Macro paste

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

paste Allows to paste identifiers together.

Reexported from the paste crate.

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Within the paste! macro, identifiers inside [<…>] are pasted together to form a single identifier.

Examples

paste! {
    // Defines a const called `QRST`.
    const [<Q R S T>]: &str = "success!";
}

fn main() {
    assert_eq!(
        paste! { [<Q R S T>].len() },
        8,
    );
}

Case conversion

Use $var:lower or $var:upper in the segment list to convert an interpolated segment to lower- or uppercase as part of the paste. For example, [<ld_ $reg:lower _expr>] would paste to ld_bc_expr if invoked with $reg=Bc.

Use $var:snake to convert CamelCase input to snake_case. Use $var:camel to convert snake_case to CamelCase. These compose, so for example $var:snake:upper would give you SCREAMING_CASE.

The precise Unicode conversions are as defined by str::to_lowercase and str::to_uppercase.

Pasting documentation strings

Within the paste! macro, arguments to a #[doc ...] attribute are implicitly concatenated together to form a coherent documentation string.

macro_rules! method_new {
    ($ret:ident) => {
        paste! {
            #[doc = "Create a new `" $ret "` object."]
            pub fn new() -> $ret { todo!() }
        }
    };
}

pub struct Paste {}

method_new!(Paste);  // expands to #[doc = "Create a new `Paste` object"]

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