CppEditor: Show info bar for project-less file

While at it, centralize the code for handling the info bars and actions.

Change-Id: Ied62e3db268aaff3ef87e246bfe2b50399341be3
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/cppeditor/cppminimizableinfobars.h

@@ -0,0 +1,79 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 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 <QAction>
+#include <QHash>
+#include <QObject>
+
+#include <functional>
+
+namespace Core {
+class Id;
+class InfoBar;
+}
+
+namespace CppEditor {
+namespace Internal {
+
+class MinimizableInfoBars : public QObject
+{
+    Q_OBJECT
+
+public:
+    using DiagnosticWidgetCreator = std::function<QWidget *()>;
+    using ActionCreator = std::function<QAction *(QWidget *widget)>;
+    using Actions = QHash<Core::Id, QAction *>;
+
+    static Actions createShowInfoBarActions(const ActionCreator &actionCreator);
+
+public:
+    explicit MinimizableInfoBars(Core::InfoBar &infoBar, QObject *parent = 0);
+
+    // Expected call order: processHasProjectPart(), processHeaderDiagnostics()
+    void processHasProjectPart(bool hasProjectPart);
+    void processHeaderDiagnostics(const DiagnosticWidgetCreator &diagnosticWidgetCreator);
+
+signals:
+    void showAction(const Core::Id &id, bool show);
+
+private:
+    void updateNoProjectConfiguration();
+    void updateHeaderErrors();
+
+    void addNoProjectConfigurationEntry(const Core::Id &id);
+    void addHeaderErrorEntry(const Core::Id &id,
+                             const DiagnosticWidgetCreator &diagnosticWidgetCreator);
+
+private:
+    Core::InfoBar &m_infoBar;
+
+    bool m_hasProjectPart = true;
+    DiagnosticWidgetCreator m_diagnosticWidgetCreator;
+};
+
+} // namespace Internal
+} // namespace CppEditor