seq-macro 0.1.0

Macro to repeat sequentially indexed copies of a fragment of code.
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seq!

Build Status Latest Version

A seq! macro to repeat a fragment of source code and substitute into each repetition a sequential numeric counter.

[dependencies]
seq-macro = "0.1"

#![feature(proc_macro_non_items)]

use seq_macro::seq;

fn main() {
    let tuple = (1000, 100, 10);
    let mut sum = 0;

    // Expands to:
    //
    //     sum += tuple.0;
    //     sum += tuple.1;
    //     sum += tuple.2;
    //
    // This cannot be written using an ordinary for-loop because elements of
    // a tuple can only be accessed by their integer literal index, not by a
    // variable.
    seq!(N in 0..=2 {
        sum += tuple.N;
    });

    assert_eq!(sum, 1110);
}

There are just two more features to know about:

  • If the input tokens contain a section surrounded by #( ... )* then only that part is repeated.

  • The numeric counter can be pasted onto the end of some prefix to form sequential identifiers.

use seq_macro::seq;

seq!(N in 64..=127 {
    #[derive(Debug)]
    enum Demo {
        // Expands to Variant64, Variant65, ...
        #(
            Variant#N,
        )*
    }
});

fn main() {
    assert_eq!("Variant99", format!("{:?}", Demo::Variant99));
}

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.