feat(completion): wire query completion into the main window

Adds the complete_query action, whose registration the assertion in
registerActions() has been demanding since keymap gained the name: a
known action nothing implements would have been a silently dead binding.

Also lands the QueryCompleter half of the manual trigger, which the
keymap commit left behind: triggerCompletion() and the focus-in filter
gated on completion_on_focus.

Tags refresh at startup, after a sync, and after a mutation introduces a
tag not already known, since that is the tag most likely to be typed
again. onAllTagsReady deliberately drops the generation the signal
carries: a tag list is not an ordered query result, so a later one is
always at least as good as an earlier one and discarding on staleness
could only throw away a good list.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/mainwindow.h b/src/mainwindow.h
index f4186ff..3623b04 100644
--- a/src/mainwindow.h
+++ b/src/mainwindow.h
@@ -44,6 +44,7 @@ class ThreadListModel;
 class MessageView;
 class MailSync;
 class NotmuchWorker;
+class QueryCompleter;
 
 class MainWindow : public QMainWindow
 {
@@ -81,6 +82,7 @@ private slots:
     void onThreadLoaded(const QVector<MessageRef> &messages, quint64 generation);
     void onWorkerError(const QString &message);
     void onSyncFinished(bool success, int exitCode);
+    void onAllTagsReady(const QStringList &tags);
 
 private:
     void buildUi();
@@ -93,6 +95,10 @@ private:
     void registerActions();
     void buildMenus();
     void wireWorker();
+
+    /// Asks the worker to re-enumerate the database tags for the completer.
+    void requestAllTags();
+
     void showWarnings();
     void showShortcutReference();
     void showAbout();
@@ -131,6 +137,7 @@ private:
     QUndoStack m_undoStack;
 
     QLineEdit *m_queryEdit = nullptr;
+    QueryCompleter *m_queryCompleter = nullptr;
     QTableView *m_threadView = nullptr;
     QSplitter *m_splitter = nullptr;
     QComboBox *m_accountBox = nullptr;
@@ -147,6 +154,11 @@ private:
     /// parallel with them.
     QHash<QString, QString> m_actionDescriptions;
 
+    /// The tag list last received from the worker. Held here and not only in
+    /// the completer so a mutation can ask whether it introduced a tag the
+    /// completer does not yet offer, without a round trip.
+    QStringList m_knownTags;
+
     quint64 m_generation = 0;
     QString m_lastQuery;
     QString m_currentThreadId;