variadic-rebind.hpp

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/*
  VARIADIC-REBIND.hpp  -  metaprogramming utilities for parameter- and type sequences
 
   Copyright (C)
     2023,            Hermann Vosseler <Ichthyostega@web.de>
 
 **Lumiera** is free software; you can redistribute it and/or modify it
 under the terms of the GNU General Public License as published by the
 Free Software Foundation; either version 2 of the License, or (at your
 option) any later version. See the file COPYING for further details.
 
*/
 
 
#ifndef LIB_META_VARIADIC_REBIND_H
#define LIB_META_VARIADIC_REBIND_H
 
 
namespace lib {
namespace meta {
  
  
  
  
  /* ==== Rebinding Variadic Arguments ==== **/
  
  template<template<typename...> class X, typename...ARGS>
  struct RebindVariadic
    {
      using Type = X<ARGS...>;
    };
  
  template<template<typename...> class X
          ,template<typename...> class U
          ,typename...ARGS>
  struct RebindVariadic<X, U<ARGS...>>
    {
      using Type = X<ARGS...>;
    };
  
  
  
  
  
  /* ==== Rebuild with remoulded variadic sequence ==== **/
  
  template<template<class...> class L, typename...XS>
  struct _Vari;
  
  template<template<class...> class L, typename X, typename...XS>
  struct _Vari<L, X, L<XS...>>
    {
      using Prepend = L<X,XS...>;
      using Append  = L<XS...,X>;
    };
  
  template<template<class...> class L, typename X1, typename X2>
  struct _Vari<L, X1,X2>
    {
      using Penult = X1;
      using Ultima = X2;
      using Prefix = L<X1>;
      using Remain = L<X2>;
      using Revers = L<X2,X1>;
    };
  
  template<template<class...> class L, typename X>
  struct _Vari<L, X>
    {
      using Ultima = X;
      using Penult = Nil;     
      using Remain = L<X>;
      using Revers = L<X>;
      using Prefix = L<>;
    };
  
  template<template<class...> class L, typename X, typename...XS>
  struct _Vari<L, X,XS...>
    {
      using Penult = _Vari<L,XS...>::Penult;
      using Ultima = _Vari<L,XS...>::Ultima;
      
      using _Tail_Pre_ = _Vari<L,XS...>::Prefix;
      using _Tail_Rev_ = _Vari<L,XS...>::Revers;
      
      using Remain = L<XS...>;
      using Prefix = _Vari<L, X,      _Tail_Pre_>::Prepend;
      using Revers = _Vari<L, Ultima, _Tail_Rev_>::Prepend;
    };
  
}} // namespace lib::meta
#endif /*LIB_META_VARIADIC_REBIND_H*/