Add bufnr segment

Ref #705

powerline/config_files/colorschemes/vim/__main__.json

@@ -14,6 +14,7 @@
 		"position":         "information:additional",
 		"single_tab":       "line_current",
 		"many_tabs":        "line_current",
+		"bufnr":            "information:unimportant",
 		"tabnr":            "file_directory"
 	}
 }

powerline/segments/vim.py

@@ -504,6 +504,18 @@ def tabnr(pl, segment_info, show_current=False):
 		return str(tabnr)
 
 
+@requires_segment_info
+def bufnr(pl, segment_info, show_current=False):
+	'''Show buffer number
+
+	:param bool show_current:
+		If False do not show current window number.
+	'''
+	bufnr = segment_info['bufnr']
+	if show_current or bufnr != vim.current.buffer.number:
+		return str(bufnr)
+
+
 def single_tab(pl, single_text='Bufs', multiple_text='Tabs'):
 	'''Show one text if there is only one tab and another if there are many
 

tests/test_segments.py

@@ -793,6 +793,12 @@ class TestVim(TestCase):
 		self.assertEqual(vim.tabnr(pl=pl, segment_info=segment_info, show_current=True), '1')
 		self.assertEqual(vim.tabnr(pl=pl, segment_info=segment_info, show_current=False), None)
 
+	def test_bufnr(self):
+		pl = Pl()
+		segment_info = vim_module._get_segment_info()
+		self.assertEqual(vim.bufnr(pl=pl, segment_info=segment_info, show_current=True), str(segment_info['bufnr']))
+		self.assertEqual(vim.bufnr(pl=pl, segment_info=segment_info, show_current=False), None)
+
 	def test_single_tab(self):
 		pl = Pl()
 		single_tab = partial(vim.single_tab, pl=pl)