types/views: add SliceContainsFunc like slices.ContainsFunc

Needed for a future change.

Updates #cleanup

Change-Id: I6d89ee8a048b3bb1eb9cfb2e5a53c93aed30b021
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

types/views/views.go

@@ -276,6 +276,16 @@ func SliceContains[T comparable](v Slice[T], e T) bool {
 	return false
 }
 
+// SliceContainsFunc reports whether f reports true for any element in v.
+func SliceContainsFunc[T any](v Slice[T], f func(T) bool) bool {
+	for i := 0; i < v.Len(); i++ {
+		if f(v.At(i)) {
+			return true
+		}
+	}
+	return false
+}
+
 // SliceEqual is like the standard library's slices.Equal, but for two views.
 func SliceEqual[T comparable](a, b Slice[T]) bool {
 	return slices.Equal(a.ж, b.ж)

types/views/views_test.go

@@ -124,6 +124,8 @@ func TestViewUtils(t *testing.T) {
 	c.Check(v.IndexFunc(func(s string) bool { return strings.HasPrefix(s, "z") }), qt.Equals, -1)
 	c.Check(SliceContains(v, "bar"), qt.Equals, true)
 	c.Check(SliceContains(v, "baz"), qt.Equals, false)
+	c.Check(SliceContainsFunc(v, func(s string) bool { return strings.HasPrefix(s, "f") }), qt.Equals, true)
+	c.Check(SliceContainsFunc(v, func(s string) bool { return len(s) > 3 }), qt.Equals, false)
 	c.Check(SliceEqualAnyOrder(v, v), qt.Equals, true)
 	c.Check(SliceEqualAnyOrder(v, SliceOf([]string{"bar", "foo"})), qt.Equals, true)
 	c.Check(SliceEqualAnyOrder(v, SliceOf([]string{"foo"})), qt.Equals, false)