Fix renderer length computation

Current sum() of once computed _len’s is completely inappropriate in case
removal of the segment caused change in divider lengths: addition or removal of
dividers or change of the divider type when dividers have different length.

Also contains some optimizations: first of all _render_segments is called only
once always, same for strwidth() function for each string. Space is considired
to always have length 1. And do not bother computing any length if no width was
specified.

powerline/renderer.py

@@ -222,20 +222,44 @@ class Renderer(object):
 		segments = theme.get_segments(side, line, self.get_segment_info(segment_info, mode))
 
 		# Handle excluded/included segments for the current mode
-		segments = [self._get_highlighting(segment, segment['mode'] or mode) for segment in segments
+		segments = [
-			if mode not in segment['exclude_modes'] and (not segment['include_modes'] or mode in segment['include_modes'])]
+			self._get_highlighting(segment, segment['mode'] or mode)
-
+			for segment in segments
-		segments = [segment for segment in self._render_segments(theme, segments)]
+			if (
+				mode not in segment['exclude_modes']
+				and (
+					not segment['include_modes']
+					or mode in segment['include_modes']
+				)
+			)
+		]
 
 		if not width:
 			# No width specified, so we don't need to crop or pad anything
-			return construct_returned_value(''.join([segment['_rendered_hl'] for segment in segments]) + self.hlstyle(), segments, output_raw)
+			return construct_returned_value(''.join([
+				segment['_rendered_hl']
+				for segment in self._render_segments(theme, segments)
+			]) + self.hlstyle(), segments, output_raw)
+
+		divider_lengths = {
+			'left': {
+				'hard': self.strwidth(theme.get_divider('left', 'hard')),
+				'soft': self.strwidth(theme.get_divider('left', 'soft')),
+			},
+			'right': {
+				'hard': self.strwidth(theme.get_divider('right', 'hard')),
+				'soft': self.strwidth(theme.get_divider('right', 'soft')),
+			},
+		}
+
+		length = self._render_length(theme, segments, divider_lengths)
 
 		# 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)
-		while sum([segment['_len'] for segment in segments]) > width and len(segments_priority):
+		for segment in segments_priority:
-			segments.remove(segments_priority[0])
+			if self._render_length(theme, segments, divider_lengths) <= width:
-			segments_priority.pop(0)
+				break
+			segments.remove(segment)
 
 		# Distribute the remaining space on spacer segments
 		segments_spacers = [segment for segment in segments if segment['width'] == 'auto']
@@ -256,6 +280,38 @@ class Renderer(object):
 
 		return construct_returned_value(rendered_highlighted, segments, output_raw)
 
+	def _render_length(self, theme, segments, divider_lengths):
+		'''Update segments lengths and return them
+		'''
+		segments_len = len(segments)
+		ret = 0
+		divider_spaces = theme.get_spaces()
+		for index, segment in enumerate(segments):
+			side = segment['side']
+			if segment['_contents_len'] is None:
+				segment_len = segment['_contents_len'] = self.strwidth(segment['contents'])
+			else:
+				segment_len = segment['_contents_len']
+
+			prev_segment = segments[index - 1] if index > 0 else theme.EMPTY_SEGMENT
+			next_segment = segments[index + 1] if index < segments_len - 1 else theme.EMPTY_SEGMENT
+			compare_segment = next_segment if side == 'left' else prev_segment
+			divider_type = 'soft' if compare_segment['highlight']['bg'] == segment['highlight']['bg'] else 'hard'
+
+			outer_padding = int(bool(
+				(index == 0 and side == 'left') or
+				(index == segments_len - 1 and side == 'right')
+			))
+
+			draw_divider = segment['draw_' + divider_type + '_divider']
+			segment_len += segment['_space_left'] + segment['_space_right'] + outer_padding
+			if draw_divider:
+				segment_len += divider_lengths[side][divider_type] + divider_spaces
+
+			segment['_len'] = segment_len
+			ret += segment_len
+		return ret
+
 	def _render_segments(self, theme, segments, render_highlighted=True):
 		'''Internal segment rendering method.
 
@@ -268,19 +324,19 @@ class Renderer(object):
 		statusline if render_highlighted is True.
 		'''
 		segments_len = len(segments)
+		divider_spaces = theme.get_spaces()
 
 		for index, segment in enumerate(segments):
-			segment['_rendered_raw'] = ''
+			side = segment['side']
-			segment['_rendered_hl'] = ''
-
 			prev_segment = segments[index - 1] if index > 0 else theme.EMPTY_SEGMENT
 			next_segment = segments[index + 1] if index < segments_len - 1 else theme.EMPTY_SEGMENT
-			compare_segment = next_segment if segment['side'] == 'left' else prev_segment
+			compare_segment = next_segment if side == 'left' else prev_segment
-			outer_padding = ' ' if (index == 0 and segment['side'] == 'left') or (index == segments_len - 1 and segment['side'] == 'right') else ''
+			outer_padding = int(bool(
+				(index == 0 and side == 'left') or
+				(index == segments_len - 1 and side == 'right')
+			)) * ' '
 			divider_type = 'soft' if compare_segment['highlight']['bg'] == segment['highlight']['bg'] else 'hard'
 
-			divider_raw = theme.get_divider(segment['side'], divider_type)
-			divider_spaces = theme.get_spaces()
 			divider_highlighted = ''
 			contents_raw = segment['contents']
 			contents_highlighted = ''
@@ -288,48 +344,64 @@ class Renderer(object):
 
 			# Pad segments first
 			if draw_divider:
-				if segment['side'] == 'left':
+				divider_raw = theme.get_divider(side, divider_type).replace(' ', NBSP)
-					contents_raw = outer_padding + (segment['_space_left'] * ' ') + contents_raw + ((divider_spaces + segment['_space_right']) * ' ')
+				if side == 'left':
+					contents_raw = (
+						outer_padding + (segment['_space_left'] * ' ')
+						+ contents_raw
+						+ ((divider_spaces + segment['_space_right']) * ' ')
+					)
 				else:
-					contents_raw = ((divider_spaces + segment['_space_left']) * ' ') + contents_raw + (segment['_space_right'] * ' ') + outer_padding
+					contents_raw = (
+						((divider_spaces + segment['_space_left']) * ' ')
+						+ contents_raw
+						+ (segment['_space_right'] * ' ') + outer_padding
+					)
 			else:
-				if segment['side'] == 'left':
+				if side == 'left':
-					contents_raw = outer_padding + (segment['_space_left'] * ' ') + contents_raw + (segment['_space_right'] * ' ')
+					contents_raw = (
+						outer_padding + (segment['_space_left'] * ' ')
+						+ contents_raw
+						+ (segment['_space_right'] * ' ')
+					)
 				else:
-					contents_raw = (segment['_space_left'] * ' ') + contents_raw + (segment['_space_right'] * ' ') + outer_padding
+					contents_raw = (
+						(segment['_space_left'] * ' ')
+						+ contents_raw
+						+ (segment['_space_right'] * ' ') + outer_padding
+					)
 
 			# Replace spaces with no-break spaces
-			divider_raw = divider_raw.replace(' ', NBSP)
 			contents_raw = contents_raw.translate(self.np_character_translations)
 
 			# Apply highlighting to padded dividers and contents
 			if render_highlighted:
-				if divider_type == 'soft':
+				if draw_divider:
-					divider_highlight_group_key = 'highlight' if segment['divider_highlight_group'] is None else 'divider_highlight'
+					if divider_type == 'soft':
-					divider_fg = segment[divider_highlight_group_key]['fg']
+						divider_highlight_group_key = 'highlight' if segment['divider_highlight_group'] is None else 'divider_highlight'
-					divider_bg = segment[divider_highlight_group_key]['bg']
+						divider_fg = segment[divider_highlight_group_key]['fg']
-				else:
+						divider_bg = segment[divider_highlight_group_key]['bg']
-					divider_fg = segment['highlight']['bg']
+					else:
-					divider_bg = compare_segment['highlight']['bg']
+						divider_fg = segment['highlight']['bg']
-				divider_highlighted = self.hl(divider_raw, divider_fg, divider_bg, False)
+						divider_bg = compare_segment['highlight']['bg']
+					divider_highlighted = self.hl(divider_raw, divider_fg, divider_bg, False)
 				contents_highlighted = self.hl(self.escape(contents_raw), **segment['highlight'])
 
 			# Append padded raw and highlighted segments to the rendered segment variables
 			if draw_divider:
-				if segment['side'] == 'left':
+				if side == 'left':
-					segment['_rendered_raw'] += contents_raw + divider_raw
+					segment['_rendered_raw'] = contents_raw + divider_raw
-					segment['_rendered_hl'] += contents_highlighted + divider_highlighted
+					segment['_rendered_hl'] = contents_highlighted + divider_highlighted
 				else:
-					segment['_rendered_raw'] += divider_raw + contents_raw
+					segment['_rendered_raw'] = divider_raw + contents_raw
-					segment['_rendered_hl'] += divider_highlighted + contents_highlighted
+					segment['_rendered_hl'] = divider_highlighted + contents_highlighted
 			else:
-				if segment['side'] == 'left':
+				if side == 'left':
-					segment['_rendered_raw'] += contents_raw
+					segment['_rendered_raw'] = contents_raw
-					segment['_rendered_hl'] += contents_highlighted
+					segment['_rendered_hl'] = contents_highlighted
 				else:
-					segment['_rendered_raw'] += contents_raw
+					segment['_rendered_raw'] = contents_raw
-					segment['_rendered_hl'] += contents_highlighted
+					segment['_rendered_hl'] = contents_highlighted
-			segment['_len'] = self.strwidth(segment['_rendered_raw'])
 			yield segment
 
 	@classmethod