1 files changed, 135 insertions, 0 deletions
diff --git a/common/maps/maps.go b/common/maps/maps.go
new file mode 100644
index 000000000..8b42ca764
--- /dev/null
+++ b/common/maps/maps.go
@@ -0,0 +1,135 @@
+// 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/gobwas/glob"
+
+	"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 Params.
+func ToLower(m Params) {
+	for k, v := range m {
+		var retyped bool
+		switch v.(type) {
+		case map[interface{}]interface{}:
+			var p Params = cast.ToStringMap(v)
+			v = p
+			ToLower(p)
+			retyped = true
+		case map[string]interface{}:
+			var p Params = v.(map[string]interface{})
+			v = p
+			ToLower(p)
+			retyped = true
+		}
+
+		lKey := strings.ToLower(k)
+		if retyped || k != lKey {
+			delete(m, k)
+			m[lKey] = v
+		}
+	}
+}
+
+func ToStringMapE(in interface{}) (map[string]interface{}, error) {
+	switch in.(type) {
+	case Params:
+		return in.(Params), nil
+	default:
+		return cast.ToStringMapE(in)
+	}
+}
+
+func ToStringMap(in interface{}) map[string]interface{} {
+	m, _ := ToStringMapE(in)
+	return m
+}
+
+type keyRename struct {
+	pattern glob.Glob
+	newKey  string
+}
+
+// KeyRenamer supports renaming of keys in a map.
+type KeyRenamer struct {
+	renames []keyRename
+}
+
+// NewKeyRenamer creates a new KeyRenamer given a list of pattern and new key
+// value pairs.
+func NewKeyRenamer(patternKeys ...string) (KeyRenamer, error) {
+	var renames []keyRename
+	for i := 0; i < len(patternKeys); i += 2 {
+		g, err := glob.Compile(strings.ToLower(patternKeys[i]), '/')
+		if err != nil {
+			return KeyRenamer{}, err
+		}
+		renames = append(renames, keyRename{pattern: g, newKey: patternKeys[i+1]})
+	}
+
+	return KeyRenamer{renames: renames}, nil
+}
+
+func (r KeyRenamer) getNewKey(keyPath string) string {
+	for _, matcher := range r.renames {
+		if matcher.pattern.Match(keyPath) {
+			return matcher.newKey
+		}
+	}
+
+	return ""
+}
+
+// Rename renames the keys in the given map according
+// to the patterns in the current KeyRenamer.
+func (r KeyRenamer) Rename(m map[string]interface{}) {
+	r.renamePath("", m)
+}
+
+func (KeyRenamer) keyPath(k1, k2 string) string {
+	k1, k2 = strings.ToLower(k1), strings.ToLower(k2)
+	if k1 == "" {
+		return k2
+	} else {
+		return k1 + "/" + k2
+	}
+}
+
+func (r KeyRenamer) renamePath(parentKeyPath string, m map[string]interface{}) {
+	for key, val := range m {
+		keyPath := r.keyPath(parentKeyPath, key)
+		switch val.(type) {
+		case map[interface{}]interface{}:
+			val = cast.ToStringMap(val)
+			r.renamePath(keyPath, val.(map[string]interface{}))
+		case map[string]interface{}:
+			r.renamePath(keyPath, val.(map[string]interface{}))
+		}
+
+		newKey := r.getNewKey(keyPath)
+
+		if newKey != "" {
+			delete(m, key)
+			m[newKey] = val
+		}
+	}
+}