tmp.H

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-------------------------------------------------------------------------------
    Copyright (C) 2011-2016 OpenFOAM Foundation
    Copyright (C) 2018-2019 OpenCFD Ltd.
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
Class
    Foam::tmp
 
Description
    A class for managing temporary objects.
 
    This is a combination of std::shared_ptr (with intrusive ref-counting)
    and a shared_ptr without ref-counting and null deleter.
    This allows the tmp to double as a pointer management and an indirect
    pointer to externally allocated objects.
 
SourceFiles
    tmpI.H
 
See also
    Foam::autoPtr
    Foam::refCount
 
\*---------------------------------------------------------------------------*/
 
#ifndef tmp_H
#define tmp_H
 
#include "refCount.H"
#include "word.H"
#include <utility>
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
/*---------------------------------------------------------------------------*\
                             Class tmp Declaration
\*---------------------------------------------------------------------------*/
 
template<class T>
class tmp
{
    // Private Data
 
        //- Object types
        enum refType
        {
            PTR,    
            CREF    
        };
 
        //- The managed pointer or the address of const-reference object
        mutable T* ptr_;
 
        //- The type (managed pointer | const-reference object)
        mutable refType type_;
 
 
    // Private Member Operators
 
        //- Increment the ref-count for a managed pointer
        inline void operator++();
 
 
public:
 
    // STL type definitions
 
        //- Type of object being managed or referenced
        typedef T element_type;
 
        //- Pointer to type of object being managed or referenced
        typedef T* pointer;
 
 
    //- Reference counter class
    typedef Foam::refCount refCount;
 
 
    // Factory Methods
 
        //- Construct tmp of T with forwarding arguments
        //  \param args list of arguments with which an instance of T
        //      will be constructed.
        //
        //  \note Similar to std::make_shared, but the overload for
        //      array types is not disabled.
        template<class... Args>
        inline static tmp<T> New(Args&&... args);
 
        //- Construct tmp from derived type with forwarding arguments
        //  \param args list of arguments with which an instance of U
        //      will be constructed.
        //
        //  \note Similar to New but for derived types
        template<class U, class... Args>
        inline static tmp<T> NewFrom(Args&&... args);
 
 
    // Constructors
 
        //- Construct with no managed pointer.
        inline constexpr tmp() noexcept;
 
        //- Construct with no managed pointer.
        inline constexpr tmp(std::nullptr_t) noexcept;
 
        //- Construct, taking ownership of the pointer.
        inline explicit tmp(T* p);
 
        //- Construct for a const reference to an object.
        inline tmp(const T& obj) noexcept;
 
        //- Move construct, transferring ownership.
        //  Does not affect ref-count
        inline tmp(tmp<T>&& t) noexcept;
 
        //- Move construct, transferring ownership.
        //  Does not affect ref-count
        //  \note Non-standard definition - should be non-const
        inline tmp(const tmp<T>&& t) noexcept;
 
        //- Copy construct, incrementing ref-count of managed pointer.
        //  \note Non-standard definition - should be non-const
        inline tmp(const tmp<T>& t);
 
        //- Copy construct. Optionally reusing ref-counted pointer.
        inline tmp(const tmp<T>& t, bool reuse);
 
 
    //- Destructor: deletes managed pointer when the ref-count is 0
    inline ~tmp();
 
 
    // Member Functions
 
    // Query
 
        //- True if this is a managed pointer (not a const reference)
        inline bool isTmp() const noexcept;
 
        //- True if this is a non-null managed pointer
        inline bool empty() const noexcept;
 
        //- True if this is a non-null managed pointer,
        //- or is a const object reference
        inline bool valid() const noexcept;
 
        //- True if this is a non-null managed pointer with a unique ref-count
        inline bool movable() const noexcept;
 
        //- Return type-name of the tmp, constructed from type-name of T
        inline word typeName() const;
 
 
    // Access
 
        //- Return pointer without nullptr checking.
        inline T* get() noexcept;
 
        //- Return const pointer without nullptr checking.
        inline const T* get() const noexcept;
 
        //- Return the const object reference or a const reference to the
        //- contents of a non-null managed pointer.
        //  Fatal for a null managed pointer
        inline const T& cref() const;
 
        //- Return non-const reference to the contents of a non-null
        //- managed pointer.
        //  Fatal for a null managed pointer or if the object is const.
        inline T& ref() const;
 
        //- Non-const dereference, even if the object is const.
        //  This is similar to ref(), but applies a const_cast to access
        //  const objects.
        //  Fatal for a null managed pointer.
        inline T& constCast() const;
 
 
    // Edit
 
        //- Return managed pointer for reuse, or clone() the const object
        //- reference.
        inline T* ptr() const;
 
        //- If object pointer points to valid object:
        //- delete object and set pointer to nullptr
        inline void clear() const noexcept;
 
        //- Release ownership of managed temporary object.
        //  After this call no object is managed.
        inline void reset() noexcept;
 
        //- Delete managed temporary object and set to new given pointer
        inline void reset(T* p) noexcept;
 
        //- Clear existing and transfer ownership.
        inline void reset(tmp<T>&& other) noexcept;
 
        //- Delete managed temporary object and set to const reference
        inline void cref(const T& obj) noexcept;
 
        //- Swaps the managed object with other.
        inline void swap(tmp<T>& other) noexcept;
 
 
    // Member Operators
 
        //- Return const reference to the object.
        //  Identical to cref() method.
        inline const T& operator()() const;
 
        //- Cast to underlying data type, using the cref() method.
        inline operator const T&() const;
 
        //- Dereferences (const) pointer to the managed object.
        //  Fatal for a null managed pointer.
        inline const T* operator->() const;
 
        //- Dereferences (non-const) pointer to the managed object.
        //  Fatal for a null managed pointer or if the object is const.
        inline T* operator->();
 
        //- Is non-null managed pointer or const object reference : valid()
        explicit inline operator bool() const noexcept;
 
        //- Take ownership of the pointer.
        //  Fatal for a null pointer, or when the pointer is non-unique.
        inline void operator=(T* p);
 
        //- Transfer ownership of the managed pointer.
        //  Fatal for a null managed pointer or if the object is const.
        inline void operator=(const tmp<T>& t);
 
        //- Clear existing and transfer ownership.
        inline void operator=(tmp<T>&& other) noexcept;
 
 
    // Housekeeping
 
        //- No assignment from literal nullptr.
        //  Consistent with run-time check for nullptr on assignment.
        void operator=(std::nullptr_t) = delete;
};
 
 
// Global Functions
 
//- Specializes the Swap algorithm for tmp.
//  Swaps the pointers and types of lhs and rhs. Calls \c lhs.swap(rhs)
template<class T>
void Swap(tmp<T>& lhs, tmp<T>& rhs)
{
    lhs.swap(rhs);
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#include "tmpI.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //