2 * This file is part of the GROMACS molecular simulation package.
4 * Copyright (c) 2016,2017,2018,2019,2020,2021, by the GROMACS development team, led by
5 * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
6 * and including many others, as listed in the AUTHORS file in the
7 * top-level source directory and at http://www.gromacs.org.
9 * GROMACS is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public License
11 * as published by the Free Software Foundation; either version 2.1
12 * of the License, or (at your option) any later version.
14 * GROMACS is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with GROMACS; if not, see
21 * http://www.gnu.org/licenses, or write to the Free Software Foundation,
22 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
24 * If you want to redistribute modifications to GROMACS, please
25 * consider that scientific software is very special. Version
26 * control is crucial - bugs must be traceable. We will be happy to
27 * consider code for inclusion in the official distribution, but
28 * derived work must not be called official GROMACS. Details are found
29 * in the README & COPYING files - if they are missing, get the
30 * official version at http://www.gromacs.org.
32 * To help us fund GROMACS development, we humbly ask that you cite
33 * the research papers on the package. Check out http://www.gromacs.org.
35 /*! \libinternal \file
39 * \author Teemu Murtola <teemu.murtola@gmail.com>
41 * \ingroup module_utility
43 #ifndef GMX_UTILITY_ANY_H
44 #define GMX_UTILITY_ANY_H
48 #include <type_traits>
53 #include "gromacs/utility/gmxassert.h"
58 /*! \libinternal \brief
59 * Represents a dynamically typed value of an arbitrary type - deprecated.
61 * New uses of this type should be avoided - prefer std::any or
64 * To create an Any, either initialize it as empty, or with the create()
65 * method (or the equivalent constructor, if the type parameter can be deduced
66 * and is clear to the reader from the context).
68 * To query the type of the contents in the any, use isEmpty(), type(), and
71 * To access the value, you need to know the type as a compile-time constant
72 * (e.g., through branching based on isType()), and then use cast() or
75 * Methods in this class do not throw unless otherwise indicated.
77 * This provides essentially the same functionality as boost::any.
79 * It would be good to replace the current uses of this type with
80 * std::any or std::variant, but see
81 * https://gitlab.com/gromacs/gromacs/-/issues/3951 for discussion
82 * about the things that have blocked such attempts.
84 * \ingroup module_utility
90 * Creates a any that holds the given value.
92 * \throws std::bad_alloc if out of memory.
94 * This method allows explicitly specifying the template argument,
95 * contrary to the templated constructor.
98 static Any create(const T& value)
103 * Creates a any that holds the given value.
105 * \throws std::bad_alloc if out of memory.
107 * In addition to allowing specifying the template argument, this
108 * method avoids copying when move-construction is possible.
111 static Any create(T&& value)
113 return Any(std::forward<T>(value));
116 //! Creates an empty any value.
119 * Creates a any that holds the given value.
121 * \throws std::bad_alloc if out of memory.
123 template<typename T, typename = std::enable_if_t<!std::is_same<T, Any>::value>>
124 explicit Any(T&& value) :
125 content_(new Content<typename std::decay<T>::type>(std::forward<T>(value)))
129 * Creates a deep copy of a any.
131 * \throws std::bad_alloc if out of memory.
133 Any(const Any& other) : content_(other.cloneContent()) {}
134 //! Move-constructs a any.
135 Any(Any&& other) noexcept : content_(std::move(other.content_)) {}
139 * \throws std::bad_alloc if out of memory.
141 Any& operator=(const Any& other)
143 content_ = other.cloneContent();
146 //! Move-assigns the any.
147 Any& operator=(Any&& other) noexcept
149 content_ = std::move(other.content_);
153 //! Whether any value is stored.
154 bool isEmpty() const { return content_ == nullptr; }
155 //! Returns the dynamic type of the value that is currently stored.
156 std::type_index type() const
158 const std::type_info& info = !isEmpty() ? content_->typeInfo() : typeid(void);
159 return std::type_index(info);
161 //! Returns whether the type stored matches the template parameter.
165 return !isEmpty() && content_->typeInfo() == typeid(T);
169 * Tries to get the value as the given type.
171 * \tparam T Type to get.
172 * \returns Pointer to the value, or nullptr if the type does not match
176 const T* tryCast() const
178 return isType<T>() ? &static_cast<Content<T>*>(content_.get())->value_ : nullptr;
181 * Gets the value when the type is known.
183 * \tparam T Type to get (which must match what the any stores).
185 * Asserts if the any is empty or does not contain the requested type.
188 const T& cast() const
190 const T* value = tryCast<T>();
191 GMX_RELEASE_ASSERT(value != nullptr, "Cast to incorrect type");
195 * Tries to get the value as the given type as a non-const pointer.
197 * \tparam T Type to get.
198 * \returns Pointer to the value, or nullptr if the type does not match
201 * This method allows modifying the value in-place, which is useful
202 * with more complicated data structures.
207 return isType<T>() ? &static_cast<Content<T>*>(content_.get())->value_ : nullptr;
210 * Gets the value when the type is known as a modifiable reference.
212 * \tparam T Type to get (which must match what the any stores).
214 * Asserts if the any is empty or does not contain the requested type.
219 T* value = tryCastRef<T>();
220 GMX_RELEASE_ASSERT(value != nullptr, "Cast to incorrect type");
228 virtual ~IContent() {}
229 virtual const std::type_info& typeInfo() const = 0;
230 virtual std::unique_ptr<IContent> clone() const = 0;
234 class Content : public IContent
237 explicit Content(const T& value) : value_(value) {}
238 explicit Content(T&& value) : value_(std::move(value)) {}
240 const std::type_info& typeInfo() const override { return typeid(T); }
241 std::unique_ptr<IContent> clone() const override
243 return std::make_unique<Content>(value_);
249 //! Creates a deep copy of the content.
250 std::unique_ptr<IContent> cloneContent() const
252 return content_ != nullptr ? content_->clone() : nullptr;
255 std::unique_ptr<IContent> content_;
260 * Converts a Any value to a string.
262 * As the name suggests, only some types of "simple" values (such as int) are
263 * supported. Asserts for unsupported types.
265 * \ingroup module_utility
267 std::string simpleValueToString(const Any& value);