Vc/traits/is_output_iterator.h

0001 /*  This file is part of the Vc library. {{{
0002 Copyright © 2015 Matthias Kretz <kretz@kde.org>
0003
0004 Redistribution and use in source and binary forms, with or without
0005 modification, are permitted provided that the following conditions are met:
0006     * Redistributions of source code must retain the above copyright
0007       notice, this list of conditions and the following disclaimer.
0008     * Redistributions in binary form must reproduce the above copyright
0009       notice, this list of conditions and the following disclaimer in the
0010       documentation and/or other materials provided with the distribution.
0011     * Neither the names of contributing organizations nor the
0012       names of its contributors may be used to endorse or promote products
0013       derived from this software without specific prior written permission.
0014
0015 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
0016 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
0017 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
0018 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
0019 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
0020 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
0021 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
0022 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
0023 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
0024 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
0025
0026 }}}*/
0027
0028 #ifndef VC_TRAITS_IS_OUTPUT_ITERATOR_H_
0029 #define VC_TRAITS_IS_OUTPUT_ITERATOR_H_
0030
0031 #include <iterator>
0032
0033 namespace Vc_VERSIONED_NAMESPACE
0034 {
0035 namespace Traits
0036 {
0037 namespace is_output_iterator_impl
0038 {
0039 template <typename T, typename ValueType = typename std::iterator_traits<T>::value_type,
0040           typename = decltype(*std::declval<T &>() = std::declval<
0041                                   ValueType>())  // tests that assignment to a
0042                                                  // dereferenced iterator is possible, if
0043                                                  // yes, T is an OutputIterator
0044           >
0045 std::true_type test(int);
0046 template <typename T> std::false_type test(...);
0047 }  // namespace is_output_iterator_impl
0048
0049 template <typename T>
0050 struct is_output_iterator
0051     : public std::conditional<
0052           std::is_void<typename std::iterator_traits<T>::value_type>::value,
0053           std::true_type, decltype(is_output_iterator_impl::test<T>(int()))>::type
0054 {
0055 };
0056
0057 static_assert(!std::is_void<std::iterator_traits<int *>::value_type>::value, "");
0058 static_assert(is_output_iterator<int *>::value, "");
0059 static_assert(!is_output_iterator<const int *>::value, "");
0060
0061 }  // namespace Traits
0062 }  // namespace Vc
0063
0064 #endif  // VC_TRAITS_IS_OUTPUT_ITERATOR_H_
0065
0066 // vim: foldmethod=marker