DwmTupleHelpers.hh

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//===========================================================================
// @(#) $DwmPath$
//===========================================================================
//  Copyright (c) Daniel W. McRobb 2020
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//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
 
#ifndef _DWMTUPLEHELPERS_HH_
#define _DWMTUPLEHELPERS_HH_
 
#include <string>
#include <tuple>
 
namespace Dwm {
 
  namespace TupleHelpers {
 
    //------------------------------------------------------------------------
    //------------------------------------------------------------------------
    template <class Tuple, class Func, std::size_t... I>
    constexpr Func ForEachImpl(Tuple && t, Func && f, std::index_sequence<I...>)
    {
      return (void)std::initializer_list<int>{(std::forward<Func>(f)(std::get<I>(std::forward<Tuple>(t))),0)...}, f;
    }
 
    //------------------------------------------------------------------------
    //------------------------------------------------------------------------
    template <class Tuple, class Func>
    constexpr Func ForEach(Tuple && t, Func && f)
    {
      return ForEachImpl(std::forward<Tuple>(t), std::forward<Func>(f),
                         std::make_index_sequence<std::tuple_size<std::remove_reference_t<Tuple>>::value>{});
    }
 
    //------------------------------------------------------------------------
    //------------------------------------------------------------------------
    template<typename Tuple, typename Pred>
    constexpr size_t FindIf(Tuple && tuple, Pred pred)
    {
      size_t index = std::tuple_size<std::remove_reference_t<Tuple>>::value;
      size_t currentIndex = 0;
      bool found = false;
      ForEach(tuple, [&](auto&& value)
                     {
                       if (!found && pred(value)) {
                         index = currentIndex;
                         found = true;
                       }
                       ++currentIndex;
                     });
      return index;
    }
    
    //------------------------------------------------------------------------
    //------------------------------------------------------------------------
    template<typename Tuple, typename Action>
    void Perform(Tuple && tpl, size_t index, Action action)
    {
      size_t currentIndex = 0;
      ForEach(tpl,
              [action = std::move(action), index, &currentIndex]
              (auto && value)
              {
                if (currentIndex == index) {
                  action(std::forward<decltype(value)>(value));
                }
                ++currentIndex;
              });
    }
 
  }  // namespace TupleHelpers
 
}  // namespace Dwm
 
#endif  // _DWMTUPLEHELPERS_HH_
 
 
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