stringOpsSort.H

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/*---------------------------------------------------------------------------*\
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  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
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-------------------------------------------------------------------------------
    Copyright (C) 2017-2025 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/>.
 
InNamespace
    Foam::stringOps
 
Description
    Specialized string sorting.
 
SourceFiles
    stringOpsSort.cxx
 
\*---------------------------------------------------------------------------*/
 
#ifndef Foam_stringOpsSort_H
#define Foam_stringOpsSort_H
 
#include "stringOps.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace stringOps
{
 
//- 'Natural' compare for C-strings
//  Uses algorithm and code from Jan-Marten Spit <jmspit@euronet.nl>
//
//  In the 'natural' comparison, strings are compared alphabetically
//  and numerically. Thus 'file010.txt' sorts after 'file2.txt'
//
//  \param s1 left string
//  \param s2 right string
//  \return -1 when s1 < s2, 0 when s1 == s2, 1 when s1 > s2
int natstrcmp(const char* s1, const char* s2);
 
 
//- Encapsulation of natural order sorting for algorithms
struct natural_sort
{
    //- Natural compare for std::string
    //  \return -1 when s1 < s2, 0 when s1 == s2, 1 when s1 > s2
    static inline int compare
    (
        const std::string& s1,
        const std::string& s2
    )
    {
        return stringOps::natstrcmp(s1.data(), s2.data());
    }
 
    //- Natural compare two strings for a less-than relationship
    static inline bool less
    (
        const std::string& s1,
        const std::string& s2
    )
    {
        return (natural_sort::compare(s1, s2) < 0);
    }
 
    //- Natural compare two strings for a greater-than relationship
    static inline bool greater
    (
        const std::string& s1,
        const std::string& s2
    )
    {
        return (natural_sort::compare(s1, s2) > 0);
    }
 
    //- Default (forward) natural sorting
    bool operator()(const std::string& s1, const std::string& s2) const
    {
        return (natural_sort::compare(s1, s2) < 0);
    }
 
    //- Reverse natural sorting
    struct reverse
    {
        //- Reverse natural sorting
        bool operator()(const std::string& s1, const std::string& s2) const
        {
            return (natural_sort::compare(s1, s2) > 0);
        }
    };
 
 
    //- A UList compare binary predicate for natural sort
    template<class T>
    struct list_less
    {
        const UList<T>& values;
 
        list_less(const UList<T>& list) noexcept
        :
            values(list)
        {}
 
        bool operator()(label a, label b) const
        {
            return (natural_sort::compare(values[a], values[b]) < 0);
        }
    };
 
 
    //- A Ulist compare binary predicate for reverse natural sort
    template<class T>
    struct list_greater
    {
        const UList<T>& values;
 
        list_greater(const UList<T>& list) noexcept
        :
            values(list)
        {}
 
        bool operator()(label a, label b) const
        {
            return (natural_sort::compare(values[a], values[b]) > 0);
        }
    };
};
 
 
} // End namespace stringOps
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //