[core/theme] Add true cycling support

Using the freshly introduced eventing system, enable cycling of widget
attributes.

core/output.py

@@ -49,6 +49,7 @@ class i3(object):
                 'background': self._theme.bg(widget),
                 'separator': self._theme.default_separators(),
             })
+            core.event.trigger('next-widget')
         return widgets
 
     def update(self, affected_modules=None):

core/theme.py

@@ -2,6 +2,8 @@ import os
 import io
 import json
 
+import core.event
+
 THEME_BASE_DIR=os.path.dirname(os.path.realpath(__file__))
 PATHS=[
     '.',
@@ -12,10 +14,13 @@ PATHS=[
 class Theme(object):
     def __init__(self, name='default', iconset=None, raw_data=None):
         self.name = name
+        self.__widget_count = 0
         if raw_data:
-            self._data = raw_data
+            self.__data = raw_data
         else:
-            self._data = self.load(name)
+            self.__data = self.load(name)
+        core.event.register('start', self.__start)
+        core.event.register('next-widget', self.__next_widget)
 
     def load(self, name):
         for path in PATHS:
@@ -34,14 +39,20 @@ class Theme(object):
     def default_separators(self, widget=None):
         return self.__get(widget, 'default-separators', True)
 
+    def __start(self):
+        self.__widget_count = 0
+
+    def __next_widget(self):
+        self.__widget_count = self.__widget_count + 1
+
     def __get(self, widget, key, default=None):
         value = default
 
         for option in ['defaults', 'cycle']:
-            if option in self._data:
-                tmp = self._data[option]
+            if option in self.__data:
+                tmp = self.__data[option]
                 if isinstance(tmp, list):
-                    tmp = tmp[0]
+                    tmp = tmp[self.__widget_count % len(tmp)]
                 value = tmp.get(key, value)
         return value
 

tests/core/test_theme.py

@@ -14,7 +14,8 @@ class theme(unittest.TestCase):
         self.cycleTheme = {
             'cycle': [
                 { 'fg': 'red', 'bg': 'black' },
-                { 'fg': 'black', 'bg': 'red' }
+                { 'fg': 'black', 'bg': 'red' },
+                { 'fg': 'white', 'bg': 'blue' }
             ]
         }
 
@@ -35,5 +36,12 @@ class theme(unittest.TestCase):
         theme = core.theme.Theme(raw_data=self.cycleTheme)
         self.assertEqual(self.cycleTheme['cycle'][0]['fg'], theme.fg())
         self.assertEqual(self.cycleTheme['cycle'][0]['bg'], theme.bg())
+        core.event.trigger('next-widget')
+        core.event.trigger('next-widget')
+        self.assertEqual(self.cycleTheme['cycle'][2]['fg'], theme.fg())
+        self.assertEqual(self.cycleTheme['cycle'][2]['bg'], theme.bg())
+        core.event.trigger('start')
+        self.assertEqual(self.cycleTheme['cycle'][0]['fg'], theme.fg())
+        self.assertEqual(self.cycleTheme['cycle'][0]['bg'], theme.bg())
 
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