text: //=================================================================================================
  /*!
  //  \file blaze/math/typetraits/HasAcos.h
  //  \brief Header file for the HasAcos type trait
  //
  //  Copyright (C) 2012-2020 Klaus Iglberger - All Rights Reserved
  //
  //  This file is part of the Blaze library. You can redistribute it and/or modify it under
  //  the terms of the New (Revised) BSD License. Redistribution and use in source and binary
  //  forms, with or without modification, are permitted provided that the following conditions
  //  are met:
  //
  //  1. Redistributions of source code must retain the above copyright notice, this list of
  //     conditions and the following disclaimer.
  //  2. Redistributions in binary form must reproduce the above copyright notice, this list
  //     of conditions and the following disclaimer in the documentation and/or other materials
  //     provided with the distribution.
  //  3. Neither the names of the Blaze development group nor the names of its contributors
  //     may be used to endorse or promote products derived from this software without specific
  //     prior written permission.
  //
  //  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
  //  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  //  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  //  SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  //  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
  //  TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  //  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  //  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  //  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
  //  DAMAGE.
  */
  //=================================================================================================
  
  #ifndef _BLAZE_MATH_TYPETRAITS_HASACOS_H_
  #define _BLAZE_MATH_TYPETRAITS_HASACOS_H_
  
  
  //*************************************************************************************************
  // Includes
  //*************************************************************************************************
  
  #include <utility>
  #include <blaze/math/typetraits/IsMatrix.h>
  #include <blaze/math/typetraits/IsVector.h>
  #include <blaze/util/EnableIf.h>
  #include <blaze/util/IntegralConstant.h>
  #include <blaze/util/typetraits/Void.h>
  
  
  namespace blaze {
  
  //=================================================================================================
  //
  //  CLASS DEFINITION
  //
  //=================================================================================================
  
  //*************************************************************************************************
  /*! \cond BLAZE_INTERNAL */
  /*!\brief Auxiliary helper struct for the HasAcos type trait.
  // \ingroup math_type_traits
  */
  template< typename T, typename = void >
  struct HasAcosHelper
     : public FalseType
  {};
  /*! \endcond */
  //*************************************************************************************************
  
  
  //*************************************************************************************************
  /*! \cond BLAZE_INTERNAL */
  /*!\brief Specialization of the HasAcosHelper type trait for types providing the acos() operation.
  // \ingroup math_type_traits
  */
  template< typename T >
  struct HasAcosHelper< T, Void_t< decltype( acos( std::declval<T>() ) ) > >
     : public TrueType
  {};
  /*! \endcond */
  //*************************************************************************************************
  
  
  //*************************************************************************************************
  /*!\brief Availability of the acos() operation for the given data types.
  // \ingroup math_type_traits
  //
  // This type trait provides the information whether the acos() operation exists for the given
  // data type \a T (taking the cv-qualifiers into account). In case the operation is available,
  // the \a value member constant is set to \a true, the nested type definition \a Type is
  // \a TrueType, and the class derives from \a TrueType. Otherwise \a value is set to \a false,
  // \a Type is \a FalseType, and the class derives from \a FalseType.
  
     \code
     struct NoAcos {};  // Definition of a type without the acos() operation
  
     blaze::HasAcos< int >::value                  // Evaluates to 1
     blaze::HasAcos< DynamicVector<float> >::Type  // Results in TrueType
     blaze::HasAcos< DynamicMatrix<double> >       // Is derived from TrueType
     blaze::HasAcos< NoAcos >::value               // Evaluates to 0
     blaze::HasAcos< NoAcos >::Type                // Results in FalseType
     blaze::HasAcos< NoAcos >                      // Is derived from FalseType
     \endcode
  */
  template< typename T, typename = void >
  struct HasAcos
     : public HasAcosHelper<T>
  {};
  //*************************************************************************************************
  
  
  //*************************************************************************************************
  /*! \cond BLAZE_INTERNAL */
  /*!\brief Specialization of the HasAcos type trait for vectors.
  // \ingroup math_type_traits
  */
  template< typename T >
  struct HasAcos< T, EnableIf_t< IsVector_v<T> > >
     : public HasAcos< typename T::ElementType >
  {};
  /*! \endcond */
  //*************************************************************************************************
  
  
  //*************************************************************************************************
  /*! \cond BLAZE_INTERNAL */
  /*!\brief Specialization of the HasAcos type trait for matrices.
  // \ingroup math_type_traits
  */
  template< typename T >
  struct HasAcos< T, EnableIf_t< IsMatrix_v<T> > >
     : public HasAcos< typename T::ElementType >
  {};
  /*! \endcond */
  //*************************************************************************************************
  
  
  //*************************************************************************************************
  /*!\brief Auxiliary variable template for the HasAcos type trait.
  // \ingroup math_type_traits
  //
  // The HasAcos_v variable template provides a convenient shortcut to access the nested \a value
  // of the HasAcos class template. For instance, given the type \a T the following two statements
  // are identical:
  
     \code
     constexpr bool value1 = blaze::HasAcos<T>::value;
     constexpr bool value2 = blaze::HasAcos_v<T>;
     \endcode
  */
  template< typename T >
  constexpr bool HasAcos_v = HasAcos<T>::value;
  //*************************************************************************************************
  
  } // namespace blaze
  
  #endif
  