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# Copyright (C) 2011-2012 Patrick Totzke <patricktotzke@gmail.com>
# This file is released under the GNU GPL, version 3 or a later revision.
# For further details see the COPYING file
from __future__ import absolute_import
import logging
import urwid
class PipeWalker(urwid.ListWalker):
"""urwid.ListWalker that reads next items from a pipe and
wraps them in `containerclass` widgets for displaying
"""
def __init__(self, pipe, containerclass, reverse=False, **kwargs):
self.pipe = pipe
self.kwargs = kwargs
self.containerclass = containerclass
self.lines = []
self.focus = 0
self.empty = False
self.direction = -1 if reverse else 1
def __contains__(self, name):
return self.lines.__contains__(name)
def get_focus(self):
return self._get_at_pos(self.focus)
def set_focus(self, focus):
self.focus = focus
self._modified()
def get_next(self, start_from):
return self._get_at_pos(start_from + self.direction)
def get_prev(self, start_from):
return self._get_at_pos(start_from - self.direction)
def remove(self, obj):
next_focus = self.focus % len(self.lines)
if self.focus == len(self.lines) - 1 and self.empty:
next_focus = self.focus - 1
self.lines.remove(obj)
if self.lines:
self.set_focus(next_focus)
self._modified()
def _get_at_pos(self, pos):
if pos < 0: # pos too low
return (None, None)
elif pos > len(self.lines): # pos too high
return (None, None)
elif len(self.lines) > pos: # pos already cached
return (self.lines[pos], pos)
else: # pos not cached yet, look at next item from iterator
if self.empty: # iterator is empty
return (None, None)
else:
widget = self._get_next_item()
if widget:
return (widget, pos)
else:
return (None, None)
def _get_next_item(self):
if self.empty:
return None
try:
# the next line blocks until it can read from the pipe or
# EOFError is raised. No races here.
next_obj = self.pipe.recv()
next_widget = self.containerclass(next_obj, **self.kwargs)
self.lines.append(next_widget)
except EOFError:
logging.debug('EMPTY PIPE')
next_widget = None
self.empty = True
return next_widget
def get_lines(self):
return self.lines
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