// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2013 Christian Seiler <christian@iwakd.de>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_CXX11WORKAROUNDS_H
#define EIGEN_CXX11WORKAROUNDS_H

/* COMPATIBILITY CHECKS
 * (so users of compilers that are too old get some realistic error messages)
 */
#if defined(__INTEL_COMPILER) && (__INTEL_COMPILER < 1310)
#error Intel Compiler only supports required C++ features since version 13.1.
// note that most stuff in principle works with 13.0 but when combining
// some features, at some point 13.0 will just fail with an internal assertion
#elif defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6))
// G++ < 4.6 by default will continue processing the source files - even if we use #error to make
// it error out. For this reason, we use the pragma to make sure G++ aborts at the first error
// it sees. Unfortunately, that is still not our #error directive, but at least the output is
// short enough the user has a chance to see that the compiler version is not sufficient for
// the funky template mojo we use.
#pragma GCC diagnostic error "-Wfatal-errors"
#error GNU C++ Compiler (g++) only supports required C++ features since version 4.6.
#endif

/* Check that the compiler at least claims to support C++11. It might not be sufficient
 * because the compiler may not implement it correctly, but at least we'll know.
 */
#if __cplusplus <= 199711L
#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER)
#pragma GCC diagnostic error "-Wfatal-errors"
#endif
#error This library needs at least a C++11 compliant compiler. If you use g++/clang, please enable the -std=c++11 compiler flag. (-std=c++0x on older versions.)
#endif

namespace Eigen {

// Use std::array as Eigen array
template <typename T, std::size_t N> using array = std::array<T, N>;

namespace internal {

/* std::get is only constexpr in C++14, not yet in C++11
 *     - libstdc++ from version 4.7 onwards has it nevertheless,
 *                                          so use that
 *     - libstdc++ older versions: use _M_instance directly
 *     - libc++ all versions so far: use __elems_ directly
 *     - all other libs: use std::get to be portable, but
 *                       this may not be constexpr
 */
#if defined(__GLIBCXX__) && __GLIBCXX__ < 20120322
#define STD_GET_ARR_HACK             a._M_instance[I]
#elif defined(_LIBCPP_VERSION)
#define STD_GET_ARR_HACK             a.__elems_[I]
#else
#define STD_GET_ARR_HACK             std::template get<I, T, N>(a)
#endif

template<std::size_t I, class T, std::size_t N> constexpr inline T&       array_get(std::array<T,N>&       a) { return (T&)       STD_GET_ARR_HACK; }
template<std::size_t I, class T, std::size_t N> constexpr inline T&&      array_get(std::array<T,N>&&      a) { return (T&&)      STD_GET_ARR_HACK; }
template<std::size_t I, class T, std::size_t N> constexpr inline T const& array_get(std::array<T,N> const& a) { return (T const&) STD_GET_ARR_HACK; }

template<std::size_t I, class T> constexpr inline T&       array_get(std::vector<T>&       a) { return a[I]; }
template<std::size_t I, class T> constexpr inline T&&      array_get(std::vector<T>&&      a) { return a[I]; }
template<std::size_t I, class T> constexpr inline T const& array_get(std::vector<T> const& a) { return a[I]; }

#undef STD_GET_ARR_HACK

template <typename T> struct array_size;
template<class T, std::size_t N> struct array_size<const std::array<T,N> > {
  static const size_t value = N;
};
template <typename T> struct array_size;
template<class T, std::size_t N> struct array_size<std::array<T,N> > {
  static const size_t value = N;
};

/* Suppose you have a template of the form
 * template<typename T> struct X;
 * And you want to specialize it in such a way:
 *    template<typename S1, typename... SN> struct X<Foo<S1, SN...>> { ::: };
 *    template<>                            struct X<Foo<>>          { ::: };
 * This will work in Intel's compiler 13.0, but only to some extent in g++ 4.6, since
 * g++ can only match templates called with parameter packs if the number of template
 * arguments is not a fixed size (so inside the first specialization, referencing
 * X<Foo<Sn...>> will fail in g++). On the other hand, g++ will accept the following:
 *    template<typename S...> struct X<Foo<S...>> { ::: }:
 * as an additional (!) specialization, which will then only match the empty case.
 * But Intel's compiler 13.0 won't accept that, it will only accept the empty syntax,
 * so we have to create a workaround for this.
 */
#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
#define EIGEN_TPL_PP_SPEC_HACK_DEF(mt, n)    mt... n
#define EIGEN_TPL_PP_SPEC_HACK_DEFC(mt, n)   , EIGEN_TPL_PP_SPEC_HACK_DEF(mt, n)
#define EIGEN_TPL_PP_SPEC_HACK_USE(n)        n...
#define EIGEN_TPL_PP_SPEC_HACK_USEC(n)       , n...
#else
#define EIGEN_TPL_PP_SPEC_HACK_DEF(mt, n)
#define EIGEN_TPL_PP_SPEC_HACK_DEFC(mt, n)
#define EIGEN_TPL_PP_SPEC_HACK_USE(n)
#define EIGEN_TPL_PP_SPEC_HACK_USEC(n)
#endif

} // end namespace internal

} // end namespace Eigen

#endif // EIGEN_CXX11WORKAROUNDS_H

/*
 * kate: space-indent on; indent-width 2; mixedindent off; indent-mode cstyle;
 */