Implementation of RFC #240

.gitignore

@@ -1,3 +1,3 @@
 target
-/Cargo.lock
+Cargo.lock
 /fuzz/hfuzz_target

Cargo.toml

@@ -12,16 +12,12 @@ readme = "README.md"
 documentation = "https://docs.rs/smallvec/"
 
 [features]
-const_generics = []
-const_new = ["const_generics"]
 write = []
-union = []
 specialization = []
 may_dangle = []
 
 [dependencies]
 serde = { version = "1", optional = true, default-features = false }
-arbitrary = { version = "1", optional = true }
 
 [dev_dependencies]
 bincode = "1.0.1"

benches/bench.rs

@@ -6,19 +6,20 @@ extern crate smallvec;
 extern crate test;
 
 use self::test::Bencher;
-use smallvec::{ExtendFromSlice, SmallVec};
+use smallvec::SmallVec;
 
 const VEC_SIZE: usize = 16;
 const SPILLED_SIZE: usize = 100;
 
-trait Vector<T>: for<'a> From<&'a [T]> + Extend<T> + ExtendFromSlice<T> {
+trait Vector<T>: for<'a> From<&'a [T]> + Extend<T> {
     fn new() -> Self;
     fn push(&mut self, val: T);
     fn pop(&mut self) -> Option<T>;
     fn remove(&mut self, p: usize) -> T;
     fn insert(&mut self, n: usize, val: T);
     fn from_elem(val: T, n: usize) -> Self;
     fn from_elems(val: &[T]) -> Self;
+    fn extend_from_slice(&mut self, other: &[T]);
 }
 
 impl<T: Copy> Vector<T> for Vec<T> {
@@ -49,9 +50,13 @@ impl<T: Copy> Vector<T> for Vec<T> {
     fn from_elems(val: &[T]) -> Self {
         val.to_owned()
     }
+
+    fn extend_from_slice(&mut self, other: &[T]) {
+        Vec::extend_from_slice(self, other)
+    }
 }
 
-impl<T: Copy> Vector<T> for SmallVec<[T; VEC_SIZE]> {
+impl<T: Copy> Vector<T> for SmallVec<T, VEC_SIZE> {
     fn new() -> Self {
         Self::new()
     }
@@ -79,6 +84,10 @@ impl<T: Copy> Vector<T> for SmallVec<[T; VEC_SIZE]> {
     fn from_elems(val: &[T]) -> Self {
         SmallVec::from_slice(val)
     }
+
+    fn extend_from_slice(&mut self, other: &[T]) {
+        SmallVec::extend_from_slice(self, other)
+    }
 }
 
 macro_rules! make_benches {
@@ -93,7 +102,7 @@ macro_rules! make_benches {
 }
 
 make_benches! {
-    SmallVec<[u64; VEC_SIZE]> {
+    SmallVec<u64, VEC_SIZE> {
         bench_push => gen_push(SPILLED_SIZE as _),
         bench_push_small => gen_push(VEC_SIZE as _),
         bench_insert_push => gen_insert_push(SPILLED_SIZE as _),
@@ -104,6 +113,8 @@ make_benches! {
         bench_remove_small => gen_remove(VEC_SIZE as _),
         bench_extend => gen_extend(SPILLED_SIZE as _),
         bench_extend_small => gen_extend(VEC_SIZE as _),
+        bench_extend_filtered => gen_extend_filtered(SPILLED_SIZE as _),
+        bench_extend_filtered_small => gen_extend_filtered(VEC_SIZE as _),
         bench_from_iter => gen_from_iter(SPILLED_SIZE as _),
         bench_from_iter_small => gen_from_iter(VEC_SIZE as _),
         bench_from_slice => gen_from_slice(SPILLED_SIZE as _),
@@ -128,6 +139,8 @@ make_benches! {
         bench_remove_vec_small => gen_remove(VEC_SIZE as _),
         bench_extend_vec => gen_extend(SPILLED_SIZE as _),
         bench_extend_vec_small => gen_extend(VEC_SIZE as _),
+        bench_extend_vec_filtered => gen_extend_filtered(SPILLED_SIZE as _),
+        bench_extend_vec_filtered_small => gen_extend_filtered(VEC_SIZE as _),
         bench_from_iter_vec => gen_from_iter(SPILLED_SIZE as _),
         bench_from_iter_vec_small => gen_from_iter(VEC_SIZE as _),
         bench_from_slice_vec => gen_from_slice(SPILLED_SIZE as _),
@@ -211,6 +224,14 @@ fn gen_extend<V: Vector<u64>>(n: u64, b: &mut Bencher) {
     });
 }
 
+fn gen_extend_filtered<V: Vector<u64>>(n: u64, b: &mut Bencher) {
+    b.iter(|| {
+        let mut vec = V::new();
+        vec.extend((0..n).filter(|i| i % 2 == 0));
+        vec
+    });
+}
+
 fn gen_from_iter<V: Vector<u64>>(n: u64, b: &mut Bencher) {
     let v: Vec<u64> = (0..n).collect();
     b.iter(|| {
@@ -263,15 +284,15 @@ fn gen_from_elem<V: Vector<u64>>(n: usize, b: &mut Bencher) {
 fn bench_insert_many(b: &mut Bencher) {
     #[inline(never)]
     fn insert_many_noinline<I: IntoIterator<Item = u64>>(
-        vec: &mut SmallVec<[u64; VEC_SIZE]>,
+        vec: &mut SmallVec<u64, VEC_SIZE>,
         index: usize,
         iterable: I,
     ) {
         vec.insert_many(index, iterable)
     }
 
     b.iter(|| {
-        let mut vec = SmallVec::<[u64; VEC_SIZE]>::new();
+        let mut vec = SmallVec::<u64, VEC_SIZE>::new();
         insert_many_noinline(&mut vec, 0, 0..SPILLED_SIZE as _);
         insert_many_noinline(&mut vec, 0, 0..SPILLED_SIZE as _);
         vec
@@ -282,7 +303,7 @@ fn bench_insert_many(b: &mut Bencher) {
 fn bench_insert_from_slice(b: &mut Bencher) {
     let v: Vec<u64> = (0..SPILLED_SIZE as _).collect();
     b.iter(|| {
-        let mut vec = SmallVec::<[u64; VEC_SIZE]>::new();
+        let mut vec = SmallVec::<u64, VEC_SIZE>::new();
         vec.insert_from_slice(0, &v);
         vec.insert_from_slice(0, &v);
         vec
@@ -292,7 +313,7 @@ fn bench_insert_from_slice(b: &mut Bencher) {
 #[bench]
 fn bench_macro_from_list(b: &mut Bencher) {
     b.iter(|| {
-        let vec: SmallVec<[u64; 16]> = smallvec![
+        let vec: SmallVec<u64, 16> = smallvec![
             0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 20, 24, 32, 36, 0x40, 0x80,
             0x100, 0x200, 0x400, 0x800, 0x1000, 0x2000, 0x4000, 0x8000, 0x10000, 0x20000, 0x40000,
             0x80000, 0x100000,

fuzz/fuzz_targets/smallvec_ops.rs

@@ -31,8 +31,8 @@ fn black_box_mut_slice(s: &mut [u8]) {
     black_box_iter((s as &[u8]).iter().copied())
 }
 
-fn do_test<A: smallvec::Array<Item = u8>>(data: &[u8]) -> SmallVec<A> {
-    let mut v = SmallVec::<A>::new();
+fn do_test<const N: usize>(data: &[u8]) -> SmallVec<u8, N> {
+    let mut v = SmallVec::<u8, N>::new();
 
     let mut bytes = data.iter().copied();
 
@@ -170,11 +170,11 @@ fn do_test<A: smallvec::Array<Item = u8>>(data: &[u8]) -> SmallVec<A> {
 }
 
 fn do_test_all(data: &[u8]) {
-    do_test::<[u8; 0]>(data);
-    do_test::<[u8; 1]>(data);
-    do_test::<[u8; 2]>(data);
-    do_test::<[u8; 7]>(data);
-    do_test::<[u8; 8]>(data);
+    do_test::<0>(data);
+    do_test::<1>(data);
+    do_test::<2>(data);
+    do_test::<7>(data);
+    do_test::<8>(data);
 }
 
 #[cfg(feature = "afl")]