python/mach/mach/terminal.py
author Christian Holler <choller@mozilla.com>
Tue, 22 Jan 2013 16:48:02 +0100
changeset 125574 08c14f94fbb73b64f0338d8332fa28e0b26e0856
parent 111702 4621dc706abc54c668f15d83455c898f6007fbe2
permissions -rw-r--r--
Bug 833018 - Enable special ASan options for tests when running with low memory. r=jmaher,a=nonlibxul

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

"""This file contains code for interacting with terminals.

All the terminal interaction code is consolidated so the complexity can be in
one place, away from code that is commonly looked at.
"""

from __future__ import print_function, unicode_literals

import logging
import sys


class LoggingHandler(logging.Handler):
    """Custom logging handler that works with terminal window dressing.

    This is alternative terminal logging handler which contains smarts for
    emitting terminal control characters properly. Currently, it has generic
    support for "footer" elements at the bottom of the screen. Functionality
    can be added when needed.
    """
    def __init__(self):
        logging.Handler.__init__(self)

        self.fh = sys.stdout
        self.footer = None

    def flush(self):
        self.acquire()

        try:
            self.fh.flush()
        finally:
            self.release()

    def emit(self, record):
        msg = self.format(record)

        if self.footer:
            self.footer.clear()

        self.fh.write(msg)
        self.fh.write('\n')

        if self.footer:
            self.footer.draw()

        # If we don't flush, the footer may not get drawn.
        self.flush()


class TerminalFooter(object):
    """Represents something drawn on the bottom of a terminal."""
    def __init__(self, terminal):
        self.t = terminal
        self.fh = sys.stdout

    def _clear_lines(self, n):
        for i in xrange(n):
            self.fh.write(self.t.move_x(0))
            self.fh.write(self.t.clear_eol())
            self.fh.write(self.t.move_up())

        self.fh.write(self.t.move_down())
        self.fh.write(self.t.move_x(0))

    def clear(self):
        raise Exception('clear() must be implemented.')

    def draw(self):
        raise Exception('draw() must be implemented.')