Add initial vim binding functions and segments

Each segment is a function that can accept parameters like the branch or
readonly symbol for overriding the defaults.

vim/bindings.py

@@ -0,0 +1,47 @@
+# -*- coding: utf-8 -*-
+
+import vim
+
+try:
+	_vim_globals = vim.bindeval('g:')
+
+	def vim_set_global_var(var, val):
+		'''Set a global var in vim using bindeval().
+		'''
+		_vim_globals[var] = val
+
+	def vim_get_func(f, rettype=None):
+		'''Return a vim function binding.
+		'''
+		try:
+			return vim.bindeval('function("' + f + '")')
+		except vim.error:
+			return None
+except AttributeError:
+	import json
+
+	def vim_set_global_var(var, val):  # NOQA
+		'''Set a global var in vim using vim.command().
+
+		This is a fallback function for older vim versions.
+		'''
+		vim.command('let g:{0}={1}'.format(var, json.dumps(val)))
+
+	class VimFunc(object):
+		'''Evaluate a vim function using vim.eval().
+
+		This is a fallback class for older vim versions.
+		'''
+		__slots__ = ('f', 'rettype')
+
+		def __init__(self, f, rettype=None):
+			self.f = f
+			self.rettype = rettype
+
+		def __call__(self, *args):
+			r = vim.eval(self.f + '(' + json.dumps(args)[1:-1] + ')')
+			if self.rettype:
+				return self.rettype(r)
+			return r
+
+	vim_get_func = VimFunc

vim/segments/__init__.py

@@ -0,0 +1,5 @@
+# flake8: noqa
+
+from core import (mode, modified_indicator, paste_indicator,
+	readonly_indicator, branch, file_directory, file_name, file_format,
+	file_encoding, file_type, line_percent, line_current, col_current)

vim/segments/core.py

@@ -0,0 +1,144 @@
+# -*- coding: utf-8 -*-
+
+import vim
+
+from bindings import vim_get_func
+
+vim_funcs = {
+	'col': vim_get_func('col', rettype=int),
+	'expand': vim_get_func('expand'),
+	'line': vim_get_func('line', rettype=int),
+	'mode': vim_get_func('mode'),
+	'vcs': {
+		'fugitive': vim_get_func('fugitive#head'),
+	},
+}
+
+vim_modes = {
+	'n': 'NORMAL',
+	'no': 'N·OPER',
+	'v': 'VISUAL',
+	'V': 'V·LINE',
+	'': 'V·BLCK',
+	's': 'SELECT',
+	'S': 'S·LINE',
+	'': 'S·BLCK',
+	'i': 'INSERT',
+	'R': 'REPLACE',
+	'Rv': 'V·RPLCE',
+	'c': 'COMMND',
+	'cv': 'VIM EX',
+	'ce': 'EX',
+	'r': 'PROMPT',
+	'rm': 'MORE',
+	'r?': 'CONFIRM',
+	'!': 'SHELL',
+}
+
+
+def mode(override=None):
+	'''Return the current vim mode.
+
+	This function returns a tuple with the shorthand mode and the mode expanded
+	into a descriptive string. The longer string can be overridden by providing
+	a dict with the mode and the new string::
+
+		mode = mode({ 'n': 'NORM' })
+	'''
+	mode = vim_funcs['mode']()
+
+	try:
+		return override[mode]
+	except TypeError:
+		return vim_modes[mode]
+
+
+def modified_indicator(text=u'+'):
+	'''Return a file modified indicator.
+	'''
+	return text if int(vim.eval('&modified')) else None
+
+
+def paste_indicator(text='PASTE'):
+	'''Return a paste mode indicator.
+	'''
+	return text if int(vim.eval('&paste')) else None
+
+
+def readonly_indicator(text=u'⭤'):
+	'''Return a read-only indicator.
+	'''
+	return text if int(vim.eval('&readonly')) else None
+
+
+def branch(symbol=u'⭠'):
+	'''Return VCS branch.
+
+	TODO: Expand this function to handle several VCS plugins.
+	'''
+	branch = None
+	try:
+		branch = vim_funcs['vcs']['fugitive'](5)
+	except vim.error:
+		vim_funcs['vcs']['fugitive'] = None
+	except TypeError:
+		pass
+
+	return symbol + ' ' + branch if branch else None
+
+
+def file_directory():
+	'''Return file directory (head component of the file path).
+	'''
+	return vim_funcs['expand']('%:~:.:h')
+
+
+def file_name():
+	'''Return file name (tail component of the file path).
+	'''
+	return vim_funcs['expand']('%:~:.:t')
+
+
+def file_format():
+	'''Return file format (i.e. line ending type).
+
+	Returns None for unknown or missing file format.
+	'''
+	return vim.eval('&fileformat') or None
+
+
+def file_encoding():
+	'''Return file encoding/character set.
+
+	Returns None for unknown or missing file encoding.
+	'''
+	return vim.eval('&fileencoding') or None
+
+
+def file_type():
+	'''Return file type.
+
+	Returns None for unknown file types.
+	'''
+	return vim.eval('&filetype') or None
+
+
+def line_percent():
+	'''Return the cursor position in the file as a percentage.
+	'''
+	line_current = vim_funcs['line']('.')
+	line_last = vim_funcs['line']('$')
+
+	return line_current * 100 // line_last
+
+
+def line_current():
+	'''Return the current cursor line.
+	'''
+	return vim_funcs['line']('.')
+
+
+def col_current():
+	'''Return the current cursor column.
+	'''
+	return vim_funcs['col']('.')