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# Copyright 2010 Lars Wirzenius
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import fcntl
import signal
import struct
import sys
import termios
import time
class Messager(object):
'''Write messages to the terminal.'''
def __init__(self, output=None, period=None):
self._enabled = True
self.output = output or self._open_tty()
self._period = 1.0 if period is None else period
self._last_msg = '' # What did we write last?
self._last_time = 0 # When did we write last?
self._cached_msg = '' # Last message from user, to write() method.
self.set_width(self._get_terminal_width()) # Width of terminal
signal.signal(signal.SIGWINCH, self._sigwinch_handler)
def _open_tty(self): # pragma: no cover
return open('/dev/tty', 'w')
def set_width(self, actual_width):
self.width = actual_width - 1
def _now(self):
'''Return current time.'''
# This is a wrapper around time.time(), for testing.
return time.time()
def _get_terminal_width(self): # pragma: no cover
'''Return width of terminal in characters.
If this fails, assume 80.
Borrowed and adapted from bzrlib.
'''
default_width = 80
try:
s = struct.pack('HHHH', 0, 0, 0, 0)
x = fcntl.ioctl(self.output.fileno(), termios.TIOCGWINSZ, s)
return struct.unpack('HHHH', x)[1]
except IOError:
return default_width
except AttributeError:
if not hasattr(self.output, 'fileno'):
return default_width
raise
def _sigwinch_handler(self, signum, frame): # pragma: no cover
# Clear the terminal from old stuff, using the old width.
self.clear()
# Get new width.
self.set_width(self._get_terminal_width())
def _raw_write(self, string):
'''Write raw data if output is terminal.'''
if self._enabled and self.output and self.output.isatty():
try:
self.output.write(string)
self.output.flush()
except IOError: # pragma: no cover
self._enabled = False
def _overwrite(self, string):
'''Overwrite current message on terminal.'''
if self._last_msg:
self._raw_write('\r' + (' ' * len(self._last_msg)) + '\r')
self._raw_write(string)
self._last_msg = string
def time_to_write(self):
'''Is it time to write now?'''
return self._now() - self._last_time >= self._period
def write(self, string):
'''Write raw data, but only once per period.'''
string = string[:self.width]
if self.time_to_write():
self._overwrite(string)
self._last_time = self._now()
self._cached_msg = string
def clear(self):
'''Remove current message from terminal.'''
self._overwrite('')
def notify(self, string):
'''Show a notification message string to the user.
Notifications are meant for error messages and other things
that do not belong in, say, progress bars. Whatever is currently
on the terminal is wiped, then the notification message is shown,
a new line is started, and the old message is restored.
Notifications are written even when the output is not going
to a terminal.
'''
old = self._last_msg
self.clear()
try:
self.output.write('%s\n' % string)
except IOError: # pragma: no cover
# We ignore these. No point in crashing if terminal is bad.
self.output.flush()
self._overwrite(old)
def finish(self):
'''Finalize output.'''
self._overwrite(self._cached_msg)
self._raw_write('\n')
def disable(self):
'''Disable all output.'''
self._enabled = False
def enable(self):
'''Enable output to happen.'''
self._enabled = True
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