1 files changed, 44 insertions, 0 deletions
diff --git a/common/maps/maps.go b/common/maps/maps.go
new file mode 100644
index 000000000..a114b557c
--- /dev/null
+++ b/common/maps/maps.go
@@ -0,0 +1,44 @@
+// Copyright 2018 The Hugo Authors. All rights reserved.
+//
+// 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 maps
+
+import (
+	"strings"
+
+	"github.com/spf13/cast"
+)
+
+// ToLower makes all the keys in the given map lower cased and will do so
+// recursively.
+// Notes:
+// * This will modify the map given.
+// * Any nested map[interface{}]interface{} will be converted to map[string]interface{}.
+func ToLower(m map[string]interface{}) {
+	for k, v := range m {
+		switch v.(type) {
+		case map[interface{}]interface{}:
+			v = cast.ToStringMap(v)
+			ToLower(v.(map[string]interface{}))
+		case map[string]interface{}:
+			ToLower(v.(map[string]interface{}))
+		}
+
+		lKey := strings.ToLower(k)
+		if k != lKey {
+			delete(m, k)
+			m[lKey] = v
+		}
+
+	}
+}