TextEditor: Let BaseHoverHandler handle help id callbacks

...to support asynchronous hover handlers like ClangHoverHandler.

Change-Id: I8dc7189db37ec3a923cf493b8957c59ec9be447c
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/texteditor/basehoverhandler.cpp

@@ -70,16 +70,16 @@ void BaseHoverHandler::setPriority(int priority)
     m_priority = priority;
 }
 
-QString BaseHoverHandler::contextHelpId(TextEditorWidget *widget, int pos)
+void BaseHoverHandler::contextHelpId(TextEditorWidget *widget,
+                                     int pos,
+                                     const Core::IContext::HelpIdCallback &callback)
 {
     // If the tooltip is visible and there is a help match, this match is used to update
     // the help id. Otherwise, let the identification process happen.
     if (!Utils::ToolTip::isVisible() || !lastHelpItemIdentified().isValid())
-        process(widget, pos, [](int){});
+        process(widget, pos, [this, widget, callback](int) { propagateHelpId(widget, callback); });
-
+    else
-    if (lastHelpItemIdentified().isValid())
+        propagateHelpId(widget, callback);
-        return lastHelpItemIdentified().helpId();
-    return QString();
 }
 
 void BaseHoverHandler::setToolTip(const QString &tooltip)
@@ -102,6 +102,17 @@ const HelpItem &BaseHoverHandler::lastHelpItemIdentified() const
     return m_lastHelpItemIdentified;
 }
 
+void BaseHoverHandler::propagateHelpId(TextEditorWidget *widget,
+                                       const Core::IContext::HelpIdCallback &callback)
+{
+    QString id;
+    if (lastHelpItemIdentified().isValid())
+        id = lastHelpItemIdentified().helpId();
+
+    widget->setContextHelpId(id);
+    callback(id);
+}
+
 void BaseHoverHandler::process(TextEditorWidget *widget, int pos, ReportPriority report)
 {
     m_toolTip.clear();

src/plugins/texteditor/basehoverhandler.h

@@ -28,6 +28,8 @@
 #include "texteditor_global.h"
 #include "helpitem.h"
 
+#include <coreplugin/icontext.h>
+
 #include <functional>
 
 QT_BEGIN_NAMESPACE
@@ -43,7 +45,9 @@ class TEXTEDITOR_EXPORT BaseHoverHandler
 public:
     virtual ~BaseHoverHandler();
 
-    QString contextHelpId(TextEditorWidget *widget, int pos);
+    void contextHelpId(TextEditorWidget *widget,
+                       int pos,
+                       const Core::IContext::HelpIdCallback &callback);
 
     using ReportPriority = std::function<void(int priority)>;
     void checkPriority(TextEditorWidget *widget, int pos, ReportPriority report);
@@ -67,6 +71,8 @@ protected:
     void setLastHelpItemIdentified(const HelpItem &help);
     const HelpItem &lastHelpItemIdentified() const;
 
+    void propagateHelpId(TextEditorWidget *widget, const Core::IContext::HelpIdCallback &callback);
+
     // identifyMatch() is required to report a priority by using the "report" callback.
     // It is recommended to use e.g.
     //    Utils::ExecuteOnDestruction reportPriority([this, report](){ report(priority()); });

src/plugins/texteditor/texteditor.cpp

@@ -7925,8 +7925,9 @@ void BaseTextEditor::setContextHelpId(const QString &id)
 void TextEditorWidget::contextHelpId(const IContext::HelpIdCallback &callback)
 {
     if (d->m_contextHelpId.isEmpty() && !d->m_hoverHandlers.isEmpty())
-        d->m_contextHelpId = d->m_hoverHandlers.first()->contextHelpId(this, textCursor().position());
+        d->m_hoverHandlers.first()->contextHelpId(this, textCursor().position(), callback);
-    callback(d->m_contextHelpId);
+    else
+        callback(d->m_contextHelpId);
 }
 
 void TextEditorWidget::setContextHelpId(const QString &id)