Add basic unknown fields collector

add basic unknown fields collector

1 files changed, 29 insertions, 0 deletions

diff --git a/library/cpp/protobuf/json/unknown_fields_collector.h b/library/cpp/protobuf/json/unknown_fields_collector.h
new file mode 100644
index 0000000000..1e71f2164c
--- /dev/null
+++ b/library/cpp/protobuf/json/unknown_fields_collector.h
@@ -0,0 +1,29 @@
+#pragma once
+
+#include <util/generic/string.h>
+
+namespace google {
+    namespace protobuf {
+        class FieldDescriptor;
+        class Descriptor;
+    }
+}
+
+namespace NProtobufJson {
+    /*  Methods OnEnter.../OnLeave... are called on every field of structure
+     *  during traverse and should be used to build context
+     *  Method OnUnknownField are called every time when field which can't
+     *  be mapped
+     */
+    struct IUnknownFieldsCollector {
+        virtual ~IUnknownFieldsCollector() = default;
+
+        virtual void OnEnterMapItem(const TString& key) = 0;
+        virtual void OnLeaveMapItem() = 0;
+
+        virtual void OnEnterArrayItem(ui64 id) = 0;
+        virtual void OnLeaveArrayItem() = 0;
+
+        virtual void OnUnknownField(const TString& key, const google::protobuf::Descriptor& value) = 0;
+    };
+}