feat:(slice add AppendIfAbsent function) (#52)

Co-authored-by: george.zheng <george.zheng@ambergroup.io>

slice/slice.go

@@ -851,3 +851,11 @@ func ToSlice[T any](value ...T) []T {
 	}
 	return out
 }
+
+// AppendIfAbsent only absent append the value
+func AppendIfAbsent[T comparable](slices []T, value T) []T {
+	if !Contain(slices, value) {
+		slices = append(slices, value)
+	}
+	return slices
+}

slice/slice_test.go

@@ -609,3 +609,11 @@ func TestToSlicePointer(t *testing.T) {
 	assert.Equal([]*string{&str1}, ToSlicePointer(str1))
 	assert.Equal([]*string{&str1, &str2}, ToSlicePointer(str1, str2))
 }
+
+func TestToAppendIfAbsent(t *testing.T) {
+	assert := internal.NewAssert(t, "TestToAppendIfAbsent")
+
+	str1 := []string{"a", "b"}
+	assert.Equal([]string{"a", "b"}, AppendIfAbsent(str1, "a"))
+	assert.Equal([]string{"a", "b", "c"}, AppendIfAbsent(str1, "c"))
+}