should be it

external/duckdb/extension/json/include/json_serializer.hpp

@@ -0,0 +1,97 @@
+#pragma once
+
+#include "json_common.hpp"
+#include "duckdb/common/serializer/serializer.hpp"
+
+namespace duckdb {
+
+struct JsonSerializer : Serializer {
+private:
+	yyjson_mut_doc *doc;
+	yyjson_mut_val *current_tag;
+	vector<yyjson_mut_val *> stack;
+
+	// Skip writing property if null
+	bool skip_if_null = false;
+	// Skip writing property if empty string, empty list or empty map.
+	bool skip_if_empty = false;
+
+	// Get the current json value
+	inline yyjson_mut_val *Current() {
+		return stack.back();
+	};
+
+	// Either adds a value to the current object with the current tag, or appends it to the current array
+	void PushValue(yyjson_mut_val *val);
+
+public:
+	explicit JsonSerializer(yyjson_mut_doc *doc, bool skip_if_null, bool skip_if_empty, bool skip_if_default)
+	    : doc(doc), stack({yyjson_mut_obj(doc)}), skip_if_null(skip_if_null), skip_if_empty(skip_if_empty) {
+		options.serialize_enum_as_string = true;
+		options.serialize_default_values = !skip_if_default;
+	}
+
+	template <class T>
+	static yyjson_mut_val *Serialize(T &value, yyjson_mut_doc *doc, bool skip_if_null, bool skip_if_empty,
+	                                 bool skip_if_default) {
+		JsonSerializer serializer(doc, skip_if_null, skip_if_empty, skip_if_default);
+		value.Serialize(serializer);
+		return serializer.GetRootObject();
+	}
+
+	template <class T>
+	static string SerializeToString(T &value) {
+		auto doc = yyjson_mut_doc_new(nullptr);
+		JsonSerializer serializer(doc, false, false, false);
+		value.Serialize(serializer);
+		auto result_obj = serializer.GetRootObject();
+		idx_t len = 0;
+		auto data = yyjson_mut_val_write_opts(result_obj, JSONCommon::WRITE_PRETTY_FLAG, nullptr,
+		                                      reinterpret_cast<size_t *>(&len), nullptr);
+		return string(data, len);
+	}
+
+	yyjson_mut_val *GetRootObject() {
+		D_ASSERT(stack.size() == 1); // or we forgot to pop somewhere
+		return stack.front();
+	};
+
+	//===--------------------------------------------------------------------===//
+	// Nested Types Hooks
+	//===--------------------------------------------------------------------===//
+	void OnPropertyBegin(const field_id_t field_id, const char *tag) final;
+	void OnPropertyEnd() final;
+	void OnOptionalPropertyBegin(const field_id_t field_id, const char *tag, bool present) final;
+	void OnOptionalPropertyEnd(bool present) final;
+
+	void OnListBegin(idx_t count) final;
+	void OnListEnd() final;
+	void OnObjectBegin() final;
+	void OnObjectEnd() final;
+	void OnNullableBegin(bool present) final;
+	void OnNullableEnd() final;
+
+	//===--------------------------------------------------------------------===//
+	// Primitive Types
+	//===--------------------------------------------------------------------===//
+	void WriteNull() final;
+	void WriteValue(uint8_t value) final;
+	void WriteValue(int8_t value) final;
+	void WriteValue(uint16_t value) final;
+	void WriteValue(int16_t value) final;
+	void WriteValue(uint32_t value) final;
+	void WriteValue(int32_t value) final;
+	void WriteValue(uint64_t value) final;
+	void WriteValue(int64_t value) final;
+	void WriteValue(hugeint_t value) final;
+	void WriteValue(uhugeint_t value) final;
+	void WriteValue(float value) final;
+	void WriteValue(double value) final;
+	void WriteValue(const string_t value) final;
+	void WriteValue(const string &value) final;
+	void WriteValue(const char *value) final;
+	void WriteValue(bool value) final;
+	void WriteDataPtr(const_data_ptr_t ptr, idx_t count) final;
+};
+
+} // namespace duckdb