SelfAwareBranch.h

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// SPDX-License-Identifier: GPLv3-or-later
//
// SPDX-FileCopyrightText: Patrick L.S. Connor <patrick.connor@cern.ch>
 
#pragma once
 
#include <cmath>
 
#include <functional>
#include <string>
#include <vector>
 
namespace Darwin::Tools {
 
template<typename... Args>
class SelfAwareBranch {
public:
    virtual void Fill (Args... args) = 0;
    virtual void Clear () = 0;
    virtual ~SelfAwareBranch () = default;
};
 
template<typename U /* output branch type */, typename... Args>
class SelfAwarePlainBranch : public SelfAwareBranch<Args...> {
    U * ptr; 
    std::function<U(Args...)> setter;
public:
    SelfAwarePlainBranch (Tools::Flow& flow,
                          const std::string& name, 
                          std::function<U(Args...)> setter 
            ) : ptr(flow.GetBranchWriteOnly<U>(name))
              , setter(setter) { }
    void Fill (Args... args) override { *ptr = setter(args...); }
    void Clear () override { *ptr = std::nan("NaN"); }
};
 
template<typename U /* output branch type */, typename... Args>
class SelfAwareVectorBranch : public SelfAwareBranch<Args...> {
    std::vector<U> * ptr;
    std::function<U(Args...)> setter;
public:
    SelfAwareVectorBranch (Tools::Flow& flow,
                           const std::string& name, 
                           std::function<U(Args...)> setter 
            ) : ptr(flow.GetBranchWriteOnly<std::vector<U>>(name))
              , setter(setter) { }
    void Fill (Args... args) override { ptr->push_back(setter(args...)); }
    void Clear () override { ptr->clear(); }
};
 
} // end of Darwin::Tools namespace