Rename pkg/{tagging,lifecycle} to pkg/bucket sub-directory (#8892)

Rename to allow for more such features to come in a more
proper hierarchical manner.

pkg/bucket/policy/id.go

@@ -0,0 +1,56 @@
+/*
+ * MinIO Cloud Storage, (C) 2018 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package policy
+
+import (
+	"encoding/json"
+	"unicode/utf8"
+)
+
+// ID - policy ID.
+type ID string
+
+// IsValid - checks if ID is valid or not.
+func (id ID) IsValid() bool {
+	return utf8.ValidString(string(id))
+}
+
+// MarshalJSON - encodes ID to JSON data.
+func (id ID) MarshalJSON() ([]byte, error) {
+	if !id.IsValid() {
+		return nil, Errorf("invalid ID %v", id)
+	}
+
+	return json.Marshal(string(id))
+}
+
+// UnmarshalJSON - decodes JSON data to ID.
+func (id *ID) UnmarshalJSON(data []byte) error {
+	var s string
+	if err := json.Unmarshal(data, &s); err != nil {
+		return err
+	}
+
+	i := ID(s)
+	if !i.IsValid() {
+		return Errorf("invalid ID %v", s)
+	}
+
+	*id = i
+
+	return nil
+}