Messagelib

modelinvariantindex.h
1/******************************************************************************
2 *
3 * SPDX-FileCopyrightText: 2008 Szymon Tomasz Stefanek <pragma@kvirc.net>
4 *
5 * SPDX-License-Identifier: GPL-2.0-or-later
6 *
7 *******************************************************************************/
8
9#pragma once
10
11#include <memory>
12#include <qglobal.h> // defines uint, at least.
13namespace MessageList
14{
15namespace Core
16{
17class ModelInvariantRowMapper;
18class ModelInvariantRowMapperPrivate;
19class RowShift;
20
21/**
22 * An invariant index that can be ALWAYS used to reference
23 * an item inside a QAbstractItemModel.
24 *
25 * This class is meant to be used together with ModelInvariantRowMapper.
26 */
28{
29 friend class ModelInvariantRowMapper;
30 friend class ModelInvariantRowMapperPrivate;
31 friend class RowShift;
32
33public:
34 explicit ModelInvariantIndex();
35 virtual ~ModelInvariantIndex();
36
37public:
38 /**
39 * Returns true if this ModelInvariantIndex is valid, that is, it has been attached
40 * to a ModelInvariantRowMapper. Returns false otherwise.
41 * An invalid index will always map to the current row -1 (which is invalid as QModelIndex row).
42 */
43 [[nodiscard]] bool isValid() const;
44
45 /**
46 * Returns the current model index row for this invariant index. This function
47 * calls the mapper and asks it to perform the persistent mapping.
48 * If this index isn't valid then the returned value is -1.
49 *
50 * If you actually own the row mapper then you may save some clock cycles
51 * by calling the modelInvariantIndexToModelIndexRow() by your own. If you don't
52 * own the mapper then this function is the only way to go.
53 */
54 [[nodiscard]] int currentModelIndexRow();
55
56private:
57 class ModelInvariantIndexPrivate;
58 std::unique_ptr<ModelInvariantIndexPrivate> const d;
59};
60} // namespace Core
61} // namespace MessageList
An invariant index that can be ALWAYS used to reference an item inside a QAbstractItemModel.
bool isValid() const
Returns true if this ModelInvariantIndex is valid, that is, it has been attached to a ModelInvariantR...
int currentModelIndexRow()
Returns the current model index row for this invariant index.
This class is an optimizing helper for dealing with large flat QAbstractItemModel objects.
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