1*b0d29bc4SBrooks Davis // Copyright 2010 The Kyua Authors. 2*b0d29bc4SBrooks Davis // All rights reserved. 3*b0d29bc4SBrooks Davis // 4*b0d29bc4SBrooks Davis // Redistribution and use in source and binary forms, with or without 5*b0d29bc4SBrooks Davis // modification, are permitted provided that the following conditions are 6*b0d29bc4SBrooks Davis // met: 7*b0d29bc4SBrooks Davis // 8*b0d29bc4SBrooks Davis // * Redistributions of source code must retain the above copyright 9*b0d29bc4SBrooks Davis // notice, this list of conditions and the following disclaimer. 10*b0d29bc4SBrooks Davis // * Redistributions in binary form must reproduce the above copyright 11*b0d29bc4SBrooks Davis // notice, this list of conditions and the following disclaimer in the 12*b0d29bc4SBrooks Davis // documentation and/or other materials provided with the distribution. 13*b0d29bc4SBrooks Davis // * Neither the name of Google Inc. nor the names of its contributors 14*b0d29bc4SBrooks Davis // may be used to endorse or promote products derived from this software 15*b0d29bc4SBrooks Davis // without specific prior written permission. 16*b0d29bc4SBrooks Davis // 17*b0d29bc4SBrooks Davis // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18*b0d29bc4SBrooks Davis // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19*b0d29bc4SBrooks Davis // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20*b0d29bc4SBrooks Davis // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21*b0d29bc4SBrooks Davis // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22*b0d29bc4SBrooks Davis // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23*b0d29bc4SBrooks Davis // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24*b0d29bc4SBrooks Davis // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25*b0d29bc4SBrooks Davis // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26*b0d29bc4SBrooks Davis // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27*b0d29bc4SBrooks Davis // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28*b0d29bc4SBrooks Davis 29*b0d29bc4SBrooks Davis /// \file utils/optional.hpp 30*b0d29bc4SBrooks Davis /// Provides the utils::optional class. 31*b0d29bc4SBrooks Davis /// 32*b0d29bc4SBrooks Davis /// The class is provided as a separate module on its own to minimize 33*b0d29bc4SBrooks Davis /// header-inclusion side-effects. 34*b0d29bc4SBrooks Davis 35*b0d29bc4SBrooks Davis #if !defined(UTILS_OPTIONAL_HPP) 36*b0d29bc4SBrooks Davis #define UTILS_OPTIONAL_HPP 37*b0d29bc4SBrooks Davis 38*b0d29bc4SBrooks Davis #include "utils/optional_fwd.hpp" 39*b0d29bc4SBrooks Davis 40*b0d29bc4SBrooks Davis #include <ostream> 41*b0d29bc4SBrooks Davis 42*b0d29bc4SBrooks Davis namespace utils { 43*b0d29bc4SBrooks Davis 44*b0d29bc4SBrooks Davis 45*b0d29bc4SBrooks Davis /// Holds a data value or none. 46*b0d29bc4SBrooks Davis /// 47*b0d29bc4SBrooks Davis /// This class allows users to represent values that may be uninitialized. 48*b0d29bc4SBrooks Davis /// Instead of having to keep separate variables to track whether a variable is 49*b0d29bc4SBrooks Davis /// supposed to have a value or not, this class allows multiplexing the 50*b0d29bc4SBrooks Davis /// behaviors. 51*b0d29bc4SBrooks Davis /// 52*b0d29bc4SBrooks Davis /// This class is a simplified version of Boost.Optional. 53*b0d29bc4SBrooks Davis template< class T > 54*b0d29bc4SBrooks Davis class optional { 55*b0d29bc4SBrooks Davis /// Internal representation of the optional data value. 56*b0d29bc4SBrooks Davis T* _data; 57*b0d29bc4SBrooks Davis 58*b0d29bc4SBrooks Davis public: 59*b0d29bc4SBrooks Davis optional(void); 60*b0d29bc4SBrooks Davis optional(utils::detail::none_t); 61*b0d29bc4SBrooks Davis optional(const optional< T >&); 62*b0d29bc4SBrooks Davis explicit optional(const T&); 63*b0d29bc4SBrooks Davis ~optional(void); 64*b0d29bc4SBrooks Davis 65*b0d29bc4SBrooks Davis optional& operator=(utils::detail::none_t); 66*b0d29bc4SBrooks Davis optional& operator=(const T&); 67*b0d29bc4SBrooks Davis optional& operator=(const optional< T >&); 68*b0d29bc4SBrooks Davis 69*b0d29bc4SBrooks Davis bool operator==(const optional< T >&) const; 70*b0d29bc4SBrooks Davis bool operator!=(const optional< T >&) const; 71*b0d29bc4SBrooks Davis 72*b0d29bc4SBrooks Davis operator bool(void) const; 73*b0d29bc4SBrooks Davis 74*b0d29bc4SBrooks Davis const T& get(void) const; 75*b0d29bc4SBrooks Davis const T& get_default(const T&) const; 76*b0d29bc4SBrooks Davis T& get(void); 77*b0d29bc4SBrooks Davis }; 78*b0d29bc4SBrooks Davis 79*b0d29bc4SBrooks Davis 80*b0d29bc4SBrooks Davis template< class T > 81*b0d29bc4SBrooks Davis std::ostream& operator<<(std::ostream&, const optional< T >&); 82*b0d29bc4SBrooks Davis 83*b0d29bc4SBrooks Davis 84*b0d29bc4SBrooks Davis template< class T > 85*b0d29bc4SBrooks Davis optional< T > make_optional(const T&); 86*b0d29bc4SBrooks Davis 87*b0d29bc4SBrooks Davis 88*b0d29bc4SBrooks Davis } // namespace utils 89*b0d29bc4SBrooks Davis 90*b0d29bc4SBrooks Davis #endif // !defined(UTILS_OPTIONAL_HPP) 91