Merge branch 'master' into format-panic

.github/workflows/ci.yml

@@ -54,6 +54,21 @@ jobs:
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo test --all-features
 
+  miri:
+    runs-on: ubuntu-latest
+    env:
+      CARGO_TERM_COLOR: always
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: nightly
+          components: miri
+      - uses: taiki-e/install-action@nextest
+      - run: |
+          cargo miri nextest run --all-features
+          cargo miri test --doc
+
   check-format:
     name: check format
     runs-on: ubuntu-latest

Cargo.toml

@@ -27,7 +27,7 @@ either = { version = "1.0", default-features = false }
 
 [dev-dependencies]
 rand = "0.7"
-criterion = "0.4.0"
+criterion = { version = "0.4.0", features = ["html_reports"] }
 paste = "1.0.0"  # Used in test_std to instantiate generic tests
 permutohedron = "0.2"
 quickcheck = { version = "0.9", default_features = false }
@@ -75,3 +75,7 @@ harness = false
 [[bench]]
 name = "specializations"
 harness = false
+
+[[bench]]
+name = "k_smallest"
+harness = false

benches/k_smallest.rs

@@ -0,0 +1,61 @@
+use criterion::{black_box, criterion_group, criterion_main, Bencher, BenchmarkId, Criterion};
+use itertools::Itertools;
+use rand::{rngs::StdRng, seq::SliceRandom, SeedableRng};
+
+fn strict(b: &mut Bencher, (k, vals): &(usize, &Vec<usize>)) {
+    b.iter(|| black_box(vals.iter()).k_smallest(*k))
+}
+
+fn relaxed(b: &mut Bencher, (k, vals): &(usize, &Vec<usize>)) {
+    b.iter(|| black_box(vals.iter()).k_smallest_relaxed(*k))
+}
+
+fn ascending(n: usize) -> Vec<usize> {
+    (0..n).collect()
+}
+
+fn random(n: usize) -> Vec<usize> {
+    let mut vals = (0..n).collect_vec();
+    vals.shuffle(&mut StdRng::seed_from_u64(42));
+    vals
+}
+
+fn descending(n: usize) -> Vec<usize> {
+    (0..n).rev().collect()
+}
+
+fn k_smallest(c: &mut Criterion, order: &str, vals: fn(usize) -> Vec<usize>) {
+    let mut g = c.benchmark_group(format!("k-smallest/{order}"));
+
+    for log_n in 20..23 {
+        let n = 1 << log_n;
+
+        let vals = vals(n);
+
+        for log_k in 7..10 {
+            let k = 1 << log_k;
+
+            let params = format!("{log_n}/{log_k}");
+            let input = (k, &vals);
+            g.bench_with_input(BenchmarkId::new("strict", &params), &input, strict);
+            g.bench_with_input(BenchmarkId::new("relaxed", &params), &input, relaxed);
+        }
+    }
+
+    g.finish()
+}
+
+fn k_smallest_asc(c: &mut Criterion) {
+    k_smallest(c, "asc", ascending);
+}
+
+fn k_smallest_rand(c: &mut Criterion) {
+    k_smallest(c, "rand", random);
+}
+
+fn k_smallest_desc(c: &mut Criterion) {
+    k_smallest(c, "desc", descending);
+}
+
+criterion_group!(benches, k_smallest_asc, k_smallest_rand, k_smallest_desc);
+criterion_main!(benches);

src/cons_tuples_impl.rs

@@ -1,58 +1,39 @@
+use crate::adaptors::map::{MapSpecialCase, MapSpecialCaseFn};
+
 macro_rules! impl_cons_iter(
     ($_A:ident, $_B:ident, ) => (); // stop
 
     ($A:ident, $($B:ident,)*) => (
         impl_cons_iter!($($B,)*);
         #[allow(non_snake_case)]
-        impl<X, Iter, $($B),*> Iterator for ConsTuples<Iter, (($($B,)*), X)>
-            where Iter: Iterator<Item = (($($B,)*), X)>,
-        {
-            type Item = ($($B,)* X, );
-            fn next(&mut self) -> Option<Self::Item> {
-                self.iter.next().map(|(($($B,)*), x)| ($($B,)* x, ))
-            }
-
-            fn size_hint(&self) -> (usize, Option<usize>) {
-                self.iter.size_hint()
-            }
-            fn fold<Acc, Fold>(self, accum: Acc, mut f: Fold) -> Acc
-                where Fold: FnMut(Acc, Self::Item) -> Acc,
-            {
-                self.iter.fold(accum, move |acc, (($($B,)*), x)| f(acc, ($($B,)* x, )))
+        impl<$($B),*, X> MapSpecialCaseFn<(($($B,)*), X)> for ConsTuplesFn {
+            type Out = ($($B,)* X, );
+            fn call(&mut self, (($($B,)*), X): (($($B,)*), X)) -> Self::Out {
+                ($($B,)* X, )
             }
         }
     );
 );
 
 impl_cons_iter!(A, B, C, D, E, F, G, H, I, J, K, L,);
 
+#[derive(Debug, Clone)]
+pub struct ConsTuplesFn;
+
 /// An iterator that maps an iterator of tuples like
 /// `((A, B), C)` to an iterator of `(A, B, C)`.
 ///
 /// Used by the `iproduct!()` macro.
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
-#[derive(Debug)]
-pub struct ConsTuples<I, J>
-where
-    I: Iterator<Item = J>,
-{
-    iter: I,
-}
-
-impl<I, J> Clone for ConsTuples<I, J>
-where
-    I: Clone + Iterator<Item = J>,
-{
-    clone_fields!(iter);
-}
+pub type ConsTuples<I> = MapSpecialCase<I, ConsTuplesFn>;
 
 /// Create an iterator that maps for example iterators of
 /// `((A, B), C)` to `(A, B, C)`.
-pub fn cons_tuples<I, J>(iterable: I) -> ConsTuples<I::IntoIter, J>
+pub fn cons_tuples<I>(iterable: I) -> ConsTuples<I::IntoIter>
 where
-    I: IntoIterator<Item = J>,
+    I: IntoIterator,
 {
     ConsTuples {
         iter: iterable.into_iter(),
+        f: ConsTuplesFn,
     }
 }

src/diff.rs

@@ -1,7 +1,7 @@
 //! "Diff"ing iterators for caching elements to sequential collections without requiring the new
 //! elements' iterator to be `Clone`.
 //!
-//! - [`Diff`] (produced by the [`diff_with`] function)
+//! [`Diff`] (produced by the [`diff_with`] function)
 //! describes the difference between two non-`Clone` iterators `I` and `J` after breaking ASAP from
 //! a lock-step comparison.
 

src/free.rs

@@ -36,7 +36,7 @@ pub use crate::zip_eq_impl::zip_eq;
 /// ```
 /// use itertools::intersperse;
 ///
-/// itertools::assert_equal(intersperse((0..3), 8), vec![0, 8, 1, 8, 2]);
+/// itertools::assert_equal(intersperse(0..3, 8), vec![0, 8, 1, 8, 2]);
 /// ```
 pub fn intersperse<I>(iterable: I, element: I::Item) -> Intersperse<I::IntoIter>
 where
@@ -55,7 +55,7 @@ where
 /// use itertools::intersperse_with;
 ///
 /// let mut i = 10;
-/// itertools::assert_equal(intersperse_with((0..3), || { i -= 1; i }), vec![0, 9, 1, 8, 2]);
+/// itertools::assert_equal(intersperse_with(0..3, || { i -= 1; i }), vec![0, 9, 1, 8, 2]);
 /// assert_eq!(i, 8);
 /// ```
 pub fn intersperse_with<I, F>(iterable: I, element: F) -> IntersperseWith<I::IntoIter, F>
@@ -75,6 +75,7 @@ where
 ///
 /// for (i, elt) in enumerate(&[1, 2, 3]) {
 ///     /* loop body */
+///     # let _ = (i, elt);
 /// }
 /// ```
 pub fn enumerate<I>(iterable: I) -> iter::Enumerate<I::IntoIter>
@@ -93,6 +94,7 @@ where
 ///
 /// for elt in rev(&[1, 2, 3]) {
 ///     /* loop body */
+///     # let _ = elt;
 /// }
 /// ```
 pub fn rev<I>(iterable: I) -> iter::Rev<I::IntoIter>

src/k_smallest.rs

@@ -88,6 +88,46 @@ where
     storage
 }
 
+pub(crate) fn k_smallest_relaxed_general<I, F>(iter: I, k: usize, mut comparator: F) -> Vec<I::Item>
+where
+    I: Iterator,
+    F: FnMut(&I::Item, &I::Item) -> Ordering,
+{
+    if k == 0 {
+        iter.last();
+        return Vec::new();
+    }
+
+    let mut iter = iter.fuse();
+    let mut buf = iter.by_ref().take(2 * k).collect::<Vec<_>>();
+
+    if buf.len() < k {
+        buf.sort_unstable_by(&mut comparator);
+        return buf;
+    }
+
+    buf.select_nth_unstable_by(k - 1, &mut comparator);
+    buf.truncate(k);
+
+    iter.for_each(|val| {
+        if comparator(&val, &buf[k - 1]) != Ordering::Less {
+            return;
+        }
+
+        assert_ne!(buf.len(), buf.capacity());
+        buf.push(val);
+
+        if buf.len() == 2 * k {
+            buf.select_nth_unstable_by(k - 1, &mut comparator);
+            buf.truncate(k);
+        }
+    });
+
+    buf.sort_unstable_by(&mut comparator);
+    buf.truncate(k);
+    buf
+}
+
 #[inline]
 pub(crate) fn key_to_cmp<T, K, F>(mut key: F) -> impl FnMut(&T, &T) -> Ordering
 where

src/kmerge_impl.rs

@@ -134,6 +134,7 @@ impl<T, F: FnMut(&T, &T) -> bool> KMergePredicate<T> for F {
 ///
 /// for elt in kmerge(vec![vec![0, 2, 4], vec![1, 3, 5], vec![6, 7]]) {
 ///     /* loop body */
+///     # let _ = elt;
 /// }
 /// ```
 pub fn kmerge<I>(iterable: I) -> KMerge<<I::Item as IntoIterator>::IntoIter>