diff --git a/vendor/github.com/modern-go/reflect2/safe_map.go b/vendor/github.com/modern-go/reflect2/safe_map.go
new file mode 100644
index 0000000..8836220
--- /dev/null
+++ b/vendor/github.com/modern-go/reflect2/safe_map.go
@@ -0,0 +1,101 @@
+package reflect2
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+type safeMapType struct {
+	safeType
+}
+
+func (type2 *safeMapType) Key() Type {
+	return type2.safeType.cfg.Type2(type2.Type.Key())
+}
+
+func (type2 *safeMapType) MakeMap(cap int) interface{} {
+	ptr := reflect.New(type2.Type)
+	ptr.Elem().Set(reflect.MakeMap(type2.Type))
+	return ptr.Interface()
+}
+
+func (type2 *safeMapType) UnsafeMakeMap(cap int) unsafe.Pointer {
+	panic("does not support unsafe operation")
+}
+
+func (type2 *safeMapType) SetIndex(obj interface{}, key interface{}, elem interface{}) {
+	keyVal := reflect.ValueOf(key)
+	elemVal := reflect.ValueOf(elem)
+	val := reflect.ValueOf(obj)
+	val.Elem().SetMapIndex(keyVal.Elem(), elemVal.Elem())
+}
+
+func (type2 *safeMapType) UnsafeSetIndex(obj unsafe.Pointer, key unsafe.Pointer, elem unsafe.Pointer) {
+	panic("does not support unsafe operation")
+}
+
+func (type2 *safeMapType) TryGetIndex(obj interface{}, key interface{}) (interface{}, bool) {
+	keyVal := reflect.ValueOf(key)
+	if key == nil {
+		keyVal = reflect.New(type2.Type.Key()).Elem()
+	}
+	val := reflect.ValueOf(obj).MapIndex(keyVal)
+	if !val.IsValid() {
+		return nil, false
+	}
+	return val.Interface(), true
+}
+
+func (type2 *safeMapType) GetIndex(obj interface{}, key interface{}) interface{} {
+	val := reflect.ValueOf(obj).Elem()
+	keyVal := reflect.ValueOf(key).Elem()
+	elemVal := val.MapIndex(keyVal)
+	if !elemVal.IsValid() {
+		ptr := reflect.New(reflect.PtrTo(val.Type().Elem()))
+		return ptr.Elem().Interface()
+	}
+	ptr := reflect.New(elemVal.Type())
+	ptr.Elem().Set(elemVal)
+	return ptr.Interface()
+}
+
+func (type2 *safeMapType) UnsafeGetIndex(obj unsafe.Pointer, key unsafe.Pointer) unsafe.Pointer {
+	panic("does not support unsafe operation")
+}
+
+func (type2 *safeMapType) Iterate(obj interface{}) MapIterator {
+	m := reflect.ValueOf(obj).Elem()
+	return &safeMapIterator{
+		m:    m,
+		keys: m.MapKeys(),
+	}
+}
+
+func (type2 *safeMapType) UnsafeIterate(obj unsafe.Pointer) MapIterator {
+	panic("does not support unsafe operation")
+}
+
+type safeMapIterator struct {
+	i    int
+	m    reflect.Value
+	keys []reflect.Value
+}
+
+func (iter *safeMapIterator) HasNext() bool {
+	return iter.i != len(iter.keys)
+}
+
+func (iter *safeMapIterator) Next() (interface{}, interface{}) {
+	key := iter.keys[iter.i]
+	elem := iter.m.MapIndex(key)
+	iter.i += 1
+	keyPtr := reflect.New(key.Type())
+	keyPtr.Elem().Set(key)
+	elemPtr := reflect.New(elem.Type())
+	elemPtr.Elem().Set(elem)
+	return keyPtr.Interface(), elemPtr.Interface()
+}
+
+func (iter *safeMapIterator) UnsafeNext() (unsafe.Pointer, unsafe.Pointer) {
+	panic("does not support unsafe operation")
+}