modeliterator.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 <QModelIndex>
#include "modelsconfig.h"

namespace LC::Util
{
    class UTIL_MODELS_API ModelIterator
    {
        const QAbstractItemModel *Model_ = nullptr;
        QModelIndex Parent_;

        int Row_;
        int Col_;
    public:
        enum class Direction
        {
            Rows,

            Cols
        };
    private:
        Direction Dir_;
    public:
        ModelIterator (const QAbstractItemModel *model, int row, int col = 0,
                Direction dir = Direction::Rows, const QModelIndex& parent = {});

        ModelIterator& operator++ ();

        ModelIterator operator++ (int);

        ModelIterator& operator-- ();

        ModelIterator operator-- (int);

        ModelIterator& operator+= (int count);

        ModelIterator& operator-= (int count);

        int operator- (const ModelIterator& other) const;

        friend UTIL_MODELS_API bool operator== (const ModelIterator& left, const ModelIterator& right);

        QModelIndex operator* () const;

        int GetRow () const;

        int GetCol () const;

        Direction GetDirection () const;
    private:
        int& GetIncrementable ();
        int GetIncrementable () const;
    };


    struct ModelRange
    {
        const ModelIterator Begin_;

        struct Sentinel
        {
            // One past the end
            int End_ = 0;
        };
        const Sentinel End_;

        auto begin () const { return Begin_; }
        auto end () const { return End_; }
    };

    bool UTIL_MODELS_API operator== (const ModelIterator& left, const ModelRange::Sentinel& right);

    inline ModelRange AllModelRows (const QAbstractItemModel& model, int column = 0)
    {
        return ModelRange
        {
            .Begin_ = { &model, 0, column, ModelIterator::Direction::Rows },
            .End_ = { model.rowCount () },
        };
    }

    inline ModelRange ModelRows (const QAbstractItemModel& model, int from, int to, int column = 0)
    {
        return ModelRange
        {
            .Begin_ = { &model, from, column, ModelIterator::Direction::Rows },
            .End_ = { to + 1 },
        };
    }
}

template<>
struct std::iterator_traits<LC::Util::ModelIterator>
{
    typedef QModelIndex value_type;
    typedef int difference_type;

    typedef random_access_iterator_tag iterator_category;
};

static_assert (std::ranges::input_range<LC::Util::ModelRange>);