Configurable.h

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// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
#ifndef O2_FRAMEWORK_CONFIGURABLE_H_
#define O2_FRAMEWORK_CONFIGURABLE_H_
#include "Framework/ConfigurableKinds.h"
#include "Framework/Traits.h"
#include <string>
#include <vector>
namespace o2::framework
{
namespace expressions
{
struct PlaceholderNode;
}
 
template <typename T, ConfigParamKind K>
struct ConfigurableBase {
  ConfigurableBase(std::string const& name, T&& defaultValue, std::string const& help)
    : name(name), value{std::forward<T>(defaultValue)}, help(help)
  {
  }
  using type = T;
  std::string name;
  T value;
  std::string help;
  static constexpr ConfigParamKind kind = K;
};
 
template <typename T, ConfigParamKind K>
struct ConfigurablePolicyConst : ConfigurableBase<T, K> {
  ConfigurablePolicyConst(std::string const& name, T&& defaultValue, std::string const& help)
    : ConfigurableBase<T, K>{name, std::forward<T>(defaultValue), help}
  {
  }
  operator T()
  {
    return this->value;
  }
  T const* operator->() const
  {
    return &this->value;
  }
};
 
template <typename T, ConfigParamKind K>
struct ConfigurablePolicyMutable : ConfigurableBase<T, K> {
  ConfigurablePolicyMutable(std::string const& name, T&& defaultValue, std::string const& help)
    : ConfigurableBase<T, K>{name, std::forward<T>(defaultValue), help}
  {
  }
  operator T()
  {
    return this->value;
  }
  T* operator->()
  {
    return &this->value;
  }
};
 
template <typename T, ConfigParamKind K = ConfigParamKind::kGeneric, typename IP = ConfigurablePolicyConst<T, K>>
struct Configurable : IP {
  Configurable(std::string const& name, T&& defaultValue, std::string const& help)
    : IP{name, std::forward<T>(defaultValue), help}
  {
  }
  auto node()
  {
    return expressions::PlaceholderNode{*this};
  }
};
 
template <typename T, ConfigParamKind K = ConfigParamKind::kGeneric>
using MutableConfigurable = Configurable<T, K, ConfigurablePolicyMutable<T, K>>;
 
template <typename T>
concept is_configurable = requires(T& t) {
  typename T::type;
  requires std::same_as<std::string, decltype(t.name)>;
  &T::operator typename T::type;
};
 
using ConfigurableAxis = Configurable<std::vector<double>, ConfigParamKind::kAxisSpec, ConfigurablePolicyConst<std::vector<double>, ConfigParamKind::kAxisSpec>>;
 
template <typename T>
concept is_configurable_axis = is_configurable<T>&&
  requires()
{
  T::kind == ConfigParamKind::kAxisSpec;
};
 
template <typename R, typename T, typename... As>
struct ProcessConfigurable : Configurable<bool, ConfigParamKind::kProcessFlag> {
  ProcessConfigurable(R (T::*process_)(As...), std::string const& name_, bool&& value_, std::string const& help_)
    : process{process_},
      Configurable<bool, ConfigParamKind::kProcessFlag>(name_, std::forward<bool>(value_), help_)
  {
  }
  R(T::*process)
  (As...);
};
 
template <typename T>
concept is_process_configurable = is_configurable<T> && requires(T& t) { t.process; };
 
#define PROCESS_SWITCH(_Class_, _Name_, _Help_, _Default_) \
  decltype(ProcessConfigurable{&_Class_ ::_Name_, #_Name_, _Default_, _Help_}) do##_Name_ = ProcessConfigurable{&_Class_ ::_Name_, #_Name_, _Default_, _Help_};
#define PROCESS_SWITCH_FULL(_Class_, _Method_, _Name_, _Help_, _Default_) \
  decltype(ProcessConfigurable{&_Class_ ::_Method_, #_Name_, _Default_, _Help_}) do##_Name_ = ProcessConfigurable{&_Class_ ::_Method_, #_Name_, _Default_, _Help_};
 
template <typename T, ConfigParamKind K, typename IP>
std::ostream& operator<<(std::ostream& os, Configurable<T, K, IP> const& c)
{
  os << c.value;
  return os;
}
 
struct ConfigurableGroup {
};
 
template <typename T>
concept is_configurable_group = std::derived_from<T, ConfigurableGroup>;
 
} // namespace o2::framework
#endif // O2_FRAMEWORK_CONFIGURABLE_H_