Take overrides from environment variables

Ref #1201

docs/source/configuration/local.rst

@@ -67,11 +67,82 @@ Powerline script has a number of options controlling powerline behavior. Here
     performed by powerline script itself, but ``-p ~/.powerline`` will likely be 
     expanded by the shell to something like ``-p /home/user/.powerline``.
 
+Environment variables overrides
+===============================
+
+All bindings that use ``POWERLINE_COMMAND`` environment variable support taking 
+overrides from environment variables. In this case overrides should look like 
+the following::
+
+    OVERRIDE='key1.key2.key3=value;key4.key5={"value":1};key6=true;key1.key7=10'
+
+. This will be parsed into
+
+.. code-block:: Python
+
+    {
+        "key1": {
+            "key2": {
+                "key3": "value"
+            },
+            "key7": 10,
+        },
+        "key4": {
+            "key5": {
+                "value": 1,
+            },
+        },
+        "key6": True,
+    }
+
+. Rules:
+
+#. Environment variable must form a semicolon-separated list of key-value pairs: 
+   ``key=value;key2=value2``.
+#. Keys are always dot-separated strings that must not contain equals sign (as 
+   well as semicolon) or start with an underscore. They are interpreted 
+   literally and create a nested set of dictionaries: ``k1.k2.k3`` creates 
+   ``{"k1":{"k2":{}}}`` and inside the innermost dictionary last key (``k3`` in 
+   the example) is contained with its value.
+#. Value may be empty in which case they are interpreted as an order to remove 
+   some value: ``k1.k2=`` will form ``{"k1":{"k2":REMOVE_THIS_KEY}}`` nested 
+   dictionary where ``k2`` value is a special value that tells 
+   dictionary-merging function to remove ``k2`` rather then replace it with 
+   something.
+#. Value may be a JSON strings like ``{"a":1}`` (JSON dictionary), ``["a",1]`` 
+   (JSON list), ``1`` or ``-1`` (JSON number), ``"abc"`` (JSON string) or 
+   ``true``, ``false`` and ``null`` (JSON boolean objects and ``Null`` object 
+   from JSON). General rule is that anything starting with a digit (U+0030 till 
+   U+0039, inclusive), a hyphenminus (U+002D), a quotation mark (U+0022), a left 
+   curly bracket (U+007B) or a left square bracket (U+005B) is considered to be 
+   some JSON object, same for *exact* values ``true``, ``false`` and ``null``.
+#. Any other value is considered to be literal string: ``k1=foo:bar`` parses to 
+   ``{"k1": "foo:bar"}``.
+
+The following environment variables may be used for overrides according to the 
+above rules:
+
+``POWERLINE_CONFIG_OVERRIDES``
+    Overrides values from :file:`powerline/config.json`.
+
+``POWERLINE_THEME_OVERRIDES``
+    Overrides values from :file:`powerline/themes/{ext}/{key}.json`. Top-level 
+    key is treated as a name of the theme for which overrides are used: e.g. to 
+    disable cwd segment defined in :file:`powerline/themes/shell/default.json` 
+    one needs to use::
+
+        POWERLINE_THEME_OVERRIDES=default.segment_data.cwd.display=false
+
+Additionally one environment variable is a usual *colon*-separated list of 
+directories: ``POWERLINE_CONFIG_PATHS``. This one defines paths which will be 
+searched for configuration.
+
 Zsh/zpython overrides
 =====================
 
 Here overrides are controlled by similarly to the powerline script, but values 
-are taken from zsh variables.
+are taken from zsh variables. :ref:`Environment variable overrides` are also 
+supported: if variable is a string this variant is used.
 
 ``POWERLINE_CONFIG_OVERRIDES``
     Overrides options from :file:`powerline/config.json`. Should be a zsh 

powerline/bindings/zsh/__init__.py

@@ -8,7 +8,7 @@ from weakref import WeakValueDictionary, ref
 import zsh
 
 from powerline.shell import ShellPowerline
-from powerline.lib import parsedotval
+from powerline.lib.overrides import parsedotval
 from powerline.lib.unicode import unicode, u
 from powerline.lib.encoding import (get_preferred_output_encoding,
                                     get_preferred_environment_encoding)

powerline/commands/main.py

@@ -5,7 +5,9 @@ from __future__ import (division, absolute_import, print_function)
 import argparse
 import sys
 
-from powerline.lib import parsedotval
+from itertools import chain
+
+from powerline.lib.overrides import parsedotval, parse_override_var
 from powerline.lib.dict import mergeargs
 from powerline.lib.encoding import get_preferred_arguments_encoding
 
@@ -14,21 +16,23 @@ if sys.version_info < (3,):
 	encoding = get_preferred_arguments_encoding()
 
 	def arg_to_unicode(s):
-		return unicode(s, encoding, 'replace') if not isinstance(s, unicode) else s
+		return unicode(s, encoding, 'replace') if not isinstance(s, unicode) else s  # NOQA
 else:
 	def arg_to_unicode(s):
 		return s
 
 
-def finish_args(args):
-	if args.config_override:
-		args.config_override = mergeargs((parsedotval(v) for v in args.config_override))
-	if args.theme_override:
-		args.theme_override = mergeargs((parsedotval(v) for v in args.theme_override))
-	else:
-		args.theme_override = {}
+def finish_args(environ, args):
+	args.config_override = mergeargs(chain(
+		(parsedotval(v) for v in args.config_override or ()),
+		parse_override_var(environ.get('POWERLINE_CONFIG_OVERRIDES', '')),
+	))
+	args.theme_override = mergeargs(chain(
+		(parsedotval(v) for v in args.theme_override or ()),
+		parse_override_var(environ.get('POWERLINE_THEME_OVERRIDES', '')),
+	))
 	if args.renderer_arg:
-		args.renderer_arg = mergeargs((parsedotval(v) for v in args.renderer_arg))
+		args.renderer_arg = mergeargs((parsedotval(v) for v in args.renderer_arg), remove=True)
 
 
 def get_argparser(ArgumentParser=argparse.ArgumentParser):

powerline/lib/__init__.py

@@ -1,12 +1,8 @@
 # vim:fileencoding=utf-8:noet
 from __future__ import (unicode_literals, division, absolute_import, print_function)
 
-import json
-
 from functools import wraps
 
-from powerline.lib.dict import REMOVE_THIS_KEY
-
 
 def wraps_saveargs(wrapped):
 	def dec(wrapper):
@@ -30,59 +26,3 @@ def add_divider_highlight_group(highlight_group):
 				return None
 		return f
 	return dec
-
-
-def parse_value(s):
-	'''Convert string to Python object
-
-	Rules:
-
-	* Empty string means that corresponding key should be removed from the 
-	  dictionary.
-	* Strings that start with a minus, digit or with some character that starts 
-	  JSON collection or string object are parsed as JSON.
-	* JSON special values ``null``, ``true``, ``false`` (case matters) are 
-	  parsed  as JSON.
-	* All other values are considered to be raw strings.
-
-	:param str s: Parsed string.
-
-	:return: Python object.
-	'''
-	if not s:
-		return REMOVE_THIS_KEY
-	elif s[0] in '"{[0193456789-' or s in ('null', 'true', 'false'):
-		return json.loads(s)
-	else:
-		return s
-
-
-def keyvaluesplit(s):
-	if '=' not in s:
-		raise TypeError('Option must look like option=json_value')
-	if s[0] == '_':
-		raise ValueError('Option names must not start with `_\'')
-	idx = s.index('=')
-	o = s[:idx]
-	val = parse_value(s[idx + 1:])
-	return (o, val)
-
-
-def parsedotval(s):
-	if type(s) is tuple:
-		o, val = s
-		val = parse_value(val)
-	else:
-		o, val = keyvaluesplit(s)
-
-	keys = o.split('.')
-	if len(keys) > 1:
-		r = (keys[0], {})
-		rcur = r[1]
-		for key in keys[1:-1]:
-			rcur[key] = {}
-			rcur = rcur[key]
-		rcur[keys[-1]] = val
-		return r
-	else:
-		return (o, val)

powerline/lib/dict.py

@@ -5,26 +5,44 @@ from __future__ import (unicode_literals, division, absolute_import, print_funct
 REMOVE_THIS_KEY = object()
 
 
-def mergeargs(argvalue):
+def mergeargs(argvalue, remove=False):
 	if not argvalue:
 		return None
 	r = {}
 	for subval in argvalue:
-		mergedicts(r, dict([subval]))
+		mergedicts(r, dict([subval]), remove=remove)
 	return r
 
 
-def mergedicts(d1, d2):
+def _clear_special_values(d):
+	'''Remove REMOVE_THIS_KEY values from dictionary
+	'''
+	l = [d]
+	while l:
+		i = l.pop()
+		pops = []
+		for k, v in i.items():
+			if v is REMOVE_THIS_KEY:
+				pops.append(k)
+			elif isinstance(v, dict):
+				l.append(v)
+		for k in pops:
+			i.pop(k)
+
+
+def mergedicts(d1, d2, remove=True):
 	'''Recursively merge two dictionaries
 
 	First dictionary is modified in-place.
 	'''
 	for k in d2:
 		if k in d1 and isinstance(d1[k], dict) and isinstance(d2[k], dict):
-			mergedicts(d1[k], d2[k])
-		elif d2[k] is REMOVE_THIS_KEY:
+			mergedicts(d1[k], d2[k], remove)
+		elif remove and d2[k] is REMOVE_THIS_KEY:
 			d1.pop(k, None)
 		else:
+			if remove and isinstance(d2[k], dict):
+				_clear_special_values(d2[k])
 			d1[k] = d2[k]
 
 

powerline/lib/overrides.py

@@ -0,0 +1,80 @@
+# vim:fileencoding=utf-8:noet
+from __future__ import (unicode_literals, division, absolute_import, print_function)
+
+import json
+
+from powerline.lib.dict import REMOVE_THIS_KEY
+
+
+def parse_value(s):
+	'''Convert string to Python object
+
+	Rules:
+
+	* Empty string means that corresponding key should be removed from the 
+	  dictionary.
+	* Strings that start with a minus, digit or with some character that starts 
+	  JSON collection or string object are parsed as JSON.
+	* JSON special values ``null``, ``true``, ``false`` (case matters) are 
+	  parsed  as JSON.
+	* All other values are considered to be raw strings.
+
+	:param str s: Parsed string.
+
+	:return: Python object.
+	'''
+	if not s:
+		return REMOVE_THIS_KEY
+	elif s[0] in '"{[0193456789-' or s in ('null', 'true', 'false'):
+		return json.loads(s)
+	else:
+		return s
+
+
+def keyvaluesplit(s):
+	'''Split K1.K2=VAL into K1.K2 and parsed VAL
+	'''
+	if '=' not in s:
+		raise TypeError('Option must look like option=json_value')
+	if s[0] == '_':
+		raise ValueError('Option names must not start with `_\'')
+	idx = s.index('=')
+	o = s[:idx]
+	val = parse_value(s[idx + 1:])
+	return (o, val)
+
+
+def parsedotval(s):
+	'''Parse K1.K2=VAL into {"K1":{"K2":VAL}}
+
+	``VAL`` is processed according to rules defined in :py:func:`parse_value`.
+	'''
+	if type(s) is tuple:
+		o, val = s
+		val = parse_value(val)
+	else:
+		o, val = keyvaluesplit(s)
+
+	keys = o.split('.')
+	if len(keys) > 1:
+		r = (keys[0], {})
+		rcur = r[1]
+		for key in keys[1:-1]:
+			rcur[key] = {}
+			rcur = rcur[key]
+		rcur[keys[-1]] = val
+		return r
+	else:
+		return (o, val)
+
+
+def parse_override_var(s):
+	'''Parse a semicolon-separated list of strings into a sequence of values
+
+	Emits the same items in sequence as :py:func:`parsedotval` does.
+	'''
+	return (
+		parsedotval(item)
+		for item in s.split(';')
+		if item
+	)

scripts/powerline-daemon

@@ -78,8 +78,11 @@ def render(args, environ, cwd):
 		tuple(args.config_override) if args.config_override else None,
 		tuple(args.theme_override) if args.theme_override else None,
 		tuple(args.config_path) if args.config_path else None,
+		environ.get('POWERLINE_THEME_OVERRIDES', ''),
+		environ.get('POWERLINE_CONFIG_OVERRIDES', ''),
+		environ.get('POWERLINE_CONFIG_PATHS', ''),
 	)
-	finish_args(args)
+	finish_args(environ, args)
 	powerline = None
 	try:
 		powerline = powerlines[key]

scripts/powerline-render

@@ -24,7 +24,7 @@ else:
 
 if __name__ == '__main__':
 	args = get_argparser().parse_args()
-	finish_args(args)
+	finish_args(os.environ, args)
 	powerline = ShellPowerline(args, run_once=True)
 	segment_info = {'args': args, 'environ': os.environ}
 	write_output(args, powerline, segment_info, write, get_preferred_output_encoding())

tests/test_cmdline.py

@@ -114,7 +114,7 @@ class TestParser(TestCase):
 				(['shell', '-c', 'common={ }'], {'ext': ['shell'], 'config_override': {'common': {}}}),
 			]:
 				args = parser.parse_args(argv)
-				finish_args(args)
+				finish_args({}, args)
 				for key, val in expargs.items():
 					self.assertEqual(getattr(args, key), val)
 				for key, val in args.__dict__.items():