Improve handling of situation when stdin is not a terminal.

Print warning and continue instead of failing with an assertion.

Author: jonathanslenders

prompt_toolkit/application/application.py

@@ -240,6 +240,7 @@ def __init__(self, layout=None,
  self.renderer = Renderer(
  self._merged_style,
  self.output,
+ self.input,
  full_screen=full_screen,
  mouse_support=mouse_support,
  cpr_not_supported_callback=self.cpr_not_supported_callback)

prompt_toolkit/input/vt100.py

@@ -23,10 +23,10 @@ class Vt100Input(Input):
  Vt100 input for Posix systems.
  (This uses a posix file descriptor that can be registered in the event loop.)
  """
- def __init__(self, stdin):
- # The input object should be a TTY.
- assert stdin.isatty()
+ _fds_not_a_terminal = set() # For the error messages. Only display "Input
+ # is not a terminal" once per file descriptor.
 
+ def __init__(self, stdin):
  # Test whether the given input object has a file descriptor.
  # (Idle reports stdin to be a TTY, but fileno() is not implemented.)
  try:
@@ -39,6 +39,20 @@ def __init__(self, stdin):
  else:
  raise io.UnsupportedOperation('Stdin is not a terminal.')
 
+ # Even when we have a file descriptor, it doesn't mean it's a TTY.
+ # Normally, this requires a real TTY device, but people instantiate
+ # this class often during unit tests as well. They use for instance
+ # pexpect to pipe data into an application. For convenience, we print
+ # an error message and go on.
+ isatty = stdin.isatty()
+ fd = stdin.fileno()
+
+ if not isatty and fd not in Vt100Input._fds_not_a_terminal:
+ msg = 'Warning: Input is not to a terminal (fd=%r).\n'
+ sys.stderr.write(msg % fd)
+ Vt100Input._fds_not_a_terminal.add(fd)
+
+ #
  self.stdin = stdin
 
  # Create a backup of the fileno(). We want this to work even if the
@@ -52,7 +66,9 @@ def __init__(self, stdin):
 
  @property
  def responds_to_cpr(self):
- return True
+ # When the input is a tty, we assume that CPR is supported.
+ # It's not when the input is piped from Pexpect.
+ return self.stdin.isatty()
 
  def attach(self, input_ready_callback):
  """

prompt_toolkit/renderer.py

@@ -7,6 +7,7 @@
 from prompt_toolkit.eventloop import Future, From, ensure_future, get_event_loop
 from prompt_toolkit.filters import to_filter
 from prompt_toolkit.formatted_text import to_formatted_text
+from prompt_toolkit.input.base import Input
 from prompt_toolkit.layout.mouse_handlers import MouseHandlers
 from prompt_toolkit.layout.screen import Point, Screen, WritePosition
 from prompt_toolkit.output import Output, ColorDepth
@@ -265,13 +266,17 @@ class Renderer(object):
  """
  CPR_TIMEOUT = 2 # Time to wait until we consider CPR to be not supported.
 
- def __init__(self, style, output, full_screen=False, mouse_support=False, cpr_not_supported_callback=None):
+ def __init__(self, style, output, input, full_screen=False,
+ mouse_support=False, cpr_not_supported_callback=None):
+
  assert isinstance(style, BaseStyle)
  assert isinstance(output, Output)
+ assert isinstance(input, Input)
  assert callable(cpr_not_supported_callback) or cpr_not_supported_callback is None
 
  self.style = style
  self.output = output
+ self.input = input
  self.full_screen = full_screen
  self.mouse_support = to_filter(mouse_support)
  self.cpr_not_supported_callback = cpr_not_supported_callback
@@ -283,6 +288,8 @@ def __init__(self, style, output, full_screen=False, mouse_support=False, cpr_no
  # Future set when we are waiting for a CPR flag.
  self._waiting_for_cpr_futures = deque()
  self.cpr_support = CPR_Support.UNKNOWN
+ if not input.responds_to_cpr:
+ self.cpr_support = CPR_Support.NOT_SUPPORTED
 
  # Cache for the style.
  self._attrs_for_style = None