`seq!`
======
[
](https://github.com/dtolnay/seq-macro)
[
](https://crates.io/crates/seq-macro)
[
](https://docs.rs/seq-macro)
[
](https://github.com/dtolnay/seq-macro/actions?query=branch%3Amaster)
A `seq!` macro to repeat a fragment of source code and substitute into each
repetition a sequential numeric counter.
```toml
[dependencies]
seq-macro = "0.3"
```
```rust
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);
}
```
- 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.
```rust
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));
}
```
- Byte and character ranges are supported: `b'a'..=b'z'`, `'a'..='z'`.
- If the range bounds are written in binary, octal, hex, or with zero padding,
those features are preserved in any generated tokens.
```rust
use seq_macro::seq;
seq!(P in 0x000..=0x00F {
// expands to structs Pin000, ..., Pin009, Pin00A, ..., Pin00F
struct Pin~P;
});
```
#### License
Licensed under either of Apache License, Version
2.0 or MIT license at your option.
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.