get_or_throw(map, key) returns references

[folly.git] / folly / MapUtil.h

diff --git a/folly/MapUtil.h b/folly/MapUtil.h
index f042bd2d5e86f328d4c0df508cb79a3aecc44d7a..143dadc26314e6f16c50a32d49381dbaa398d763 100644 (file)
--- a/folly/MapUtil.h
+++ b/folly/MapUtil.h
@@ -55,8 +55,21 @@ get_default(const Map& map, const typename Map::key_type& key, Func&& dflt) {
  * or throw an exception of the specified type.
  */
 template <class E = std::out_of_range, class Map>
-typename Map::mapped_type get_or_throw(
-    const Map& map, const typename Map::key_type& key,
+const typename Map::mapped_type& get_or_throw(
+    const Map& map,
+    const typename Map::key_type& key,
+    const std::string& exceptionStrPrefix = std::string()) {
+  auto pos = map.find(key);
+  if (pos != map.end()) {
+    return pos->second;
+  }
+  throw E(folly::to<std::string>(exceptionStrPrefix, key));
+}
+
+template <class E = std::out_of_range, class Map>
+typename Map::mapped_type& get_or_throw(
+    Map& map,
+    const typename Map::key_type& key,
     const std::string& exceptionStrPrefix = std::string()) {
   auto pos = map.find(key);
   if (pos != map.end()) {