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// 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)
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