1 files changed, 35 insertions, 35 deletions

diff --git a/absl/strings/internal/str_split_internal.h b/absl/strings/internal/str_split_internal.h
index a2f41c15..e7664216 100644
--- a/absl/strings/internal/str_split_internal.h
+++ b/absl/strings/internal/str_split_internal.h
@@ -32,7 +32,7 @@
 #include <array>
 #include <initializer_list>
 #include <iterator>
-#include <map>
+#include <tuple>
 #include <type_traits>
 #include <utility>
 #include <vector>
@@ -64,7 +64,7 @@ class ConvertibleToStringView {
   ConvertibleToStringView(const std::string& s)  // NOLINT(runtime/explicit)
       : value_(s) {}
 
-  // Matches rvalue strings and moves their data to a member.
+  // Disable conversion from rvalue strings.
   ConvertibleToStringView(std::string&& s) = delete;
   ConvertibleToStringView(const std::string&& s) = delete;
 
@@ -182,6 +182,13 @@ template <typename T>
 struct HasConstIterator<T, absl::void_t<typename T::const_iterator>>
     : std::true_type {};
 
+// HasEmplace<T>::value is true iff there exists a method T::emplace().
+template <typename T, typename = void>
+struct HasEmplace : std::false_type {};
+template <typename T>
+struct HasEmplace<T, absl::void_t<decltype(std::declval<T>().emplace())>>
+    : std::true_type {};
+
 // IsInitializerList<T>::value is true iff T is an std::initializer_list. More
 // details below in Splitter<> where this is used.
 std::false_type IsInitializerListDispatch(...);  // default: No
@@ -372,50 +379,43 @@ class Splitter {
   // value.
   template <typename Container, typename First, typename Second>
   struct ConvertToContainer<Container, std::pair<const First, Second>, true> {
+    using iterator = typename Container::iterator;
+
     Container operator()(const Splitter& splitter) const {
       Container m;
-      typename Container::iterator it;
+      iterator it;
       bool insert = true;
-      for (const auto& sp : splitter) {
+      for (const absl::string_view sv : splitter) {
         if (insert) {
-          it = Inserter<Container>::Insert(&m, First(sp), Second());
+          it = InsertOrEmplace(&m, sv);
         } else {
-          it->second = Second(sp);
+          it->second = Second(sv);
         }
         insert = !insert;
       }
       return m;
     }
 
-    // Inserts the key and value into the given map, returning an iterator to
-    // the inserted item. Specialized for std::map and std::multimap to use
-    // emplace() and adapt emplace()'s return value.
-    template <typename Map>
-    struct Inserter {
-      using M = Map;
-      template <typename... Args>
-      static typename M::iterator Insert(M* m, Args&&... args) {
-        return m->insert(std::make_pair(std::forward<Args>(args)...)).first;
-      }
-    };
-
-    template <typename... Ts>
-    struct Inserter<std::map<Ts...>> {
-      using M = std::map<Ts...>;
-      template <typename... Args>
-      static typename M::iterator Insert(M* m, Args&&... args) {
-        return m->emplace(std::make_pair(std::forward<Args>(args)...)).first;
-      }
-    };
-
-    template <typename... Ts>
-    struct Inserter<std::multimap<Ts...>> {
-      using M = std::multimap<Ts...>;
-      template <typename... Args>
-      static typename M::iterator Insert(M* m, Args&&... args) {
-        return m->emplace(std::make_pair(std::forward<Args>(args)...));
-      }
-    };
+    // Inserts the key and an empty value into the map, returning an iterator to
+    // the inserted item. We use emplace() if available, otherwise insert().
+    template <typename M>
+    static absl::enable_if_t<HasEmplace<M>::value, iterator> InsertOrEmplace(
+        M* m, absl::string_view key) {
+      // Use piecewise_construct to support old versions of gcc in which pair
+      // constructor can't otherwise construct string from string_view.
+      return ToIter(m->emplace(std::piecewise_construct, std::make_tuple(key),
+                               std::tuple<>()));
+    }
+    template <typename M>
+    static absl::enable_if_t<!HasEmplace<M>::value, iterator> InsertOrEmplace(
+        M* m, absl::string_view key) {
+      return ToIter(m->insert(std::make_pair(First(key), Second(""))));
+    }
+
+    static iterator ToIter(std::pair<iterator, bool> pair) {
+      return pair.first;
+    }
+    static iterator ToIter(iterator iter) { return iter; }
   };
 
   StringType text_;