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Diffstat (limited to 'utils/optional.ipp')
| -rw-r--r-- | utils/optional.ipp | 252 |
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diff --git a/utils/optional.ipp b/utils/optional.ipp new file mode 100644 index 000000000000..3e2f3f878f2a --- /dev/null +++ b/utils/optional.ipp @@ -0,0 +1,252 @@ +// 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. + +#if !defined(UTILS_OPTIONAL_IPP) +#define UTILS_OPTIONAL_IPP + +#include <cstddef> + +#include "utils/defs.hpp" +#include "utils/optional.hpp" +#include "utils/sanity.hpp" + + +/// Initializes an optional object to the none value. +template< class T > +utils::optional< T >::optional(void) : + _data(NULL) +{ +} + + +/// Explicitly initializes an optional object to the none value. +template< class T > +utils::optional< T >::optional(utils::detail::none_t /* none */) : + _data(NULL) +{ +} + + +/// Initializes an optional object to a non-none value. +/// +/// \param data The initial value for the object. +template< class T > +utils::optional< T >::optional(const T& data) : + _data(new T(data)) +{ +} + + +/// Copy constructor. +/// +/// \param other The optional object to copy from. +template< class T > +utils::optional< T >::optional(const optional< T >& other) : + _data(other._data == NULL ? NULL : new T(*(other._data))) +{ +} + + +/// Destructor. +template< class T > +utils::optional< T >::~optional(void) +{ + if (_data != NULL) + delete _data; + _data = NULL; // Prevent accidental reuse. +} + + +/// Explicitly assigns an optional object to the none value. +/// +/// \return A reference to this. +template< class T > +utils::optional< T >& +utils::optional< T >::operator=(utils::detail::none_t /* none */) +{ + if (_data != NULL) + delete _data; + _data = NULL; + return *this; +} + + +/// Assigns a new value to the optional object. +/// +/// \param data The initial value for the object. +/// +/// \return A reference to this. +template< class T > +utils::optional< T >& +utils::optional< T >::operator=(const T& data) +{ + T* new_data = new T(data); + if (_data != NULL) + delete _data; + _data = new_data; + return *this; +} + + +/// Copies an optional value. +/// +/// \param other The optional object to copy from. +/// +/// \return A reference to this. +template< class T > +utils::optional< T >& +utils::optional< T >::operator=(const optional< T >& other) +{ + T* new_data = other._data == NULL ? NULL : new T(*(other._data)); + if (_data != NULL) + delete _data; + _data = new_data; + return *this; +} + + +/// Equality comparator. +/// +/// \param other The other object to compare this one to. +/// +/// \return True if this object and other are equal; false otherwise. +template< class T > +bool +utils::optional< T >::operator==(const optional< T >& other) const +{ + if (_data == NULL && other._data == NULL) { + return true; + } else if (_data == NULL || other._data == NULL) { + return false; + } else { + INV(_data != NULL && other._data != NULL); + return *_data == *other._data; + } +} + + +/// Inequality comparator. +/// +/// \param other The other object to compare this one to. +/// +/// \return True if this object and other are different; false otherwise. +template< class T > +bool +utils::optional< T >::operator!=(const optional< T >& other) const +{ + return !(*this == other); +} + + +/// Gets the value hold by the optional object. +/// +/// \pre The optional object must not be none. +/// +/// \return A reference to the data. +template< class T > +const T& +utils::optional< T >::get(void) const +{ + PRE(_data != NULL); + return *_data; +} + + +/// Gets the value of this object with a default fallback. +/// +/// \param default_value The value to return if this object holds no value. +/// +/// \return A reference to the data in the optional object, or the reference +/// passed in as a parameter. +template< class T > +const T& +utils::optional< T >::get_default(const T& default_value) const +{ + if (_data != NULL) + return *_data; + else + return default_value; +} + + +/// Tests whether the optional object contains data or not. +/// +/// \return True if the object is not none; false otherwise. +template< class T > +utils::optional< T >::operator bool(void) const +{ + return _data != NULL; +} + + +/// Tests whether the optional object contains data or not. +/// +/// \return True if the object is not none; false otherwise. +template< class T > +T& +utils::optional< T >::get(void) +{ + PRE(_data != NULL); + return *_data; +} + + +/// Injects the object into a stream. +/// +/// \param output The stream into which to inject the object. +/// \param object The object to format. +/// +/// \return The output stream. +template< class T > +std::ostream& utils::operator<<(std::ostream& output, + const optional< T >& object) +{ + if (!object) { + output << "none"; + } else { + output << object.get(); + } + return output; +} + + +/// Helper function to instantiate optional objects. +/// +/// \param value The value for the optional object. Shouldn't be none, as +/// optional objects can be constructed from none right away. +/// +/// \return A new optional object. +template< class T > +utils::optional< T > +utils::make_optional(const T& value) +{ + return optional< T >(value); +} + + +#endif // !defined(UTILS_OPTIONAL_IPP) |