Add a quick-complete option.

This moves to the next commandline part when completing if there's only
one possible completion.

TODO

@@ -56,7 +56,6 @@ Improvements / minor features
 - Zoom with ctrl + mousewheel
 - search highlighting
 - max height for completion (be smaller if possible)
-- tab should directly insert word and space if there's only one option
 - vertical tabbar
 - reload config command
     - config changed signals for sections (optimization)

qutebrowser/config/configdata.py

@@ -266,6 +266,10 @@ DATA = OrderedDict([
          "How many commands to save in the history. 0: no history / -1: "
          "unlimited"),
 
+        ('quick-complete',
+         SettingValue(types.Bool(), 'true'),
+         "Whether to move on to the next part when there's only one possible "
+         "completion left."),
     )),
 
     ('input', sect.KeyValue(

qutebrowser/widgets/_completion.py

@@ -65,7 +65,10 @@ class CompletionView(QTreeView):
     Signals:
         change_completed_part: Text which should be substituted for the word
                                we're currently completing.
-                               arg: The text to change to.
+                               arg 0: The text to change to.
+                               arg 1: True if the text should be set
+                                      immediately, without continuing
+                                      completing the current field.
     """
 
     STYLESHEET = """
@@ -100,7 +103,7 @@ class CompletionView(QTreeView):
 
     # FIXME style scrollbar
 
-    change_completed_part = pyqtSignal(str)
+    change_completed_part = pyqtSignal(str, bool)
 
     def __init__(self, parent=None):
         super().__init__(parent)
@@ -367,9 +370,15 @@ class CompletionView(QTreeView):
         if indexes:
             data = self._model.data(indexes[0])
             if data is not None:
-                self._ignore_change = True
-                self.change_completed_part.emit(data)
-                self._ignore_change = False
+                if (self._model.rowCount(indexes[0].parent()) == 1 and
+                        config.get('completion', 'quick-complete')):
+                    # If we only have one item, we want to apply it immediately
+                    # and go on to the next part.
+                    self.change_completed_part.emit(data, True)
+                else:
+                    self._ignore_change = True
+                    self.change_completed_part.emit(data, False)
+                    self._ignore_change = False
         super().selectionChanged(selected, deselected)
 
     def resizeEvent(self, e):

qutebrowser/widgets/statusbar/_command.py

@@ -140,19 +140,32 @@ class Command(MinimalLineEdit):
         self.setFocus()
         self.show_cmd.emit()
 
-    @pyqtSlot(str)
-    def on_change_completed_part(self, newtext):
+    @pyqtSlot(str, bool)
+    def on_change_completed_part(self, newtext, immediate):
         """Change the part we're currently completing in the commandline.
 
         Args:
             text: The text to set (string).
+            immediate: True if the text should be completed immediately
+                       including a trailing space and we shouldn't continue
+                       completing the current item.
         """
         parts = self.parts[:]
         logger.debug("parts: {}, changing {} to '{}'".format(
             parts, self.cursor_part, newtext))
         parts[self.cursor_part] = newtext
+        # We want to place the cursor directly after the part we just changed.
         cursor_str = self.prefix + ' '.join(parts[:self.cursor_part + 1])
-        self.setText(self.prefix + ' '.join(parts))
+        if immediate:
+            # If we should complete immediately, we want to move the cursor by
+            # one more char, to get to the next field.
+            cursor_str += ' '
+        text = self.prefix + ' '.join(parts)
+        if immediate and self.cursor_part == len(parts) - 1:
+            # If we should complete immediately and we're completing the last
+            # part in the commandline, we automatically add a space.
+            text += ' '
+        self.setText(text)
         logger.debug("Placing cursor after '{}'".format(cursor_str))
         self.setCursorPosition(len(cursor_str))
         self.setFocus()