Allow buffers to be read-only.

prompt_toolkit/buffer.py

@@ -21,12 +21,16 @@
 import tempfile
 
 __all__ = (
+ 'EditReadOnlyBuffer',
  'AcceptAction',
  'Buffer',
  'indent',
  'unindent',
 )
 
+class EditReadOnlyBuffer(Exception):
+ " Attempt editing of read-only buffer. "
+
 
 class AcceptAction(object):
  """
@@ -169,13 +173,14 @@ class Buffer(object):
  def __init__(self, completer=None, history=None, validator=None, tempfile_suffix='',
  is_multiline=Never(), complete_while_typing=Never(),
  enable_history_search=Never(), initial_document=None,
- accept_action=AcceptAction.RETURN_DOCUMENT,
+ accept_action=AcceptAction.RETURN_DOCUMENT, read_only=False,
  on_text_changed=None, on_text_insert=None, on_cursor_position_changed=None):
 
  # Accept both filters and booleans as input.
  enable_history_search = to_simple_filter(enable_history_search)
  is_multiline = to_simple_filter(is_multiline)
  complete_while_typing = to_simple_filter(complete_while_typing)
+ read_only = to_simple_filter(read_only)
 
  # Validate input.
  assert completer is None or isinstance(completer, Completer)
@@ -193,6 +198,7 @@ def __init__(self, completer=None, history=None, validator=None, tempfile_suffix
  self.is_multiline = is_multiline
  self.complete_while_typing = complete_while_typing
  self.enable_history_search = enable_history_search
+ self.read_only = read_only
 
  #: The command buffer history.
  # Note that we shouldn't use a lazy 'or' here. bool(history) could be
@@ -277,6 +283,10 @@ def text(self, value):
  assert isinstance(value, six.text_type), 'Got %r' % value
  assert self.cursor_position <= len(value)
 
+ # Don't allow editing of read-only buffers.
+ if self.read_only():
+ raise EditReadOnlyBuffer()
+
  changed = self._set_text(value)
 
  if changed:
@@ -350,6 +360,10 @@ def document(self, value):
  """
  assert isinstance(value, Document)
 
+ # Don't allow editing of read-only buffers.
+ if self.read_only():
+ raise EditReadOnlyBuffer()
+
  # Set text and cursor position first.
  text_changed = self._set_text(value.text)
  cursor_position_changed = self._set_cursor_position(value.cursor_position)
@@ -1001,6 +1015,9 @@ def open_in_editor(self):
  """
  Open code in editor.
  """
+ if self.read_only():
+ raise EditReadOnlyBuffer()
+
  # Write to temporary file
  descriptor, filename = tempfile.mkstemp(self.tempfile_suffix)
  os.write(descriptor, self.text.encode('utf-8'))

prompt_toolkit/key_binding/input_processor.py

@@ -9,6 +9,7 @@
 from __future__ import unicode_literals
 from ..keys import Keys
 from ..utils import Callback
+from prompt_toolkit.buffer import EditReadOnlyBuffer
 
 import weakref
 
@@ -171,10 +172,16 @@ def _call_handler(self, handler, key_sequence=None):
  arg = self.arg
  self.arg = None
 
- event = Event(weakref.ref(self), arg=arg, key_sequence=key_sequence,
- previous_key_sequence=self._previous_key_sequence)
- handler.call(event)
- self._registry.on_handler_called.fire(event)
+ try:
+ event = Event(weakref.ref(self), arg=arg, key_sequence=key_sequence,
+ previous_key_sequence=self._previous_key_sequence)
+ handler.call(event)
+ self._registry.on_handler_called.fire(event)
+
+ except EditReadOnlyBuffer:
+ # When a key binding does an attempt to change a buffer which is read-only,
+ # we can just silently ignore that.
+ pass
 
  self._previous_key_sequence = key_sequence