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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.
+
+#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)