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use criterion::Criterion;
use hashbrown::HashMap;
use std::hint::black_box;
type Map<K, V> = HashMap<K, V>;
macro_rules! bench_with_capacity {
($c:ident, $name:ident, $cap:expr) => {
$c.bench_function(stringify!($name), |b| {
b.iter(|| {
// Construct a new empty map with a given capacity and return it to avoid
// being optimized away. Dropping it measures allocation + minimal setup.
let m: Map<usize, usize> = Map::with_capacity($cap);
black_box(m)
});
});
};
}
pub(crate) fn register_benches(c: &mut Criterion) {
bench_with_capacity!(c, with_capacity_000000, 0);
bench_with_capacity!(c, with_capacity_000001, 1);
bench_with_capacity!(c, with_capacity_000003, 3);
bench_with_capacity!(c, with_capacity_000007, 7);
bench_with_capacity!(c, with_capacity_000008, 8);
bench_with_capacity!(c, with_capacity_000016, 16);
bench_with_capacity!(c, with_capacity_000032, 32);
bench_with_capacity!(c, with_capacity_000064, 64);
bench_with_capacity!(c, with_capacity_000128, 128);
bench_with_capacity!(c, with_capacity_000256, 256);
bench_with_capacity!(c, with_capacity_000512, 512);
bench_with_capacity!(c, with_capacity_001024, 1024);
bench_with_capacity!(c, with_capacity_004096, 4096);
bench_with_capacity!(c, with_capacity_016384, 16384);
bench_with_capacity!(c, with_capacity_065536, 65536);
}