Add ability to specify some segment keys once in top theme

docs/source/configuration.rst

@@ -145,9 +145,13 @@ Common configuration is a subdictionary that is a value of ``ext`` key in
     Defines the colorscheme used for this extension.
 
 ``theme``
+    .. _config-ext-theme:
+
     Defines the theme used for this extension.
 
 ``local_themes``
+    .. _config-ext-local_themes:
+
     Defines themes used when certain conditions are met, e.g. for 
     buffer-specific statuslines in vim. Requires a custom matcher and theme.
 
@@ -219,6 +223,21 @@ Themes
 ``default_module``
     Python module where segments will be looked by default.
 
+.. _config-themes-segment_data:
+
+``segment_data``
+    A dict where keys are segment names or strings ``{module}.{name}``. Used to 
+    specify default values for various keys:
+    :ref:`after <config-theme-seg-after>`,
+    :ref:`before <config-theme-seg-before>`,
+    :ref:`contents <config-theme-seg-contents>` (only for string segments
+    if :ref:`name <config-themes-seg-name>` is defined),
+    :ref:`args <config-themes-seg-args>` (only for function segments). When 
+    using :ref:`local themes <config-ext-local_themes>` values of these keys are 
+    first searched in the segment description, then in ``segment_data`` key of 
+    a local theme, then in ``segment_data`` key of a :ref:`default theme 
+    <config-ext-theme>`.
+
 ``segments``
     A dict with a ``left`` and a ``right`` list, consisting of segment 
     dicts. Each segment has the following options:
@@ -257,9 +276,13 @@ Themes
         available in the colorscheme is used.
 
     ``before``
+        .. _config-themes-seg-before:
+
         A string which will be prepended to the segment contents.
 
     ``after``
+        .. _config-themes-seg-after:
+
         A string which will be appended to the segment contents.
 
     ``contents``
@@ -268,6 +291,8 @@ Themes
         Segment contents, only required for ``string`` segments.
 
     ``args``
+        .. _config-themes-seg-args:
+
         A dict of arguments to be passed to a ``function`` segment.
 
     ``align``

powerline/config_files/themes/vim/default.json

@@ -1,4 +1,19 @@
 {
+	"segment_data": {
+		"branch": {
+			"before": " "
+		},
+		"modified_indicator": {
+			"args": { "text": "+" }
+		},
+		"line_percent": {
+			"args": { "gradient": true },
+			"after": "%"
+		},
+		"line_current_symbol": {
+			"contents": " "
+		}
+	},
 	"segments": {
 		"left": [
 			{
@@ -14,7 +29,6 @@
 				"name": "branch",
 				"exclude_modes": ["nc"],
 				"priority": 60,
-				"before": " ",
 				"divider_highlight_group": "branch:divider"
 			},
 			{
@@ -38,7 +52,6 @@
 			},
 			{
 				"name": "modified_indicator",
-				"args": { "text": "+" },
 				"before": " "
 			},
 			{
@@ -70,15 +83,13 @@
 			},
 			{
 				"name": "line_percent",
-				"args": { "gradient": true },
 				"priority": 30,
-				"after": "%",
 				"width": 4,
 				"align": "r"
 			},
 			{
 				"type": "string",
-				"contents": " ",
+				"name": "line_current_symbol",
 				"highlight_group": ["line_current_symbol", "line_current"]
 			},
 			{

powerline/config_files/themes/vim/help.json

@@ -15,15 +15,13 @@
 		"right": [
 			{
 				"name": "line_percent",
-				"args": { "gradient": true },
 				"priority": 30,
-				"after": "%",
 				"width": 4,
 				"align": "r"
 			},
 			{
 				"type": "string",
-				"contents": " ",
+				"name": "line_current_symbol",
 				"highlight_group": ["line_current_symbol", "line_current"]
 			},
 			{

powerline/renderer.py

@@ -7,6 +7,7 @@ from powerline.theme import Theme
 class Renderer(object):
 	def __init__(self, theme_config, local_themes, theme_kwargs, **options):
 		self.__dict__.update(options)
+		self.theme_config = theme_config
 		self.theme = Theme(theme_config=theme_config, **theme_kwargs)
 		self.local_themes = local_themes
 		self.theme_kwargs = theme_kwargs
@@ -21,7 +22,7 @@ class Renderer(object):
 			if matcher(matcher_info):
 				match = self.local_themes[matcher]
 				if 'config' in match:
-					match['theme'] = Theme(theme_config=match.pop('config'), **self.theme_kwargs)
+					match['theme'] = Theme(theme_config=match.pop('config'), top_theme_config=self.theme_config, **self.theme_kwargs)
 				return match['theme']
 		else:
 			return self.theme

powerline/segment.py

@@ -4,18 +4,34 @@ from importlib import import_module
 import sys
 
 
+def get_segment_key(segment, theme_configs, key, module=None, default=None):
+	try:
+		return segment[key]
+	except KeyError:
+		if 'name' in segment:
+			name = segment['name']
+			for theme_config in theme_configs:
+				if 'segment_data' in theme_config:
+					for segment_key in ((module+'.'+name, name) if module else (name,)):
+						try:
+							return theme_config['segment_data'][segment_key][key]
+						except KeyError:
+							pass
+	return default
+
+
 def get_function(data, segment):
 	oldpath = sys.path
 	sys.path = data['path'] + sys.path
 	segment_module = str(segment.get('module', data['default_module']))
 	try:
-		return None, getattr(import_module(segment_module), segment['name']), '{0}.{1}'.format(segment_module, segment['name'])
+		return None, getattr(import_module(segment_module), segment['name']), segment_module
 	finally:
 		sys.path = oldpath
 
 
 def get_string(data, segment):
-	return segment.get('contents'), None, None
+	return data['get_key'](segment, None, 'contents'), None, None
 
 
 def get_filler(data, segment):
@@ -29,11 +45,14 @@ segment_getters = {
 		}
 
 
-def gen_segment_getter(ext, path, default_module=None):
+def gen_segment_getter(ext, path, theme_configs, default_module=None):
 	data = {
-			"default_module": default_module or 'powerline.segments.'+ext,
-			"path": path
+			'default_module': default_module or 'powerline.segments.'+ext,
+			'path': path,
 			}
+	def get_key(segment, module, key, default=None):
+		return get_segment_key(segment, theme_configs, key, module, default)
+	data['get_key'] = get_key
 
 	def get(segment, side):
 		segment_type = segment.get('type', 'function')
@@ -41,19 +60,18 @@ def gen_segment_getter(ext, path, default_module=None):
 			get_segment_info = segment_getters[segment_type]
 		except KeyError:
 			raise TypeError('Unknown segment type: {0}'.format(segment_type))
-		contents, contents_func, key = get_segment_info(data, segment)
+		contents, contents_func, module = get_segment_info(data, segment)
 		highlight_group = segment.get('highlight_group', segment.get('name'))
 		divider_highlight_group = segment.get('divider_highlight_group')
 		return {
-			'key': key,
 			'type': segment_type,
 			'highlight_group': highlight_group,
 			'divider_highlight_group': divider_highlight_group,
-			'before': segment.get('before', ''),
-			'after': segment.get('after', ''),
+			'before': get_key(segment, module, 'before', ''),
+			'after':  get_key(segment, module, 'after', ''),
 			'contents_func': contents_func,
 			'contents': contents,
-			'args': segment.get('args', {}),
+			'args': get_key(segment, module, 'args', {}) if segment_type == 'function' else {},
 			'priority': segment.get('priority', -1),
 			'draw_divider': segment.get('draw_divider', True),
 			'side': side,

powerline/theme.py

@@ -18,7 +18,7 @@ def requires_segment_info(func):
 
 
 class Theme(object):
-	def __init__(self, ext, colorscheme, theme_config, common_config, segment_info=None):
+	def __init__(self, ext, colorscheme, theme_config, common_config, top_theme_config=None, segment_info=None):
 		self.colorscheme = colorscheme
 		self.dividers = theme_config.get('dividers', common_config['dividers'])
 		self.spaces = theme_config.get('spaces', common_config['spaces'])
@@ -31,7 +31,10 @@ class Theme(object):
 			'highlight': defaultdict(lambda: {'fg': False, 'bg': False, 'attr': 0})
 			}
 		self.segment_info = segment_info
-		get_segment = gen_segment_getter(ext, common_config['paths'], theme_config.get('default_module'))
+		theme_configs = [theme_config]
+		if top_theme_config:
+			theme_configs.append(top_theme_config)
+		get_segment = gen_segment_getter(ext, common_config['paths'], theme_configs, theme_config.get('default_module'))
 		for side in ['left', 'right']:
 			self.segments[side].extend((get_segment(segment, side) for segment in theme_config['segments'].get(side, [])))