vendor/itertools-0.9.0/benches/fold_specialization.rs

   1 use criterion::{criterion_group, criterion_main, Criterion};
   2 use itertools::Itertools;
   3
   4 struct Unspecialized<I>(I);
   5
   6 impl<I> Iterator for Unspecialized<I>
   7 where I: Iterator
   8 {
   9     type Item = I::Item;
  10
  11     #[inline(always)]
  12     fn next(&mut self) -> Option<I::Item> {
  13         self.0.next()
  14     }
  15
  16     #[inline(always)]
  17     fn size_hint(&self) -> (usize, Option<usize>) {
  18         self.0.size_hint()
  19     }
  20 }
  21
  22 mod specialization {
  23     use super::*;
  24
  25     pub mod intersperse {
  26         use super::*;
  27
  28         pub fn external(c: &mut Criterion)
  29         {
  30             let arr = [1; 1024];
  31
  32             c.bench_function("external", move |b| {
  33                 b.iter(|| {
  34                     let mut sum = 0;
  35                     for &x in arr.iter().intersperse(&0) {
  36                         sum += x;
  37                     }
  38                     sum
  39                 })
  40             });
  41         }
  42
  43         pub fn internal_specialized(c: &mut Criterion)
  44         {
  45             let arr = [1; 1024];
  46
  47             c.bench_function("internal specialized", move |b| {
  48                 b.iter(|| {
  49                     arr.iter().intersperse(&0).fold(0, |acc, x| acc + x)
  50                 })
  51             });
  52         }
  53
  54         pub fn internal_unspecialized(c: &mut Criterion)
  55         {
  56             let arr = [1; 1024];
  57
  58             c.bench_function("internal unspecialized", move |b| {
  59                 b.iter(|| {
  60                     Unspecialized(arr.iter().intersperse(&0)).fold(0, |acc, x| acc + x)
  61                 })
  62             });
  63         }
  64     }
  65 }
  66
  67 criterion_group!(
  68     benches,
  69     specialization::intersperse::external,
  70     specialization::intersperse::internal_specialized,
  71     specialization::intersperse::internal_unspecialized,
  72 );
  73 criterion_main!(benches);