#![feature(test)]

extern crate test;

use test::{black_box, Bencher};
use std::borrow::Cow;

const APPEND_LOG: &str = "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff";

#[bench]
fn bench_check_no_alloc(b: &mut Bencher) {
    b.iter(|| {
       no_alloc(black_box(APPEND_LOG))
    })
}

#[bench]
fn bench_check(b: &mut Bencher) {
    let v = black_box(APPEND_LOG);
    b.iter(|| {
        v.to_lowercase()
    })
}

fn no_alloc(s: &str) -> Cow<str> {
   if s.chars().all(char::is_lowercase) {
       Cow::Borrowed(s)
   } else {
       Cow::Owned(s.to_lowercase())
   }
}