Update `google::protobuf::MapValueRef` and `google::protobuf::MapValueConstRef` to use `absl::string_view`

PiperOrigin-RevId: 681485247

src/google/protobuf/map_field.cc

@@ -269,7 +269,8 @@ void MapFieldBase::SyncRepeatedFieldWithMapNoLock() {
     const MapValueRef& map_val = it.GetValueRef();
     switch (val_des->cpp_type()) {
       case FieldDescriptor::CPPTYPE_STRING:
-        reflection->SetString(new_entry, val_des, map_val.GetStringValue());
+        reflection->SetString(new_entry, val_des,
+                              std::string(map_val.GetStringValue()));
         break;
       case FieldDescriptor::CPPTYPE_INT64:
         reflection->SetInt64(new_entry, val_des, map_val.GetInt64Value());

src/google/protobuf/map_field.h

@@ -762,10 +762,10 @@ class PROTOBUF_EXPORT MapValueConstRef {
     TYPE_CHECK(FieldDescriptor::CPPTYPE_ENUM, "MapValueConstRef::GetEnumValue");
     return *reinterpret_cast<int*>(data_);
   }
-  const std::string& GetStringValue() const {
+  absl::string_view GetStringValue() const {
     TYPE_CHECK(FieldDescriptor::CPPTYPE_STRING,
                "MapValueConstRef::GetStringValue");
-    return *reinterpret_cast<std::string*>(data_);
+    return absl::string_view(*reinterpret_cast<std::string*>(data_));
   }
   float GetFloatValue() const {
     TYPE_CHECK(FieldDescriptor::CPPTYPE_FLOAT,
@@ -855,9 +855,9 @@ class PROTOBUF_EXPORT MapValueRef final : public MapValueConstRef {
     TYPE_CHECK(FieldDescriptor::CPPTYPE_ENUM, "MapValueRef::SetEnumValue");
     *reinterpret_cast<int*>(data_) = value;
   }
-  void SetStringValue(const std::string& value) {
+  void SetStringValue(absl::string_view value) {
     TYPE_CHECK(FieldDescriptor::CPPTYPE_STRING, "MapValueRef::SetStringValue");
-    *reinterpret_cast<std::string*>(data_) = value;
+    reinterpret_cast<std::string*>(data_)->assign(value.data(), value.size());
   }
   void SetFloatValue(float value) {
     TYPE_CHECK(FieldDescriptor::CPPTYPE_FLOAT, "MapValueRef::SetFloatValue");

src/google/protobuf/reflection_visit_field_info.h

@@ -1245,7 +1245,7 @@ PROTOBUF_MAP_VALUE_INFO(Bool, bool, BOOL);
 PROTOBUF_MAP_VALUE_INFO(Enum, int, ENUM);
 PROTOBUF_MAP_VALUE_INFO(Float, float, FLOAT);
 PROTOBUF_MAP_VALUE_INFO(Double, double, DOUBLE);
-PROTOBUF_MAP_VALUE_INFO(String, const std::string&, STRING);
+PROTOBUF_MAP_VALUE_INFO(String, absl::string_view, STRING);
 
 #undef PROTOBUF_MAP_VALUE_INFO
 

src/google/protobuf/text_format.cc

@@ -2608,7 +2608,8 @@ void MapFieldPrinterHelper::CopyValue(const MapValueRef& value,
       return;
     }
     case FieldDescriptor::CPPTYPE_STRING:
-      reflection->SetString(message, field_desc, value.GetStringValue());
+      reflection->SetString(message, field_desc,
+                            std::string(value.GetStringValue()));
       return;
     case FieldDescriptor::CPPTYPE_INT64:
       reflection->SetInt64(message, field_desc, value.GetInt64Value());

src/google/protobuf/util/field_comparator.h

@@ -16,6 +16,7 @@
 
 #include "google/protobuf/stubs/common.h"
 #include "absl/container/flat_hash_map.h"
+#include "absl/strings/string_view.h"
 #include "google/protobuf/port.h"
 
 // Must be included last.
@@ -192,7 +193,7 @@ class PROTOBUF_EXPORT SimpleFieldComparator : public FieldComparator {
   }
 
   bool CompareString(const FieldDescriptor& /* unused */,
-                     const std::string& value_1, const std::string& value_2) {
+                     absl::string_view value_1, absl::string_view value_2) {
     return value_1 == value_2;
   }