Integrate new filter engine

Adapt the code to deprecated usage of map as a multi map,
hence all cases replaced by QMultiMap.

Change-Id: I2d480467cd6e91d3e880555e6a21058dec056b3f
Reviewed-by: Karsten Heimrich <karsten.heimrich@qt.io>

src/plugins/coreplugin/helpitem.cpp

@@ -211,7 +211,7 @@ const HelpItem::Links &HelpItem::links() const
             m_helpLinks.emplace(Links{{m_keyword, m_helpUrl}});
         } else {
             m_helpLinks.emplace(); // set a value even if there are no help IDs
-            QMap<QString, QUrl> helpLinks;
+            QMultiMap<QString, QUrl> helpLinks;
             for (const QString &id : m_helpIds) {
                 helpLinks = Core::HelpManager::linksForIdentifier(id);
                 if (!helpLinks.isEmpty()) {

src/plugins/coreplugin/helpmanager.cpp

@@ -86,14 +86,14 @@ void unregisterDocumentation(const QStringList &fileNames)
         m_instance->unregisterDocumentation(fileNames);
 }
 
-QMap<QString, QUrl> linksForIdentifier(const QString &id)
+QMultiMap<QString, QUrl> linksForIdentifier(const QString &id)
 {
-    return checkInstance() ? m_instance->linksForIdentifier(id) : QMap<QString, QUrl>();
+    return checkInstance() ? m_instance->linksForIdentifier(id) : QMultiMap<QString, QUrl>();
 }
 
-QMap<QString, QUrl> linksForKeyword(const QString &keyword)
+QMultiMap<QString, QUrl> linksForKeyword(const QString &keyword)
 {
-    return checkInstance() ? m_instance->linksForKeyword(keyword) : QMap<QString, QUrl>();
+    return checkInstance() ? m_instance->linksForKeyword(keyword) : QMultiMap<QString, QUrl>();
 }
 
 QByteArray fileData(const QUrl &url)

src/plugins/coreplugin/helpmanager.h

@@ -63,8 +63,8 @@ CORE_EXPORT QString documentationPath();
 CORE_EXPORT void registerDocumentation(const QStringList &fileNames);
 CORE_EXPORT void unregisterDocumentation(const QStringList &fileNames);
 
-CORE_EXPORT QMap<QString, QUrl> linksForIdentifier(const QString &id);
+CORE_EXPORT QMultiMap<QString, QUrl> linksForIdentifier(const QString &id);
-CORE_EXPORT QMap<QString, QUrl> linksForKeyword(const QString &id);
+CORE_EXPORT QMultiMap<QString, QUrl> linksForKeyword(const QString &id);
 CORE_EXPORT QByteArray fileData(const QUrl &url);
 
 CORE_EXPORT void showHelpUrl(const QUrl &url, HelpViewerLocation location = HelpModeAlways);

src/plugins/coreplugin/helpmanager_implementation.h

@@ -40,8 +40,8 @@ protected:
 public:
     virtual void registerDocumentation(const QStringList &fileNames) = 0;
     virtual void unregisterDocumentation(const QStringList &fileNames) = 0;
-    virtual QMap<QString, QUrl> linksForIdentifier(const QString &id) = 0;
+    virtual QMultiMap<QString, QUrl> linksForIdentifier(const QString &id) = 0;
-    virtual QMap<QString, QUrl> linksForKeyword(const QString &keyword) = 0;
+    virtual QMultiMap<QString, QUrl> linksForKeyword(const QString &keyword) = 0;
     virtual QByteArray fileData(const QUrl &url) = 0;
     virtual void showHelpUrl(const QUrl &url, HelpViewerLocation location = HelpModeAlways) = 0;
 };

src/plugins/help/filtersettingspage.cpp

@@ -24,8 +24,10 @@
 ****************************************************************************/
 
 #include "filtersettingspage.h"
-
 #include "helpconstants.h"
+
+#ifndef HELP_NEW_FILTER_ENGINE
+
 #include "helpmanager.h"
 
 #include <filternamedialog.h>
@@ -38,6 +40,15 @@
 #include <QFileDialog>
 #include <QMessageBox>
 
+#else
+
+#include <QtCore/QVersionNumber>
+#include <QtHelp/QHelpFilterEngine>
+#include <QtHelp/QHelpFilterSettingsWidget>
+#include "localhelpmanager.h"
+
+#endif
+
 using namespace Help::Internal;
 
 FilterSettingsPage::FilterSettingsPage()
@@ -47,6 +58,8 @@ FilterSettingsPage::FilterSettingsPage()
     setCategory(Help::Constants::HELP_CATEGORY);
 }
 
+#ifndef HELP_NEW_FILTER_ENGINE
+
 QWidget *FilterSettingsPage::widget()
 {
     if (!m_widget) {
@@ -254,3 +267,48 @@ void FilterSettingsPage::updateFilterDescription(const QString &filter)
 {
     m_ui.label->setText(msgFilterLabel(filter));
 }
+
+#else
+
+QWidget *FilterSettingsPage::widget()
+{
+    if (!m_widget) {
+        LocalHelpManager::setupGuiHelpEngine();
+        m_widget = new QHelpFilterSettingsWidget(nullptr);
+        m_widget->readSettings(LocalHelpManager::filterEngine());
+
+        connect(Core::HelpManager::Signals::instance(),
+                &Core::HelpManager::Signals::documentationChanged,
+                this,
+                &FilterSettingsPage::updateFilterPage);
+
+        updateFilterPage();
+    }
+    return m_widget;
+}
+
+void FilterSettingsPage::apply()
+{
+    if (m_widget->applySettings(LocalHelpManager::filterEngine()))
+        emit filtersChanged();
+
+    m_widget->readSettings(LocalHelpManager::filterEngine());
+}
+
+void FilterSettingsPage::finish()
+{
+    disconnect(Core::HelpManager::Signals::instance(),
+               &Core::HelpManager::Signals::documentationChanged,
+               this,
+               &FilterSettingsPage::updateFilterPage);
+    delete m_widget;
+}
+
+void FilterSettingsPage::updateFilterPage()
+{
+    m_widget->setAvailableComponents(LocalHelpManager::filterEngine()->availableComponents());
+    m_widget->setAvailableVersions(LocalHelpManager::filterEngine()->availableVersions());
+}
+
+#endif
+

src/plugins/help/filtersettingspage.h

@@ -25,11 +25,16 @@
 
 #pragma once
 
-#include "ui_filtersettingspage.h"
 #include <coreplugin/dialogs/ioptionspage.h>
 
 #include <QPointer>
 
+#ifndef HELP_NEW_FILTER_ENGINE
+#include "ui_filtersettingspage.h"
+#else
+class QHelpFilterSettingsWidget;
+#endif
+
 namespace Help {
 namespace Internal {
 
@@ -48,9 +53,11 @@ signals:
     void filtersChanged();
 
 private:
+
+    void updateFilterPage();
+#ifndef HELP_NEW_FILTER_ENGINE
     void updateAttributes(QListWidgetItem *item);
     void updateFilterMap();
-    void updateFilterPage();
     void addFilter();
     void removeFilter();
     void updateFilterDescription(const QString &filter);
@@ -64,6 +71,10 @@ private:
     FilterMap m_filterMapBackup;
 
     QStringList m_removedFilters;
+#else
+    QPointer<QHelpFilterSettingsWidget> m_widget;
+#endif
+
 };
 
 } // namespace Help

src/plugins/help/help.pro

@@ -4,6 +4,10 @@ INCLUDEPATH += $$PWD
 
 include(../../qtcreatorplugin.pri)
 
+minQtVersion(5, 15, 0) {
+DEFINES += HELP_NEW_FILTER_ENGINE
+}
+
 DEFINES += \
     QT_CLUCENE_SUPPORT \
     HELP_LIBRARY

src/plugins/help/help.qbs

@@ -1,4 +1,4 @@
-import qbs 1.0
+import qbs.Utilities
 
 Project {
     name: "Help"
@@ -28,6 +28,8 @@ Project {
                 defines.push("QTC_WEBENGINE_HELPVIEWER");
             if (qlitehtml.present)
                 defines.push("QTC_LITEHTML_HELPVIEWER")
+            if (Utilities.versionCompare(Qt.core.version, "5.15") >= 0)
+                defines.push("HELP_NEW_FILTER_ENGINE");
             return defines;
         }
 

src/plugins/help/helpindexfilter.cpp

@@ -32,15 +32,27 @@
 #include <coreplugin/icore.h>
 #include <coreplugin/helpmanager.h>
 #include <extensionsystem/pluginmanager.h>
-#include <utils/algorithm.h>
 #include <utils/utilsicons.h>
 
 #include <QIcon>
+
+#ifndef HELP_NEW_FILTER_ENGINE
+
+#include <utils/algorithm.h>
+
 #include <QSqlDatabase>
 #include <QSqlDriver>
 #include <QSqlError>
 #include <QSqlQuery>
 
+#else
+
+#include "localhelpmanager.h"
+#include <QtHelp/QHelpEngine>
+#include <QtHelp/QHelpFilterEngine>
+#include <QtHelp/QHelpLink>
+
+#endif
 
 using namespace Core;
 using namespace Help;
@@ -66,6 +78,8 @@ HelpIndexFilter::HelpIndexFilter()
 
 HelpIndexFilter::~HelpIndexFilter() = default;
 
+#ifndef HELP_NEW_FILTER_ENGINE
+
 void HelpIndexFilter::prepareSearch(const QString &entry)
 {
     Q_UNUSED(entry)
@@ -133,6 +147,70 @@ QList<LocatorFilterEntry> HelpIndexFilter::matchesFor(QFutureInterface<LocatorFi
     return entries;
 }
 
+#else
+
+bool HelpIndexFilter::updateCache(QFutureInterface<LocatorFilterEntry> &future,
+                                  const QStringList &cache, const QString &entry)
+{
+    const Qt::CaseSensitivity cs = caseSensitivity(entry);
+    QStringList bestKeywords;
+    QStringList worseKeywords;
+    bestKeywords.reserve(cache.size());
+    worseKeywords.reserve(cache.size());
+    for (const QString &keyword : cache) {
+        if (future.isCanceled())
+            return false;
+        if (keyword.startsWith(entry, cs))
+            bestKeywords.append(keyword);
+        else if (keyword.contains(entry, cs))
+            worseKeywords.append(keyword);
+    }
+    bestKeywords << worseKeywords;
+    m_lastIndicesCache = bestKeywords;
+    m_lastEntry = entry;
+
+    return true;
+}
+
+QList<LocatorFilterEntry> HelpIndexFilter::matchesFor(QFutureInterface<LocatorFilterEntry> &future, const QString &entry)
+{
+    m_mutex.lock(); // guard m_needsUpdate
+    bool forceUpdate = m_needsUpdate;
+    m_mutex.unlock();
+
+    if (forceUpdate) {
+        QStringList indices;
+        QMetaObject::invokeMethod(this, "allIndices", Qt::BlockingQueuedConnection,
+                                  Q_RETURN_ARG(QStringList, indices));
+        m_mutex.lock(); // guard m_needsUpdate
+        m_needsUpdate = false;
+        m_mutex.unlock();
+        m_allIndicesCache = indices;
+        // force updating the cache taking the m_allIndicesCache
+        m_lastIndicesCache = QStringList();
+        m_lastEntry = QString();
+    }
+
+    const QStringList cacheBase = m_lastEntry.isEmpty() || !entry.contains(m_lastEntry)
+            ? m_allIndicesCache : m_lastIndicesCache;
+
+    if (!updateCache(future, cacheBase, entry))
+        return QList<LocatorFilterEntry>();
+
+    const Qt::CaseSensitivity cs = caseSensitivity(entry);
+    QList<LocatorFilterEntry> entries;
+    for (const QString &keyword : qAsConst(m_lastIndicesCache)) {
+        const int index = keyword.indexOf(entry, 0, cs);
+        LocatorFilterEntry filterEntry(this, keyword, QVariant(), m_icon);
+        filterEntry.highlightInfo = {index, entry.length()};
+        entries.append(filterEntry);
+    }
+
+    return entries;
+}
+
+#endif
+
 void HelpIndexFilter::accept(LocatorFilterEntry selection,
                              QString *newText, int *selectionStart, int *selectionLength) const
 {
@@ -140,7 +218,14 @@ void HelpIndexFilter::accept(LocatorFilterEntry selection,
     Q_UNUSED(selectionStart)
     Q_UNUSED(selectionLength)
     const QString &key = selection.displayName;
-    const QMap<QString, QUrl> &links = HelpManager::instance()->linksForKeyword(key);
+#ifndef HELP_NEW_FILTER_ENGINE
+    const QMultiMap<QString, QUrl> &links = HelpManager::instance()->linksForKeyword(key);
+#else
+    QMultiMap<QString, QUrl> links;
+    const QList<QHelpLink> docs = LocalHelpManager::helpEngine().documentsForKeyword(key, QString());
+    for (const auto doc : docs)
+        links.insert(doc.title, doc.url);
+#endif
     emit linksActivated(links, key);
 }
 
@@ -150,6 +235,8 @@ void HelpIndexFilter::refresh(QFutureInterface<void> &future)
     invalidateCache();
 }
 
+#ifndef HELP_NEW_FILTER_ENGINE
+
 QSet<QString> HelpIndexFilter::searchMatches(const QString &databaseFilePath,
                                            const QString &term, int limit)
 {
@@ -180,6 +267,16 @@ QSet<QString> HelpIndexFilter::searchMatches(const QString &databaseFilePath,
     return keywords;
 }
 
+#else
+
+QStringList HelpIndexFilter::allIndices() const
+{
+    LocalHelpManager::setupGuiHelpEngine();
+    return LocalHelpManager::filterEngine()->indices(QString());
+}
+
+#endif
+
 void HelpIndexFilter::invalidateCache()
 {
     m_mutex.lock();

src/plugins/help/helpindexfilter.h

@@ -42,24 +42,38 @@ public:
     ~HelpIndexFilter() final;
 
     // ILocatorFilter
-    void prepareSearch(const QString &entry) override;
     QList<Core::LocatorFilterEntry> matchesFor(QFutureInterface<Core::LocatorFilterEntry> &future,
                                                const QString &entry) override;
     void accept(Core::LocatorFilterEntry selection,
                 QString *newText, int *selectionStart, int *selectionLength) const override;
     void refresh(QFutureInterface<void> &future) override;
 
+#ifndef HELP_NEW_FILTER_ENGINE
+    void prepareSearch(const QString &entry) override;
     Q_INVOKABLE QSet<QString> searchMatches(const QString &databaseFilePath,
                                           const QString &term, int limit);
+#else
+    Q_INVOKABLE QStringList allIndices() const;
+#endif
+
 signals:
-    void linksActivated(const QMap<QString, QUrl> &links, const QString &key) const;
+    void linksActivated(const QMultiMap<QString, QUrl> &links, const QString &key) const;
 
 private:
     void invalidateCache();
 
+#ifndef HELP_NEW_FILTER_ENGINE
     QStringList m_helpDatabases;
     QSet<QString> m_keywordCache;
     QString m_searchTermCache;
+#else
+    bool updateCache(QFutureInterface<Core::LocatorFilterEntry> &future,
+                     const QStringList &cache, const QString &entry);
+
+    QStringList m_allIndicesCache;
+    QStringList m_lastIndicesCache;
+    QString m_lastEntry;
+#endif
     bool m_needsUpdate = true;
     QMutex m_mutex;
     QIcon m_icon;

src/plugins/help/helpmanager.cpp

@@ -43,10 +43,15 @@
 #include <QHelpEngineCore>
 
 #include <QMutexLocker>
+
+#ifndef HELP_NEW_FILTER_ENGINE
 #include <QSqlDatabase>
 #include <QSqlDriver>
 #include <QSqlError>
 #include <QSqlQuery>
+#else
+#include <QtHelp/QHelpLink>
+#endif
 
 using namespace Core;
 
@@ -84,6 +89,8 @@ struct HelpManagerPrivate
 static HelpManager *m_instance = nullptr;
 static HelpManagerPrivate *d = nullptr;
 
+#ifndef HELP_NEW_FILTER_ENGINE
+
 // -- DbCleaner
 
 struct DbCleaner
@@ -93,6 +100,8 @@ struct DbCleaner
     QString name;
 };
 
+#endif
+
 // -- HelpManager
 
 HelpManager::HelpManager(QObject *parent) :
@@ -225,20 +234,36 @@ QSet<QString> HelpManager::userDocumentationPaths()
 }
 
 // This should go into Qt 4.8 once we start using it for Qt Creator
-QMap<QString, QUrl> HelpManager::linksForKeyword(const QString &key)
+QMultiMap<QString, QUrl> HelpManager::linksForKeyword(const QString &key)
 {
     QTC_ASSERT(!d->m_needsSetup, return {});
     if (key.isEmpty())
         return {};
+#ifndef HELP_NEW_FILTER_ENGINE
     return d->m_helpEngine->linksForKeyword(key);
+#else
+    QMultiMap<QString, QUrl> links;
+    const QList<QHelpLink> docs = d->m_helpEngine->documentsForKeyword(key, QString());
+    for (const auto doc : docs)
+        links.insert(doc.title, doc.url);
+    return links;
+#endif
 }
 
-QMap<QString, QUrl> HelpManager::linksForIdentifier(const QString &id)
+QMultiMap<QString, QUrl> HelpManager::linksForIdentifier(const QString &id)
 {
     QTC_ASSERT(!d->m_needsSetup, return {});
     if (id.isEmpty())
         return {};
+#ifndef HELP_NEW_FILTER_ENGINE
     return d->m_helpEngine->linksForIdentifier(id);
+#else
+    QMultiMap<QString, QUrl> links;
+    const QList<QHelpLink> docs = d->m_helpEngine->documentsForIdentifier(id, QString());
+    for (const auto doc : docs)
+        links.insert(doc.title, doc.url);
+    return links;
+#endif
 }
 
 QUrl HelpManager::findFile(const QUrl &url)
@@ -292,6 +317,8 @@ QVariant HelpManager::customValue(const QString &key, const QVariant &value)
     return d->m_helpEngine->customValue(key, value);
 }
 
+#ifndef HELP_NEW_FILTER_ENGINE
+
 HelpManager::Filters HelpManager::filters()
 {
     QTC_ASSERT(!d->m_needsSetup, return {});
@@ -358,6 +385,8 @@ void HelpManager::addUserDefinedFilter(const QString &filter, const QStringList
         emit m_instance->collectionFileChanged();
 }
 
+#endif
+
 void HelpManager::aboutToShutdown()
 {
     if (d && d->m_registerFuture.isRunning()) {
@@ -378,6 +407,9 @@ void HelpManager::setupHelpManager()
 
     // create the help engine
     d->m_helpEngine = new QHelpEngineCore(collectionFilePath(), m_instance);
+#ifdef HELP_NEW_FILTER_ENGINE
+    d->m_helpEngine->setUsesFilterEngine(true);
+#endif
     d->m_helpEngine->setupData();
 
     for (const QString &filePath : d->documentationFromInstaller())

src/plugins/help/helpmanager.h

@@ -40,8 +40,6 @@ class HelpManager : public QObject, public Core::HelpManager::Implementation
     Q_OBJECT
 
 public:
-    using Filters = QHash<QString, QStringList>;
-
     explicit HelpManager(QObject *parent = nullptr);
     ~HelpManager() override;
 
@@ -56,8 +54,8 @@ public:
     static void registerUserDocumentation(const QStringList &filePaths);
     static QSet<QString> userDocumentationPaths();
 
-    QMap<QString, QUrl> linksForIdentifier(const QString &id) override;
+    QMultiMap<QString, QUrl> linksForIdentifier(const QString &id) override;
-    QMap<QString, QUrl> linksForKeyword(const QString &key) override;
+    QMultiMap<QString, QUrl> linksForKeyword(const QString &key) override;
 
     static QUrl findFile(const QUrl &url);
     QByteArray fileData(const QUrl &url) override;
@@ -69,12 +67,16 @@ public:
     static void setCustomValue(const QString &key, const QVariant &value);
     static QVariant customValue(const QString &key, const QVariant &value = QVariant());
 
+#ifndef HELP_NEW_FILTER_ENGINE
+    using Filters = QHash<QString, QStringList>;
+
     static Filters filters();
     static Filters fixedFilters();
 
     static Filters userDefinedFilters();
     static void removeUserDefinedFilter(const QString &filter);
     static void addUserDefinedFilter(const QString &filter, const QStringList &attr);
+#endif
 
     static void aboutToShutdown();
 

src/plugins/help/helpplugin.cpp

@@ -116,7 +116,7 @@ public:
     void activateContents();
 
     void saveExternalWindowSettings();
-    void showLinksInCurrentViewer(const QMap<QString, QUrl> &links, const QString &key);
+    void showLinksInCurrentViewer(const QMultiMap<QString, QUrl> &links, const QString &key);
 
     void setupHelpEngineIfNeeded();
 
@@ -124,7 +124,10 @@ public:
 
     void slotSystemInformation();
 
+#ifndef HELP_NEW_FILTER_ENGINE
     void resetFilter();
+#endif
+
     static void activateHelpMode() { ModeManager::activateMode(Constants::ID_MODE_HELP); }
     static bool canShowHelpSideBySide();
 
@@ -314,6 +317,8 @@ ExtensionSystem::IPlugin::ShutdownFlag HelpPlugin::aboutToShutdown()
     return SynchronousShutdown;
 }
 
+#ifndef HELP_NEW_FILTER_ENGINE
+
 void HelpPluginPrivate::resetFilter()
 {
     const QString &filterInternal = QString::fromLatin1("Qt Creator %1.%2.%3")
@@ -348,6 +353,8 @@ void HelpPluginPrivate::resetFilter()
             LocalHelpManager::instance(), &LocalHelpManager::updateFilterModel);
 }
 
+#endif
+
 void HelpPluginPrivate::saveExternalWindowSettings()
 {
     if (!m_externalWindow)
@@ -436,7 +443,7 @@ HelpWidget *HelpPlugin::modeHelpWidget()
     return dd->m_centralWidget;
 }
 
-void HelpPluginPrivate::showLinksInCurrentViewer(const QMap<QString, QUrl> &links, const QString &key)
+void HelpPluginPrivate::showLinksInCurrentViewer(const QMultiMap<QString, QUrl> &links, const QString &key)
 {
     if (links.size() < 1)
         return;
@@ -577,7 +584,7 @@ void HelpPluginPrivate::showContextHelp(const HelpItem &contextHelp)
     } else if (links.size() == 1 && !contextHelp.isFuzzyMatch()) {
         showHelpUrl(links.front().second, LocalHelpManager::contextHelpOption());
     } else {
-        QMap<QString, QUrl> map;
+        QMultiMap<QString, QUrl> map;
         for (const HelpItem::Link &link : links)
             map.insert(link.first, link.second);
         auto tc = new TopicChooser(ICore::dialogParent(), contextHelp.keyword(), map);
@@ -683,7 +690,9 @@ void HelpPluginPrivate::doSetupIfNeeded()
 {
     LocalHelpManager::setupGuiHelpEngine();
     if (m_setupNeeded) {
+#ifndef HELP_NEW_FILTER_ENGINE
         resetFilter();
+#endif
         m_setupNeeded = false;
         m_centralWidget->openPagesManager()->setupInitialPages();
         LocalHelpManager::bookmarkManager().setupBookmarkModels();

src/plugins/help/helpwidget.cpp

@@ -61,6 +61,11 @@
 #include <QStatusBar>
 #include <QToolButton>
 
+#ifdef HELP_NEW_FILTER_ENGINE
+#include <QtHelp/QHelpEngine>
+#include <QtHelp/QHelpFilterEngine>
+#endif
+
 static const char kWindowSideBarSettingsKey[] = "Help/WindowSideBar";
 static const char kModeSideBarSettingsKey[] = "Help/ModeSideBar";
 
@@ -359,15 +364,24 @@ HelpWidget::HelpWidget(const Core::Context &context, WidgetStyle style, QWidget
 
         m_filterComboBox = new QComboBox;
         m_filterComboBox->setMinimumContentsLength(15);
+        layout->addWidget(m_filterComboBox);
+#ifndef HELP_NEW_FILTER_ENGINE
         m_filterComboBox->setModel(LocalHelpManager::filterModel());
         m_filterComboBox->setCurrentIndex(LocalHelpManager::filterIndex());
-        layout->addWidget(m_filterComboBox);
         connect(m_filterComboBox, QOverload<int>::of(&QComboBox::activated),
                 LocalHelpManager::instance(), &LocalHelpManager::setFilterIndex);
         connect(LocalHelpManager::instance(),
                 &LocalHelpManager::filterIndexChanged,
                 m_filterComboBox,
                 &QComboBox::setCurrentIndex);
+#else
+        connect(&LocalHelpManager::helpEngine(), &QHelpEngine::setupFinished,
+                this, &HelpWidget::setupFilterCombo, Qt::QueuedConnection);
+        connect(m_filterComboBox, QOverload<int>::of(&QComboBox::activated),
+                this, &HelpWidget::filterDocumentation);
+        connect(LocalHelpManager::filterEngine(), &QHelpFilterEngine::filterActivated,
+                this, &HelpWidget::currentFilterChanged);
+#endif
 
         Core::ActionContainer *windowMenu = Core::ActionManager::actionContainer(
             Core::Constants::M_WINDOW);
@@ -487,6 +501,41 @@ HelpWidget::HelpWidget(const Core::Context &context, WidgetStyle style, QWidget
     }
 }
 
+#ifdef HELP_NEW_FILTER_ENGINE
+
+void HelpWidget::setupFilterCombo()
+{
+    const QString currentFilter = LocalHelpManager::filterEngine()->activeFilter();
+    m_filterComboBox->clear();
+    m_filterComboBox->addItem(tr("Unfiltered"));
+    const QStringList allFilters = LocalHelpManager::filterEngine()->filters();
+    if (!allFilters.isEmpty())
+        m_filterComboBox->insertSeparator(1);
+    for (const QString &filter : allFilters)
+        m_filterComboBox->addItem(filter, filter);
+
+    int idx = m_filterComboBox->findData(currentFilter);
+    if (idx < 0)
+        idx = 0;
+    m_filterComboBox->setCurrentIndex(idx);
+}
+
+void HelpWidget::filterDocumentation(int filterIndex)
+{
+    const QString filter = m_filterComboBox->itemData(filterIndex).toString();
+    LocalHelpManager::filterEngine()->setActiveFilter(filter);
+}
+
+void HelpWidget::currentFilterChanged(const QString &filter)
+{
+    int index = m_filterComboBox->findData(filter);
+    if (index < 0)
+        index = 0;
+    m_filterComboBox->setCurrentIndex(index);
+}
+
+#endif
+
 HelpWidget::~HelpWidget()
 {
     saveState();
@@ -753,7 +802,7 @@ HelpViewer *HelpWidget::openNewPage(const QUrl &url)
     return page;
 }
 
-void HelpWidget::showLinks(const QMap<QString, QUrl> &links,
+void HelpWidget::showLinks(const QMultiMap<QString, QUrl> &links,
     const QString &keyword, bool newPage)
 {
     if (links.size() < 1)

src/plugins/help/helpwidget.h

@@ -96,7 +96,7 @@ public:
     void open(const QUrl &url, bool newPage = false);
     HelpViewer *openNewPage(const QUrl &url);
     void openFromSearch(const QUrl &url, const QStringList &searchTerms, bool newPage = false);
-    void showLinks(const QMap<QString, QUrl> &links, const QString &key,
+    void showLinks(const QMultiMap<QString, QUrl> &links, const QString &key,
                           bool newPage = false);
     void activateSideBarItem(const QString &id);
 
@@ -142,6 +142,12 @@ private:
     void addSideBar();
     QString sideBarSettingsKey() const;
 
+#ifdef HELP_NEW_FILTER_ENGINE
+    void setupFilterCombo();
+    void filterDocumentation(int filterIndex);
+    void currentFilterChanged(const QString &filter);
+#endif
+
     OpenPagesModel m_model;
     OpenPagesManager *m_openPagesManager = nullptr;
     Core::IContext *m_context = nullptr;

src/plugins/help/localhelpmanager.cpp

@@ -70,10 +70,14 @@ QHelpEngine* LocalHelpManager::m_guiEngine = nullptr;
 QMutex LocalHelpManager::m_bkmarkMutex;
 BookmarkManager* LocalHelpManager::m_bookmarkManager = nullptr;
 
+#ifndef HELP_NEW_FILTER_ENGINE
+
 QStandardItemModel *LocalHelpManager::m_filterModel = nullptr;
 QString LocalHelpManager::m_currentFilter = QString();
 int LocalHelpManager::m_currentFilterIndex = -1;
 
+#endif
+
 static const char kHelpHomePageKey[] = "Help/HomePage";
 static const char kFontFamilyKey[] = "Help/FallbackFontFamily";
 static const char kFontStyleNameKey[] = "Help/FallbackFontStyleName";
@@ -123,7 +127,9 @@ LocalHelpManager::LocalHelpManager(QObject *parent)
 {
     m_instance = this;
     qRegisterMetaType<Help::Internal::LocalHelpManager::HelpData>("Help::Internal::LocalHelpManager::HelpData");
+#ifndef HELP_NEW_FILTER_ENGINE
     m_filterModel = new QStandardItemModel(this);
+#endif
 }
 
 LocalHelpManager::~LocalHelpManager()
@@ -396,8 +402,12 @@ QHelpEngine &LocalHelpManager::helpEngine()
 {
     if (!m_guiEngine) {
         QMutexLocker _(&m_guiMutex);
-        if (!m_guiEngine)
+        if (!m_guiEngine) {
             m_guiEngine = new QHelpEngine(QString());
+#ifdef HELP_NEW_FILTER_ENGINE
+            m_guiEngine->setUsesFilterEngine(true);
+#endif
+        }
     }
     return *m_guiEngine;
 }
@@ -495,6 +505,8 @@ LocalHelpManager::HelpData LocalHelpManager::helpData(const QUrl &url)
     return data;
 }
 
+#ifndef HELP_NEW_FILTER_ENGINE
+
 QAbstractItemModel *LocalHelpManager::filterModel()
 {
     return m_filterModel;
@@ -544,6 +556,15 @@ void LocalHelpManager::updateFilterModel()
     emit m_instance->filterIndexChanged(m_currentFilterIndex);
 }
 
+#else
+
+QHelpFilterEngine *LocalHelpManager::filterEngine()
+{
+    return helpEngine().filterEngine();
+}
+
+#endif
+
 bool LocalHelpManager::canOpenOnlineHelp(const QUrl &url)
 {
     const QString address = url.toString();

src/plugins/help/localhelpmanager.h

@@ -31,9 +31,12 @@
 #include <QMutex>
 #include <QObject>
 #include <QUrl>
+#ifndef HELP_NEW_FILTER_ENGINE
 #include <QStandardItemModel>
-
 #include <functional>
+#else
+QT_FORWARD_DECLARE_CLASS(QHelpFilterEngine)
+#endif
 
 QT_FORWARD_DECLARE_CLASS(QHelpEngine)
 
@@ -116,17 +119,23 @@ public:
     static QByteArray loadErrorMessage(const QUrl &url, const QString &errorString);
     Q_INVOKABLE static Help::Internal::LocalHelpManager::HelpData helpData(const QUrl &url);
 
+#ifndef HELP_NEW_FILTER_ENGINE
     static QAbstractItemModel *filterModel();
     static void setFilterIndex(int index);
     static int filterIndex();
 
     static void updateFilterModel();
+#else
+    static QHelpFilterEngine *filterEngine();
+#endif
 
     static bool canOpenOnlineHelp(const QUrl &url);
     static bool openOnlineHelp(const QUrl &url);
 
 signals:
+#ifndef HELP_NEW_FILTER_ENGINE
     void filterIndexChanged(int index);
+#endif
     void fallbackFontChanged(const QFont &font);
     void returnOnCloseChanged();
     void scrollWheelZoomingEnabledChanged(bool enabled);
@@ -136,9 +145,11 @@ private:
     static bool m_guiNeedsSetup;
     static bool m_needsCollectionFile;
 
+#ifndef HELP_NEW_FILTER_ENGINE
     static QStandardItemModel *m_filterModel;
     static QString m_currentFilter;
     static int m_currentFilterIndex;
+#endif
 
     static QMutex m_guiMutex;
     static QHelpEngine *m_guiEngine;

src/shared/help/indexwindow.cpp

@@ -196,7 +196,7 @@ void IndexWindow::disableSearchLineEdit()
 void IndexWindow::open(const QModelIndex &index, bool newPage)
 {
     QString keyword = m_filteredIndexModel->data(index, Qt::DisplayRole).toString();
-    QMap<QString, QUrl> links = LocalHelpManager::helpEngine().indexModel()->linksForKeyword(keyword);
+    QMultiMap<QString, QUrl> links = LocalHelpManager::helpEngine().indexModel()->linksForKeyword(keyword);
     emit linksActivated(links, keyword, newPage);
 }
 

src/shared/help/indexwindow.h

@@ -88,7 +88,7 @@ public:
     void setOpenInNewPageActionVisible(bool visible);
 
 signals:
-    void linksActivated(const QMap<QString, QUrl> &links,
+    void linksActivated(const QMultiMap<QString, QUrl> &links,
         const QString &keyword, bool newPage);
 
 private:

src/shared/help/topicchooser.cpp

@@ -33,7 +33,7 @@
 #include <QSortFilterProxyModel>
 
 TopicChooser::TopicChooser(QWidget *parent, const QString &keyword,
-        const QMap<QString, QUrl> &links)
+        const QMultiMap<QString, QUrl> &links)
     : QDialog(parent)
     , m_filterModel(new QSortFilterProxyModel(this))
 {
@@ -49,7 +49,7 @@ TopicChooser::TopicChooser(QWidget *parent, const QString &keyword,
     m_filterModel->setSourceModel(model);
     m_filterModel->setFilterCaseSensitivity(Qt::CaseInsensitive);
 
-    QMap<QString, QUrl>::const_iterator it = links.constBegin();
+    QMultiMap<QString, QUrl>::const_iterator it = links.constBegin();
     for (; it != links.constEnd(); ++it) {
         m_links.append(it.value());
         QStandardItem *item = new QStandardItem(it.key());

src/shared/help/topicchooser.h

@@ -42,7 +42,7 @@ class TopicChooser : public QDialog
 
 public:
     TopicChooser(QWidget *parent, const QString &keyword,
-        const QMap<QString, QUrl> &links);
+        const QMultiMap<QString, QUrl> &links);
 
     QUrl link() const;