are not supported). There is a difference in
+/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
+/// literals (lifetimes and documentation strings are not supported). There is a difference in
/// supported modifiers as well.
///
/// # Example
@@ -337,6 +337,24 @@ pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
/// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
/// ```
///
+/// # Literals
+///
+/// Literals can also be concatenated with other identifiers
+///
+/// ```ignore
+/// macro_rules! create_numbered_fn {
+/// ($name:literal, $val:literal) => {
+/// kernel::macros::paste! {
+/// fn [<some_ $name _fn $val>]() -> u32 { $val }
+/// }
+/// };
+/// }
+///
+/// create_numbered_fn!("foo", 100);
+///
+/// assert_eq!(some_foo_fn100(), 100)
+/// ```
+///
/// [`paste`]: https://docs.rs/paste/
#[proc_macro]
pub fn paste(input: TokenStream) -> TokenStream {
diff --git a/rust/macros/paste.rs b/rust/macros/paste.rs
index 385a78434224..f40d42b35b58 100644
--- a/rust/macros/paste.rs
+++ b/rust/macros/paste.rs
@@ -9,7 +9,15 @@ fn concat(tokens: &[TokenTree], group_span: Span) -> TokenTree {
loop {
match tokens.next() {
None => break,
- Some(TokenTree::Literal(lit)) => segments.push((lit.to_string(), lit.span())),
+ Some(TokenTree::Literal(lit)) => {
+ // Allow us to concat string literals by stripping quotes
+ let mut value = lit.to_string();
+ if value.starts_with('"') && value.ends_with('"') {
+ value.remove(0);
+ value.pop();
+ }
+ segments.push((value, lit.span()));
+ }
Some(TokenTree::Ident(ident)) => {
let mut value = ident.to_string();
if value.starts_with("r#") {
--
2.34.1
On Sat, Nov 18, 2023 at 2:41 AM Trevor Gross <[email protected]> wrote:
>
> Enable combining identifiers with literals in the 'paste!' macro. This
> allows combining user-specified strings with affixes to create
> namespaced identifiers.
>
> This sample code:
>
> macro_rules! m {
> ($name:lit) => {
> paste!(struct [<_some_ $name _struct_>] {})
> }
> }
>
> m!("foo_bar");
>
> Would previously cause a compilation error. It will now generate:
>
> struct _some_foo_bar_struct_ {}
>
> Signed-off-by: Trevor Gross <[email protected]>
> Reviewed-by: Martin Rodriguez Reboredo <[email protected]>
> Reviewed-by: Vincenzo Palazzo <[email protected]>
> Reviewed-by: Alice Ryhl <[email protected]>
> Reviewed-by: Benno Lossin <[email protected]>
> Reviewed-by: Gary Guo <[email protected]>
Since there are no other replies to this version, I'll confirm that
this still looks good to me.
Alice
On Sat, Nov 18, 2023 at 2:43 AM Trevor Gross <[email protected]> wrote:
>
> Enable combining identifiers with literals in the 'paste!' macro. This
> allows combining user-specified strings with affixes to create
> namespaced identifiers.
>
> This sample code:
>
> macro_rules! m {
> ($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 <[email protected]>
> Reviewed-by: Martin Rodriguez Reboredo <[email protected]>
> Reviewed-by: Vincenzo Palazzo <[email protected]>
> Reviewed-by: Alice Ryhl <[email protected]>
> Reviewed-by: Benno Lossin <[email protected]>
> Reviewed-by: Gary Guo <[email protected]>
Applied to `rust-next` (with an added `:` before the example since
that is our usual convention).
Thanks everyone!
Cheers,
Miguel