strip trailing \n for history lines

IPython/core/history.py

@@ -1,515 +1,515 b''
 """ History related magics and functionality """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010 The IPython Development Team.
 #
 #  Distributed under the terms of the BSD License.
 #
 #  The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 from __future__ import print_function
 
 # Stdlib imports
 import fnmatch
 import json
 import os
 import sys
 
 # Our own packages
 import IPython.utils.io
 
 from IPython.utils.pickleshare import PickleShareDB
 from IPython.utils.io import ask_yes_no
 from IPython.utils.warn import warn
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 class HistoryManager(object):
     """A class to organize all history-related functionality in one place.
     """
     # Public interface
 
     # An instance of the IPython shell we are attached to
     shell = None
     # A list to hold processed history
     input_hist_parsed = None
     # A list to hold raw history (as typed by user)
     input_hist_raw = None
     # A list of directories visited during session
     dir_hist = None
     # A dict of output history, keyed with ints from the shell's execution count
     output_hist = None
     # String with path to the history file
     hist_file = None
     # PickleShareDB instance holding the raw data for the shadow history
     shadow_db = None
     # ShadowHist instance with the actual shadow history
     shadow_hist = None
     
     # Private interface
     # Variables used to store the three last inputs from the user.  On each new
     # history update, we populate the user's namespace with these, shifted as
     # necessary.
     _i00, _i, _ii, _iii = '','','',''
     
     def __init__(self, shell):
         """Create a new history manager associated with a shell instance.
         """
         # We need a pointer back to the shell for various tasks.
         self.shell = shell
         
         # List of input with multi-line handling.
         self.input_hist_parsed = []
         # This one will hold the 'raw' input history, without any
         # pre-processing.  This will allow users to retrieve the input just as
         # it was exactly typed in by the user, with %hist -r.
         self.input_hist_raw = []
 
         # list of visited directories
         try:
             self.dir_hist = [os.getcwd()]
         except OSError:
             self.dir_hist = []
 
         # dict of output history
         self.output_hist = {}
 
         # Now the history file
         if shell.profile:
             histfname = 'history-%s' % shell.profile
         else:
             histfname = 'history'
         self.hist_file = os.path.join(shell.ipython_dir, histfname + '.json')
 
         # Objects related to shadow history management
         self._init_shadow_hist()
     
         self._i00, self._i, self._ii, self._iii = '','','',''
 
         # Object is fully initialized, we can now call methods on it.
         
         # Fill the history zero entry, user counter starts at 1
         self.store_inputs('\n', '\n')
  
     def _init_shadow_hist(self):
         try:
             self.shadow_db = PickleShareDB(os.path.join(
                                            self.shell.ipython_dir, 'db'))
         except UnicodeDecodeError:
             print("Your ipython_dir can't be decoded to unicode!")
             print("Please set HOME environment variable to something that")
             print(r"only has ASCII characters, e.g. c:\home")
             print("Now it is", self.ipython_dir)
             sys.exit()
         self.shadow_hist = ShadowHist(self.shadow_db, self.shell)
         
     def populate_readline_history(self):
         """Populate the readline history from the raw history.
 
         We only store one copy of the raw history, which is persisted to a json
         file on disk.  The readline history is repopulated from the contents of
         this file."""
 
         try:
             self.shell.readline.clear_history()
         except AttributeError:
             pass
         else:
             for h in self.input_hist_raw:
                 if not h.isspace():
                     for line in h.splitlines():
                         self.shell.readline.add_history(line)
 
     def save_history(self):
         """Save input history to a file (via readline library)."""
         hist = dict(raw=self.input_hist_raw, #[-self.shell.history_length:],
                     parsed=self.input_hist_parsed) #[-self.shell.history_length:])
         with open(self.hist_file,'wt') as hfile:
             json.dump(hist, hfile,
                       sort_keys=True, indent=4)
         
     def reload_history(self):
         """Reload the input history from disk file."""
 
         with open(self.hist_file,'rt') as hfile:
             hist = json.load(hfile)
             self.input_hist_parsed = hist['parsed']
             self.input_hist_raw = hist['raw']
             if self.shell.has_readline:
                 self.populate_readline_history()
         
     def get_history(self, index=None, raw=False, output=True):
         """Get the history list.
 
         Get the input and output history.
 
         Parameters
         ----------
         index : n or (n1, n2) or None
             If n, then the last entries. If a tuple, then all in
             range(n1, n2). If None, then all entries. Raises IndexError if
             the format of index is incorrect.
         raw : bool
             If True, return the raw input.
         output : bool
             If True, then return the output as well.
 
         Returns
         -------
         If output is True, then return a dict of tuples, keyed by the prompt
         numbers and with values of (input, output). If output is False, then
         a dict, keyed by the prompt number with the values of input. Raises
         IndexError if no history is found.
         """
         if raw:
             input_hist = self.input_hist_raw
         else:
             input_hist = self.input_hist_parsed
         if output:
             output_hist = self.output_hist
         n = len(input_hist)
         if index is None:
             start=0; stop=n
         elif isinstance(index, int):
             start=n-index; stop=n
         elif isinstance(index, tuple) and len(index) == 2:
             start=index[0]; stop=index[1]
         else:
             raise IndexError('Not a valid index for the input history: %r'
                              % index)
         hist = {}
         for i in range(start, stop):
             if output:
                 hist[i] = (input_hist[i], output_hist.get(i))
             else:
                 hist[i] = input_hist[i]
         if not hist:
             raise IndexError('No history for range of indices: %r' % index)
         return hist
 
     def store_inputs(self, source, source_raw=None):
         """Store source and raw input in history and create input cache
         variables _i*.
         
         Parameters
         ----------
         source : str
           Python input.
 
         source_raw : str, optional
           If given, this is the raw input without any IPython transformations
           applied to it.  If not given, ``source`` is used.
         """
         if source_raw is None:
             source_raw = source
         # do not store quit/exit commands
         if source_raw in ['Quit', 'quit', 'Exit', 'exit', '%Quit', '%quit', '%Exit', '%exit']:
             return
-        self.input_hist_parsed.append(source)
-        self.input_hist_raw.append(source_raw)
+        self.input_hist_parsed.append(source.rstrip())
+        self.input_hist_raw.append(source_raw.rstrip())
         self.shadow_hist.add(source)
 
         # update the auto _i variables
         self._iii = self._ii
         self._ii = self._i
         self._i = self._i00
         self._i00 = source_raw
 
         # hackish access to user namespace to create _i1,_i2... dynamically
         new_i = '_i%s' % self.shell.execution_count
         to_main = {'_i': self._i,
                    '_ii': self._ii,
                    '_iii': self._iii,
                    new_i : self._i00 }
         self.shell.user_ns.update(to_main)
 
     def sync_inputs(self):
         """Ensure raw and translated histories have same length."""
         if len(self.input_hist_parsed) != len (self.input_hist_raw):
             self.input_hist_raw[:] = self.input_hist_parsed
 
     def reset(self):
         """Clear all histories managed by this object."""
         self.input_hist_parsed[:] = []
         self.input_hist_raw[:] = []
         self.output_hist.clear()
         # The directory history can't be completely empty
         self.dir_hist[:] = [os.getcwd()]
 
 
 def magic_history(self, parameter_s = ''):
     """Print input history (_i<n> variables), with most recent last.
     
     %history       -> print at most 40 inputs (some may be multi-line)\\
     %history n     -> print at most n inputs\\
     %history n1 n2 -> print inputs between n1 and n2 (n2 not included)\\
 
     By default, input history is printed without line numbers so it can be
     directly pasted into an editor.
 
     With -n, each input's number <n> is shown, and is accessible as the
     automatically generated variable _i<n> as well as In[<n>].  Multi-line
     statements are printed starting at a new line for easy copy/paste.
 
     Options:
 
       -n: print line numbers for each input.
       This feature is only available if numbered prompts are in use.
 
       -o: also print outputs for each input.
 
       -p: print classic '>>>' python prompts before each input.  This is useful
        for making documentation, and in conjunction with -o, for producing
        doctest-ready output.
 
       -r: (default) print the 'raw' history, i.e. the actual commands you typed.
       
       -t: print the 'translated' history, as IPython understands it.  IPython
       filters your input and converts it all into valid Python source before
       executing it (things like magics or aliases are turned into function
       calls, for example). With this option, you'll see the native history
       instead of the user-entered version: '%cd /' will be seen as
       'get_ipython().magic("%cd /")' instead of '%cd /'.
       
       -g: treat the arg as a pattern to grep for in (full) history.
       This includes the "shadow history" (almost all commands ever written).
       Use '%hist -g' to show full shadow history (may be very long).
       In shadow history, every index nuwber starts with 0.
 
       -f FILENAME: instead of printing the output to the screen, redirect it to
        the given file.  The file is always overwritten, though IPython asks for
        confirmation first if it already exists.
     """
 
     if not self.shell.displayhook.do_full_cache:
         print('This feature is only available if numbered prompts are in use.')
         return
     opts,args = self.parse_options(parameter_s,'gnoptsrf:',mode='list')
 
     # Check if output to specific file was requested.
     try:
         outfname = opts['f']
     except KeyError:
         outfile = IPython.utils.io.Term.cout  # default
         # We don't want to close stdout at the end!
         close_at_end = False
     else:
         if os.path.exists(outfname):
             if not ask_yes_no("File %r exists. Overwrite?" % outfname): 
                 print('Aborting.')
                 return
 
         outfile = open(outfname,'w')
         close_at_end = True
 
     if 't' in opts:
         input_hist = self.shell.history_manager.input_hist_parsed
     elif 'r' in opts:
         input_hist = self.shell.history_manager.input_hist_raw
     else:
         # Raw history is the default
         input_hist = self.shell.history_manager.input_hist_raw
             
     default_length = 40
     pattern = None
     if 'g' in opts:
         init = 1
         final = len(input_hist)
         parts = parameter_s.split(None, 1)
         if len(parts) == 1:
             parts += '*'
         head, pattern = parts
         pattern = "*" + pattern + "*"
     elif len(args) == 0:
         final = len(input_hist)-1
         init = max(1,final-default_length)
     elif len(args) == 1:
         final = len(input_hist)
         init = max(1, final-int(args[0]))
     elif len(args) == 2:
         init, final = map(int, args)
     else:
         warn('%hist takes 0, 1 or 2 arguments separated by spaces.')
         print(self.magic_hist.__doc__, file=IPython.utils.io.Term.cout)
         return
     
     width = len(str(final))
     line_sep = ['','\n']
     print_nums = 'n' in opts
     print_outputs = 'o' in opts
     pyprompts = 'p' in opts
     
     found = False
     if pattern is not None:
         sh = self.shell.history_manager.shadowhist.all()
         for idx, s in sh:
             if fnmatch.fnmatch(s, pattern):
                 print("0%d: %s" %(idx, s.expandtabs(4)), file=outfile)
                 found = True
     
     if found:
         print("===", file=outfile)
         print("shadow history ends, fetch by %rep <number> (must start with 0)",
               file=outfile)
         print("=== start of normal history ===", file=outfile)
         
     for in_num in range(init, final):
         # Print user history with tabs expanded to 4 spaces.  The GUI clients
         # use hard tabs for easier usability in auto-indented code, but we want
         # to produce PEP-8 compliant history for safe pasting into an editor.
         inline = input_hist[in_num].expandtabs(4)
 
         if pattern is not None and not fnmatch.fnmatch(inline, pattern):
             continue
             
         multiline = int(inline.count('\n') > 1)
         if print_nums:
             print('%s:%s' % (str(in_num).ljust(width), line_sep[multiline]),
                   file=outfile)
         if pyprompts:
             print('>>>', file=outfile)
             if multiline:
                 lines = inline.splitlines()
                 print('\n... '.join(lines), file=outfile)
                 print('... ', file=outfile)
             else:
                 print(inline, end='', file=outfile)
         else:
             print(inline, end='', file=outfile)
         if print_outputs:
             output = self.shell.history_manager.output_hist.get(in_num)
             if output is not None:
                 print(repr(output), file=outfile)
 
     if close_at_end:
         outfile.close()
 
 
 def magic_hist(self, parameter_s=''):
     """Alternate name for %history."""
     return self.magic_history(parameter_s)
 
 
 def rep_f(self, arg):
     r""" Repeat a command, or get command to input line for editing
 
     - %rep (no arguments):
     
     Place a string version of last computation result (stored in the special '_'
     variable) to the next input prompt. Allows you to create elaborate command
     lines without using copy-paste::
     
         $ l = ["hei", "vaan"]       
         $ "".join(l)        
         ==> heivaan        
         $ %rep        
         $ heivaan_ <== cursor blinking    
     
     %rep 45
     
     Place history line 45 to next input prompt. Use %hist to find out the
     number.
     
     %rep 1-4 6-7 3
     
     Repeat the specified lines immediately. Input slice syntax is the same as
     in %macro and %save.
     
     %rep foo
     
     Place the most recent line that has the substring "foo" to next input.
     (e.g. 'svn ci -m foobar').    
     """
     
     opts,args = self.parse_options(arg,'',mode='list')
     if not args:
         self.set_next_input(str(self.shell.user_ns["_"]))
         return
 
     if len(args) == 1 and not '-' in args[0]:
         arg = args[0]
         if len(arg) > 1 and arg.startswith('0'):
             # get from shadow hist
             num = int(arg[1:])
             line = self.shell.shadowhist.get(num)
             self.set_next_input(str(line))
             return
         try:
             num = int(args[0])
             self.set_next_input(str(self.shell.input_hist_raw[num]).rstrip())
             return
         except ValueError:
             pass
         
         for h in reversed(self.shell.input_hist_raw):
             if 'rep' in h:
                 continue
             if fnmatch.fnmatch(h,'*' + arg + '*'):
                 self.set_next_input(str(h).rstrip())
                 return
         
     try:
         lines = self.extract_input_slices(args, True)
         print("lines", lines)
         self.run_cell(lines)
     except ValueError:
         print("Not found in recent history:", args)
         
 
 _sentinel = object()
 
 class ShadowHist(object):
     def __init__(self, db, shell):
         # cmd => idx mapping
         self.curidx = 0
         self.db = db
         self.disabled = False
         self.shell = shell
     
     def inc_idx(self):
         idx = self.db.get('shadowhist_idx', 1)
         self.db['shadowhist_idx'] = idx + 1
         return idx
         
     def add(self, ent):
         if self.disabled:
             return
         try:
             old = self.db.hget('shadowhist', ent, _sentinel)
             if old is not _sentinel:
                 return
             newidx = self.inc_idx()
             #print("new", newidx) # dbg
             self.db.hset('shadowhist',ent, newidx)
         except:
             self.shell.showtraceback()
             print("WARNING: disabling shadow history")
             self.disabled = True
     
     def all(self):
         d = self.db.hdict('shadowhist')
         items = [(i,s) for (s,i) in d.iteritems()]
         items.sort()
         return items
 
     def get(self, idx):
         all = self.all()
         
         for k, v in all:
             if k == idx:
                 return v
 
 
 def init_ipython(ip):
     ip.define_magic("rep",rep_f)        
     ip.define_magic("hist",magic_hist)            
     ip.define_magic("history",magic_history)
 
     # XXX - ipy_completers are in quarantine, need to be updated to new apis
     #import ipy_completers
     #ipy_completers.quick_completer('%hist' ,'-g -t -r -n')

IPython/frontend/qt/console/ipython_widget.py

@@ -1,467 +1,467 b''
 """ A FrontendWidget that emulates the interface of the console IPython and
     supports the additional functionality provided by the IPython kernel.
 
     TODO: Add support for retrieving the system default editor. Requires code
           paths for Windows (use the registry), Mac OS (use LaunchServices), and
           Linux (use the xdg system).
 """
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # Standard library imports
 from collections import namedtuple
 import re
 from subprocess import Popen
 from textwrap import dedent
 
 # System library imports
 from PyQt4 import QtCore, QtGui
 
 # Local imports
 from IPython.core.inputsplitter import IPythonInputSplitter, \
     transform_ipy_prompt
 from IPython.core.usage import default_gui_banner
 from IPython.utils.traitlets import Bool, Str
 from frontend_widget import FrontendWidget
 from styles import (default_light_style_sheet,  default_light_syntax_style,
                     default_dark_style_sheet, default_dark_syntax_style,
                     default_bw_style_sheet, default_bw_syntax_style)
 
 #-----------------------------------------------------------------------------
 # 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'
 
 #-----------------------------------------------------------------------------
 # 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.pyqtSignal(object, object)
 
     # 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 = Str('default', config=True)
 
     # 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.
     editor_line = Str(config=True)
 
     # 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
     style_sheet = Str(config=True)
     
     # If not empty, use this Pygments style for syntax highlighting. Otherwise,
     # the style sheet is queried for Pygments style information.
     syntax_style = Str(config=True)
 
     # Prompts.
     in_prompt = Str(default_in_prompt, config=True)
     out_prompt = Str(default_out_prompt, config=True)
     input_sep = Str(default_input_sep, config=True)
     output_sep = Str(default_output_sep, config=True)
     output_sep2 = Str(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_loadpy = zmq_shell_source + '.magic_loadpy'
     _payload_source_page = 'IPython.zmq.page.page'
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
     
     def __init__(self, *args, **kw):
         super(IPythonWidget, self).__init__(*args, **kw)
 
         # IPythonWidget protected variables.
         self._code_to_load = None
         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_loadpy : self._handle_payload_loadpy }
         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.
         """
         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 = self._request_info.get('execute')
         if info and info.id == msg['parent_header']['msg_id']:
             if info.kind == 'prompt':
                 number = msg['content']['execution_count'] + 1
                 self._show_interpreter_prompt(number)
             else:
                 super(IPythonWidget, self)._handle_execute_reply(msg)
 
     def _handle_history_reply(self, msg):
         """ Implemented to handle history replies, which are only supported by
             the IPython kernel.
         """
         history_dict = msg['content']['history']
         input_history_dict = {}
         for key,val in history_dict.items():
             input_history_dict[int(key)] = val
-        items = [ val for _, val in sorted(input_history_dict.items()) ]
+        items = [ val.rstrip() for _, val in sorted(input_history_dict.items()) ]
         self._set_history(items)
 
     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['execution_count']
             self._append_plain_text(self.output_sep)
             self._append_html(self._make_out_prompt(prompt_number))
             self._append_plain_text(content['data']+self.output_sep2)
 
     def _started_channels(self):
         """ Reimplemented to make a history request.
         """
         super(IPythonWidget, self)._started_channels()
         self.kernel_manager.xreq_channel.history(raw=True, output=False)
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' public interface
     #---------------------------------------------------------------------------
 
     def copy(self):
         """ Copy the currently selected text to the clipboard, removing prompts
             if possible.
         """
         text = unicode(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.
         """
         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.xreq_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 _get_banner(self):
         """ Reimplemented to return IPython's default banner.
         """
         return default_gui_banner
 
     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.xreq_channel.execute('', silent=True)
             info = self._ExecutionRequest(msg_id, 'prompt')
             self._request_info['execute'] = 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)
 
         # Load code from the %loadpy magic, if necessary.
         if self._code_to_load is not None:
             self.input_buffer = dedent(unicode(self._code_to_load).rstrip())
             self._code_to_load = None
 
     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['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 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.
         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 = default_light_style_sheet
             self.syntax_style = default_light_syntax_style
         elif colors=='linux':
             self.style_sheet = default_dark_style_sheet
             self.syntax_style = default_dark_syntax_style
         elif colors=='nocolor':
             self.style_sheet = default_bw_style_sheet
             self.syntax_style = 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 self.editor == 'default':
             self._append_plain_text('No default editor available.\n')
         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.
         """
         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
 
     #------ 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()
 
     def _handle_payload_loadpy(self, item):
         # Simple save the text of the .py file for later. The text is written
         # to the buffer when _prompt_started_hook is called.
         self._code_to_load = item['text']
 
     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().background().color()
         self._ansi_processor.set_background_color(bg_color)
 
     def _syntax_style_changed(self):
         """ Set the style for the syntax highlighter.
         """
         if self.syntax_style:
             self._highlighter.set_style(self.syntax_style)
         else:
             self._highlighter.set_style_sheet(self.style_sheet)