// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
//
// 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
//
// 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.
// ------------------------------------------------------------------------

//! \addtogroup upgrade_val
//! @{

//! upgrade_val is used to ensure an operation such as multiplication is possible between
//! two types. values are upgraded only where necessary.

template <typename T1, typename T2>
struct upgrade_val {
  typedef typename promote_type<T1, T2>::result T1_result;
  typedef typename promote_type<T1, T2>::result T2_result;

  arma_inline static typename promote_type<T1, T2>::result apply(const T1 x) {
    typedef typename promote_type<T1, T2>::result out_type;
    return out_type(x);
  }

  arma_inline static typename promote_type<T1, T2>::result apply(const T2 x) {
    typedef typename promote_type<T1, T2>::result out_type;
    return out_type(x);
  }
};

// template<>
template <typename T>
struct upgrade_val<T, T> {
  typedef T T1_result;
  typedef T T2_result;

  arma_inline static const T& apply(const T& x) { return x; }
};

//! upgrade a type to allow multiplication with a complex type
//! eg. the int in "int * complex<double>" is upgraded to a double
// template<>
template <typename T, typename T2>
struct upgrade_val<std::complex<T>, T2> {
  typedef std::complex<T> T1_result;
  typedef T T2_result;

  arma_inline static const std::complex<T>& apply(const std::complex<T>& x) { return x; }
  arma_inline static T apply(const T2 x) { return T(x); }
};

// template<>
template <typename T1, typename T>
struct upgrade_val<T1, std::complex<T> > {
  typedef T T1_result;
  typedef std::complex<T> T2_result;

  arma_inline static T apply(const T1 x) { return T(x); }
  arma_inline static const std::complex<T>& apply(const std::complex<T>& x) { return x; }
};

//! ensure we don't lose precision when multiplying a complex number with a higher
//! precision real number
template <>
struct upgrade_val<std::complex<float>, double> {
  typedef std::complex<double> T1_result;
  typedef double T2_result;

  arma_inline static const std::complex<double> apply(const std::complex<float>& x) {
    return std::complex<double>(x);
  }
  arma_inline static double apply(const double x) { return x; }
};

template <>
struct upgrade_val<double, std::complex<float> > {
  typedef double T1_result;
  typedef std::complex<float> T2_result;

  arma_inline static double apply(const double x) { return x; }
  arma_inline static const std::complex<double> apply(const std::complex<float>& x) {
    return std::complex<double>(x);
  }
};

//! ensure we don't lose precision when multiplying complex numbers with different
//! underlying types
template <>
struct upgrade_val<std::complex<float>, std::complex<double> > {
  typedef std::complex<double> T1_result;
  typedef std::complex<double> T2_result;

  arma_inline static const std::complex<double> apply(const std::complex<float>& x) {
    return std::complex<double>(x);
  }
  arma_inline static const std::complex<double>& apply(const std::complex<double>& x) {
    return x;
  }
};

template <>
struct upgrade_val<std::complex<double>, std::complex<float> > {
  typedef std::complex<double> T1_result;
  typedef std::complex<double> T2_result;

  arma_inline static const std::complex<double>& apply(const std::complex<double>& x) {
    return x;
  }
  arma_inline static const std::complex<double> apply(const std::complex<float>& x) {
    return std::complex<double>(x);
  }
};

//! work around limitations in the complex class (at least as present in gcc 4.1 & 4.3)
template <>
struct upgrade_val<std::complex<double>, float> {
  typedef std::complex<double> T1_result;
  typedef double T2_result;

  arma_inline static const std::complex<double>& apply(const std::complex<double>& x) {
    return x;
  }
  arma_inline static double apply(const float x) { return double(x); }
};

template <>
struct upgrade_val<float, std::complex<double> > {
  typedef double T1_result;
  typedef std::complex<double> T2_result;

  arma_inline static double apply(const float x) { return double(x); }
  arma_inline static const std::complex<double>& apply(const std::complex<double>& x) {
    return x;
  }
};

//! @}
