Merge pull request #1043 from ZyX-I/truncate-expand

Add segment.truncate and segment.expand attributes support

docs/source/configuration/reference.rst

@@ -369,6 +369,8 @@ ascii                       Theme without any unicode characters at all
 
     Each segment dictionary has the following options:
 
+    .. _config-themes-seg-type:
+
     ``type``
         The segment type. Can be one of ``function`` (default), ``string`` or 
         ``segments_list``:
@@ -439,9 +441,13 @@ ascii                       Theme without any unicode characters at all
     ``args``
         A dict of arguments to be passed to a ``function`` segment.
 
+    .. _config-themes-seg-align:
+
     ``align``
         Aligns the segments contents to the left (``l``), center (``c``) or 
-        right (``r``).
+        right (``r``). Has no sense if ``width`` key was not specified or if 
+        segment provides its own function for ``auto`` ``width`` handling and 
+        does not care about this option.
 
     .. _config-themes-seg-width:
 
@@ -454,6 +460,8 @@ ascii                       Theme without any unicode characters at all
         either returned by a function or a static string, and the contents 
         can be aligned with the ``align`` property.
 
+    .. _config-themes-seg-priority:
+
     ``priority``
         Optional segment priority. Segments with priority ``None`` (the default 
         priority, represented by ``null`` in json) will always be included, 
@@ -482,6 +490,8 @@ ascii                       Theme without any unicode characters at all
         segments. Only applicable for functions returning multiple segments. 
         Defaults to ``False``.
 
+    .. _config-themes-seg-exclude_modes:
+
     ``exclude_modes``
         A list of modes where this segment will be excluded: The segment is 
         included in all modes, *except* for the modes in this list.

docs/source/develop/listers.rst

@@ -36,8 +36,11 @@ Listers must return a sequence of pairs. First item in the pair must contain
 a ``segment_info`` dictionary specific to one of the listed entities.
 
 Second item must contain another dictionary: it will be used to modify the 
-resulting segment. In addition to usual keys that describe segment the following 
+resulting segment. In addition to :ref:`usual keys that describe segment 
-keys may be present (it is advised that *only* the following keys will be used):
+<dev-segments-segment>` the following keys may be present (it is advised that 
+*only* the following keys will be used):
+
+.. _dev-listers-mode:
 
 ``mode``
     Segment-specific mode. Used to alter segment highlighting.

docs/source/develop/segments.rst

@@ -51,6 +51,8 @@ powerline:
     theme-specific values go directly to :ref:`top-level themes 
     <config-themes>`.
 
+.. _dev-segments-startup:
+
 ``startup``
     This attribute must be a callable which accepts the following keyword 
     arguments:
@@ -68,6 +70,8 @@ powerline:
     used (more specific: when :py:class:`powerline.Powerline` constructor 
     received true ``run_once`` argument).
 
+.. _dev-segments-shutdown:
+
 ``shutdown``
     This attribute must be a callable that accepts no arguments and shuts down 
     threads and frees any other resources allocated in ``startup`` method of the 
@@ -75,6 +79,39 @@ powerline:
 
     This function is not called when ``startup`` method is not called.
 
+.. _dev-segments-expand:
+
+``expand``
+    This attribute must be a callable that accepts the following keyword 
+    arguments:
+
+    * ``pl``: :py:class:`powerline.PowerlineLogger` instance which is to be used 
+      for logging.
+    * ``amount``: integer number representing amount of display cells result 
+      must occupy.
+
+      .. warning::
+         “Amount of display cells” is *not* number of Unicode codepoints, string 
+         length, or byte count. It is suggested that your function should look 
+         something like ``return (' ' * amount) + segment['contents']`` where 
+         ``' '`` may be replaced with anything that is known to occupy exactly 
+         one display cell.
+    * ``segment``: :ref:`segment dictionary <dev-segments-segment>`.
+    * Any arguments found in user configuration for the given segment (i.e. 
+      :ref:`args key <config-themes-seg-args>`).
+
+    It must return new value of :ref:`contents <dev-segments-seg-contents>` key.
+
+.. _dev-segments-truncate:
+
+``truncate``
+    Like :ref:`expand function <dev-segments-expand>`, but for truncating 
+    segments. Here ``amount`` means the number of display cells which must be 
+    freed.
+
+    This function is called for all segments before powerline starts purging 
+    them to free space.
+
 This callable object should may return either a string (``unicode`` in Python2 
 or ``str`` in Python3, *not* ``str`` in Python2 or ``bytes`` in Python3) object 
 or a list of dictionaries. String object is a short form of the following return 
@@ -87,6 +124,8 @@ value:
         'highlight_group': [segment_name],
     }]
 
+.. _dev-segments-return:
+
 Returned list is a list of segments treated independently, except for 
 :ref:`draw_inner_divider key <dev-segments-draw_inner_divider>`.
 
@@ -158,6 +197,87 @@ Detailed description of used dictionary keys:
     No error occurs if segment has this key, but no used highlight groups use 
     gradient color.
 
+``_*``
+    Keys starting with underscore are reserved for powerline and must not be 
+    returned.
+
+``__*``
+    Keys starting with two underscores are reserved for the segment functions, 
+    specifically for :ref:`expand function <dev-segments-expand>`.
+
+.. _dev-segments-segment:
+
+Segment dictionary
+==================
+
+Segment dictionary contains the following keys:
+
+* All keys returned by segment function (if it was used).
+
+* All of the following keys:
+
+  ``name``
+    Segment name: value of the :ref:`name key <config-themes-seg-name>` or 
+    function name (last component of the :ref:`function key 
+    <config-themes-seg-function>`). May be ``None``.
+
+  ``type``
+    :ref:`Segment type <config-themes-seg-type>`. Always represents actual type 
+    and is never ``None``.
+
+  ``highlight_group``, ``divider_highlight_group``
+    Used highlight groups. May be ``None``.
+
+  .. _dev-segments-seg-around:
+
+  ``before``, ``after``
+    Value of :ref:`before <config-themes-seg-before>` or :ref:`after 
+    <config-themes-seg-after>` configuration options. May be ``None`` as well as 
+    an empty string.
+
+  ``contents_func``
+    Function used to get segment contents. May be ``None``.
+
+  .. _dev-segments-seg-contents:
+
+  ``contents``
+    Actual segment contents, excluding dividers and :ref:`before/after 
+    <dev-segments-seg-around>`. May be ``None``.
+
+  ``priority``
+    :ref:`Segment priority <config-themes-seg-priority>`. May be ``None`` for no 
+    priority (such segments are always shown).
+
+  ``draw_soft_divider``, ``draw_hard_divider``, ``draw_inner_divider``
+    :ref:`Divider control flags <dev-segments-draw_inner_divider>`.
+
+  ``side``
+    Segment side: ``right`` or ``left``.
+
+  ``exclude_modes``, ``include_modes``
+    :ref:`Mode display control lists <config-themes-seg-exclude_modes>`. May be 
+    empty, but may not be ``None``.
+
+  ``width``, ``align``
+    :ref:`Width and align options <config-themes-seg-align>`. May be ``None``.
+
+  ``expand``, ``truncate``
+    Partially applied :ref:`expand <dev-segments-expand>` or :ref:`truncate 
+    <dev-segments-truncate>` function. Accepts ``pl``, ``amount`` and 
+    ``segment`` positional parameters, keyword parameters from :ref:`args 
+    <config-themes-seg-args>` key were applied.
+
+  ``startup``
+    Partially applied :ref:`startup function <dev-segments-startup>`. Accepts 
+    ``pl`` and ``shutdown_event`` positional parameters, keyword parameters from 
+    :ref:`args <config-themes-seg-args>` key were applied.
+
+  ``shutdown``
+    :ref:`Shutdown function <dev-segments-shutdown>`. Accepts no argument.
+
+  ``mode``
+    :ref:`Segment-specific mode <dev-listers-mode>`. May be ``None``.
+
 Segments layout
 ===============
 

powerline/renderer.py

@@ -1,9 +1,12 @@
 # vim:fileencoding=utf-8:noet
 
-from powerline.theme import Theme
-from unicodedata import east_asian_width, combining
 import os
 
+from unicodedata import east_asian_width, combining
+from itertools import chain
+
+from powerline.theme import Theme
+
 try:
 	NBSP = unicode(' ', 'utf-8')
 except NameError:
@@ -262,14 +265,20 @@ class Renderer(object):
 
 		# Create an ordered list of segments that can be dropped
 		segments_priority = sorted((segment for segment in segments if segment['priority'] is not None), key=lambda segment: segment['priority'], reverse=True)
-		for segment in segments_priority:
+		no_priority_segments = filter(lambda segment: segment['priority'] is None, segments)
-			current_width = self._render_length(theme, segments, divider_widths)
+		current_width = self._render_length(theme, segments, divider_widths)
-			if current_width <= width:
+		if current_width > width:
-				break
+			for segment in chain(segments_priority, no_priority_segments):
-			segments.remove(segment)
+				if segment['truncate'] is not None:
+					segment['contents'] = segment['truncate'](self.pl, current_width - width, segment)
+			for segment in segments_priority:
+				if current_width <= width:
+					break
+				segments.remove(segment)
+				current_width = self._render_length(theme, segments, divider_widths)
 
 		# Distribute the remaining space on spacer segments
-		segments_spacers = [segment for segment in segments if segment['width'] == 'auto']
+		segments_spacers = [segment for segment in segments if segment['expand'] is not None]
 		if segments_spacers:
 			if not segments_priority:
 				# Update segment['_len'] and current_width if not already done 
@@ -278,15 +287,12 @@ class Renderer(object):
 				current_width = self._render_length(theme, segments, divider_widths)
 			distribute_len, distribute_len_remainder = divmod(width - current_width, len(segments_spacers))
 			for segment in segments_spacers:
-				if segment['align'] == 'l':
+				segment['contents'] = (
-					segment['_space_right'] += distribute_len
+					segment['expand'](
-				elif segment['align'] == 'r':
+						self.pl,
-					segment['_space_left'] += distribute_len
+						distribute_len + (1 if distribute_len_remainder > 0 else 0),
-				elif segment['align'] == 'c':
+						segment))
-					space_side, space_side_remainder = divmod(distribute_len, 2)
+				distribute_len_remainder -= 1
-					segment['_space_left'] += space_side + space_side_remainder
-					segment['_space_right'] += space_side
-			segments_spacers[0]['_space_right'] += distribute_len_remainder
 			# `_len` key is not needed anymore, but current_width should have an 
 			# actual value for various bindings.
 			current_width = width
@@ -321,7 +327,7 @@ class Renderer(object):
 			))
 
 			draw_divider = segment['draw_' + divider_type + '_divider']
-			segment_len += segment['_space_left'] + segment['_space_right'] + outer_padding
+			segment_len += outer_padding
 			if draw_divider:
 				segment_len += divider_widths[side][divider_type] + divider_spaces
 
@@ -363,30 +369,14 @@ class Renderer(object):
 			if draw_divider:
 				divider_raw = self.escape(theme.get_divider(side, divider_type))
 				if side == 'left':
-					contents_raw = (
+					contents_raw = outer_padding + contents_raw + (divider_spaces * ' ')
-						outer_padding + (segment['_space_left'] * ' ')
-						+ contents_raw
-						+ ((divider_spaces + segment['_space_right']) * ' ')
-					)
 				else:
-					contents_raw = (
+					contents_raw = (divider_spaces * ' ') + contents_raw + outer_padding
-						((divider_spaces + segment['_space_left']) * ' ')
-						+ contents_raw
-						+ (segment['_space_right'] * ' ') + outer_padding
-					)
 			else:
 				if side == 'left':
-					contents_raw = (
+					contents_raw = outer_padding + contents_raw
-						outer_padding + (segment['_space_left'] * ' ')
-						+ contents_raw
-						+ (segment['_space_right'] * ' ')
-					)
 				else:
-					contents_raw = (
+					contents_raw = contents_raw + outer_padding
-						(segment['_space_left'] * ' ')
-						+ contents_raw
-						+ (segment['_space_right'] * ' ') + outer_padding
-					)
 
 			# Replace spaces with no-break spaces
 			contents_raw = contents_raw.translate(self.np_character_translations)

powerline/segment.py

@@ -82,14 +82,20 @@ segment_getters = {
 }
 
 
-def get_attr_func(contents_func, key, args):
+def get_attr_func(contents_func, key, args, is_space_func=False):
 	try:
 		func = getattr(contents_func, key)
 	except AttributeError:
 		return None
 	else:
-		if args is None:
+		if is_space_func:
-			return lambda: func()
+			def expand_func(pl, amount, segment):
+				try:
+					return func(pl=pl, amount=amount, segment=segment, **args)
+				except Exception as e:
+					pl.exception('Exception while computing {0} function: {1}', key, str(e))
+					return segment['contents'] + (' ' * amount)
+			return expand_func
 		else:
 			return lambda pl, shutdown_event: func(pl=pl, shutdown_event=shutdown_event, **args)
 
@@ -285,6 +291,8 @@ def gen_segment_getter(pl, ext, common_config, theme_configs, default_module, ge
 				'include_modes': segment.get('include_modes', []),
 				'width': None,
 				'align': None,
+				'expand': None,
+				'truncate': None,
 				'startup': None,
 				'shutdown': None,
 				'mode': None,
@@ -292,13 +300,13 @@ def gen_segment_getter(pl, ext, common_config, theme_configs, default_module, ge
 				'_rendered_hl': '',
 				'_len': None,
 				'_contents_len': None,
-				'_space_left': 0,
-				'_space_right': 0,
 			}
 
 		if segment_type == 'function':
 			startup_func = get_attr_func(_contents_func, 'startup', args)
-			shutdown_func = get_attr_func(_contents_func, 'shutdown', None)
+			shutdown_func = getattr(_contents_func, 'shutdown', None)
+			expand_func = get_attr_func(_contents_func, 'expand', args, True)
+			truncate_func = get_attr_func(_contents_func, 'truncate', args, True)
 
 			if hasattr(_contents_func, 'powerline_requires_filesystem_watcher'):
 				create_watcher = lambda: create_file_watcher(pl, common_config['watcher'])
@@ -312,6 +320,8 @@ def gen_segment_getter(pl, ext, common_config, theme_configs, default_module, ge
 			startup_func = None
 			shutdown_func = None
 			contents_func = None
+			expand_func = None
+			truncate_func = None
 
 		return {
 			'name': name or function_name,
@@ -331,6 +341,8 @@ def gen_segment_getter(pl, ext, common_config, theme_configs, default_module, ge
 			'include_modes': segment.get('include_modes', []),
 			'width': segment.get('width'),
 			'align': segment.get('align', 'l'),
+			'expand': expand_func,
+			'truncate': truncate_func,
 			'startup': startup_func,
 			'shutdown': shutdown_func,
 			'mode': None,
@@ -338,8 +350,6 @@ def gen_segment_getter(pl, ext, common_config, theme_configs, default_module, ge
 			'_rendered_hl': '',
 			'_len': None,
 			'_contents_len': None,
-			'_space_left': 0,
-			'_space_right': 0,
 		}
 
 	return get

powerline/theme.py

@@ -23,6 +23,26 @@ def new_empty_segment_line():
 	}
 
 
+def add_spaces_left(pl, amount, segment):
+	return (' ' * amount) + segment['contents']
+
+
+def add_spaces_right(pl, amount, segment):
+	return segment['contents'] + (' ' * amount)
+
+
+def add_spaces_center(pl, amount, segment):
+	amount, remainder = divmod(amount, 2)
+	return (' ' * (amount + remainder)) + segment['contents'] + (' ' * amount)
+
+
+expand_functions = {
+	'l': add_spaces_right,
+	'r': add_spaces_left,
+	'c': add_spaces_center,
+}
+
+
 class Theme(object):
 	def __init__(self,
 	             ext,
@@ -128,6 +148,13 @@ class Theme(object):
 						self.colorscheme,
 					)
 			for segment in parsed_segments:
+				width = segment['width']
+				align = segment['align']
+				if width == 'auto' and segment['expand'] is None:
+					segment['expand'] = expand_functions.get(align)
+					if segment['expand'] is None:
+						self.pl.error('Align argument must be “r”, “l” or “c”, not “{0}”', align)
+
 				segment['contents'] = segment['before'] + u(segment['contents'] if segment['contents'] is not None else '') + segment['after']
 				# Align segment contents
 				if segment['width'] and segment['width'] != 'auto':

tests/lib/__init__.py

@@ -44,6 +44,7 @@ def urllib_read(query_url):
 	else:
 		raise NotImplementedError
 
+
 class Process(object):
 	def __init__(self, output, err):
 		self.output = output

tests/test_configuration.py

@@ -94,7 +94,7 @@ config = {
 				highlighted_string('g', 'str2'),
 			],
 			'right': [
-				highlighted_string('f', 'str2', width='auto', align='right'),
+				highlighted_string('f', 'str2', width='auto', align='r'),
 			],
 		},
 	},
@@ -474,6 +474,45 @@ class TestSegmentAttributes(TestRender):
 		}
 		self.assertRenderEqual(p, '{56} pl;{6-}>>{--}')
 
+	@add_args
+	def test_expand(self, p, config):
+		def m1(divider=',', **kwargs):
+			return divider.join(kwargs.keys()) + divider
+
+		def expand(pl, amount, segment, **kwargs):
+			return ('-' * amount) + segment['contents']
+
+		m1.expand = expand
+		sys.modules['bar'] = Args(m1=m1)
+		config['themes/test/default']['segments'] = {
+			'left': [
+				{
+					'function': 'bar.m1',
+					'width': 'auto'
+				}
+			]
+		}
+		self.assertRenderEqual(p, '{56} ----pl,{6-}>>{--}', width=10)
+
+	@add_args
+	def test_truncate(self, p, config):
+		def m1(divider=',', **kwargs):
+			return divider.join(kwargs.keys()) + divider
+
+		def truncate(pl, amount, segment, **kwargs):
+			return segment['contents'][:-amount]
+
+		m1.truncate = truncate
+		sys.modules['bar'] = Args(m1=m1)
+		config['themes/test/default']['segments'] = {
+			'left': [
+				{
+					'function': 'bar.m1'
+				}
+			]
+		}
+		self.assertRenderEqual(p, '{56} p{6-}>>{--}', width=4)
+
 
 class TestSegmentData(TestRender):
 	@add_args