qt-everywhere-src-5.14.1/qt3d/src/render/backend/stringtoint.cpp

/****************************************************************************
**
** Copyright (C) 2016 Klaralvdalens Datakonsult AB (KDAB).
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt3D module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "stringtoint_p.h"
#include <QMutex>
#include <QReadWriteLock>
#include <QHash>

QT_BEGIN_NAMESPACE

namespace Qt3DRender {

namespace Render {

namespace {

struct StringToIntCache
{
    QReadWriteLock lock;
    QHash<QString, int> map = QHash<QString, int>();
    QVector<QString> reverseMap = QVector<QString>();

    static StringToIntCache& instance()
    {
        static StringToIntCache c;
        return c;
    }
};

} // anonymous

int StringToInt::lookupId(QLatin1String str)
{
    // ### optimize me
    return lookupId(QString(str));
}

int StringToInt::lookupId(const QString &str)
{
    auto& cache = StringToIntCache::instance();
    int idx;
    {
        QReadLocker readLocker(&cache.lock);
        idx = cache.map.value(str, -1);
    }

    if (Q_UNLIKELY(idx < 0)) {
        QWriteLocker writeLocker(&cache.lock);
        idx = cache.map.value(str, -1);
        if (idx < 0) {
            idx = cache.reverseMap.size();
            Q_ASSERT(cache.map.size() == cache.reverseMap.size());
            cache.map.insert(str, idx);
            cache.reverseMap.append(str);
        }
    }
    return idx;
}

QString StringToInt::lookupString(int idx)
{
    auto& cache = StringToIntCache::instance();
    QReadLocker readLocker(&cache.lock);
    if (Q_LIKELY(cache.reverseMap.size() > idx))
        return cache.reverseMap.at(idx);

    return QString();
}

} // Render

} // Qt3DRender

QT_END_NAMESPACE