108 lines
3.1 KiB
C++
108 lines
3.1 KiB
C++
/***************************************************************************
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* Copyright (C) gempa GmbH *
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* All rights reserved. *
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* Contact: gempa GmbH (seiscomp-dev@gempa.de) *
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* *
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* GNU Affero General Public License Usage *
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* This file may be used under the terms of the GNU Affero *
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* Public License version 3.0 as published by the Free Software Foundation *
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* and appearing in the file LICENSE included in the packaging of this *
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* file. Please review the following information to ensure the GNU Affero *
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* Public License version 3.0 requirements will be met: *
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* https://www.gnu.org/licenses/agpl-3.0.html. *
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* *
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* Other Usage *
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* Alternatively, this file may be used in accordance with the terms and *
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* conditions contained in a signed written agreement between you and *
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* gempa GmbH. *
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***************************************************************************/
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#ifndef SEISCOMP_CORE_OPTIONAL_H
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#define SEISCOMP_CORE_OPTIONAL_H
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#include <seiscomp/core.h>
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#include <boost/optional.hpp>
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#include <exception>
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#include <optional>
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#include <type_traits>
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namespace Seiscomp {
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namespace Core {
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/** \brief Redefines std::optional<T>
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* Optional values can be set or unset.
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* \code
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* void print(const Optional<int> &v) {
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* if ( !v )
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* cout << "value of v is not set" << endl;
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* else
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* cout << *v << endl;
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* }
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*
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* Optional<int> a = 5;
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* print(a); // output: "5"
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* a = None;
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* print(a); // output: "value of v is not set"
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* \endcode
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*/
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template <typename T>
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using Optional = ::std::optional<T>;
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using NoneType = ::std::nullopt_t;
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/** Defines None */
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SC_SYSTEM_CORE_API extern NoneType const None;
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template <class...>
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struct False : std::integral_constant<bool, false> {};
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template <class...>
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struct True : std::integral_constant<bool, true> {};
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// Checks whether a type is wrapped with optional or not.
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template <typename>
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struct isOptional : std::false_type {};
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template<template<class...> class U, typename ...Args>
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struct isOptional<U<Args...>>
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: std::integral_constant<
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bool,
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std::is_base_of<std::optional<Args...>, U<Args...>>::value
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|| std::is_base_of<boost::optional<Args...>, U<Args...>>::value
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> {};
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template <typename T>
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T value(const Optional<T>&);
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class SC_SYSTEM_CORE_API ValueError : public std::exception {
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public:
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ValueError() throw();
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~ValueError() throw();
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public:
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const char* what() const throw() override;
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};
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/** Macro to use optional values easily */
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#define OPT(T) Seiscomp::Core::Optional<T>
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/** Macro to use optional values as const reference */
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#define OPT_CR(T) const Seiscomp::Core::Optional<T>&
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#include <seiscomp/core/optional.inl>
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}
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}
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#endif
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