functional.h

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/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2014 John Wellbelove
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
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copies or substantial portions of the Software.
 
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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******************************************************************************/
 
#ifndef ETL_FUNCTIONAL_INCLUDED
#define ETL_FUNCTIONAL_INCLUDED
 
#include "platform.h"
#include "utility.h"


 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  template <typename T>
  class reference_wrapper
  {
  public:
 
    typedef T type;
 
    ETL_CONSTEXPR20 explicit reference_wrapper(T& t_) ETL_NOEXCEPT
      : t(&t_)
    {
    }
 
    ETL_CONSTEXPR20 reference_wrapper(const reference_wrapper& rhs) ETL_NOEXCEPT
      : t(rhs.t)
    {
    }
 
    ETL_CONSTEXPR20 reference_wrapper<T>& operator=(const reference_wrapper& rhs) ETL_NOEXCEPT
    {
      t = rhs.t;
      return *this;
    }
 
    ETL_CONSTEXPR20 T& get() const ETL_NOEXCEPT
    {
      return *t;
    }
 
    ETL_CONSTEXPR20 operator T&() const ETL_NOEXCEPT
    {
      return *t;
    }
 
#if ETL_USING_CPP11
    // implementation without etl::invoke, which would add a circular dependency
    template <typename... TArgs>
    ETL_CONSTEXPR20 auto operator()(TArgs&&... args) const
      noexcept(noexcept(etl::declval<T&>()(etl::declval<TArgs>()...))) -> decltype(etl::declval<T&>()(etl::declval<TArgs>()...))
    {
      return get()(etl::forward<TArgs>(args)...);
    }
#endif
 
  private:
 
    T* t;
  };
 
  //***************************************************************************
  template <typename T>
  reference_wrapper<T> ref(T& t)
  {
    return reference_wrapper<T>(t);
  }
 
  //***************************************************************************
  template <typename T>
  reference_wrapper<T> ref(reference_wrapper<T> t)
  {
    return reference_wrapper<T>(t.get());
  }
 
  //***************************************************************************
  template <typename T>
  reference_wrapper<const T> cref(const T& t)
  {
    return reference_wrapper<const T>(t);
  }
 
  //***************************************************************************
  template <typename T>
  reference_wrapper<const T> cref(reference_wrapper<T> t)
  {
    return reference_wrapper<const T>(t.get());
  }
 
  //***************************************************************************
  //***************************************************************************
  template <class T>
  struct unwrap_reference
  {
    typedef T type;
  };
 
  template <typename T>
  struct unwrap_reference<etl::reference_wrapper<T> >
  {
    typedef T& type;
  };
 
#if ETL_USING_CPP11
  template <typename T>
  using unwrap_reference_t = typename unwrap_reference<T>::type;
#endif
 
  //***************************************************************************
  //***************************************************************************
  template <typename T>
  struct unwrap_ref_decay : etl::unwrap_reference<typename etl::decay<T>::type>
  {
  };
 
#if ETL_USING_CPP11
  template <typename T>
  using unwrap_ref_decay_t = typename unwrap_ref_decay<T>::type;
#endif
 
  //***************************************************************************
  // is_reference_wrapper
  // Detect etl::reference_wrapper<T>
  //***************************************************************************
  template <typename T>
  struct is_reference_wrapper : etl::false_type
  {
  };
 
  template <typename T>
  struct is_reference_wrapper<etl::reference_wrapper<T> > : etl::true_type
  {
  };
 
#if ETL_USING_CPP17
  template <typename T>
  inline constexpr bool is_reference_wrapper_v = is_reference_wrapper<T>::value;
#endif
 
  //***************************************************************************
  //***************************************************************************
  template <typename TArgumentType, typename TResultType>
  struct unary_function
  {
    typedef TArgumentType argument_type;
    typedef TResultType   result_type;
  };
 
  //***************************************************************************
  //***************************************************************************
  template <typename TFirstArgumentType, typename TSecondArgumentType, typename TResultType>
  struct binary_function
  {
    typedef TFirstArgumentType  first_argument_type;
    typedef TSecondArgumentType second_argument_type;
    typedef TResultType         result_type;
  };
 
  //***************************************************************************
  template <typename T = void>
  struct less : public etl::binary_function<T, T, bool>
  {
    typedef T value_type;
 
    ETL_CONSTEXPR bool operator()(const T& lhs, const T& rhs) const
    {
      return (lhs < rhs);
    }
  };
 
#if ETL_USING_CPP11
  template <>
  struct less<void> : public etl::binary_function<void, void, bool>
  {
    typedef int is_transparent;
 
    template <typename T1, typename T2>
    constexpr auto operator()(T1&& lhs, T2&& rhs) const -> decltype(static_cast<T1&&>(lhs) < static_cast<T2&&>(rhs))
    {
      return static_cast<T1&&>(lhs) < static_cast<T2&&>(rhs);
    }
  };
#endif
 
  //***************************************************************************
  template <typename T = void>
  struct less_equal : public etl::binary_function<T, T, bool>
  {
    typedef T value_type;
 
    ETL_CONSTEXPR bool operator()(const T& lhs, const T& rhs) const
    {
      return !(rhs < lhs);
    }
  };
 
#if ETL_USING_CPP11
  template <>
  struct less_equal<void> : public etl::binary_function<void, void, bool>
  {
    typedef int is_transparent;
 
    template <typename T1, typename T2>
    constexpr auto operator()(T1&& lhs, T2&& rhs) const -> decltype(!(static_cast<T2&&>(rhs) < static_cast<T1&&>(lhs)))
    {
      return !(static_cast<T2&&>(rhs) < static_cast<T1&&>(lhs));
    }
  };
#endif
 
  //***************************************************************************
  template <typename T = void>
  struct greater : public etl::binary_function<T, T, bool>
  {
    typedef T value_type;
 
    ETL_CONSTEXPR bool operator()(const T& lhs, const T& rhs) const
    {
      return (rhs < lhs);
    }
  };
 
#if ETL_USING_CPP11
  template <>
  struct greater<void> : public etl::binary_function<void, void, bool>
  {
    typedef int is_transparent;
 
    template <typename T1, typename T2>
    constexpr auto operator()(T1&& lhs, T2&& rhs) const -> decltype(static_cast<T2&&>(rhs) < static_cast<T1&&>(lhs))
    {
      return static_cast<T2&&>(rhs) < static_cast<T1&&>(lhs);
    }
  };
#endif
 
  //***************************************************************************
  template <typename T = void>
  struct greater_equal : public etl::binary_function<T, T, bool>
  {
    typedef T value_type;
 
    ETL_CONSTEXPR bool operator()(const T& lhs, const T& rhs) const
    {
      return !(lhs < rhs);
    }
  };
 
#if ETL_USING_CPP11
  template <>
  struct greater_equal<void> : public etl::binary_function<void, void, bool>
  {
    typedef int is_transparent;
 
    template <typename T1, typename T2>
    constexpr auto operator()(T1&& lhs, T2&& rhs) const -> decltype(!(static_cast<T1&&>(lhs) < static_cast<T2&&>(rhs)))
    {
      return !(static_cast<T1&&>(lhs) < static_cast<T2&&>(rhs));
    }
  };
#endif
 
  //***************************************************************************
  template <typename T = void>
  struct equal_to : public etl::binary_function<T, T, bool>
  {
    typedef T value_type;
 
    ETL_CONSTEXPR bool operator()(const T& lhs, const T& rhs) const
    {
      return lhs == rhs;
    }
  };
 
#if ETL_USING_CPP11
  template <>
  struct equal_to<void> : public etl::binary_function<void, void, bool>
  {
    typedef void value_type;
    typedef int  is_transparent;
 
    template <typename T1, typename T2>
    constexpr auto operator()(T1&& lhs, T2&& rhs) const -> decltype(static_cast<T1&&>(lhs) == static_cast<T2&&>(rhs))
    {
      return static_cast<T1&&>(lhs) == static_cast<T2&&>(rhs);
    }
  };
#endif
 
  //***************************************************************************
  template <typename T = void>
  struct not_equal_to : public etl::binary_function<T, T, bool>
  {
    typedef T value_type;
 
    ETL_CONSTEXPR bool operator()(const T& lhs, const T& rhs) const
    {
      return !(lhs == rhs);
    }
  };
 
#if ETL_USING_CPP11
  template <>
  struct not_equal_to<void> : public etl::binary_function<void, void, bool>
  {
    typedef int is_transparent;
 
    template <typename T1, typename T2>
    constexpr auto operator()(T1&& lhs, T2&& rhs) const -> decltype(!(static_cast<T1&&>(lhs) == static_cast<T2&&>(rhs)))
    {
      return !(static_cast<T1&&>(lhs) == static_cast<T2&&>(rhs));
    }
  };
#endif
 
  //***************************************************************************
  template <typename TFunction>
  class binder1st : public etl::unary_function<typename TFunction::second_argument_type, typename TFunction::result_type>
  {
  protected:
 
    TFunction                               operation;
    typename TFunction::first_argument_type value;
 
  public:
 
    binder1st(const TFunction& f, const typename TFunction::first_argument_type& v)
      : operation(f)
      , value(v)
    {
    }
 
    typename TFunction::result_type operator()(typename TFunction::second_argument_type& x) const
    {
      return operation(value, x);
    }
 
    typename TFunction::result_type operator()(const typename TFunction::second_argument_type& x) const
    {
      return operation(value, x);
    }
  };
 
  template <typename F, typename T>
  binder1st<F> bind1st(const F& f, const T& x)
  {
    return binder1st<F>(f, x);
  }
 
  //***************************************************************************
  template <typename TFunction >
  class binder2nd : public etl::unary_function<typename TFunction::first_argument_type, typename TFunction::result_type>
  {
  protected:
 
    TFunction                                operation;
    typename TFunction::second_argument_type value;
 
  public:
 
    binder2nd(const TFunction& f, const typename TFunction::second_argument_type& v)
      : operation(f)
      , value(v)
    {
    }
 
    typename TFunction::result_type operator()(typename TFunction::first_argument_type& x) const
    {
      return operation(x, value);
    }
 
    typename TFunction::result_type operator()(const typename TFunction::first_argument_type& x) const
    {
      return operation(x, value);
    }
  };
 
  template <typename F, typename T>
  binder2nd<F> bind2nd(const F& f, const T& x)
  {
    return binder2nd<F>(f, x);
  }
 
  //***************************************************************************
  template <typename T = void>
  struct plus
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs + rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct minus
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs - rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct negate
  {
    typedef T argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs) const
    {
      return -lhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct multiplies
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs * rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct divides
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs / rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct modulus
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs % rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct logical_and
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs && rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct logical_or
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs || rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct logical_not
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs) const
    {
      return !lhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct bit_and
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs & rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct bit_or
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs | rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct bit_xor
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs, const T& rhs) const
    {
      return lhs ^ rhs;
    }
  };
 
  //***************************************************************************
  template <typename T = void>
  struct bit_not
  {
    typedef T first_argument_type;
    typedef T second_argument_type;
    typedef T result_type;
 
    ETL_CONSTEXPR T operator()(const T& lhs) const
    {
      return ~lhs;
    }
  };
 
#if ETL_USING_CPP11
  namespace private_functional
  {
    //***************************************************************************
    template <typename TReturnType, typename TClassType, typename... TArgs>
    class mem_fn_impl
    {
    public:
 
      typedef TReturnType (TClassType::*MemberFunctionType)(TArgs...);
 
      ETL_CONSTEXPR mem_fn_impl(MemberFunctionType member_function_)
        : member_function(member_function_)
      {
      }
 
      ETL_CONSTEXPR TReturnType operator()(TClassType& instance, TArgs... args) const
      {
        return (instance.*member_function)(etl::forward<TArgs>(args)...);
      }
 
    private:
 
      MemberFunctionType member_function;
    };
 
    //***************************************************************************
    template <typename TReturnType, typename TClassType, typename... TArgs>
    class const_mem_fn_impl
    {
    public:
 
      typedef TReturnType (TClassType::*MemberFunctionType)(TArgs...) const;
 
      ETL_CONSTEXPR const_mem_fn_impl(MemberFunctionType member_function_)
        : member_function(member_function_)
      {
      }
 
      ETL_CONSTEXPR TReturnType operator()(const TClassType& instance, TArgs... args) const
      {
        return (instance.*member_function)(etl::forward<TArgs>(args)...);
      }
 
    private:
 
      MemberFunctionType member_function;
    };
  } // namespace private_functional
 
  //***************************************************************************
  template <typename TReturnType, typename TClassType, typename... TArgs>
  ETL_CONSTEXPR private_functional::mem_fn_impl<TReturnType, TClassType, TArgs...> mem_fn(TReturnType (TClassType::*member_function)(TArgs...))
  {
    return private_functional::mem_fn_impl<TReturnType, TClassType, TArgs...>(member_function);
  }
 
  //***************************************************************************
  template <typename TReturnType, typename TClassType, typename... TArgs>
  ETL_CONSTEXPR private_functional::const_mem_fn_impl<TReturnType, TClassType, TArgs...> mem_fn(TReturnType (TClassType::*member_function)(TArgs...)
                                                                                              const)
  {
    return private_functional::const_mem_fn_impl<TReturnType, TClassType, TArgs...>(member_function);
  }
#endif
 
#if ETL_USING_CPP14
  struct identity
  {
    template <class T>
    constexpr T&& operator()(T&& t) const noexcept
    {
      return etl::forward<T>(t);
    }
  };
#endif
 
#if ETL_USING_CPP17
  namespace ranges
  {
    struct equal_to
    {
      template <typename T, typename U>
      constexpr auto operator()(T&& t, U&& u) const -> decltype(static_cast<T&&>(t) == static_cast<U&&>(u))
      {
        return static_cast<T&&>(t) == static_cast<U&&>(u);
      }
    };
 
    struct less
    {
      template <typename T, typename U>
      constexpr auto operator()(T&& t, U&& u) const -> decltype(static_cast<T&&>(t) < static_cast<U&&>(u))
      {
        return static_cast<T&&>(t) < static_cast<U&&>(u);
      }
    };
  } // namespace ranges
#endif
 
} // namespace etl
 
#endif