Cargoify servo

python/mach/mach/terminal.py

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+# 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.')
+