fix to minrk suggestion

IPython/frontend/qt/console/frontend_widget.py

@@ -1,731 +1,729 b''
 from __future__ import print_function
 
 # Standard library imports
 from collections import namedtuple
 import sys
 import time
 import uuid
 
 # System library imports
 from pygments.lexers import PythonLexer
 from IPython.external import qt
 from IPython.external.qt import QtCore, QtGui
 
 # Local imports
 from IPython.core.inputsplitter import InputSplitter, transform_classic_prompt
 from IPython.core.oinspect import call_tip
 from IPython.frontend.qt.base_frontend_mixin import BaseFrontendMixin
 from IPython.utils.traitlets import Bool, Instance, Unicode
 from bracket_matcher import BracketMatcher
 from call_tip_widget import CallTipWidget
 from completion_lexer import CompletionLexer
 from history_console_widget import HistoryConsoleWidget
 from pygments_highlighter import PygmentsHighlighter
 
 
 class FrontendHighlighter(PygmentsHighlighter):
     """ A PygmentsHighlighter that understands and ignores prompts.
     """
 
     def __init__(self, frontend):
         super(FrontendHighlighter, self).__init__(frontend._control.document())
         self._current_offset = 0
         self._frontend = frontend
         self.highlighting_on = False
 
     def highlightBlock(self, string):
         """ Highlight a block of text. Reimplemented to highlight selectively.
         """
         if not self.highlighting_on:
             return
 
         # The input to this function is a unicode string that may contain
         # paragraph break characters, non-breaking spaces, etc. Here we acquire
         # the string as plain text so we can compare it.
         current_block = self.currentBlock()
         string = self._frontend._get_block_plain_text(current_block)
 
         # Decide whether to check for the regular or continuation prompt.
         if current_block.contains(self._frontend._prompt_pos):
             prompt = self._frontend._prompt
         else:
             prompt = self._frontend._continuation_prompt
 
         # Only highlight if we can identify a prompt, but make sure not to
         # highlight the prompt.
         if string.startswith(prompt):
             self._current_offset = len(prompt)
             string = string[len(prompt):]
             super(FrontendHighlighter, self).highlightBlock(string)
 
     def rehighlightBlock(self, block):
         """ Reimplemented to temporarily enable highlighting if disabled.
         """
         old = self.highlighting_on
         self.highlighting_on = True
         super(FrontendHighlighter, self).rehighlightBlock(block)
         self.highlighting_on = old
 
     def setFormat(self, start, count, format):
         """ Reimplemented to highlight selectively.
         """
         start += self._current_offset
         super(FrontendHighlighter, self).setFormat(start, count, format)
 
 
 class FrontendWidget(HistoryConsoleWidget, BaseFrontendMixin):
     """ A Qt frontend for a generic Python kernel.
     """
 
     # The text to show when the kernel is (re)started.
     banner = Unicode()
 
     # An option and corresponding signal for overriding the default kernel
     # interrupt behavior.
     custom_interrupt = Bool(False)
     custom_interrupt_requested = QtCore.Signal()
 
     # An option and corresponding signals for overriding the default kernel
     # restart behavior.
     custom_restart = Bool(False)
     custom_restart_kernel_died = QtCore.Signal(float)
     custom_restart_requested = QtCore.Signal()
 
     # Whether to automatically show calltips on open-parentheses.
     enable_calltips = Bool(True, config=True,
         help="Whether to draw information calltips on open-parentheses.")
 
     # Emitted when a user visible 'execute_request' has been submitted to the
     # kernel from the FrontendWidget. Contains the code to be executed.
     executing = QtCore.Signal(object)
 
     # Emitted when a user-visible 'execute_reply' has been received from the
     # kernel and processed by the FrontendWidget. Contains the response message.
     executed = QtCore.Signal(object)
 
     # Emitted when an exit request has been received from the kernel.
     exit_requested = QtCore.Signal(object)
 
     # Protected class variables.
     _CallTipRequest = namedtuple('_CallTipRequest', ['id', 'pos'])
     _CompletionRequest = namedtuple('_CompletionRequest', ['id', 'pos'])
     _ExecutionRequest = namedtuple('_ExecutionRequest', ['id', 'kind'])
     _input_splitter_class = InputSplitter
     _local_kernel = False
     _highlighter = Instance(FrontendHighlighter)
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
 
     def __init__(self, *args, **kw):
         super(FrontendWidget, self).__init__(*args, **kw)
         # FIXME: remove this when PySide min version is updated past 1.0.7
         # forcefully disable calltips if PySide is < 1.0.7, because they crash
         if qt.QT_API == qt.QT_API_PYSIDE:
             import PySide
             if PySide.__version_info__ < (1,0,7):
                 self.log.warn("PySide %s < 1.0.7 detected, disabling calltips" % PySide.__version__)
                 self.enable_calltips = False
 
         # FrontendWidget protected variables.
         self._bracket_matcher = BracketMatcher(self._control)
         self._call_tip_widget = CallTipWidget(self._control)
         self._completion_lexer = CompletionLexer(PythonLexer())
         self._copy_raw_action = QtGui.QAction('Copy (Raw Text)', None)
         self._hidden = False
         self._highlighter = FrontendHighlighter(self)
         self._input_splitter = self._input_splitter_class(input_mode='cell')
         self._kernel_manager = None
         self._request_info = {}
         self._request_info['execute'] = {};
         self._callback_dict = {}
 
         # Configure the ConsoleWidget.
         self.tab_width = 4
         self._set_continuation_prompt('... ')
 
         # Configure the CallTipWidget.
         self._call_tip_widget.setFont(self.font)
         self.font_changed.connect(self._call_tip_widget.setFont)
 
         # Configure actions.
         action = self._copy_raw_action
         key = QtCore.Qt.CTRL | QtCore.Qt.SHIFT | QtCore.Qt.Key_C
         action.setEnabled(False)
         action.setShortcut(QtGui.QKeySequence(key))
         action.setShortcutContext(QtCore.Qt.WidgetWithChildrenShortcut)
         action.triggered.connect(self.copy_raw)
         self.copy_available.connect(action.setEnabled)
         self.addAction(action)
 
         # Connect signal handlers.
         document = self._control.document()
         document.contentsChange.connect(self._document_contents_change)
 
         # Set flag for whether we are connected via localhost.
         self._local_kernel = kw.get('local_kernel',
                                     FrontendWidget._local_kernel)
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' public interface
     #---------------------------------------------------------------------------
 
     def copy(self):
         """ Copy the currently selected text to the clipboard, removing prompts.
         """
         text = self._control.textCursor().selection().toPlainText()
         if text:
             lines = map(transform_classic_prompt, text.splitlines())
             text = '\n'.join(lines)
             QtGui.QApplication.clipboard().setText(text)
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' abstract interface
     #---------------------------------------------------------------------------
 
     def _is_complete(self, source, interactive):
         """ Returns whether 'source' can be completely processed and a new
             prompt created. When triggered by an Enter/Return key press,
             'interactive' is True; otherwise, it is False.
         """
         complete = self._input_splitter.push(source)
         if interactive:
             complete = not self._input_splitter.push_accepts_more()
         return complete
 
     def _execute(self, source, hidden):
         """ Execute 'source'. If 'hidden', do not show any output.
 
         See parent class :meth:`execute` docstring for full details.
         """
         msg_id = self.kernel_manager.shell_channel.execute(source, hidden)
         self._request_info['execute'][msg_id] = self._ExecutionRequest(msg_id, 'user')
         self._hidden = hidden
         if not hidden:
             self.executing.emit(source)
 
     def _prompt_started_hook(self):
         """ Called immediately after a new prompt is displayed.
         """
         if not self._reading:
             self._highlighter.highlighting_on = True
 
     def _prompt_finished_hook(self):
         """ Called immediately after a prompt is finished, i.e. when some input
             will be processed and a new prompt displayed.
         """
         # Flush all state from the input splitter so the next round of
         # reading input starts with a clean buffer.
         self._input_splitter.reset()
 
         if not self._reading:
             self._highlighter.highlighting_on = False
 
     def _tab_pressed(self):
         """ Called when the tab key is pressed. Returns whether to continue
             processing the event.
         """
         # Perform tab completion if:
         # 1) The cursor is in the input buffer.
         # 2) There is a non-whitespace character before the cursor.
         text = self._get_input_buffer_cursor_line()
         if text is None:
             return False
         complete = bool(text[:self._get_input_buffer_cursor_column()].strip())
         if complete:
             self._complete()
         return not complete
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _context_menu_make(self, pos):
         """ Reimplemented to add an action for raw copy.
         """
         menu = super(FrontendWidget, self)._context_menu_make(pos)
         for before_action in menu.actions():
             if before_action.shortcut().matches(QtGui.QKeySequence.Paste) == \
                     QtGui.QKeySequence.ExactMatch:
                 menu.insertAction(before_action, self._copy_raw_action)
                 break
         return menu
 
     def request_interrupt_kernel(self):
         if self._executing:
             self.interrupt_kernel()
 
     def request_restart_kernel(self):
         message = 'Are you sure you want to restart the kernel?'
         self.restart_kernel(message, now=False)
 
     def _event_filter_console_keypress(self, event):
         """ Reimplemented for execution interruption and smart backspace.
         """
         key = event.key()
         if self._control_key_down(event.modifiers(), include_command=False):
 
             if key == QtCore.Qt.Key_C and self._executing:
                 self.request_interrupt_kernel()
                 return True
 
             elif key == QtCore.Qt.Key_Period:
                 self.request_restart_kernel()
                 return True
 
         elif not event.modifiers() & QtCore.Qt.AltModifier:
 
             # Smart backspace: remove four characters in one backspace if:
             # 1) everything left of the cursor is whitespace
             # 2) the four characters immediately left of the cursor are spaces
             if key == QtCore.Qt.Key_Backspace:
                 col = self._get_input_buffer_cursor_column()
                 cursor = self._control.textCursor()
                 if col > 3 and not cursor.hasSelection():
                     text = self._get_input_buffer_cursor_line()[:col]
                     if text.endswith('    ') and not text.strip():
                         cursor.movePosition(QtGui.QTextCursor.Left,
                                             QtGui.QTextCursor.KeepAnchor, 4)
                         cursor.removeSelectedText()
                         return True
 
         return super(FrontendWidget, self)._event_filter_console_keypress(event)
 
     def _insert_continuation_prompt(self, cursor):
         """ Reimplemented for auto-indentation.
         """
         super(FrontendWidget, self)._insert_continuation_prompt(cursor)
         cursor.insertText(' ' * self._input_splitter.indent_spaces)
 
     #---------------------------------------------------------------------------
     # 'BaseFrontendMixin' abstract interface
     #---------------------------------------------------------------------------
 
     def _handle_complete_reply(self, rep):
         """ Handle replies for tab completion.
         """
         self.log.debug("complete: %s", rep.get('content', ''))
         cursor = self._get_cursor()
         info = self._request_info.get('complete')
         if info and info.id == rep['parent_header']['msg_id'] and \
                 info.pos == cursor.position():
             text = '.'.join(self._get_context())
             cursor.movePosition(QtGui.QTextCursor.Left, n=len(text))
             self._complete_with_items(cursor, rep['content']['matches'])
 
     def _silent_exec_callback(self, expr, callback):
         """Silently execute `expr` in the kernel and call `callback` with reply
 
         the `expr` is evaluated silently in the kernel (without) output in
         the frontend. Call `callback` with the
         `repr <http://docs.python.org/library/functions.html#repr> `_ as first argument
 
         Parameters
         ----------
         expr : string
             valid string to be executed by the kernel.
         callback : function
             function accepting one arguement, as a string. The string will be
             the `repr` of the result of evaluating `expr`
 
         The `callback` is called with the 'repr()' of the result of `expr` as
         first argument. To get the object, do 'eval()' onthe passed value.
 
         See Also
         --------
         _handle_exec_callback : private method, deal with calling callback with reply
 
         """
 
         # generate uuid, which would be used as a indication of wether or not
         # the unique request originate from here (can use msg id ?)
         local_uuid = str(uuid.uuid1())
         msg_id = self.kernel_manager.shell_channel.execute('',
             silent=True, user_expressions={ local_uuid:expr })
         self._callback_dict[local_uuid] = callback
         self._request_info['execute'][msg_id] = self._ExecutionRequest(msg_id, 'silent_exec_callback')
 
     def _handle_exec_callback(self, msg):
         """Execute `callback` corresonding to `msg` reply, after ``_silent_exec_callback``
 
         Parameters
         ----------
         msg : raw message send by the kernel containing an `user_expressions`
                 and having a 'silent_exec_callback' kind.
 
         Notes
         -----
         This fonction will look for a `callback` associated with the
         corresponding message id. Association has been made by
         `_silent_exec_callback`. `callback` is then called with the `repr()`
         of the value of corresponding `user_expressions` as argument.
         `callback` is then removed from the known list so that any message
         coming again with the same id won't trigger it.
 
         """
 
         user_exp = msg['content']['user_expressions']
         for expression in user_exp:
             if expression in self._callback_dict:
                 self._callback_dict.pop(expression)(user_exp[expression])
 
     def _handle_execute_reply(self, msg):
         """ Handles replies for code execution.
         """
         self.log.debug("execute: %s", msg.get('content', ''))
-        info_list = self._request_info.get('execute')
         msg_id = msg['parent_header']['msg_id']
-        if msg_id in info_list:
-            info = info_list[msg_id]
+        info = self._request_info['execute'].get(msg_id)
         # unset reading flag, because if execute finished, raw_input can't
         # still be pending.
         self._reading = False
         if info and info.kind == 'user' and not self._hidden:
             # Make sure that all output from the SUB channel has been processed
             # before writing a new prompt.
             self.kernel_manager.sub_channel.flush()
 
             # Reset the ANSI style information to prevent bad text in stdout
             # from messing up our colors. We're not a true terminal so we're
             # allowed to do this.
             if self.ansi_codes:
                 self._ansi_processor.reset_sgr()
 
             content = msg['content']
             status = content['status']
             if status == 'ok':
                 self._process_execute_ok(msg)
             elif status == 'error':
                 self._process_execute_error(msg)
             elif status == 'aborted':
                 self._process_execute_abort(msg)
 
             self._show_interpreter_prompt_for_reply(msg)
             self.executed.emit(msg)
-            info_list.pop(msg_id)
+            self._request_info['execute'].pop(msg_id)
         elif info and info.kind == 'silent_exec_callback' and not self._hidden:
             self._handle_exec_callback(msg)
         else:
             super(FrontendWidget, self)._handle_execute_reply(msg)
 
     def _handle_input_request(self, msg):
         """ Handle requests for raw_input.
         """
         self.log.debug("input: %s", msg.get('content', ''))
         if self._hidden:
             raise RuntimeError('Request for raw input during hidden execution.')
 
         # Make sure that all output from the SUB channel has been processed
         # before entering readline mode.
         self.kernel_manager.sub_channel.flush()
 
         def callback(line):
             self.kernel_manager.stdin_channel.input(line)
         if self._reading:
             self.log.debug("Got second input request, assuming first was interrupted.")
             self._reading = False
         self._readline(msg['content']['prompt'], callback=callback)
 
     def _handle_kernel_died(self, since_last_heartbeat):
         """ Handle the kernel's death by asking if the user wants to restart.
         """
         self.log.debug("kernel died: %s", since_last_heartbeat)
         if self.custom_restart:
             self.custom_restart_kernel_died.emit(since_last_heartbeat)
         else:
             message = 'The kernel heartbeat has been inactive for %.2f ' \
                 'seconds. Do you want to restart the kernel? You may ' \
                 'first want to check the network connection.' % \
                 since_last_heartbeat
             self.restart_kernel(message, now=True)
 
     def _handle_object_info_reply(self, rep):
         """ Handle replies for call tips.
         """
         self.log.debug("oinfo: %s", rep.get('content', ''))
         cursor = self._get_cursor()
         info = self._request_info.get('call_tip')
         if info and info.id == rep['parent_header']['msg_id'] and \
                 info.pos == cursor.position():
             # Get the information for a call tip.  For now we format the call
             # line as string, later we can pass False to format_call and
             # syntax-highlight it ourselves for nicer formatting in the
             # calltip.
             content = rep['content']
             # if this is from pykernel, 'docstring' will be the only key
             if content.get('ismagic', False):
                 # Don't generate a call-tip for magics. Ideally, we should
                 # generate a tooltip, but not on ( like we do for actual
                 # callables.
                 call_info, doc = None, None
             else:
                 call_info, doc = call_tip(content, format_call=True)
             if call_info or doc:
                 self._call_tip_widget.show_call_info(call_info, doc)
 
     def _handle_pyout(self, msg):
         """ Handle display hook output.
         """
         self.log.debug("pyout: %s", msg.get('content', ''))
         if not self._hidden and self._is_from_this_session(msg):
             text = msg['content']['data']
             self._append_plain_text(text + '\n', before_prompt=True)
 
     def _handle_stream(self, msg):
         """ Handle stdout, stderr, and stdin.
         """
         self.log.debug("stream: %s", msg.get('content', ''))
         if not self._hidden and self._is_from_this_session(msg):
             # Most consoles treat tabs as being 8 space characters. Convert tabs
             # to spaces so that output looks as expected regardless of this
             # widget's tab width.
             text = msg['content']['data'].expandtabs(8)
 
             self._append_plain_text(text, before_prompt=True)
             self._control.moveCursor(QtGui.QTextCursor.End)
 
     def _handle_shutdown_reply(self, msg):
         """ Handle shutdown signal, only if from other console.
         """
         self.log.debug("shutdown: %s", msg.get('content', ''))
         if not self._hidden and not self._is_from_this_session(msg):
             if self._local_kernel:
                 if not msg['content']['restart']:
                     self.exit_requested.emit(self)
                 else:
                     # we just got notified of a restart!
                     time.sleep(0.25) # wait 1/4 sec to reset
                                      # lest the request for a new prompt
                                      # goes to the old kernel
                     self.reset()
             else: # remote kernel, prompt on Kernel shutdown/reset
                 title = self.window().windowTitle()
                 if not msg['content']['restart']:
                     reply = QtGui.QMessageBox.question(self, title,
                         "Kernel has been shutdown permanently. "
                         "Close the Console?",
                         QtGui.QMessageBox.Yes,QtGui.QMessageBox.No)
                     if reply == QtGui.QMessageBox.Yes:
                         self.exit_requested.emit(self)
                 else:
                     reply = QtGui.QMessageBox.question(self, title,
                         "Kernel has been reset. Clear the Console?",
                         QtGui.QMessageBox.Yes,QtGui.QMessageBox.No)
                     if reply == QtGui.QMessageBox.Yes:
                         time.sleep(0.25) # wait 1/4 sec to reset
                                          # lest the request for a new prompt
                                          # goes to the old kernel
                         self.reset()
 
     def _started_channels(self):
         """ Called when the KernelManager channels have started listening or
             when the frontend is assigned an already listening KernelManager.
         """
         self.reset()
 
     #---------------------------------------------------------------------------
     # 'FrontendWidget' public interface
     #---------------------------------------------------------------------------
 
     def copy_raw(self):
         """ Copy the currently selected text to the clipboard without attempting
             to remove prompts or otherwise alter the text.
         """
         self._control.copy()
 
     def execute_file(self, path, hidden=False):
         """ Attempts to execute file with 'path'. If 'hidden', no output is
             shown.
         """
         self.execute('execfile(%r)' % path, hidden=hidden)
 
     def interrupt_kernel(self):
         """ Attempts to interrupt the running kernel.
         
         Also unsets _reading flag, to avoid runtime errors
         if raw_input is called again.
         """
         if self.custom_interrupt:
             self._reading = False
             self.custom_interrupt_requested.emit()
         elif self.kernel_manager.has_kernel:
             self._reading = False
             self.kernel_manager.interrupt_kernel()
         else:
             self._append_plain_text('Kernel process is either remote or '
                                     'unspecified. Cannot interrupt.\n')
 
     def reset(self):
         """ Resets the widget to its initial state. Similar to ``clear``, but
             also re-writes the banner and aborts execution if necessary.
         """
         if self._executing:
             self._executing = False
             self._request_info['execute'] = {}
         self._reading = False
         self._highlighter.highlighting_on = False
 
         self._control.clear()
         self._append_plain_text(self.banner)
         # update output marker for stdout/stderr, so that startup
         # messages appear after banner:
         self._append_before_prompt_pos = self._get_cursor().position()
         self._show_interpreter_prompt()
 
     def restart_kernel(self, message, now=False):
         """ Attempts to restart the running kernel.
         """
         # FIXME: now should be configurable via a checkbox in the dialog.  Right
         # now at least the heartbeat path sets it to True and the manual restart
         # to False.  But those should just be the pre-selected states of a
         # checkbox that the user could override if so desired.  But I don't know
         # enough Qt to go implementing the checkbox now.
 
         if self.custom_restart:
             self.custom_restart_requested.emit()
 
         elif self.kernel_manager.has_kernel:
             # Pause the heart beat channel to prevent further warnings.
             self.kernel_manager.hb_channel.pause()
 
             # Prompt the user to restart the kernel. Un-pause the heartbeat if
             # they decline. (If they accept, the heartbeat will be un-paused
             # automatically when the kernel is restarted.)
             buttons = QtGui.QMessageBox.Yes | QtGui.QMessageBox.No
             result = QtGui.QMessageBox.question(self, 'Restart kernel?',
                                                 message, buttons)
             if result == QtGui.QMessageBox.Yes:
                 try:
                     self.kernel_manager.restart_kernel(now=now)
                 except RuntimeError:
                     self._append_plain_text('Kernel started externally. '
                                             'Cannot restart.\n')
                 else:
                     self.reset()
             else:
                 self.kernel_manager.hb_channel.unpause()
 
         else:
             self._append_plain_text('Kernel process is either remote or '
                                     'unspecified. Cannot restart.\n')
 
     #---------------------------------------------------------------------------
     # 'FrontendWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _call_tip(self):
         """ Shows a call tip, if appropriate, at the current cursor location.
         """
         # Decide if it makes sense to show a call tip
         if not self.enable_calltips:
             return False
         cursor = self._get_cursor()
         cursor.movePosition(QtGui.QTextCursor.Left)
         if cursor.document().characterAt(cursor.position()) != '(':
             return False
         context = self._get_context(cursor)
         if not context:
             return False
 
         # Send the metadata request to the kernel
         name = '.'.join(context)
         msg_id = self.kernel_manager.shell_channel.object_info(name)
         pos = self._get_cursor().position()
         self._request_info['call_tip'] = self._CallTipRequest(msg_id, pos)
         return True
 
     def _complete(self):
         """ Performs completion at the current cursor location.
         """
         context = self._get_context()
         if context:
             # Send the completion request to the kernel
             msg_id = self.kernel_manager.shell_channel.complete(
                 '.'.join(context),                       # text
                 self._get_input_buffer_cursor_line(),    # line
                 self._get_input_buffer_cursor_column(),  # cursor_pos
                 self.input_buffer)                       # block
             pos = self._get_cursor().position()
             info = self._CompletionRequest(msg_id, pos)
             self._request_info['complete'] = info
 
     def _get_context(self, cursor=None):
         """ Gets the context for the specified cursor (or the current cursor
             if none is specified).
         """
         if cursor is None:
             cursor = self._get_cursor()
         cursor.movePosition(QtGui.QTextCursor.StartOfBlock,
                             QtGui.QTextCursor.KeepAnchor)
         text = cursor.selection().toPlainText()
         return self._completion_lexer.get_context(text)
 
     def _process_execute_abort(self, msg):
         """ Process a reply for an aborted execution request.
         """
         self._append_plain_text("ERROR: execution aborted\n")
 
     def _process_execute_error(self, msg):
         """ Process a reply for an execution request that resulted in an error.
         """
         content = msg['content']
         # If a SystemExit is passed along, this means exit() was called - also
         # all the ipython %exit magic syntax of '-k' to be used to keep
         # the kernel running
         if content['ename']=='SystemExit':
             keepkernel = content['evalue']=='-k' or content['evalue']=='True'
             self._keep_kernel_on_exit = keepkernel
             self.exit_requested.emit(self)
         else:
             traceback = ''.join(content['traceback'])
             self._append_plain_text(traceback)
 
     def _process_execute_ok(self, msg):
         """ Process a reply for a successful execution equest.
         """
         payload = msg['content']['payload']
         for item in payload:
             if not self._process_execute_payload(item):
                 warning = 'Warning: received unknown payload of type %s'
                 print(warning % repr(item['source']))
 
     def _process_execute_payload(self, item):
         """ Process a single payload item from the list of payload items in an
             execution reply. Returns whether the payload was handled.
         """
         # The basic FrontendWidget doesn't handle payloads, as they are a
         # mechanism for going beyond the standard Python interpreter model.
         return False
 
     def _show_interpreter_prompt(self):
         """ Shows a prompt for the interpreter.
         """
         self._show_prompt('>>> ')
 
     def _show_interpreter_prompt_for_reply(self, msg):
         """ Shows a prompt for the interpreter given an 'execute_reply' message.
         """
         self._show_interpreter_prompt()
 
     #------ Signal handlers ----------------------------------------------------
 
     def _document_contents_change(self, position, removed, added):
         """ Called whenever the document's content changes. Display a call tip
             if appropriate.
         """
         # Calculate where the cursor should be *after* the change:
         position += added
 
         document = self._control.document()
         if position == self._get_cursor().position():
             self._call_tip()
 
     #------ Trait default initializers -----------------------------------------
 
     def _banner_default(self):
         """ Returns the standard Python banner.
         """
         banner = 'Python %s on %s\nType "help", "copyright", "credits" or ' \
             '"license" for more information.'
         return banner % (sys.version, sys.platform)

IPython/frontend/qt/console/history_console_widget.py

@@ -1,285 +1,283 b''
 # System library imports
 from IPython.external.qt import QtGui
 
 # Local imports
 from IPython.utils.traitlets import Bool
 from console_widget import ConsoleWidget
 
 
 class HistoryConsoleWidget(ConsoleWidget):
     """ A ConsoleWidget that keeps a history of the commands that have been
         executed and provides a readline-esque interface to this history.
     """
 
     #------ Configuration ------------------------------------------------------
 
     # If enabled, the input buffer will become "locked" to history movement when
     # an edit is made to a multi-line input buffer. To override the lock, use
     # Shift in conjunction with the standard history cycling keys.
     history_lock = Bool(False, config=True)
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
 
     def __init__(self, *args, **kw):
         super(HistoryConsoleWidget, self).__init__(*args, **kw)
 
         # HistoryConsoleWidget protected variables.
         self._history = []
         self._history_edits = {}
         self._history_index = 0
         self._history_prefix = ''
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' public interface
     #---------------------------------------------------------------------------
 
     def execute(self, source=None, hidden=False, interactive=False):
         """ Reimplemented to the store history.
         """
         if not hidden:
             history = self.input_buffer if source is None else source
 
         executed = super(HistoryConsoleWidget, self).execute(
             source, hidden, interactive)
 
         if executed and not hidden:
             # Save the command unless it was an empty string or was identical
             # to the previous command.
             history = history.rstrip()
             if history and (not self._history or self._history[-1] != history):
                 self._history.append(history)
 
             # Emulate readline: reset all history edits.
             self._history_edits = {}
 
             # Move the history index to the most recent item.
             self._history_index = len(self._history)
 
         return executed
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' abstract interface
     #---------------------------------------------------------------------------
 
     def _up_pressed(self, shift_modifier):
         """ Called when the up key is pressed. Returns whether to continue
             processing the event.
         """
         prompt_cursor = self._get_prompt_cursor()
         if self._get_cursor().blockNumber() == prompt_cursor.blockNumber():
             # Bail out if we're locked.
             if self._history_locked() and not shift_modifier:
                 return False
 
             # Set a search prefix based on the cursor position.
             col = self._get_input_buffer_cursor_column()
             input_buffer = self.input_buffer
             if self._history_index == len(self._history) or \
                     (self._history_prefix and col != len(self._history_prefix)):
                 self._history_index = len(self._history)
                 self._history_prefix = input_buffer[:col]
 
             # Perform the search.
             self.history_previous(self._history_prefix,
                                     as_prefix=not shift_modifier)
 
             # Go to the first line of the prompt for seemless history scrolling.
             # Emulate readline: keep the cursor position fixed for a prefix
             # search.
             cursor = self._get_prompt_cursor()
             if self._history_prefix:
                 cursor.movePosition(QtGui.QTextCursor.Right,
                                     n=len(self._history_prefix))
             else:
                 cursor.movePosition(QtGui.QTextCursor.EndOfLine)
             self._set_cursor(cursor)
 
             return False
 
         return True
 
     def _down_pressed(self, shift_modifier):
         """ Called when the down key is pressed. Returns whether to continue
             processing the event.
         """
         end_cursor = self._get_end_cursor()
         if self._get_cursor().blockNumber() == end_cursor.blockNumber():
             # Bail out if we're locked.
             if self._history_locked() and not shift_modifier:
                 return False
 
             # Perform the search.
             replaced = self.history_next(self._history_prefix,
                                             as_prefix=not shift_modifier)
 
             # Emulate readline: keep the cursor position fixed for a prefix
             # search. (We don't need to move the cursor to the end of the buffer
             # in the other case because this happens automatically when the
             # input buffer is set.)
             if self._history_prefix and replaced:
                 cursor = self._get_prompt_cursor()
                 cursor.movePosition(QtGui.QTextCursor.Right,
                                     n=len(self._history_prefix))
                 self._set_cursor(cursor)
 
             return False
 
         return True
 
     #---------------------------------------------------------------------------
     # 'HistoryConsoleWidget' public interface
     #---------------------------------------------------------------------------
 
     def history_previous(self, substring='', as_prefix=True):
         """ If possible, set the input buffer to a previous history item.
 
         Parameters:
         -----------
         substring : str, optional
             If specified, search for an item with this substring.
         as_prefix : bool, optional
             If True, the substring must match at the beginning (default).
 
         Returns:
         --------
         Whether the input buffer was changed.
         """
         index = self._history_index
         replace = False
         while index > 0:
             index -= 1
             history = self._get_edited_history(index)
             if (as_prefix and history.startswith(substring)) \
                 or (not as_prefix and substring in history):
                 replace = True
                 break
 
         if replace:
             self._store_edits()
             self._history_index = index
             self.input_buffer = history
 
         return replace
 
     def history_next(self, substring='', as_prefix=True):
         """ If possible, set the input buffer to a subsequent history item.
 
         Parameters:
         -----------
         substring : str, optional
             If specified, search for an item with this substring.
         as_prefix : bool, optional
             If True, the substring must match at the beginning (default).
 
         Returns:
         --------
         Whether the input buffer was changed.
         """
         index = self._history_index
         replace = False
         while self._history_index < len(self._history):
             index += 1
             history = self._get_edited_history(index)
             if (as_prefix and history.startswith(substring)) \
                 or (not as_prefix and substring in history):
                 replace = True
                 break
 
         if replace:
             self._store_edits()
             self._history_index = index
             self.input_buffer = history
 
         return replace
 
     def history_tail(self, n=10):
         """ Get the local history list.
 
         Parameters:
         -----------
         n : int
             The (maximum) number of history items to get.
         """
         return self._history[-n:]
 
     def _request_update_session_history_length(self):
         msg_id = self.kernel_manager.shell_channel.execute('',
             silent=True,
             user_expressions={
                 'hlen':'len(get_ipython().history_manager.input_hist_raw)',
                 }
             )
         self._request_info['execute'][msg_id] = self._ExecutionRequest(msg_id, 'save_magic')
 
     def _handle_execute_reply(self, msg):
         """ Handles replies for code execution, here only session history length
         """
-        info_list = self._request_info.get('execute')
         msg_id = msg['parent_header']['msg_id']
-        if msg_id in info_list:
-            info = info_list.pop(msg_id)
-            if info.kind == 'save_magic' and not self._hidden:
-                content = msg['content']
-                status = content['status']
-                if status == 'ok':
-                    self._max_session_history=(int(content['user_expressions']['hlen']))
+        info = self._request_info.get['execute'].pop(msg_id,None)
+        if info and info.kind == 'save_magic' and not self._hidden:
+            content = msg['content']
+            status = content['status']
+            if status == 'ok':
+                self._max_session_history=(int(content['user_expressions']['hlen']))
 
     def save_magic(self):
         # update the session history length
         self._request_update_session_history_length()
 
         file_name,extFilter = QtGui.QFileDialog.getSaveFileName(self,
             "Enter A filename",
             filter='Python File (*.py);; All files (*.*)'
             )
 
         # let's the user search/type for a file name, while the history length
         # is fetched
 
         if file_name:
             hist_range, ok = QtGui.QInputDialog.getText(self,
                 'Please enter an interval of command to save',
                 'Saving commands:',
                 text=str('1-'+str(self._max_session_history))
                 )
             if ok:
                 self.execute("%save"+" "+file_name+" "+str(hist_range))
 
     #---------------------------------------------------------------------------
     # 'HistoryConsoleWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _history_locked(self):
         """ Returns whether history movement is locked.
         """
         return (self.history_lock and
                 (self._get_edited_history(self._history_index) !=
                  self.input_buffer) and
                 (self._get_prompt_cursor().blockNumber() !=
                  self._get_end_cursor().blockNumber()))
 
     def _get_edited_history(self, index):
         """ Retrieves a history item, possibly with temporary edits.
         """
         if index in self._history_edits:
             return self._history_edits[index]
         elif index == len(self._history):
             return unicode()
         return self._history[index]
 
     def _set_history(self, history):
         """ Replace the current history with a sequence of history items.
         """
         self._history = list(history)
         self._history_edits = {}
         self._history_index = len(self._history)
 
     def _store_edits(self):
         """ If there are edits to the current input buffer, store them.
         """
         current = self.input_buffer
         if self._history_index == len(self._history) or \
                 self._history[self._history_index] != current:
             self._history_edits[self._history_index] = current

IPython/frontend/qt/console/ipython_widget.py

@@ -1,565 +1,563 b''
 """ A FrontendWidget that emulates the interface of the console IPython and
     supports the additional functionality provided by the IPython kernel.
 """
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # Standard library imports
 from collections import namedtuple
 import os.path
 import re
 from subprocess import Popen
 import sys
 import time
 from textwrap import dedent
 
 # System library imports
 from IPython.external.qt import QtCore, QtGui
 
 # Local imports
 from IPython.core.inputsplitter import IPythonInputSplitter, \
     transform_ipy_prompt
 from IPython.utils.traitlets import Bool, Unicode
 from frontend_widget import FrontendWidget
 import styles
 
 #-----------------------------------------------------------------------------
 # Constants
 #-----------------------------------------------------------------------------
 
 # Default strings to build and display input and output prompts (and separators
 # in between)
 default_in_prompt = 'In [<span class="in-prompt-number">%i</span>]: '
 default_out_prompt = 'Out[<span class="out-prompt-number">%i</span>]: '
 default_input_sep = '\n'
 default_output_sep = ''
 default_output_sep2 = ''
 
 # Base path for most payload sources.
 zmq_shell_source = 'IPython.zmq.zmqshell.ZMQInteractiveShell'
 
 if sys.platform.startswith('win'):
     default_editor = 'notepad'
 else:
     default_editor = ''
 
 #-----------------------------------------------------------------------------
 # IPythonWidget class
 #-----------------------------------------------------------------------------
 
 class IPythonWidget(FrontendWidget):
     """ A FrontendWidget for an IPython kernel.
     """
 
     # If set, the 'custom_edit_requested(str, int)' signal will be emitted when
     # an editor is needed for a file. This overrides 'editor' and 'editor_line'
     # settings.
     custom_edit = Bool(False)
     custom_edit_requested = QtCore.Signal(object, object)
 
     editor = Unicode(default_editor, config=True,
         help="""
         A command for invoking a system text editor. If the string contains a
         {filename} format specifier, it will be used. Otherwise, the filename
         will be appended to the end the command.
         """)
 
     editor_line = Unicode(config=True,
         help="""
         The editor command to use when a specific line number is requested. The
         string should contain two format specifiers: {line} and {filename}. If
         this parameter is not specified, the line number option to the %edit
         magic will be ignored.
         """)
 
     style_sheet = Unicode(config=True,
         help="""
         A CSS stylesheet. The stylesheet can contain classes for:
             1. Qt: QPlainTextEdit, QFrame, QWidget, etc
             2. Pygments: .c, .k, .o, etc. (see PygmentsHighlighter)
             3. IPython: .error, .in-prompt, .out-prompt, etc
         """)
 
     syntax_style = Unicode(config=True,
         help="""
         If not empty, use this Pygments style for syntax highlighting.
         Otherwise, the style sheet is queried for Pygments style
         information.
         """)
 
     # Prompts.
     in_prompt = Unicode(default_in_prompt, config=True)
     out_prompt = Unicode(default_out_prompt, config=True)
     input_sep = Unicode(default_input_sep, config=True)
     output_sep = Unicode(default_output_sep, config=True)
     output_sep2 = Unicode(default_output_sep2, config=True)
 
     # FrontendWidget protected class variables.
     _input_splitter_class = IPythonInputSplitter
 
     # IPythonWidget protected class variables.
     _PromptBlock = namedtuple('_PromptBlock', ['block', 'length', 'number'])
     _payload_source_edit = zmq_shell_source + '.edit_magic'
     _payload_source_exit = zmq_shell_source + '.ask_exit'
     _payload_source_next_input = zmq_shell_source + '.set_next_input'
     _payload_source_page = 'IPython.zmq.page.page'
     _retrying_history_request = False
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
 
     def __init__(self, *args, **kw):
         super(IPythonWidget, self).__init__(*args, **kw)
 
         # IPythonWidget protected variables.
         self._payload_handlers = {
             self._payload_source_edit : self._handle_payload_edit,
             self._payload_source_exit : self._handle_payload_exit,
             self._payload_source_page : self._handle_payload_page,
             self._payload_source_next_input : self._handle_payload_next_input }
         self._previous_prompt_obj = None
         self._keep_kernel_on_exit = None
 
         # Initialize widget styling.
         if self.style_sheet:
             self._style_sheet_changed()
             self._syntax_style_changed()
         else:
             self.set_default_style()
 
     #---------------------------------------------------------------------------
     # 'BaseFrontendMixin' abstract interface
     #---------------------------------------------------------------------------
 
     def _handle_complete_reply(self, rep):
         """ Reimplemented to support IPython's improved completion machinery.
         """
         self.log.debug("complete: %s", rep.get('content', ''))
         cursor = self._get_cursor()
         info = self._request_info.get('complete')
         if info and info.id == rep['parent_header']['msg_id'] and \
                 info.pos == cursor.position():
             matches = rep['content']['matches']
             text = rep['content']['matched_text']
             offset = len(text)
 
             # Clean up matches with period and path separators if the matched
             # text has not been transformed. This is done by truncating all
             # but the last component and then suitably decreasing the offset
             # between the current cursor position and the start of completion.
             if len(matches) > 1 and matches[0][:offset] == text:
                 parts = re.split(r'[./\\]', text)
                 sep_count = len(parts) - 1
                 if sep_count:
                     chop_length = sum(map(len, parts[:sep_count])) + sep_count
                     matches = [ match[chop_length:] for match in matches ]
                     offset -= chop_length
 
             # Move the cursor to the start of the match and complete.
             cursor.movePosition(QtGui.QTextCursor.Left, n=offset)
             self._complete_with_items(cursor, matches)
 
     def _handle_execute_reply(self, msg):
         """ Reimplemented to support prompt requests.
         """
-        info_list = self._request_info.get('execute')
-        msg_id = msg['parent_header']['msg_id']
-        if msg_id in info_list:
-            info = info_list[msg_id]
-            if info.kind == 'prompt':
-                number = msg['content']['execution_count'] + 1
-                self._show_interpreter_prompt(number)
-                info_list.pop(msg_id)
-            else:
-                super(IPythonWidget, self)._handle_execute_reply(msg)
+        msg_id = msg['parent_header'].get('msg_id')
+        info = self._request_info['execute'].get(msg_id)
+        if info and info.kind == 'prompt':
+           number = msg['content']['execution_count'] + 1
+           self._show_interpreter_prompt(number)
+           self._request_info['execute'].pop(msg_id)
+        else:
+           super(IPythonWidget, self)._handle_execute_reply(msg)
 
     def _handle_history_reply(self, msg):
         """ Implemented to handle history tail replies, which are only supported
             by the IPython kernel.
         """
         self.log.debug("history: %s", msg.get('content', ''))
         content = msg['content']
         if 'history' not in content:
             self.log.error("History request failed: %r"%content)
             if content.get('status', '') == 'aborted' and \
                                             not self._retrying_history_request:
                 # a *different* action caused this request to be aborted, so
                 # we should try again.
                 self.log.error("Retrying aborted history request")
                 # prevent multiple retries of aborted requests:
                 self._retrying_history_request = True
                 # wait out the kernel's queue flush, which is currently timed at 0.1s
                 time.sleep(0.25)
                 self.kernel_manager.shell_channel.history(hist_access_type='tail',n=1000)
             else:
                 self._retrying_history_request = False
             return
         # reset retry flag
         self._retrying_history_request = False
         history_items = content['history']
         items = []
         last_cell = u""
         for _, _, cell in history_items:
             cell = cell.rstrip()
             if cell != last_cell:
                 items.append(cell)
                 last_cell = cell
         self._set_history(items)
 
     def _handle_pyout(self, msg):
         """ Reimplemented for IPython-style "display hook".
         """
         self.log.debug("pyout: %s", msg.get('content', ''))
         if not self._hidden and self._is_from_this_session(msg):
             content = msg['content']
             prompt_number = content['execution_count']
             data = content['data']
             if data.has_key('text/html'):
                 self._append_plain_text(self.output_sep, True)
                 self._append_html(self._make_out_prompt(prompt_number), True)
                 html = data['text/html']
                 self._append_plain_text('\n', True)
                 self._append_html(html + self.output_sep2, True)
             elif data.has_key('text/plain'):
                 self._append_plain_text(self.output_sep, True)
                 self._append_html(self._make_out_prompt(prompt_number), True)
                 text = data['text/plain']
                 # If the repr is multiline, make sure we start on a new line,
                 # so that its lines are aligned.
                 if "\n" in text and not self.output_sep.endswith("\n"):
                     self._append_plain_text('\n', True)
                 self._append_plain_text(text + self.output_sep2, True)
 
     def _handle_display_data(self, msg):
         """ The base handler for the ``display_data`` message.
         """
         self.log.debug("display: %s", msg.get('content', ''))
         # For now, we don't display data from other frontends, but we
         # eventually will as this allows all frontends to monitor the display
         # data. But we need to figure out how to handle this in the GUI.
         if not self._hidden and self._is_from_this_session(msg):
             source = msg['content']['source']
             data = msg['content']['data']
             metadata = msg['content']['metadata']
             # In the regular IPythonWidget, we simply print the plain text
             # representation.
             if data.has_key('text/html'):
                 html = data['text/html']
                 self._append_html(html, True)
             elif data.has_key('text/plain'):
                 text = data['text/plain']
                 self._append_plain_text(text, True)
             # This newline seems to be needed for text and html output.
             self._append_plain_text(u'\n', True)
 
     def _started_channels(self):
         """ Reimplemented to make a history request.
         """
         super(IPythonWidget, self)._started_channels()
         self.kernel_manager.shell_channel.history(hist_access_type='tail',
                                                   n=1000)
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' public interface
     #---------------------------------------------------------------------------
 
     def copy(self):
         """ Copy the currently selected text to the clipboard, removing prompts
             if possible.
         """
         text = self._control.textCursor().selection().toPlainText()
         if text:
             lines = map(transform_ipy_prompt, text.splitlines())
             text = '\n'.join(lines)
             QtGui.QApplication.clipboard().setText(text)
 
     #---------------------------------------------------------------------------
     # 'FrontendWidget' public interface
     #---------------------------------------------------------------------------
 
     def execute_file(self, path, hidden=False):
         """ Reimplemented to use the 'run' magic.
         """
         # Use forward slashes on Windows to avoid escaping each separator.
         if sys.platform == 'win32':
             path = os.path.normpath(path).replace('\\', '/')
 
         # Perhaps we should not be using %run directly, but while we
         # are, it is necessary to quote filenames containing spaces or quotes.
         # Escaping quotes in filename in %run seems tricky and inconsistent,
         # so not trying it at present.
         if '"' in path:
             if "'" in path:
                 raise ValueError("Can't run filename containing both single "
                                  "and double quotes: %s" % path)
             path = "'%s'" % path
         elif ' ' in path or "'" in path:
             path = '"%s"' % path
 
         self.execute('%%run %s' % path, hidden=hidden)
 
     #---------------------------------------------------------------------------
     # 'FrontendWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _complete(self):
         """ Reimplemented to support IPython's improved completion machinery.
         """
         # We let the kernel split the input line, so we *always* send an empty
         # text field. Readline-based frontends do get a real text field which
         # they can use.
         text = ''
 
         # Send the completion request to the kernel
         msg_id = self.kernel_manager.shell_channel.complete(
             text,                                    # text
             self._get_input_buffer_cursor_line(),    # line
             self._get_input_buffer_cursor_column(),  # cursor_pos
             self.input_buffer)                       # block
         pos = self._get_cursor().position()
         info = self._CompletionRequest(msg_id, pos)
         self._request_info['complete'] = info
 
     def _process_execute_error(self, msg):
         """ Reimplemented for IPython-style traceback formatting.
         """
         content = msg['content']
         traceback = '\n'.join(content['traceback']) + '\n'
         if False:
             # FIXME: For now, tracebacks come as plain text, so we can't use
             # the html renderer yet.  Once we refactor ultratb to produce
             # properly styled tracebacks, this branch should be the default
             traceback = traceback.replace(' ', '&nbsp;')
             traceback = traceback.replace('\n', '<br/>')
 
             ename = content['ename']
             ename_styled = '<span class="error">%s</span>' % ename
             traceback = traceback.replace(ename, ename_styled)
 
             self._append_html(traceback)
         else:
             # This is the fallback for now, using plain text with ansi escapes
             self._append_plain_text(traceback)
 
     def _process_execute_payload(self, item):
         """ Reimplemented to dispatch payloads to handler methods.
         """
         handler = self._payload_handlers.get(item['source'])
         if handler is None:
             # We have no handler for this type of payload, simply ignore it
             return False
         else:
             handler(item)
             return True
 
     def _show_interpreter_prompt(self, number=None):
         """ Reimplemented for IPython-style prompts.
         """
         # If a number was not specified, make a prompt number request.
         if number is None:
             msg_id = self.kernel_manager.shell_channel.execute('', silent=True)
             info = self._ExecutionRequest(msg_id, 'prompt')
             self._request_info['execute'][msg_id] = info
             return
 
         # Show a new prompt and save information about it so that it can be
         # updated later if the prompt number turns out to be wrong.
         self._prompt_sep = self.input_sep
         self._show_prompt(self._make_in_prompt(number), html=True)
         block = self._control.document().lastBlock()
         length = len(self._prompt)
         self._previous_prompt_obj = self._PromptBlock(block, length, number)
 
         # Update continuation prompt to reflect (possibly) new prompt length.
         self._set_continuation_prompt(
             self._make_continuation_prompt(self._prompt), html=True)
 
     def _show_interpreter_prompt_for_reply(self, msg):
         """ Reimplemented for IPython-style prompts.
         """
         # Update the old prompt number if necessary.
         content = msg['content']
         # abort replies do not have any keys:
         if content['status'] == 'aborted':
             if self._previous_prompt_obj:
                 previous_prompt_number = self._previous_prompt_obj.number
             else:
                 previous_prompt_number = 0
         else:
             previous_prompt_number = content['execution_count']
         if self._previous_prompt_obj and \
                 self._previous_prompt_obj.number != previous_prompt_number:
             block = self._previous_prompt_obj.block
 
             # Make sure the prompt block has not been erased.
             if block.isValid() and block.text():
 
                 # Remove the old prompt and insert a new prompt.
                 cursor = QtGui.QTextCursor(block)
                 cursor.movePosition(QtGui.QTextCursor.Right,
                                     QtGui.QTextCursor.KeepAnchor,
                                     self._previous_prompt_obj.length)
                 prompt = self._make_in_prompt(previous_prompt_number)
                 self._prompt = self._insert_html_fetching_plain_text(
                     cursor, prompt)
 
                 # When the HTML is inserted, Qt blows away the syntax
                 # highlighting for the line, so we need to rehighlight it.
                 self._highlighter.rehighlightBlock(cursor.block())
 
             self._previous_prompt_obj = None
 
         # Show a new prompt with the kernel's estimated prompt number.
         self._show_interpreter_prompt(previous_prompt_number + 1)
 
     #---------------------------------------------------------------------------
     # 'IPythonWidget' interface
     #---------------------------------------------------------------------------
 
     def set_default_style(self, colors='lightbg'):
         """ Sets the widget style to the class defaults.
 
         Parameters:
         -----------
         colors : str, optional (default lightbg)
             Whether to use the default IPython light background or dark
             background or B&W style.
         """
         colors = colors.lower()
         if colors=='lightbg':
             self.style_sheet = styles.default_light_style_sheet
             self.syntax_style = styles.default_light_syntax_style
         elif colors=='linux':
             self.style_sheet = styles.default_dark_style_sheet
             self.syntax_style = styles.default_dark_syntax_style
         elif colors=='nocolor':
             self.style_sheet = styles.default_bw_style_sheet
             self.syntax_style = styles.default_bw_syntax_style
         else:
             raise KeyError("No such color scheme: %s"%colors)
 
     #---------------------------------------------------------------------------
     # 'IPythonWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _edit(self, filename, line=None):
         """ Opens a Python script for editing.
 
         Parameters:
         -----------
         filename : str
             A path to a local system file.
 
         line : int, optional
             A line of interest in the file.
         """
         if self.custom_edit:
             self.custom_edit_requested.emit(filename, line)
         elif not self.editor:
             self._append_plain_text('No default editor available.\n'
             'Specify a GUI text editor in the `IPythonWidget.editor` '
             'configurable to enable the %edit magic')
         else:
             try:
                 filename = '"%s"' % filename
                 if line and self.editor_line:
                     command = self.editor_line.format(filename=filename,
                                                       line=line)
                 else:
                     try:
                         command = self.editor.format()
                     except KeyError:
                         command = self.editor.format(filename=filename)
                     else:
                         command += ' ' + filename
             except KeyError:
                 self._append_plain_text('Invalid editor command.\n')
             else:
                 try:
                     Popen(command, shell=True)
                 except OSError:
                     msg = 'Opening editor with command "%s" failed.\n'
                     self._append_plain_text(msg % command)
 
     def _make_in_prompt(self, number):
         """ Given a prompt number, returns an HTML In prompt.
         """
         try:
             body = self.in_prompt % number
         except TypeError:
             # allow in_prompt to leave out number, e.g. '>>> '
             body = self.in_prompt
         return '<span class="in-prompt">%s</span>' % body
 
     def _make_continuation_prompt(self, prompt):
         """ Given a plain text version of an In prompt, returns an HTML
             continuation prompt.
         """
         end_chars = '...: '
         space_count = len(prompt.lstrip('\n')) - len(end_chars)
         body = '&nbsp;' * space_count + end_chars
         return '<span class="in-prompt">%s</span>' % body
 
     def _make_out_prompt(self, number):
         """ Given a prompt number, returns an HTML Out prompt.
         """
         body = self.out_prompt % number
         return '<span class="out-prompt">%s</span>' % body
 
     #------ Payload handlers --------------------------------------------------
 
     # Payload handlers with a generic interface: each takes the opaque payload
     # dict, unpacks it and calls the underlying functions with the necessary
     # arguments.
 
     def _handle_payload_edit(self, item):
         self._edit(item['filename'], item['line_number'])
 
     def _handle_payload_exit(self, item):
         self._keep_kernel_on_exit = item['keepkernel']
         self.exit_requested.emit(self)
 
     def _handle_payload_next_input(self, item):
         self.input_buffer = dedent(item['text'].rstrip())
 
     def _handle_payload_page(self, item):
         # Since the plain text widget supports only a very small subset of HTML
         # and we have no control over the HTML source, we only page HTML
         # payloads in the rich text widget.
         if item['html'] and self.kind == 'rich':
             self._page(item['html'], html=True)
         else:
             self._page(item['text'], html=False)
 
     #------ Trait change handlers --------------------------------------------
 
     def _style_sheet_changed(self):
         """ Set the style sheets of the underlying widgets.
         """
         self.setStyleSheet(self.style_sheet)
         self._control.document().setDefaultStyleSheet(self.style_sheet)
         if self._page_control:
             self._page_control.document().setDefaultStyleSheet(self.style_sheet)
 
         bg_color = self._control.palette().window().color()
         self._ansi_processor.set_background_color(bg_color)
 
 
     def _syntax_style_changed(self):
         """ Set the style for the syntax highlighter.
         """
         if self._highlighter is None:
             # ignore premature calls
             return
         if self.syntax_style:
             self._highlighter.set_style(self.syntax_style)
         else:
             self._highlighter.set_style_sheet(self.style_sheet)
 
     #------ Trait default initializers -----------------------------------------
 
     def _banner_default(self):
         from IPython.core.usage import default_gui_banner
         return default_gui_banner