core,server: Make json expression templatized

The json expression maker function is templatized so it can be used with
both short lived and storable JSON values.

The short lived variant is used within search family validation.

Signed-off-by: Abhijat Malviya <[email protected]>

Author: abhijat

src/core/json/json_object.h

@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <glog/logging.h>
+
 #include <version>  // for __cpp_lib_to_chars macro.
 
 // std::from_chars is available in C++17 if __cpp_lib_to_chars is defined.
@@ -90,10 +92,13 @@ std::optional<JsonType> ParseJsonUsingShardHeap(std::string_view input);
 // malloc.
 JsonType DeepCopyJSON(const JsonType* j);
 
-inline auto MakeJsonPathExpr(std::string_view path, std::error_code& ec)
-    -> jsoncons::jsonpath::jsonpath_expression<JsonType> {
-  return jsoncons::jsonpath::make_expression<JsonType, std::allocator<char>>(
-      jsoncons::allocator_set<JsonType::allocator_type, std::allocator<char>>(), path, ec);
+template <typename Json = JsonType>
+auto MakeJsonPathExpr(std::string_view path, std::error_code& ec)
+    -> jsoncons::jsonpath::jsonpath_expression<Json> {
+  using result_allocator_t = typename Json::allocator_type;
+  using temp_allocator_t = std::allocator<char>;
+  using allocator_set_t = jsoncons::allocator_set<result_allocator_t, temp_allocator_t>;
+  return jsoncons::jsonpath::make_expression<Json, temp_allocator_t>(allocator_set_t(), path, ec);
 }
 
 }  // namespace dfly

src/server/search/search_family.cc

@@ -81,7 +81,7 @@ bool SendErrorIfOccurred(const ParseResult<T>& result, CmdArgParser* parser,
 
 bool IsValidJsonPath(string_view path) {
   error_code ec;
-  MakeJsonPathExpr(path, ec);
+  MakeJsonPathExpr<ShortLivedJSON>(path, ec);
   return !ec;
 }