Add a benchmark of FromIterator

Author: meithecatte

benches/from_iterator.rs

@@ -0,0 +1,47 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use enumflags2::BitFlags;
+
+#[derive(Clone, Copy, BitFlags)]
+pub enum Test {
+    Flag1 = 1 << 0,
+    Flag2 = 1 << 1,
+    Flag3 = 1 << 2,
+    Flag4 = 1 << 3,
+    Flag5 = 1 << 4,
+    Flag6 = 1 << 5,
+    Flag7 = 1 << 6,
+    Flag8 = 1 << 7,
+    Flag9 = 1 << 8,
+    Flag10 = 1 << 9,
+    Flag11 = 1 << 10,
+}
+
+pub fn from_iterator(c: &mut Criterion) {
+    let v = vec![
+        Test::Flag3,
+        Test::Flag7,
+        Test::Flag5,
+        Test::Flag11,
+    ];
+
+    let v2 = vec![
+        Test::Flag10,
+        Test::Flag3,
+        Test::Flag1,
+        Test::Flag4,
+    ];
+
+    c.bench_function("simple iterator", |b| b.iter(|| {
+        black_box(&v).iter().copied().collect::<BitFlags<_>>()
+    }));
+
+    c.bench_function("chained iterator", |b| b.iter(|| {
+        black_box(&v).iter()
+            .chain(black_box(&v2).iter())
+            .copied()
+            .collect::<BitFlags<_>>()
+    }));
+}
+
+criterion_group!(benches, from_iterator);
+criterion_main!(benches);

enumflags/Cargo.toml

@@ -22,3 +22,11 @@ optional = true
 [features]
 std = []
 not_literal = ["enumflags2_derive/not_literal"]
+
+[dev-dependencies]
+criterion = "0.3"
+
+[[bench]]
+name = "from_iterator"
+harness = false
+path = "../benches/from_iterator.rs"