functor.h

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// -----------------------------------------------------------------------------
//
// Copyright (C) 2021 CERN & University of Surrey for the benefit of the
// BioDynaMo collaboration. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
//
// See the LICENSE file distributed with this work for details.
// See the NOTICE file distributed with this work for additional information
// regarding copyright ownership.
//
// -----------------------------------------------------------------------------
 
#ifndef CORE_FUNCTOR_H_
#define CORE_FUNCTOR_H_
 
#include <utility>
 
namespace bdm {
 
// -----------------------------------------------------------------------------
template <typename TReturn, typename... TArgs>
class Functor {
 public:
  virtual ~Functor() = default;
  virtual TReturn operator()(TArgs... args) = 0;
};
 
// -----------------------------------------------------------------------------
template <typename TLambda>
struct LambdaFunctor {};
 
template <typename TLambda, typename TReturn, typename... TArgs>
struct LambdaFunctor<TReturn (TLambda::*)(TArgs...) const> final
    : public Functor<TReturn, TArgs...> {
  TLambda lambda;
 
  LambdaFunctor(const TLambda& lambda) : lambda(lambda) {}
  LambdaFunctor(const LambdaFunctor& other) : lambda(other.lambda) {}
  virtual ~LambdaFunctor() = default;
 
  TReturn operator()(TArgs... args) override {
    return lambda(std::forward<TArgs>(args)...);
  }
};
 
template <typename TLambda, typename TReturn, typename... TArgs>
struct LambdaFunctor<TReturn (TLambda::*)(TArgs...)> final
    : public Functor<TReturn, TArgs...> {
  TLambda lambda;
 
  LambdaFunctor(const TLambda& lambda) : lambda(lambda) {}
  LambdaFunctor(const LambdaFunctor& other) : lambda(other.lambda) {}
  virtual ~LambdaFunctor() = default;
 
  TReturn operator()(TArgs... args) override {
    return lambda(std::forward<TArgs>(args)...);
  }
};
 
// -----------------------------------------------------------------------------
template <typename TLambda>
LambdaFunctor<decltype(&TLambda::operator())> L2F(const TLambda& l) {
  return LambdaFunctor<decltype(&TLambda::operator())>(l);
}
 
}  // namespace bdm
 
#endif  // CORE_FUNCTOR_H_