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Diffstat (limited to 'utils/optional.hpp')
-rw-r--r-- | utils/optional.hpp | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/utils/optional.hpp b/utils/optional.hpp new file mode 100644 index 000000000000..a4557bff5dc8 --- /dev/null +++ b/utils/optional.hpp @@ -0,0 +1,90 @@ +// Copyright 2010 The Kyua Authors. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in the +// documentation and/or other materials provided with the distribution. +// * Neither the name of Google Inc. nor the names of its contributors +// may be used to endorse or promote products derived from this software +// without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +/// \file utils/optional.hpp +/// Provides the utils::optional class. +/// +/// The class is provided as a separate module on its own to minimize +/// header-inclusion side-effects. + +#if !defined(UTILS_OPTIONAL_HPP) +#define UTILS_OPTIONAL_HPP + +#include "utils/optional_fwd.hpp" + +#include <ostream> + +namespace utils { + + +/// Holds a data value or none. +/// +/// This class allows users to represent values that may be uninitialized. +/// Instead of having to keep separate variables to track whether a variable is +/// supposed to have a value or not, this class allows multiplexing the +/// behaviors. +/// +/// This class is a simplified version of Boost.Optional. +template< class T > +class optional { + /// Internal representation of the optional data value. + T* _data; + +public: + optional(void); + optional(utils::detail::none_t); + optional(const optional< T >&); + explicit optional(const T&); + ~optional(void); + + optional& operator=(utils::detail::none_t); + optional& operator=(const T&); + optional& operator=(const optional< T >&); + + bool operator==(const optional< T >&) const; + bool operator!=(const optional< T >&) const; + + operator bool(void) const; + + const T& get(void) const; + const T& get_default(const T&) const; + T& get(void); +}; + + +template< class T > +std::ostream& operator<<(std::ostream&, const optional< T >&); + + +template< class T > +optional< T > make_optional(const T&); + + +} // namespace utils + +#endif // !defined(UTILS_OPTIONAL_HPP) |