itkMetaProgrammingLibrary.h

Go to the documentation of this file.

/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkMetaProgrammingLibrary_h
#define itkMetaProgrammingLibrary_h

#include "itkMacro.h"

namespace itk {

namespace mpl {

struct TrueType
{
  using ValueType = bool;
  using Type = TrueType;

  static constexpr ValueType Value = true;
  operator ValueType() { return Value; }
};

struct FalseType
{
  using ValueType = bool;
  using Type = FalseType;
  static constexpr ValueType Value = false;
  operator ValueType() { return Value; }
};

template <bool VP, typename T1, typename T2> struct If;
template <typename T1, typename T2> struct If<true , T1, T2>{ using Type = T1; };
template <typename T1, typename T2> struct If<false, T1, T2>{ using Type = T2; };

template < bool VF1, bool VF2, bool VF3=false> struct OrC : TrueType { };
template <> struct OrC<false, false,false> : FalseType {};

template < typename TF1, typename TF2, typename TF3=FalseType> struct Or : OrC<TF1::Value, TF2::Value, TF3::Value>
{ using Type = typename OrC<TF1::Value, TF2::Value, TF3::Value>::Type; };

template < bool VF1, bool VF2> struct AndC : FalseType { };
template <> struct AndC<true, true> : TrueType {};

template < typename TF1, typename TF2> struct And : AndC<TF1::Value, TF2::Value>
{ using Type = typename AndC<TF1::Value, TF2::Value>::Type; };

template < bool VF1, bool VF2> struct XorC : FalseType { };
template <> struct XorC<true, false> : TrueType {};
template <> struct XorC<false, true> : TrueType {};

template < typename TF1, typename TF2> struct Xor : XorC<TF1::Value, TF2::Value>
{ using Type = typename XorC<TF1::Value, TF2::Value>::Type; };

template < bool VF > struct NotC : FalseType { };
template <> struct NotC<false> : TrueType {};
template <> struct NotC<true>  : FalseType {};

template < typename TF> struct Not : NotC<TF::Value>
{ using Type = typename NotC<TF::Value>::Type; };

} // mpl namespace

// TrueType and FalseType have moved to itk::mpl.
// Expect itk::TrueType and itk::False type to be deprecated.
using mpl::TrueType;
using mpl::FalseType;

} // itk namespace
#endif // itkMetaProgrammingLibrary_h