Files
qBittorrent/src/base/utils/compare.cpp
Vladimir Golovnev (Glassez) 399d3ad85a Replace QStringRef with QStringView
2021-07-15 10:56:49 +03:00

97 lines
3.8 KiB
C++

/*
* Bittorrent Client using Qt and libtorrent.
* Copyright (C) 2021 Mike Tzou (Chocobo1)
*
* This program 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 2
* of the License, or (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* In addition, as a special exception, the copyright holders give permission to
* link this program with the OpenSSL project's "OpenSSL" library (or with
* modified versions of it that use the same license as the "OpenSSL" library),
* and distribute the linked executables. You must obey the GNU General Public
* License in all respects for all of the code used other than "OpenSSL". If you
* modify file(s), you may extend this exception to your version of the file(s),
* but you are not obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*/
#include "compare.h"
#include <QChar>
#include <QString>
#ifndef QBT_USE_QCOLLATOR
int Utils::Compare::naturalCompare(const QString &left, const QString &right, const Qt::CaseSensitivity caseSensitivity)
{
// Return value <0: `left` is smaller than `right`
// Return value >0: `left` is greater than `right`
// Return value =0: both strings are equal
int posL = 0;
int posR = 0;
while (true)
{
if ((posL == left.size()) || (posR == right.size()))
return (left.size() - right.size()); // when a shorter string is another string's prefix, shorter string place before longer string
const QChar leftChar = (caseSensitivity == Qt::CaseSensitive) ? left[posL] : left[posL].toLower();
const QChar rightChar = (caseSensitivity == Qt::CaseSensitive) ? right[posR] : right[posR].toLower();
// Compare only non-digits.
// Numbers should be compared as a whole
// otherwise the string->int conversion can yield a wrong value
if ((leftChar == rightChar) && !leftChar.isDigit())
{
// compare next character
++posL;
++posR;
}
else if (leftChar.isDigit() && rightChar.isDigit())
{
// Both are digits, compare the numbers
const auto numberView = [](const QStringView str, int &pos) -> QStringView
{
const int start = pos;
while ((pos < str.size()) && str[pos].isDigit())
++pos;
return str.mid(start, (pos - start));
};
const QStringView numViewL = numberView(left, posL);
const QStringView numViewR = numberView(right, posR);
if (numViewL.length() != numViewR.length())
return (numViewL.length() - numViewR.length());
// both string/view has the same length
for (int i = 0; i < numViewL.length(); ++i)
{
const QChar numL = numViewL[i];
const QChar numR = numViewR[i];
if (numL != numR)
return (numL.unicode() - numR.unicode());
}
// String + digits do match and we haven't hit the end of both strings
// then continue to consume the remainings
}
else
{
return (leftChar.unicode() - rightChar.unicode());
}
}
}
#endif