text: //=================================================================================================
  /*!
  //  \file blaze/math/typetraits/RequiresEvaluation.h
  //  \brief Header file for the RequiresEvaluation type trait
  //
  //  Copyright (C) 2012-2017 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_REQUIRESEVALUATION_H_
  #define _BLAZE_MATH_TYPETRAITS_REQUIRESEVALUATION_H_
  
  
  //*************************************************************************************************
  // Includes
  //*************************************************************************************************
  
  #include <blaze/util/IntegralConstant.h>
  #include <blaze/util/mpl/Not.h>
  #include <blaze/util/typetraits/IsReference.h>
  
  
  namespace blaze {
  
  //=================================================================================================
  //
  //  CLASS DEFINITION
  //
  //=================================================================================================
  
  //*************************************************************************************************
  /*!\brief Compile time check to query the requirement to evaluate an expression.
  // \ingroup math_type_traits
  //
  // Via this type trait it is possible to determine whether a given vector or matrix expression
  // type requires an intermediate evaluation in the context of a compound expression. In case
  // the given type requires an evaluation, 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.
  //
  // \note that this type trait can only be applied to Blaze vector or matrix expressions
  // or any other type providing the nested type \a CompositeType. In case this nested type
  // is not available, applying the type trait results in a compile time error!
  */
  template< typename T >
  struct RequiresEvaluation
     : public BoolConstant< Not< IsReference<typename T::CompositeType> >::value >
  {};
  //*************************************************************************************************
  
  } // namespace blaze
  
  #endif
  