cppcore/include/cppcore/misc/compare.inl

#pragma once

#include "compare.h"

namespace cppcore
{

    /* op_invariant_string_less */

    bool op_invariant_string_less
        ::operator()(const std::string& lhs, const std::string& rhs) const
        { return op_invariant_string_compare { } (lhs, rhs) < 0; }

    /* op_invariant_string_compare */

    int op_invariant_string_compare::operator()(const std::string& lhs, const std::string& rhs) const
    {
        auto c1 = lhs.c_str();
        auto c2 = rhs.c_str();
        auto l1 = lhs.size();
        auto l2 = rhs.size();

        while (l1 > 0 && l2 > 0 && std::tolower(*c1) == std::tolower(*c2))
        {
            ++c1;
            ++c2;
            --l1;
            --l2;
        }

        if (l1 > 0 && l2 > 0)
        {
            auto x1 = std::tolower(*c1);
            auto x2 = std::tolower(*c2);

            return
                x1 < x2 ? -1 :
                x1 > x2 ?  1 :
                           0;
        }
        else
        {
            return
                l1 < l2 ? -1 :
                l1 > l2 ?  1 :
                           0;
        }
    }


}