Macro core_extensions::rewrap_macro_parameters

macro_rules! rewrap_macro_parameters {
    (
        $($tokens:tt)*
    ) => { ... };
}

This is supported on crate feature macro_utils only.

Rewraps the tokens inside macro parameters into parentheses.

Syntax

This macro transforms ~ immediately followed by a macro parameter into its tokens wrapped in parentheses.

You can escape ~ by writing it twice (~~), returning a single ~ from the macro.

Example

pub use core_extensions::rewrap_macro_parameters;
 
crate::constify!{
    pub fn foo() -> u32 {
        100
    }
    pub unsafe fn bar() -> u32 {
        200
    }
}
 
const X: &[u32] = unsafe{ &[foo(), bar()] };
 
fn main() {
    assert_eq!(X, &[100, 200]);
}
 
#[macro_export]
macro_rules! constify {
    ($($item:item)*) => {
        rewrap_macro_parameters!{
            $crate::__priv_constify_inner!{
                hello world ~~~~
                // `__priv_constify_inner` can't destructure `$item`,
                // so you need to use `rewrap_macro_parameters` and prefix the parameter with
                // `~` to rewrap its tokens in parentheses
                $(~$item)*
            }
        }
    }
}
 
#[macro_export]
#[doc(hidden)]
macro_rules! __priv_constify_inner{
    (
        hello world ~ ~
        $((
            $(#[$attr:meta])*
            $vis:vis
            $(unsafe $(@$unsafe:tt@)?)?
            fn
            $($rem:tt)*
        ))*
    ) => {
        $(
            $(#[$attr])*
            $vis const $(unsafe $(@$unsafe@)?)? fn
            $($rem)*
        )*
    }
}