1 // Copyright 2015 The Kyua Authors. 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are 6 // met: 7 // 8 // * Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above copyright 11 // notice, this list of conditions and the following disclaimer in the 12 // documentation and/or other materials provided with the distribution. 13 // * Neither the name of Google Inc. nor the names of its contributors 14 // may be used to endorse or promote products derived from this software 15 // without specific prior written permission. 16 // 17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 29 /// \file utils/optional_fwd.hpp 30 /// Forward declarations for utils/optional.hpp 31 32 #if !defined(UTILS_OPTIONAL_FWD_HPP) 33 #define UTILS_OPTIONAL_FWD_HPP 34 35 namespace utils { 36 37 38 namespace detail { 39 40 41 /// Internal type-safe representation for the none type. 42 struct none_t {}; 43 44 45 } // namespace detail 46 47 48 /// The none value. 49 /// 50 /// This has internal linkage so it is OK to define it in the header file. 51 /// However, pointers to none from different translation units will be 52 /// different. Just don't do that. 53 const detail::none_t none = {}; 54 55 56 template< class > class optional; 57 58 59 } // namespace utils 60 61 #endif // !defined(UTILS_OPTIONAL_FWD_HPP) 62