* This file is part of the GROMACS molecular simulation package.
*
* Copyright (c) 2012,2013,2014,2015,2016 by the GROMACS development team.
- * Copyright (c) 2018,2019,2020, by the GROMACS development team, led by
+ * Copyright (c) 2018,2019,2020,2021, by the GROMACS development team, led by
* Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
* and including many others, as listed in the AUTHORS file in the
* top-level source directory and at http://www.gromacs.org.
#ifndef GMX_UTILITY_CLASSHELPERS_H
#define GMX_UTILITY_CLASSHELPERS_H
-#include <memory>
-
namespace gmx
{
#endif
//clang-format on
-/*! \brief
- * Helper class to manage a pointer to a private implementation class.
- *
- * This helper provides the following benefits (all but the last could also be
- * achieved with std::unique_ptr):
- * - Automatic memory management: the implementation pointer is freed in
- * the destructor automatically. If the destructor is not declared or is
- * defined inline in the header file, a compilation error occurs instead
- * of a memory leak or undefined behavior.
- * - Exception safety in constructors: the implementation pointer is freed
- * correctly even if the constructor of the containing class throws after
- * the implementation class is constructed.
- * - Copy and/or assignment is automatically disallowed if explicit copy
- * constructor and/or assignment operator is not provided.
- * - Compiler helps to manage const-correctness: in const methods, it is not
- * possible to change the implementation class.
- *
- * Move construction and assignment are also disallowed, but can be enabled by
- * providing explicit move constructor and/or assignment.
- *
- * Intended use:
- * \code
- // In exampleclass.h
- class ExampleClass
- {
- public:
- ExampleClass();
- ~ExampleClass(); // Must be defined, must not be defined inline
-
- // <...>
-
- private:
- class Impl;
-
- PrivateImplPointer<Impl> impl_;
- };
-
- // In exampleclass.cpp
-
- // <definition of ExampleClass::Impl>
-
- ExampleClass::ExampleClass()
- : impl_(new Impl)
- {
- }
-
- ExampleClass::~ExampleClass()
- {
- }
- \endcode
- *
- * Note that ExampleClass::~ExampleClass cannot be declared inline (or
- * generated by the compiler) because the implementation of impl_
- * requires that ExampleClass::Impl be known in size, whereas it has
- * only been forward declared. Only the translation unit where
- * ExampleClass::Impl is declared can define the destructor for
- * ExampleClass (which may be defaulted).
- *
- * \inlibraryapi
- * \ingroup module_utility
- */
-template<class Impl>
-class PrivateImplPointer
-{
-public:
- //! Allow implicit initialization from nullptr to support comparison.
- PrivateImplPointer(std::nullptr_t) : ptr_(nullptr) {}
- //! Initialize with the given implementation class.
- explicit PrivateImplPointer(Impl* ptr) : ptr_(ptr) {}
- //! \cond
- // Explicitly declared to work around MSVC problems.
- PrivateImplPointer(PrivateImplPointer&& other) noexcept : ptr_(std::move(other.ptr_)) {}
- PrivateImplPointer& operator=(PrivateImplPointer&& other) noexcept
- {
- ptr_ = std::move(other.ptr_);
- return *this;
- }
- //! \endcond
-
- /*! \brief
- * Sets a new implementation class and destructs the previous one.
- *
- * Needed, e.g., to implement lazily initializable or copy-assignable
- * classes.
- */
- void reset(Impl* ptr) { ptr_.reset(ptr); }
- //! Access the raw pointer.
- Impl* get() { return ptr_.get(); }
- //! Access the implementation class as with a raw pointer.
- Impl* operator->() { return ptr_.get(); }
- //! Access the implementation class as with a raw pointer.
- Impl& operator*() { return *ptr_; }
- //! Access the implementation class as with a raw pointer.
- const Impl* operator->() const { return ptr_.get(); }
- //! Access the implementation class as with a raw pointer.
- const Impl& operator*() const { return *ptr_; }
-
- //! Allows testing whether the implementation is initialized.
- explicit operator bool() const { return ptr_ != nullptr; }
-
- //! Tests for equality (mainly useful against nullptr).
- bool operator==(const PrivateImplPointer& other) const { return ptr_ == other.ptr_; }
- //! Tests for inequality (mainly useful against nullptr).
- bool operator!=(const PrivateImplPointer& other) const { return ptr_ != other.ptr_; }
-
-private:
- std::unique_ptr<Impl> ptr_;
-
- // Copy construction and assignment disabled by the unique_ptr member.
-};
-
} // namespace gmx
#endif
biod.pnpi.spb.ru / alexxy / gromacs.git / blobdiff