Create & Init Project...

app/service/main/bns/lib/shuffle/BUILD

@@ -0,0 +1,37 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_test",
+    "go_library",
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["shuffle_test.go"],
+    embed = [":go_default_library"],
+    rundir = ".",
+    tags = ["automanaged"],
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["shuffle.go"],
+    importpath = "go-common/app/service/main/bns/lib/shuffle",
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

app/service/main/bns/lib/shuffle/shuffle.go

@@ -0,0 +1,26 @@
+package shuffle
+
+import (
+	"math/rand"
+	"time"
+)
+
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
+// Shuffler A type, typically a collection, that satisfies Shuffler
+// can be shuffle by Shuffle func
+type Shuffler interface {
+	Len() int
+	Swap(i, j int)
+}
+
+// Shuffle s
+func Shuffle(s Shuffler) {
+	l := s.Len()
+	for i := l; i > 0; i-- {
+		j := rand.Intn(i)
+		s.Swap(l-i, j)
+	}
+}

app/service/main/bns/lib/shuffle/shuffle_test.go

@@ -0,0 +1,27 @@
+package shuffle
+
+import (
+	"strings"
+	"testing"
+)
+
+type List []string
+
+func (l List) Len() int {
+	return len(l)
+}
+
+func (l List) Swap(i, j int) {
+	l[i], l[j] = l[j], l[i]
+}
+
+func TestShuffle(t *testing.T) {
+	l := List{"0", "1", "2", "3", "4", "5", "6", "7", "8", "9"}
+	old := strings.Join(l, "")
+	Shuffle(l)
+	new := strings.Join(l, "")
+	if old == new {
+		t.Errorf("shuffle error, %s == %s", old, new)
+	}
+	t.Log(new)
+}