SubList.H

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    Copyright (C) 2011-2016 OpenFOAM Foundation
    Copyright (C) 2017-2023 OpenCFD Ltd.
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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
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    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::SubList

Description
    A non-owning sub-view of a List (allocated or unallocated storage).

SourceFiles
    SubListI.H

\*---------------------------------------------------------------------------*/

#ifndef Foam_SubList_H
#define Foam_SubList_H

#include "List.H"
#include "labelRange.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// Forward Declarations
template<class T, unsigned N> class FixedList;
template<class T> class SubList;

// Common list types
typedef SubList<bool> boolSubList;      
typedef SubList<char> charSubList;      
typedef SubList<label> labelSubList;    


/*---------------------------------------------------------------------------*\
                           Class SubList Declaration
\*---------------------------------------------------------------------------*/

template<class T>
class SubList
:
    public UList<T>
{
public:

    // Static Functions

        //- Return a null SubList (reference to a nullObject).
        //- Behaves like an empty SubList.
        static const SubList<T>& null() noexcept
        {
            return NullObjectRef<SubList<T>>();
        }


    // Generated Methods

        //- Default construct, zero-sized and nullptr
        SubList() noexcept = default;

        //- Copy construct, shallow copy
        SubList(const SubList<T>&) noexcept = default;


    // Constructors

        //- Construct from UList, the entire size
        inline explicit SubList(const UList<T>& list) noexcept;

        //- Construct from FixedList, the entire size
        template<unsigned N>
        inline explicit SubList(const FixedList<T, N>& list) noexcept;

        //- Construct from UList and sub-list size, start at 0
        inline SubList
        (
            const UList<T>& list,
            const label len
        );

        //- Construct from UList, sub-list size and start index
        inline SubList
        (
            const UList<T>& list,
            const label len,
            const label start
        );

        //- Construct from UList and a (start,size) range.
        //  The range is subsetted with the list size itself to ensure that the
        //  result always addresses a valid section of the list.
        inline SubList
        (
            const UList<T>& list,
            const labelRange& range
        );

        //- Construct from UList and a (start,size) range,
        //- but bypassing run-time range checking.
        inline SubList
        (
            const labelRange& range,
            const UList<T>& list
        );


    // Member Functions

        //- Reset to zero-sized and nullptr
        inline UList<T>& reset(std::nullptr_t) noexcept;

        //- Reset to use entire UList
        inline UList<T>& reset(const UList<T>& list) noexcept;

        //- Reset to use UList with sub-list size, start at 0
        inline UList<T>& reset
        (
            const UList<T>& list,
            const label len
        );

        //- Reset to use UList with sub-list size and start index
        inline UList<T>& reset
        (
            const UList<T>& list,
            const label len,
            const label start
        );

        //- Reset to use UList with a (start,size) range.
        //  The range is subsetted with the list size itself to ensure that the
        //  result always addresses a valid section of the list.
        inline UList<T>& reset
        (
            const UList<T>& list,
            const labelRange& range
        );

        //- Reset to use UList with a (start,size) range, but bypassing
        //- run-time range checking.
        inline UList<T>& reset
        (
            const labelRange& range,
            const UList<T>& list
        );


    // Member Operators

        //- Allow cast to a const List<T>&
        FOAM_DEPRECATED_STRICTER(2025-04, "dereference as SubList, not List?")
        operator const Foam::List<T>&() const
        {
            return *reinterpret_cast<const List<T>*>(this);
        }

        //- Copy assign entries (deep copy) from given sub-list.
        //- Sizes must match!
        inline void operator=(const SubList<T>& list);

        //- Copy assign entries (deep copy) from given list.
        //- Sizes must match!
        inline void operator=(const UList<T>& list);

        //- Copy assign entries from given indirect list. Sizes must match!
        template<class Addr>
        inline void operator=(const IndirectListBase<T, Addr>& list);

        //- Assign all entries to the given value
        inline void operator=(const T& val);

        //- Assign all entries to zero
        inline void operator=(Foam::zero);
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#include "SubListI.H"

// * * * * * * * * * * * * * * * Implementations * * * * * * * * * * * * * * //

template<class Type>
Foam::UList<Type>::UList(SubList<Type>&& list) noexcept
:
    UList<Type>(list.data(), list.size())
{}


template<class Type>
Foam::SubList<Type>
Foam::UList<Type>::slice(const label pos, label len)
{
    if (len < 0)
    {
        len = (this->size() - pos);
    }
    return SubList<Type>(*this, len, pos);
}


template<class Type>
const Foam::SubList<Type>
Foam::UList<Type>::slice(const label pos, label len) const
{
    if (len < 0)
    {
        len = (this->size() - pos);
    }
    return SubList<Type>(*this, len, pos);
}


template<class Type>
Foam::SubList<Type>
Foam::UList<Type>::slice(const labelRange& range)
{
    return SubList<Type>(*this, range);  // with range checking
}


template<class Type>
const Foam::SubList<Type>
Foam::UList<Type>::slice(const labelRange& range) const
{
    return SubList<Type>(*this, range);  // with range checking
}


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //