merge.hpp

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#pragma once
 
/// @file userver/formats/common/merge.hpp
/// @brief @copybrief formats::common::Merge
/// @ingroup userver_universal
 
#include <userver/formats/common/items.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace formats::common {
 
/// @brief Add to `original` new non-object elements from `patch` (overwriting
/// the old ones, if any) and merge object elements recursively.
/// @note For the missing `patch`, it does nothing with the `original`.
/// @note Arrays are not merged.
template <typename Value>
void Merge(typename Value::Builder& original, const Value& patch) {
    if (patch.IsObject() && original.IsObject() && !original.IsEmpty()) {
        for (const auto& [elem_key, elem_value] : common::Items(patch)) {
            auto next_origin = original[elem_key];
            Merge(next_origin, elem_value);
        }
    } else if (!patch.IsMissing()) {
        original = patch;
    }
}
 
}  // namespace formats::common
 
USERVER_NAMESPACE_END