Move config transforming of to Qt values to configtypes.

This is a preparation for #46.

qutebrowser/config/configtypes.py

@@ -29,6 +29,7 @@ import sre_constants
 from PyQt5.QtCore import QUrl
 from PyQt5.QtGui import QColor, QFont
 from PyQt5.QtNetwork import QNetworkProxy
+from PyQt5.QtWidgets import QTabWidget, QTabBar
 
 from qutebrowser.commands import cmdutils
 
@@ -1146,6 +1147,18 @@ class Position(BaseType):
 
     valid_values = ValidValues('north', 'south', 'east', 'west')
 
+    MAPPING = {
+        'north': QTabWidget.North,
+        'south': QTabWidget.South,
+        'west': QTabWidget.West,
+        'east': QTabWidget.East,
+    }
+
+    def transform(self, value):
+        if not value:
+            return None
+        return self.MAPPING[value]
+
 
 class SelectOnRemove(BaseType):
 
@@ -1156,6 +1169,17 @@ class SelectOnRemove(BaseType):
         ('right', "Select the tab on the right."),
         ('previous', "Select the previously selected tab."))
 
+    MAPPING = {
+        'left': QTabBar.SelectLeftTab,
+        'right': QTabBar.SelectRightTab,
+        'previous': QTabBar.SelectPreviousTab,
+    }
+
+    def transform(self, value):
+        if not value:
+            return None
+        return self.MAPPING[value]
+
 
 class LastClose(BaseType):
 

qutebrowser/widgets/tabwidget.py

@@ -57,26 +57,14 @@ class TabWidget(QTabWidget):
 
     def init_config(self):
         """Initialize attributes based on the config."""
-        position_conv = {
-            'north': QTabWidget.North,
-            'south': QTabWidget.South,
-            'west': QTabWidget.West,
-            'east': QTabWidget.East,
-        }
-        select_conv = {
-            'left': QTabBar.SelectLeftTab,
-            'right': QTabBar.SelectRightTab,
-            'previous': QTabBar.SelectPreviousTab,
-        }
         tabbar = self.tabBar()
         self.setMovable(config.get('tabs', 'movable'))
         self.setTabsClosable(False)
-        posstr = config.get('tabs', 'position')
-        selstr = config.get('tabs', 'select-on-remove')
-        position = position_conv[posstr]
+        position = config.get('tabs', 'position')
+        selection_behaviour = config.get('tabs', 'select-on-remove')
         self.setTabPosition(position)
         tabbar.vertical = position in (QTabWidget.West, QTabWidget.East)
-        tabbar.setSelectionBehaviorOnRemove(select_conv[selstr])
+        tabbar.setSelectionBehaviorOnRemove(selection_behaviour)
         tabbar.refresh()