AutoTest: Persist check state to project settings

Make it easier to switch between projects and restore
the former check states of the found test items if
we have these information.

Change-Id: I99a5357388c36aa8cce6f5f82184d6ab2a8bf6e8
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/autotest/itemdatacache.h

@@ -0,0 +1,87 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** 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 General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** 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-3.0.html.
+**
+****************************************************************************/
+
+#pragma once
+
+#include "testtreeitem.h"
+
+#include <utils/optional.h>
+
+#include <QVariantHash>
+
+namespace Autotest {
+namespace Internal {
+
+template<class T>
+class ItemDataCache
+{
+public:
+    void insert(TestTreeItem *item, const T &value) { m_cache[item->cacheName()] = {0, value}; }
+    void evolve()
+    {
+        auto it = m_cache.begin(), end = m_cache.end();
+        while (it != end)
+            it = it->generation++ >= maxGen ? m_cache.erase(it) : ++it;
+    }
+
+    Utils::optional<T> get(TestTreeItem *item)
+    {
+        auto entry = m_cache.find(item->cacheName());
+        if (entry == m_cache.end())
+            return Utils::nullopt;
+        entry->generation = 0;
+        return Utils::make_optional(entry->value);
+    };
+
+    void clear() { m_cache.clear(); }
+    bool isEmpty() const { return m_cache.isEmpty(); }
+
+    QVariantHash toSettings() const
+    {
+        QVariantHash result;
+        for (auto it = m_cache.cbegin(), end = m_cache.cend(); it != end; ++it)
+            result.insert(it.key(), QVariant::fromValue(it.value().value));
+        return result;
+    }
+
+    void fromSettings(const QVariantHash &stored)
+    {
+        m_cache.clear();
+        for (auto it = stored.cbegin(), end = stored.cend(); it != end; ++it)
+            m_cache[it.key()] = {0, qvariant_cast<T>(it.value())};
+    }
+
+private:
+    static constexpr int maxGen = 10;
+    struct Entry
+    {
+        int generation = 0;
+        T value;
+    };
+    QHash<QString, Entry> m_cache;
+};
+
+} // namespace Internal
+} // namespace Autotest