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