selectionproxymodel.h

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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)
 **********************************************************************/

#pragma once

#include <QIdentityProxyModel>

namespace LC::Util
{
    template<typename Id>
    class SelectionProxyModel : public QIdentityProxyModel
    {
    public:
        struct Config
        {
            int IsSelectedRole_;
            int SourceIdRole_;
            const std::function<QModelIndexList (QSet<Id>)> FindItems_;
        };
    private:
        const Config Config_;

        QSet<Id> Selections_;
    public:
        explicit SelectionProxyModel (QAbstractItemModel& source, const Config& config, QObject *parent = nullptr)
        : QIdentityProxyModel { parent }
        , Config_ { config }
        {
            QIdentityProxyModel::setSourceModel (&source);
        }

        int GetIsSelectedRole () const
        {
            return Config_.IsSelectedRole_;
        }

        void SetSelections (const QSet<Id>& selections)
        {
            if (Selections_ == selections)
                return;

            EmitByIds (std::exchange (Selections_, {}));
            Selections_ = selections;
            EmitByIds (Selections_);
        }

        QVariant data (const QModelIndex& index, int role) const override
        {
            if (role != Config_.IsSelectedRole_)
                return QIdentityProxyModel::data (index, role);

            const auto id = index.data (Config_.SourceIdRole_).template value<Id> ();
            return Selections_.contains (id);
        }
    private:
        void EmitByIds (const QSet<Id>& ids)
        {
            const auto lastColumn = sourceModel ()->columnCount () - 1;
            for (const auto& idx : Config_.FindItems_ (ids))
                emit dataChanged (idx.siblingAtColumn (0), idx.siblingAtColumn (lastColumn), { Config_.IsSelectedRole_ });
        }
    };
}