Move TlDowncastHelper to tdutils.

td/tl/tl_json.h

@@ -17,6 +17,7 @@
 #include "td/utils/SliceBuilder.h"
 #include "td/utils/Status.h"
 #include "td/utils/tl_storers.h"
+#include "td/utils/TlDowncastHelper.h"
 
 #include <type_traits>
 
@@ -149,21 +150,6 @@ Status from_json(std::vector<T> &to, JsonValue from) {
   return Status::OK();
 }
 
-template <class T>
-class DowncastHelper final : public T {
- public:
-  explicit DowncastHelper(int32 constructor) : constructor_(constructor) {
-  }
-  int32 get_id() const final {
-    return constructor_;
-  }
-  void store(TlStorerToString &s, const char *field_name) const final {
-  }
-
- private:
-  int32 constructor_{0};
-};
-
 template <class T>
 std::enable_if_t<!std::is_constructible<T>::value, Status> from_json(tl_object_ptr<T> &to, JsonValue from) {
   if (from.type() != JsonValue::Type::Object) {
@@ -185,7 +171,7 @@ std::enable_if_t<!std::is_constructible<T>::value, Status> from_json(tl_object_p
     return Status::Error(PSLICE() << "Expected String or Integer, got " << constructor_value.type());
   }
 
-  DowncastHelper<T> helper(constructor);
+  TlDowncastHelper<T> helper(constructor);
   Status status;
   bool ok = downcast_call(static_cast<T &>(helper), [&](auto &dummy) {
     auto result = make_tl_object<std::decay_t<decltype(dummy)>>();

tdutils/CMakeLists.txt

@@ -256,10 +256,10 @@ set(TDUTILS_SOURCE
   td/utils/Time.h
   td/utils/TimedStat.h
   td/utils/Timer.h
-  td/utils/TsFileLog.h
   td/utils/tl_helpers.h
   td/utils/tl_parsers.h
   td/utils/tl_storers.h
+  td/utils/TlDowncastHelper.h
   td/utils/translit.h
   td/utils/TsCerr.h
   td/utils/TsFileLog.h

tdutils/td/utils/TlDowncastHelper.h

@@ -0,0 +1,26 @@
+//
+// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2021
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+#pragma once
+
+namespace td {
+
+template <class T>
+class TlDowncastHelper final : public T {
+ public:
+  explicit TlDowncastHelper(int32 constructor) : constructor_(constructor) {
+  }
+  int32 get_id() const final {
+    return constructor_;
+  }
+  void store(TlStorerToString &s, const char *field_name) const final {
+  }
+
+ private:
+  int32 constructor_{0};
+};
+
+}  // namespace td