1. docker
  2. Commit e245fb76de36463b715e1ac2bb8193670bb26f0d
Browse code

internal/sliceutil: add utilities to map values

Functional programming for the win! Add a utility function to map the
values of a slice, along with a curried variant, to tide us over until
equivalent functionality gets added to the standard library
(https://go.dev/issue/61898)

Signed-off-by: Cory Snider <csnider@mirantis.com>

Cory Snider authored on 2024/01/25 07:56:29
Showing 2 changed files
internal/sliceutil/sliceutil.go
History View file @ e245fb7
... ... 
@@ -11,3 +11,21 @@ func Dedup[T comparable](slice []T) []T {
11 11 
 	}
12 12 
 	return out
13 13 
 }
14 
+
15 
+func Map[S ~[]In, In, Out any](s S, fn func(In) Out) []Out {
16 
+	res := make([]Out, len(s))
17 
+	for i, v := range s {
18 
+		res[i] = fn(v)
19 
+	}
20 
+	return res
21 
+}
22 
+
23 
+func Mapper[In, Out any](fn func(In) Out) func([]In) []Out {
24 
+	return func(s []In) []Out {
25 
+		res := make([]Out, len(s))
26 
+		for i, v := range s {
27 
+			res[i] = fn(v)
28 
+		}
29 
+		return res
30 
+	}
31 
+}
internal/sliceutil/sliceutil_test.go
History View file @ e245fb7
14 32 
new file mode 100644
... ... 
@@ -0,0 +1,49 @@
0 
+package sliceutil_test
1 
+
2 
+import (
3 
+	"net/netip"
4 
+	"strconv"
5 
+	"testing"
6 
+
7 
+	"github.com/docker/docker/internal/sliceutil"
8 
+)
9 
+
10 
+func TestMap(t *testing.T) {
11 
+	s := []int{1, 2, 3}
12 
+	m := sliceutil.Map(s, func(i int) int { return i * 2 })
13 
+	if len(m) != len(s) {
14 
+		t.Fatalf("expected len %d, got %d", len(s), len(m))
15 
+	}
16 
+	for i, v := range m {
17 
+		if expected := s[i] * 2; v != expected {
18 
+			t.Fatalf("expected %d, got %d", expected, v)
19 
+		}
20 
+	}
21 
+}
22 
+
23 
+func TestMap_TypeConvert(t *testing.T) {
24 
+	s := []int{1, 2, 3}
25 
+	m := sliceutil.Map(s, func(i int) string { return strconv.Itoa(i) })
26 
+	if len(m) != len(s) {
27 
+		t.Fatalf("expected len %d, got %d", len(s), len(m))
28 
+	}
29 
+	for i, v := range m {
30 
+		if expected := strconv.Itoa(s[i]); v != expected {
31 
+			t.Fatalf("expected %s, got %s", expected, v)
32 
+		}
33 
+	}
34 
+}
35 
+
36 
+func TestMapper(t *testing.T) {
37 
+	s := []string{"1.2.3.4", "fe80::1"}
38 
+	mapper := sliceutil.Mapper(netip.MustParseAddr)
39 
+	m := mapper(s)
40 
+	if len(m) != len(s) {
41 
+		t.Fatalf("expected len %d, got %d", len(s), len(m))
42 
+	}
43 
+	for i, v := range m {
44 
+		if expected := netip.MustParseAddr(s[i]); v != expected {
45 
+			t.Fatalf("expected %s, got %s", expected, v)
46 
+		}
47 
+	}
48 
+}