// ____ ______ __ // / __ \ / ____// / // / /_/ // / / / // / ____// /___ / /___ PixInsight Class Library // /_/ \____//_____/ PCL 2.4.23 // ---------------------------------------------------------------------------- // pcl/Optional.h - Released 2022-03-12T18:59:29Z // ---------------------------------------------------------------------------- // This file is part of the PixInsight Class Library (PCL). // PCL is a multiplatform C++ framework for development of PixInsight modules. // // Copyright (c) 2003-2022 Pleiades Astrophoto S.L. All Rights Reserved. // // Redistribution and use in both source and binary forms, with or without // modification, is permitted provided that the following conditions are met: // // 1. All redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // // 2. All 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. // // 3. Neither the names "PixInsight" and "Pleiades Astrophoto", nor the names // of their contributors, may be used to endorse or promote products derived // from this software without specific prior written permission. For written // permission, please contact info@pixinsight.com. // // 4. All products derived from this software, in any form whatsoever, must // reproduce the following acknowledgment in the end-user documentation // and/or other materials provided with the product: // // "This product is based on software from the PixInsight project, developed // by Pleiades Astrophoto and its contributors (https://pixinsight.com/)." // // Alternatively, if that is where third-party acknowledgments normally // appear, this acknowledgment must be reproduced in the product itself. // // THIS SOFTWARE IS PROVIDED BY PLEIADES ASTROPHOTO AND ITS 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 PLEIADES ASTROPHOTO OR ITS // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, // EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, BUSINESS // INTERRUPTION; PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; AND LOSS OF USE, // DATA OR PROFITS) 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. // ---------------------------------------------------------------------------- #ifndef __PCL_Optional_h #define __PCL_Optional_h /// \file pcl/Optional.h #include #include #include namespace pcl { // ---------------------------------------------------------------------------- /*! * \class Optional * \brief An object that can be in a defined or undefined state * * %Optional stores an instance of the template argument T along with a * defined state Boolean flag. %Optional objects update their defined * state automatically as they are created, copied and assigned. * * This class is useful to deal with objects that can be defined optionally, * when it is inconvenient to manage the object's value and its defined state * as two separate items. %Optional offers the power of encapsulation in * object-oriented languages to solve these problems efficiently. */ template class PCL_CLASS Optional { public: /*! * Constructs an undefined %Optional object. * * The value instance will be default-constructed implicitly, which means * that the type T must provide valid default construction semantics. */ Optional() : m_value() // N.B: this initialization prevents warnings such as { // 'Optional<>::m_value may be used uninitialized...' } /*! * Copy constructor. * * The value instance will be copy-constructed implicitly, which means that * the type T must provide valid copy construction semantics if this * constructor is invoked. */ Optional( const Optional& ) = default; /* * Move constructor. */ Optional( Optional&& ) = default; /*! * Constructs a defined %Optional object with the specified \a value. */ Optional( const T& value ) : m_value( value ) , m_defined( true ) { } /*! * Copy assignment operator. Returns a reference to this object. */ Optional& operator =( const Optional& x ) { if ( bool( m_defined = x.m_defined ) ) m_value = x.m_value; return *this; } /*! * Move assignment operator. Returns a reference to this object. */ Optional& operator =( Optional&& x ) { if ( bool( m_defined = x.m_defined ) ) m_value = std::move( x.m_value ); return *this; } /*! * Assigns the specified \a value to this object. Returns a reference to * this object. After assigning a value, an %Optional object will be in * defined state. */ Optional& operator =( const T& value ) { m_value = value; m_defined = true; return *this; } /*! * Type conversion operator. Returns a reference to the value stored in this * %Optional object. * * If this object is undefined, the returned value may be unpredictable, * depending on construction semantics for the type T. */ operator const T&() const { return m_value; } /*! * Returns a reference to the value stored in this %Optional object. * * If this object is undefined, the returned value may be unpredictable, * depending on construction semantics for the type T. * * This function performs the same role as operator const T&(). It is * required for cases where an automatic type conversion is not applicable. */ const T& operator ()() const { return m_value; } /*! * Returns true if this %Optional object has been defined. */ bool IsDefined() const { return m_defined; } /*! * Undefines this %Optional object. Assigns a default-constructed object of * type T to the value of this object, and sets the internal defined flag to * false. */ void Undefine() { m_value = T(); m_defined = false; } /*! * Returns the value stored in this object if it has been defined. Otherwise * returns the specified \a value. */ const T& OrElse( const T& value ) const { return m_defined ? m_value : value; } /*! * Returns the value stored in this object if it has been defined. Otherwise * throws the specified \a exception. */ template const T& OrElseThrow( const Exception& exception ) const { if ( m_defined ) return m_value; throw exception; } /*! * Returns the value stored in this object if it has been defined. Otherwise * throws an Error exception with the specified \a message. */ const T& OrElseThrow( const String& message ) const { if ( m_defined ) return m_value; throw Error( message ); } /*! * Equality operator. Returns true iff one of the following condition holds: * * \li This object has been defined, \a x has been defined, and the value in * this object equals the value in \a x. * * \li Neither this object nor \a x have been defined. */ bool operator ==( const Optional& x ) const { return m_defined ? (x.m_defined ? m_value == x.m_value : false) : !x.m_defined; } /*! * Value equality operator. Returns true iff this object has been defined * and its value equals the specified \a value. */ bool operator ==( const T& value ) const { return m_defined && m_value == value; } /*! * Less than relational operator. Returns true iff this object has been * defined and either \a x has not been defined (defined objects always * precede undefined ones), or the value in this object precedes the value * in \a x. */ bool operator <( const Optional& x ) const { return m_defined && (!x.m_defined || m_value < x.m_value); } /*! * Less-than-value relational operator. Returns true iff this object has * been defined and its value precedes the specified \a value. */ bool operator <( const T& value ) const { return m_defined && m_value < value; } private: T m_value; bool m_defined = false; }; // ---------------------------------------------------------------------------- } // pcl #endif // __PCL_Optional_h // ---------------------------------------------------------------------------- // EOF pcl/Optional.h - Released 2022-03-12T18:59:29Z