algorithms/meta/Cloner.h

0001 // SPDX-License-Identifier: LGPL-3.0-or-later
0002 // Copyright (C) 2026 Wouter Deconinck
0003
0004 #pragma once
0005
0006 #include <algorithms/algorithm.h>
0007 #include <string>
0008
0009 namespace eicrecon {
0010
0011 /**
0012  * Clone collection elements to create a new standalone collection.
0013  *
0014  * This algorithm takes an input collection and creates an output collection
0015  * containing cloned copies of those elements. This is primarily useful for
0016  * subset collections (where elements point to objects in another collection)
0017  * to create an owning (non-subset) collection.
0018  *
0019  * \note Any relations carried by the elements are cloned as-is; if you write
0020  * the output without also writing the referenced collections, you may create
0021  * dangling references in the output file.
0022  *
0023  * \note While this works on any collection, cloning non-subset collections
0024  * creates unnecessary duplicates and is generally not recommended.
0025  *
0026  * Template parameter T is the PODIO object type (e.g., edm4eic::Cluster)
0027  */
0028 template <typename T>
0029 class Cloner : public algorithms::Algorithm<algorithms::Input<typename T::collection_type>,
0030                                             algorithms::Output<typename T::collection_type>> {
0031
0032 public:
0033   Cloner(std::string name)
0034       : algorithms::Algorithm<algorithms::Input<typename T::collection_type>,
0035                               algorithms::Output<typename T::collection_type>>(
0036             std::move(name), {"inputCollection"}, {"outputCollection"},
0037             "Clone collection elements to create standalone collection") {}
0038
0039   void process(const typename Cloner::Input& input,
0040                const typename Cloner::Output& output) const final {
0041     const auto [in_coll] = input;
0042     auto [out_coll]      = output;
0043
0044     // Clone each element from input to output
0045     for (const auto& obj : *in_coll) {
0046       out_coll->push_back(obj.clone());
0047     }
0048   }
0049 };
0050
0051 } // namespace eicrecon