CppEditor: Rework showing/switching parse configurations

* Move the combox box for switching the parse configurations out of the
  "Additional Preprocessor Directives" dialog ('#'-button) to make it
  better visible/accessible. Also, decouple the extra preprocessor
  directives from the concrete parse context since this is not anymore
  in same dialog.
* The combo box appears only if multiple parse configurations are
  available for a file.
* The first time multiple parse configurations are detected, an info bar
  is shown that points the user to the combox box. A "Do Not Show Again"
  button is provided.
* Upon selecting an entry, the preferred parse configuration is saved as
  part of the session. The setting can be cleared with the context menu
  entry on the combo box.

Follow-up changes need to ensure that the display name and/or tooltip is
unambiguous, e.g. for qbs and cmake projects.

Change-Id: I9e9773704187291524ad7b605bfdddd83ef5b19d
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/cppeditor/cppparsecontext.cpp

@@ -0,0 +1,172 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 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.
+**
+****************************************************************************/
+
+#include "cppparsecontext.h"
+
+#include <QAction>
+#include <QDir>
+#include <QDebug>
+
+#include <utils/algorithm.h>
+#include <utils/qtcassert.h>
+
+namespace CppEditor {
+namespace Internal {
+
+void ParseContextModel::update(const CppTools::ProjectPartInfo &projectPartInfo)
+{
+    beginResetModel();
+    reset(projectPartInfo);
+    endResetModel();
+
+    emit updated(areMultipleAvailable());
+}
+
+QString ParseContextModel::currentToolTip() const
+{
+    const QModelIndex index = createIndex(m_currentIndex, 0);
+    if (!index.isValid())
+        return QString();
+
+    return tr("<p><b>Active Parse Context</b>:<br/>%1</p>"
+              "<p>Multiple parse contexts (set of defines, include paths, and so on) "
+              "are available for this file.</p>"
+              "<p>Choose a parse context to set it as the preferred one. "
+              "Clear the preference from the context menu.</p>")
+                .arg(data(index, Qt::ToolTipRole).toString());
+}
+
+void ParseContextModel::setPreferred(int index)
+{
+    if (index < 0)
+        return;
+
+    emit preferredParseContextChanged(m_projectParts[index]->id());
+}
+
+void ParseContextModel::clearPreferred()
+{
+    emit preferredParseContextChanged(QString());
+}
+
+bool ParseContextModel::areMultipleAvailable() const
+{
+    return m_projectParts.size() >= 2;
+}
+
+void ParseContextModel::reset(const CppTools::ProjectPartInfo &projectPartInfo)
+{
+    // Sort
+    m_hints = projectPartInfo.hints;
+    m_projectParts = projectPartInfo.projectParts;
+    Utils::sort(m_projectParts, &CppTools::ProjectPart::displayName);
+
+    // Determine index for current
+    const QString id = projectPartInfo.projectPart->id();
+    m_currentIndex = Utils::indexOf(m_projectParts, [id](const CppTools::ProjectPart::Ptr &pp) {
+        return pp->id() == id;
+    });
+    QTC_CHECK(m_currentIndex >= 0);
+}
+
+int ParseContextModel::currentIndex() const
+{
+    return m_currentIndex;
+}
+
+bool ParseContextModel::isCurrentPreferred() const
+{
+    return m_hints & CppTools::ProjectPartInfo::IsPreferredMatch;
+}
+
+QString ParseContextModel::currentId() const
+{
+    if (m_currentIndex < 0)
+        return QString();
+
+    return m_projectParts[m_currentIndex]->id();
+}
+
+int ParseContextModel::rowCount(const QModelIndex &) const
+{
+    return m_projectParts.size();
+}
+
+QVariant ParseContextModel::data(const QModelIndex &index, int role) const
+{
+    if (m_projectParts.isEmpty())
+        return QVariant();
+
+    const int row = index.row();
+    if (role == Qt::DisplayRole)
+        return m_projectParts[row]->displayName;
+    else if (role == Qt::ToolTipRole)
+        return QDir::toNativeSeparators(m_projectParts[row]->projectFile);
+
+    return QVariant();
+}
+
+ParseContextWidget::ParseContextWidget(ParseContextModel &parseContextModel, QWidget *parent)
+    : QComboBox(parent)
+    , m_parseContextModel(parseContextModel)
+{
+    // Set up context menu with a clear action
+    setContextMenuPolicy(Qt::ActionsContextMenu);
+    m_clearPreferredAction = new QAction(tr("Clear Preferred Parse Context"), this);
+    connect(m_clearPreferredAction,  &QAction::triggered,[&]() {
+        m_parseContextModel.clearPreferred();
+    });
+    addAction(m_clearPreferredAction);
+
+    // Set up sync of this widget and model in both directions
+    connect(this,
+            static_cast<void (QComboBox::*)(int)>(&QComboBox::activated),
+            &m_parseContextModel,
+            &ParseContextModel::setPreferred);
+    connect(&m_parseContextModel, &ParseContextModel::updated,
+            this, &ParseContextWidget::syncToModel);
+
+    // Set up model
+    setModel(&m_parseContextModel);
+}
+
+void ParseContextWidget::syncToModel()
+{
+    const int index = m_parseContextModel.currentIndex();
+    if (index < 0)
+        return; // E.g. editor was duplicated but no project context was determined yet.
+
+    if (currentIndex() != index)
+        setCurrentIndex(index);
+
+    setToolTip(m_parseContextModel.currentToolTip());
+
+    const bool isPreferred = m_parseContextModel.isCurrentPreferred();
+    m_clearPreferredAction->setEnabled(isPreferred);
+    QComboBox::setProperty("highlightWidget", isPreferred);
+}
+
+} // namespace Internal
+} // namespace CppEditor