etl/largest.h

///\file

/******************************************************************************
The MIT License(MIT)

Embedded Template Library.
https://github.com/ETLCPP/etl
http://www.etlcpp.com

Copyright(c) 2014 jwellbelove

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#ifndef __ETL_LARGEST__
#define __ETL_LARGEST__

///\defgroup largest largest
///\ingroup utilities

#include "type_traits.h"

namespace etl 
{
	//***************************************************************************
	/// Template to determine the largest type and size.
  /// Supports up to 16 types.
	/// Defines 'value_type' which is the type of the largest parameter.
	/// Defines 'size' which is the size of the largest parameter.
  ///\ingroup largest
	//***************************************************************************
	template <typename T1,         typename T2  = void, typename T3  = void, typename T4  = void,
			      typename T5  = void, typename T6  = void, typename T7  = void, typename T8  = void,
			      typename T9  = void, typename T10 = void, typename T11 = void, typename T12 = void,
			      typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
	struct largest_type
	{
	private:

    // Declaration.
		template <const bool Boolean, typename TrueType, typename FalseType>
		struct choose_type;

    // Specialisation for 'true'.
    // Defines 'type' as 'TrueType'.
    template <typename TrueType, typename FalseType>
    struct choose_type<true, TrueType, FalseType>
    {
      typedef TrueType type;
    };

		// Specialisation for 'false'. 
    // Defines 'type' as 'FalseType'.
    template <typename TrueType, typename FalseType>
    struct choose_type<false, TrueType, FalseType>
		{
      typedef FalseType type;
		};

	public:

		// Define 'largest_other' as 'largest_type' with all but the first parameter. 
		typedef typename largest_type<T2,  T3,  T4,  T5,  T6,  T7,  T8,  T9,  T10, T11, T12, T13, T14, T15, T16>::type largest_other;

		// Set 'type' to be the largest of the first parameter and any of the others.
    // This is recursive.
    typedef typename choose_type<(sizeof(T1) > sizeof(largest_other)), // Boolean
									               T1,                                   // TrueType
									               largest_other>                        // FalseType
									               ::type type;                          // The largest type of the two.

		// The size of the largest type.
		enum
		{
			size = sizeof(type)
		};
	};

  //***************************************************************************
	// Specialisation for one template parameter.
	//***************************************************************************
	template <typename T1>
	struct largest_type<T1,   void, void, void,
			      		      void, void, void, void, 
					            void, void, void, void, 
					            void, void, void, void>
	{
		typedef T1 type;

		enum
		{
			size = sizeof(type)
		};
	};

  //***************************************************************************
  /// Template to determine the largest alignment.
  /// Supports up to 16 types.
  /// Defines <b>value</b> which is the largest alignment of all the parameters.
  ///\ingroup largest
  //***************************************************************************
  template <typename T1,         typename T2  = void, typename T3  = void, typename T4  = void,
            typename T5  = void, typename T6  = void, typename T7  = void, typename T8  = void,
            typename T9  = void, typename T10 = void, typename T11 = void, typename T12 = void,
            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
  struct largest_alignment
  {
    // Determine the largest size.
    template <const size_t size1, const size_t size2>
    struct max_size
    {
      enum
      {
        value = (size1 > size2) ? size1 : size2
      };
    };

    // All of the alignments.
    enum
    {
      t1 = alignment_of<T1>::value,
      t2 = alignment_of<T2>::value,
      t3 = alignment_of<T3>::value,
      t4 = alignment_of<T4>::value,
      t5 = alignment_of<T5>::value,
      t6 = alignment_of<T6>::value,
      t7 = alignment_of<T7>::value,
      t8 = alignment_of<T8>::value,
      t9 = alignment_of<T9>::value,
      t10 = alignment_of<T10>::value,
      t11 = alignment_of<T11>::value,
      t12 = alignment_of<T12>::value,
      t13 = alignment_of<T13>::value,
      t14 = alignment_of<T14>::value,
      t15 = alignment_of<T15>::value,
      t16 = alignment_of<T16>::value,
    };

  public:

    // The largest of all of them.
    enum
    {
      value = max_size<t1, max_size<t2, max_size<t3, max_size<t4, max_size<t5, max_size<t6, max_size<t7, max_size<t8, 
              max_size<t9, max_size<t10, max_size<t11, max_size<t12, max_size<t13, max_size<t14, max_size<t15, t16>
              ::value>::value>::value>::value>::value>::value>::value>::value>
              ::value>::value>::value>::value>::value>::value>::value
    };
  };
}

#endif