| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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. |
| */ |
| |
| #ifndef CONDITIONAL_FORWARD_HPP_ |
| #define CONDITIONAL_FORWARD_HPP_ |
| |
| #include <type_traits> |
| |
| namespace datasketches { |
| |
| // Forward type T2 as rvalue reference if type T1 is rvalue reference |
| |
| template<typename T1, typename T2> |
| using fwd_type = typename std::conditional<std::is_lvalue_reference<T1>::value, |
| T2, typename std::remove_reference<T2>::type&&>::type; |
| |
| template<typename T1, typename T2> |
| fwd_type<T1, T2> conditional_forward(T2&& value) { |
| return std::forward<fwd_type<T1, T2>>(std::forward<T2>(value)); |
| } |
| |
| // Forward container as iterators |
| |
| template<typename Container> |
| auto forward_begin(Container&& c) -> typename std::enable_if< |
| std::is_lvalue_reference<Container>::value || |
| std::is_same<typename std::remove_reference<Container>::type::const_iterator, decltype(c.begin())>::value, |
| decltype(c.begin()) |
| >::type |
| { |
| return c.begin(); |
| } |
| |
| template<typename Container> |
| auto forward_begin(Container&& c) -> typename std::enable_if< |
| !std::is_lvalue_reference<Container>::value && |
| !std::is_same<typename std::remove_reference<Container>::type::const_iterator, decltype(c.begin())>::value, |
| decltype(std::make_move_iterator(c.begin())) |
| >::type |
| { |
| return std::make_move_iterator(c.begin()); |
| } |
| |
| template<typename Container> |
| auto forward_end(Container&& c) -> typename std::enable_if< |
| std::is_lvalue_reference<Container>::value || |
| std::is_same<typename std::remove_reference<Container>::type::const_iterator, decltype(c.begin())>::value, |
| decltype(c.end()) |
| >::type |
| { |
| return c.end(); |
| } |
| |
| template<typename Container> |
| auto forward_end(Container&& c) -> typename std::enable_if< |
| !std::is_lvalue_reference<Container>::value && |
| !std::is_same<typename std::remove_reference<Container>::type::const_iterator, decltype(c.begin())>::value, |
| decltype(std::make_move_iterator(c.end())) |
| >::type |
| { |
| return std::make_move_iterator(c.end()); |
| } |
| |
| } /* namespace datasketches */ |
| |
| #endif |