Explicitly use TCowString in TYsonString

Для ревьюеров: изменения вне `library/cpp/yt` убирают `using namespace NYT` из хедера. Эта конструкция приводила к клешу имен глобального неймспейса и  `NYT` и ошибкам сборки.
commit_hash:f598da488a6dd8671af9f1f02870ab5612ae46eb

3 files changed, 11 insertions, 19 deletions

diff --git a/library/cpp/yt/yson_string/string.cpp b/library/cpp/yt/yson_string/string.cpp
index 45a6aa7f099..c21783b204a 100644
--- a/library/cpp/yt/yson_string/string.cpp
+++ b/library/cpp/yt/yson_string/string.cpp
@@ -91,25 +91,14 @@ TYsonString::TYsonString(
     : TYsonString(TYsonStringBuf(data, type))
 { }
 
-#ifdef TSTRING_IS_STD_STRING
 TYsonString::TYsonString(
     const TString& data,
     EYsonType type)
-    : TYsonString(TYsonStringBuf(data, type))
+    : Payload_(TCowString(data))
+    , Begin_(std::get<TCowString>(Payload_).data())
+    , Size_(data.length())
+    , Type_(type)
 { }
-#else
-TYsonString::TYsonString(
-    const TString& data,
-    EYsonType type)
-{
-    // NOTE: CoW TString implementation is assumed
-    // Moving the payload MUST NOT invalidate its internal pointers
-    Payload_ = data;
-    Begin_ = data.data();
-    Size_ = data.length();
-    Type_ = type;
-}
-#endif
 
 TYsonString::TYsonString(
     const TSharedRef& data,
@@ -148,8 +137,8 @@ TString TYsonString::ToString() const
         [&] (const TSharedRangeHolderPtr&) {
             return TString(AsStringBuf());
         },
-        [] (const TString& payload) {
-            return payload;
+        [] (const TCowString& payload) {
+            return TString(payload);
         });
 }
 
@@ -163,7 +152,7 @@ TSharedRef TYsonString::ToSharedRef() const
         [&] (const TSharedRangeHolderPtr& holder) {
             return TSharedRef(Begin_, Size_, holder);
         },
-        [] (const TString& payload) {
+        [] (const TCowString& payload) {
             return TSharedRef::FromString(payload);
         });
 }
diff --git a/library/cpp/yt/yson_string/string.h b/library/cpp/yt/yson_string/string.h
index 8fbe415e0fd..b9f44e6dccd 100644
--- a/library/cpp/yt/yson_string/string.h
+++ b/library/cpp/yt/yson_string/string.h
@@ -6,6 +6,8 @@
 
 #include <library/cpp/yt/string/format.h>
 
+#include <library/cpp/containers/cow_string/cow_string.h>
+
 #include <variant>
 
 namespace NYT::NYson {
@@ -117,7 +119,7 @@ private:
     struct TNullPayload
     { };
 
-    std::variant<TNullPayload, TSharedRangeHolderPtr, TString> Payload_;
+    std::variant<TNullPayload, TSharedRangeHolderPtr, TCowString> Payload_;
 
     const char* Begin_;
     ui64 Size_ : 56;
diff --git a/library/cpp/yt/yson_string/ya.make b/library/cpp/yt/yson_string/ya.make
index ba693760f10..da180de5471 100644
--- a/library/cpp/yt/yson_string/ya.make
+++ b/library/cpp/yt/yson_string/ya.make
@@ -8,6 +8,7 @@ SRCS(
 )
 
 PEERDIR(
+    library/cpp/containers/cow_string
     library/cpp/yt/assert
     library/cpp/yt/coding
     library/cpp/yt/exception