Fixed bug where replacement prompts were occasionally inserted at inappropriate times.

IPython/frontend/qt/console/ipython_widget.py

@@ -1,323 +1,323 b''
 # Standard library imports
 from subprocess import Popen
 
 # System library imports
 from PyQt4 import QtCore, QtGui
 
 # Local imports
 from IPython.core.inputsplitter import IPythonInputSplitter
 from IPython.core.usage import default_banner
 from frontend_widget import FrontendWidget
 
 
 class IPythonPromptBlock(object):
     """ An internal storage object for IPythonWidget.
     """
     def __init__(self, block, length, number):
         self.block = block
         self.length = length
         self.number = number
 
 
 class IPythonWidget(FrontendWidget):
     """ A FrontendWidget for an IPython kernel.
     """
 
     # Signal emitted when an editor is needed for a file and the editor has been
     # specified as 'custom'. See 'set_editor' for more information.
     custom_edit_requested = QtCore.pyqtSignal(object, object)
 
     # The default stylesheet: black text on a white background.
     default_stylesheet = """
         .error { color: red; }
         .in-prompt { color: navy; }
         .in-prompt-number { font-weight: bold; }
         .out-prompt { color: darkred; }
         .out-prompt-number { font-weight: bold; }
     """
 
     # A dark stylesheet: white text on a black background.
     dark_stylesheet = """
         QPlainTextEdit, QTextEdit { background-color: black; color: white }
         QFrame { border: 1px solid grey; }
         .error { color: red; }
         .in-prompt { color: lime; }
         .in-prompt-number { color: lime; font-weight: bold; }
         .out-prompt { color: red; }
         .out-prompt-number { color: red; font-weight: bold; }
     """
 
     # Default prompts.
     in_prompt = 'In [<span class="in-prompt-number">%i</span>]: '
     out_prompt = 'Out[<span class="out-prompt-number">%i</span>]: '
 
     # FrontendWidget protected class variables.
     #_input_splitter_class = IPythonInputSplitter
 
     # IPythonWidget protected class variables.
     _payload_source_edit = 'IPython.zmq.zmqshell.ZMQInteractiveShell.edit_magic'
     _payload_source_page = 'IPython.zmq.page.page'
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
     
     def __init__(self, *args, **kw):
         super(IPythonWidget, self).__init__(*args, **kw)
 
         # IPythonWidget protected variables.
         self._previous_prompt_obj = None
 
         # Set a default editor and stylesheet.
         self.set_editor('default')
         self.reset_styling()
 
     #---------------------------------------------------------------------------
     # 'BaseFrontendMixin' abstract interface
     #---------------------------------------------------------------------------
 
     def _handle_history_reply(self, msg):
         """ Implemented to handle history replies, which are only supported by
             the IPython kernel.
         """
         history_dict = msg['content']['history']
         items = [ history_dict[key] for key in sorted(history_dict.keys()) ]
         self._set_history(items)
 
     def _handle_prompt_reply(self, msg):
         """ Implemented to handle prompt number replies, which are only
             supported by the IPython kernel.
         """
         content = msg['content']
         self._show_interpreter_prompt(content['prompt_number'], 
                                       content['input_sep'])
 
     def _handle_pyout(self, msg):
         """ Reimplemented for IPython-style "display hook".
         """
         if not self._hidden and self._is_from_this_session(msg):
             content = msg['content']
             prompt_number = content['prompt_number']
             self._append_plain_text(content['output_sep'])
             self._append_html(self._make_out_prompt(prompt_number))
             self._append_plain_text(content['data'] + '\n' + 
                                     content['output_sep2'])
 
     def _started_channels(self):
         """ Reimplemented to make a history request.
         """
         super(IPythonWidget, self)._started_channels()
         # FIXME: Disabled until history requests are properly implemented.
         #self.kernel_manager.xreq_channel.history(raw=True, output=False)
 
     #---------------------------------------------------------------------------
     # 'FrontendWidget' interface
     #---------------------------------------------------------------------------
 
     def execute_file(self, path, hidden=False):
         """ Reimplemented to use the 'run' magic.
         """
         self.execute('%%run %s' % path, hidden=hidden)
 
     #---------------------------------------------------------------------------
     # 'FrontendWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _get_banner(self):
         """ Reimplemented to return IPython's default banner.
         """
         return default_banner + '\n'
 
     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 handle %edit and paging payloads.
         """
         if item['source'] == self._payload_source_edit:
             self.edit(item['filename'], item['line_number'])
             return True
         elif item['source'] == self._payload_source_page:
             self._page(item['data'])
             return True
         else:
             return False
 
     def _show_interpreter_prompt(self, number=None, input_sep='\n'):
         """ Reimplemented for IPython-style prompts.
         """
         # If a number was not specified, make a prompt number request.
         if number is None:
             self.kernel_manager.xreq_channel.prompt()
             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._append_plain_text(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 = IPythonPromptBlock(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']
         previous_prompt_number = content['prompt_number']
         if self._previous_prompt_obj and \
                 self._previous_prompt_obj.number != previous_prompt_number:
             block = self._previous_prompt_obj.block
-            if block.isValid():
+            if block.isValid() and not block.text().isEmpty():
 
                 # 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.
         next_prompt = content['next_prompt']
         self._show_interpreter_prompt(next_prompt['prompt_number'], 
                                       next_prompt['input_sep'])
 
     #---------------------------------------------------------------------------
     # 'IPythonWidget' 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.
         
         Raises:
         -------
         OSError
             If the editor command cannot be executed.
         """
         if self._editor == 'default':
             url = QtCore.QUrl.fromLocalFile(filename)
             if not QtGui.QDesktopServices.openUrl(url):
                 message = 'Failed to open %s with the default application'
                 raise OSError(message % repr(filename))
         elif self._editor is None:
             self.custom_edit_requested.emit(filename, line)
         else:
             Popen(self._editor + [filename])
 
     def reset_styling(self):
         """ Restores the default IPythonWidget styling.
         """
         self.set_styling(self.default_stylesheet, syntax_style='default')
         #self.set_styling(self.dark_stylesheet, syntax_style='monokai')
 
     def set_editor(self, editor):
         """ Sets the editor to use with the %edit magic.
 
         Parameters:
         -----------
         editor : str or sequence of str
             A command suitable for use with Popen. This command will be executed
             with a single argument--a filename--when editing is requested.
 
             This parameter also takes two special values:
                 'default' : Files will be edited with the system default 
                             application for Python files.
                 'custom'  : Emit a 'custom_edit_requested(str, int)' signal 
                             instead of opening an editor.
         """
         if editor == 'default':
             self._editor = 'default'
         elif editor == 'custom':
             self._editor = None
         elif isinstance(editor, basestring):
             self._editor = [ editor ]
         else:
             self._editor = list(editor)
 
     def set_styling(self, stylesheet, syntax_style=None):
         """ Sets the IPythonWidget styling.
 
         Parameters:
         -----------
         stylesheet : str
             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 : str or None [default None]
             If specified, use the Pygments style with given name. Otherwise, 
             the stylesheet is queried for Pygments style information.
         """
         self.setStyleSheet(stylesheet)
         self._control.document().setDefaultStyleSheet(stylesheet)
         if self._page_control:
             self._page_control.document().setDefaultStyleSheet(stylesheet)
 
         if syntax_style is None:
             self._highlighter.set_style_sheet(stylesheet)
         else:
             self._highlighter.set_style(syntax_style)
 
     #---------------------------------------------------------------------------
     # 'IPythonWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _make_in_prompt(self, number):
         """ Given a prompt number, returns an HTML In prompt.
         """
         body = self.in_prompt % number
         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