domchildrenrange.cpp

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE or copy at https://www.boost.org/LICENSE_1_0.txt)
 **********************************************************************/
 
#include "domchildrenrange.h"
#include <QVector>
 
namespace LC::Util
{
    namespace
    {
        void DomDescendants (const QDomElement& parent, const QString& tag, QVector<QDomElement>& result)
        {
            for (const auto& elem : DomChildren (parent, {}))
            {
                if (elem.tagName () == tag)
                    result << elem;
 
                DomDescendants (elem, tag, result);
            }
        }
    }
 
    QVector<QDomElement> DomDescendants (const QDomElement& parent, const QString& tag)
    {
        const auto& allElems = parent.elementsByTagName (tag);
        const auto elemsCount = allElems.size ();
 
        QVector<QDomElement> result;
        result.reserve (elemsCount);
 
        // QDomNodeList operations are slower than explicit recursion for bigger lists,
        // and this is a somewhat empirical threshold.
        constexpr auto countThreshold = 200;
 
        if (elemsCount < countThreshold)
            for (int i = 0; i < allElems.size (); ++i)
                result << allElems.at (i).toElement ();
        else
            DomDescendants (parent, tag, result);
 
        return result;
    }
}