etl/cyclic_value.h

///\file

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

Embedded Template Library.

Copyright(c) 2014 jwellbelove

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#ifndef __ETL_CYCLIC_VALUE__
#define __ETL_CYCLIC_VALUE__

#include <stddef.h>

///\defgroup cyclic_value cyclic_value
/// Provides a value that cycles between two limits.
/// \ingroup utilities

#include <algorithm>

#include "static_assert.h"
#include "exception.h"

namespace etl
{
	//***************************************************************************
	/// Provides a value that cycles between two limits.
  /// Supports incrementing and decrementing.
	///\tparam T     The type of the variable.
	///\tparam FIRST The first value of the range.
	///\tparam LAST  The last value of the range.
  ///\ingroup cyclic_value
	//***************************************************************************
	template <typename T, const T FIRST = T(), const T LAST = T()>
	class cyclic_value
	{
	public:

    template <typename U, const U OTHER_FIRST, const U OTHER_LAST> friend class cyclic_value;

		//*************************************************************************
		/// Constructor.
		/// Sets 'first' and 'last' to the template parameter values.
    /// The initial value is set to the first value.
		//*************************************************************************
		cyclic_value()
			: value(FIRST),
        first_value(FIRST),
			  last_value(LAST)
		{
		}

		//*************************************************************************
		/// Constructor.
    /// Sets the value to the first of the range.
    ///\param first The first value in the range.
		///\param last  The last value in the range.
		//*************************************************************************
		cyclic_value(const T& first_, const T& last_)
			: value(first_),
        first_value(first_),
			  last_value(last_)
		{
		}

		//*************************************************************************
		/// Sets the range.
		/// Sets the value to the first of the range.
    ///\param first The first value in the range.
		///\param last  The last value in the range.
  	//*************************************************************************
		void set(const T& first_, const T& last_)
		{
			first_value = first_;
			last_value  = last_;
			value       = first_;
		}

    //*************************************************************************
    /// Resets the value to the first in the range.
    //*************************************************************************
    void to_first()
    {
      value = first_value;
    }

    //*************************************************************************
    /// Resets the value to the last in the range.
    //*************************************************************************
    void to_last()
    {
      value = last_value;
    }

    //*************************************************************************
    /// Advances to value by a number of steps.
    ///\param n The number of steps to advance.
    //*************************************************************************
    void advance(int n)
    {
      if (n > 0)
      {
        for (int i = 0; i < n; ++i)
        {
          operator ++();
        }
      }
      else
      {
        for (int i = 0; i < -n; ++i)
        {
          operator --();
        }
      }
    }

		//*************************************************************************
		/// Conversion operator.
    /// \return The value of the underlying type.
		//*************************************************************************
		operator T()
		{
			return value;
		}

		//*************************************************************************
		/// Const conversion operator.
		/// \return The value of the underlying type.
		//*************************************************************************
		operator const T() const
		{
			return value;
		}

		//*************************************************************************
		/// ++ operator.
		//*************************************************************************
		cyclic_value& operator ++()
		{
			if (value == last_value)
			{
				value = first_value;
			}
			else
			{
        ++value;
			}

			return *this;
		}

		//*************************************************************************
		/// ++ operator.
		//*************************************************************************
		cyclic_value operator ++(int)
		{
			cyclic_value temp(*this);

			operator++();

			return temp;
		}

		//*************************************************************************
		/// -- operator.
		//*************************************************************************
		cyclic_value& operator --()
		{
			if (value == first_value)
			{
				value = last_value;
			}
			else
			{
				--value;
			}

			return *this;
		}

		//*************************************************************************
		/// -- operator.
		//*************************************************************************
		cyclic_value operator --(int)
		{
			cyclic_value temp(*this);

			operator--();

			return temp;
		}

		//*************************************************************************
		/// = operator.
		//*************************************************************************
		cyclic_value& operator =(T t)
		{
			value = t;
			return *this;
		}	
	
    //*************************************************************************
    /// = operator.
    //*************************************************************************
    template <const T OTHER_FIRST, const T OTHER_LAST>
    cyclic_value& operator =(const cyclic_value<T, OTHER_FIRST, OTHER_LAST>& other)
    {
      value       = other.value;
      first_value = other.first_value;
      last_value  = other.last_value;
      return *this;
    }

    //*************************************************************************
		/// Gets the first value.
		//*************************************************************************
    const T& first() const
    {
      return first_value;
    }

  	//*************************************************************************
		/// Gets the last value.
		//*************************************************************************
    const T& last() const
    {
      return last_value;
    }

    //*************************************************************************
    /// Swaps the values.
    //*************************************************************************
    template <const T OTHER_FIRST, const T OTHER_LAST>
    void swap(cyclic_value<T, OTHER_FIRST, OTHER_LAST>& other)
    {
      std::swap(first_value, other.first_value);
      std::swap(last_value,  other.last_value);
      std::swap(value,       other.value);
    }

	private:

    T value;       ///< The current value.
    T first_value; ///< The first value in the range.
		T last_value;  ///< The last value in the range.
	};

  //*************************************************************************
  /// Swaps the values.
  //*************************************************************************
  template <typename T, const T LHS_FIRST, const T LHS_LAST, const T RHS_FIRST, const T RHS_LAST>
  void swap(cyclic_value<T, LHS_FIRST, LHS_LAST>& lhs,
            cyclic_value<T, RHS_FIRST, RHS_LAST>& rhs)
  {
    lhs.swap(rhs);
  }

  //*************************************************************************
  /// Equality operator.
  //*************************************************************************
  template <typename T, const T LHS_FIRST, const T LHS_LAST, const T RHS_FIRST, const T RHS_LAST>
  bool operator == (const cyclic_value<T, LHS_FIRST, LHS_LAST>& lhs,
                    const cyclic_value<T, RHS_FIRST, RHS_LAST>& rhs)
  {
    return static_cast<T>(lhs) == static_cast<T>(rhs);
  }

  //*************************************************************************
  /// Inequality operator.
  //*************************************************************************
  template <typename T, const T LHS_FIRST, const T LHS_LAST, const T RHS_FIRST, const T RHS_LAST>
  bool operator != (const cyclic_value<T, LHS_FIRST, RHS_LAST>& lhs,
                    const cyclic_value<T, RHS_FIRST, RHS_LAST>& rhs)
  {
    return !(lhs == rhs);
  }
}

#endif