Add `powerline_segment_datas` attribute

Fixes #1035

docs/source/configuration/reference.rst

@@ -265,6 +265,8 @@ extension-specific key <config-ext-top_theme>` or from :ref:`default_top_theme
 common configuration key <config-common-default_top_theme>`. Powerline ships 
 with the following top themes:
 
+.. _config-top_themes-list:
+
 ==========================  ====================================================
 Theme                       Description
 ==========================  ====================================================

docs/source/develop/segments.rst

@@ -40,6 +40,17 @@ powerline:
     This attribute controls whether segment will receive ``create_watcher`` 
     argument: if it is present argument will be received.
 
+``powerline_segment_datas``
+    This attribute must be a dictionary containing ``top_theme: segment_data`` 
+    mapping where ``top_theme`` is any theme name (it is expected that all of
+    the names from :ref:`top-level themes list <config-top_themes-list>` are 
+    present) and ``segment_data`` is a dictionary like the one that is contained 
+    inside :ref:`segment_data dictionary in configuration 
+    <config-themes-segment_data>`. This attribute should be used to specify 
+    default theme-specific values for *third-party* segments: powerline 
+    theme-specific values go directly to :ref:`top-level themes 
+    <config-themes>`.
+
 ``startup``
     This attribute must be a callable which accepts the following keyword 
     arguments:

powerline/__init__.py

@@ -485,13 +485,15 @@ class Powerline(object):
 
 			self.ext_config = config['ext'][self.ext]
 
+			top_theme = (
+				self.ext_config.get('top_theme')
+				or self.common_config['default_top_theme']
+			)
 			self.theme_levels = (
-				os.path.join('themes', (
-					self.ext_config.get('top_theme')
-					or self.common_config['default_top_theme']
-				)),
+				os.path.join('themes', top_theme),
 				os.path.join('themes', self.ext, '__main__'),
 			)
+			self.renderer_options['theme_kwargs']['top_theme'] = top_theme
 
 			if self.ext_config != self.prev_ext_config:
 				ext_config_differs = True

powerline/segment.py

@@ -4,7 +4,7 @@ from __future__ import absolute_import, unicode_literals, division, print_functi
 from powerline.lib.watcher import create_file_watcher
 
 
-def list_segment_key_values(segment, theme_configs, key, module=None, default=None):
+def list_segment_key_values(segment, theme_configs, segment_data, key, module=None, default=None):
 	try:
 		yield segment[key]
 	except KeyError:
@@ -32,6 +32,11 @@ def list_segment_key_values(segment, theme_configs, key, module=None, default=No
 						yield segment_data[name][key]
 					except KeyError:
 						pass
+	if segment_data is not None:
+		try:
+			yield segment_data[key]
+		except KeyError:
+			pass
 	yield default
 
 
@@ -173,14 +178,15 @@ def process_segment(pl, side, segment_info, parsed_segments, segment, mode):
 		parsed_segments.append(segment)
 
 
-def gen_segment_getter(pl, ext, common_config, theme_configs, default_module, get_module_attr):
+def gen_segment_getter(pl, ext, common_config, theme_configs, default_module, get_module_attr, top_theme):
 	data = {
 		'default_module': default_module or 'powerline.segments.' + ext,
 		'get_module_attr': get_module_attr,
+		'segment_data': None,
 	}
 
 	def get_key(merge, segment, module, key, default=None):
-		return get_segment_key(merge, segment, theme_configs, key, module, default)
+		return get_segment_key(merge, segment, theme_configs, data['segment_data'], key, module, default)
 	data['get_key'] = get_key
 
 	def get(segment, side):
@@ -199,6 +205,13 @@ def gen_segment_getter(pl, ext, common_config, theme_configs, default_module, ge
 		if not get_key(False, segment, module, 'display', True):
 			return None
 
+		segment_datas = getattr(_contents_func, 'powerline_segment_datas', None)
+		if segment_datas:
+			try:
+				data['segment_data'] = segment_datas[top_theme]
+			except KeyError:
+				pass
+
 		if segment_type == 'function':
 			highlight_group = [module + '.' + segment['name'], segment['name']]
 		else:

powerline/theme.py

@@ -30,6 +30,7 @@ class Theme(object):
 	             common_config,
 	             pl,
 	             get_module_attr,
+	             top_theme,
 	             main_theme_config=None,
 	             run_once=False,
 	             shutdown_event=None):
@@ -54,7 +55,15 @@ class Theme(object):
 		theme_configs = [theme_config]
 		if main_theme_config:
 			theme_configs.append(main_theme_config)
-		get_segment = gen_segment_getter(pl, ext, common_config, theme_configs, theme_config.get('default_module'), get_module_attr)
+		get_segment = gen_segment_getter(
+			pl,
+			ext,
+			common_config,
+			theme_configs,
+			theme_config.get('default_module'),
+			get_module_attr,
+			top_theme
+		)
 		for segdict in itertools.chain((theme_config['segments'],),
 		                               theme_config['segments'].get('above', ())):
 			self.segments.append(new_empty_segment_line())

tests/test_configuration.py

@@ -1,13 +1,18 @@
 # vim:fileencoding=utf-8:noet
 from __future__ import unicode_literals, absolute_import, division
-import tests.vim as vim_module
-from tests import TestCase
-from tests.lib.config_mock import get_powerline, get_powerline_raw, swap_attributes
-from functools import wraps
-from copy import deepcopy
+
 import sys
 import os
 
+from functools import wraps
+from copy import deepcopy
+
+import tests.vim as vim_module
+
+from tests import TestCase
+from tests.lib.config_mock import get_powerline, get_powerline_raw, swap_attributes
+from tests.lib import Args
+
 
 def highlighted_string(s, group, **kwargs):
 	ret = {
@@ -428,6 +433,50 @@ class TestModes(TestRender):
 		self.assertRenderEqual(p, '{56} s2{6-}>>{--}', mode='m3')
 
 
+class TestSegmentAttributes(TestRender):
+	@add_args
+	def test_no_attributes(self, p, config):
+		def m1(divider=',', **kwargs):
+			return divider.join(kwargs.keys()) + divider
+		sys.modules['bar'] = Args(m1=m1)
+		config['themes/test/default']['segments'] = {
+			'left': [
+				{
+					'name': 'm1',
+					'module': 'bar'
+				}
+			]
+		}
+		self.assertRenderEqual(p, '{56} pl,{6-}>>{--}')
+
+	@add_args
+	def test_segment_datas(self, p, config):
+		def m1(divider=',', **kwargs):
+			return divider.join(kwargs.keys()) + divider
+		m1.powerline_segment_datas = {
+			'powerline': {
+				'args': {
+					'divider': ';'
+				}
+			},
+			'ascii': {
+				'args': {
+					'divider': '--'
+				}
+			}
+		}
+		sys.modules['bar'] = Args(m1=m1)
+		config['themes/test/default']['segments'] = {
+			'left': [
+				{
+					'name': 'm1',
+					'module': 'bar'
+				}
+			]
+		}
+		self.assertRenderEqual(p, '{56} pl;{6-}>>{--}')
+
+
 class TestVim(TestCase):
 	def test_environ_update(self):
 		# Regression test: test that segment obtains environment from vim, not