Exemplo n.º 1
0
class QtKernelClientMixin(MetaQObjectHasTraits('NewBase', (HasTraits, SuperQObject), {})):
    """ A KernelClient that provides signals and slots.
    """

    # Emitted when the kernel client has started listening.
    started_channels = QtCore.Signal()

    # Emitted when the kernel client has stopped listening.
    stopped_channels = QtCore.Signal()

    #---------------------------------------------------------------------------
    # 'KernelClient' interface
    #---------------------------------------------------------------------------

    #------ Channel management -------------------------------------------------

    def start_channels(self, *args, **kw):
        """ Reimplemented to emit signal.
        """
        super(QtKernelClientMixin, self).start_channels(*args, **kw)
        self.started_channels.emit()

    def stop_channels(self):
        """ Reimplemented to emit signal.
        """
        super(QtKernelClientMixin, self).stop_channels()
        self.stopped_channels.emit()
Exemplo n.º 2
0
class TviewConsoleWidget(HistoryConsoleWidget):
    line_input = QtCore.Signal(str)

    def __init__(self, *args, **kw):
        super(TviewConsoleWidget, self).__init__(*args, **kw)

        self._prompt = '>>> '
        self.clear()

        # The bionic version of ConsoleWidget seems to get the cursor
        # position screwed up after a clear.  Let's just fix it up
        # here.
        self._append_before_prompt_cursor.setPosition(0)

    def sizeHint(self):
        return QtCore.QSize(600, 200)

    def add_text(self, data):
        assert data.endswith('\n') or data.endswith('\r')
        self._append_plain_text(data, before_prompt=True)
        self._control.moveCursor(QtGui.QTextCursor.End)

    def _handle_timeout(self):
        self._append_plain_text('%s\r\n' % time.time(),
                                before_prompt=True)
        self._control.moveCursor(QtGui.QTextCursor.End)

    def _is_complete(self, source, interactive):
        return True, False

    def _execute(self, source, hidden):
        self.line_input.emit(source)
        self._show_prompt(self._prompt)
        return True
Exemplo n.º 3
0
class QtInProcessChannel(SuperQObject, InProcessChannel):
    # Emitted when the channel is started.
    started = QtCore.Signal()

    # Emitted when the channel is stopped.
    stopped = QtCore.Signal()

    # Emitted when any message is received.
    message_received = QtCore.Signal(object)

    def start(self):
        """ Reimplemented to emit signal.
        """
        super(QtInProcessChannel, self).start()
        self.started.emit()

    def stop(self):
        """ Reimplemented to emit signal.
        """
        super(QtInProcessChannel, self).stop()
        self.stopped.emit()

    def call_handlers_later(self, *args, **kwds):
        """ Call the message handlers later.
        """
        do_later = lambda: self.call_handlers(*args, **kwds)
        QtCore.QTimer.singleShot(0, do_later)

    def call_handlers(self, msg):
        self.message_received.emit(msg)

    def process_events(self):
        """ Process any pending GUI events.
        """
        QtCore.QCoreApplication.instance().processEvents()

    def flush(self, timeout=1.0):
        """ Reimplemented to ensure that signals are dispatched immediately.
        """
        super(QtInProcessChannel, self).flush()
        self.process_events()
Exemplo n.º 4
0
class QtHBChannel(SuperQObject, HBChannel):
    # A longer timeout than the base class
    time_to_dead = 3.0

    # Emitted when the kernel has died.
    kernel_died = QtCore.Signal(object)

    def call_handlers(self, since_last_heartbeat):
        """ Reimplemented to emit signals instead of making callbacks.
        """
        # Emit the generic signal.
        self.kernel_died.emit(since_last_heartbeat)
Exemplo n.º 5
0
class QtZMQSocketChannel(ThreadedZMQSocketChannel, SuperQObject):
    """A ZMQ socket emitting a Qt signal when a message is received."""
    message_received = QtCore.Signal(object)

    def process_events(self):
        """ Process any pending GUI events.
        """
        QtCore.QCoreApplication.instance().processEvents()

    def call_handlers(self, msg):
        """This method is called in the ioloop thread when a message arrives.

        It is important to remember that this method is called in the thread
        so that some logic must be done to ensure that the application level
        handlers are called in the application thread.
        """
        # Emit the generic signal.
        self.message_received.emit(msg)
Exemplo n.º 6
0
class QtInProcessHBChannel(SuperQObject, InProcessHBChannel):
    # This signal will never be fired, but it needs to exist
    kernel_died = QtCore.Signal()
Exemplo n.º 7
0
class JupyterWidget(IPythonWidget):
    """A FrontendWidget for a Jupyter 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 GUI 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. To use a terminal text editor,
        the command should launch a new terminal, e.g.
        ``"gnome-terminal -- vim"``.
        """)

    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. QtConsole: .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)

    # JupyterWidget protected class variables.
    _PromptBlock = namedtuple('_PromptBlock', ['block', 'length', 'number'])
    _payload_source_edit = 'edit_magic'
    _payload_source_exit = 'ask_exit'
    _payload_source_next_input = 'set_next_input'
    _payload_source_page = 'page'
    _retrying_history_request = False
    _starting = False

    #---------------------------------------------------------------------------
    # 'object' interface
    #---------------------------------------------------------------------------

    def __init__(self, *args, **kw):
        super(JupyterWidget, self).__init__(*args, **kw)

        # JupyterWidget 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()

        # Initialize language name.
        self.language_name = None

    #---------------------------------------------------------------------------
    # 'BaseFrontendMixin' abstract interface
    #
    # For JupyterWidget,  override FrontendWidget methods which implement the
    # BaseFrontend Mixin abstract interface
    #---------------------------------------------------------------------------

    def _handle_complete_reply(self, rep):
        """Support Jupyter'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 == self._get_input_buffer_cursor_pos()
                and info.code == self.input_buffer):
            content = rep['content']
            matches = content['matches']
            start = content['cursor_start']
            end = content['cursor_end']

            start = max(start, 0)
            end = max(end, start)

            # Move the control's cursor to the desired end point
            cursor_pos = self._get_input_buffer_cursor_pos()
            if end < cursor_pos:
                cursor.movePosition(QtGui.QTextCursor.Left,
                                    n=(cursor_pos - end))
            elif end > cursor_pos:
                cursor.movePosition(QtGui.QTextCursor.Right,
                                    n=(end - cursor_pos))
            # This line actually applies the move to control's cursor
            self._control.setTextCursor(cursor)

            offset = end - start
            # Move the local cursor object 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):
        """Support prompt requests.
        """
        msg_id = msg['parent_header'].get('msg_id')
        info = self._request_info['execute'].get(msg_id)
        if info and info.kind == 'prompt':
            content = msg['content']
            if content['status'] == 'aborted':
                self._show_interpreter_prompt()
            else:
                number = content['execution_count'] + 1
                self._show_interpreter_prompt(number)
            self._request_info['execute'].pop(msg_id)
        else:
            super(JupyterWidget, self)._handle_execute_reply(msg)

    def _handle_history_reply(self, msg):
        """ Handle history tail replies, which are only supported
            by Jupyter kernels.
        """
        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_client.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']
        self.log.debug("Received history reply with %i entries",
                       len(history_items))
        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 _insert_other_input(self, cursor, content):
        """Insert function for input from other frontends"""
        n = content.get('execution_count', 0)
        prompt = self._make_in_prompt(n, remote=True)
        cont_prompt = self._make_continuation_prompt(self._prompt, remote=True)
        cursor.insertText('\n')
        for i, line in enumerate(content['code'].strip().split('\n')):
            if i == 0:
                self._insert_html(cursor, prompt)
            else:
                self._insert_html(cursor, cont_prompt)
            self._insert_plain_text(cursor, line + '\n')

        # Update current prompt number
        self._update_prompt(n + 1)

    def _handle_execute_input(self, msg):
        """Handle an execute_input message"""
        self.log.debug("execute_input: %s", msg.get('content', ''))
        if self.include_output(msg):
            self._append_custom(self._insert_other_input,
                                msg['content'],
                                before_prompt=True)

    def _handle_execute_result(self, msg):
        """Handle an execute_result message"""
        self.log.debug("execute_result: %s", msg.get('content', ''))
        if self.include_output(msg):
            self.flush_clearoutput()
            content = msg['content']
            prompt_number = content.get('execution_count', 0)
            data = content['data']
            if 'text/plain' in data:
                self._append_plain_text(self.output_sep, before_prompt=True)
                self._append_html(self._make_out_prompt(
                    prompt_number, remote=not self.from_here(msg)),
                                  before_prompt=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', before_prompt=True)
                self._append_plain_text(text + self.output_sep2,
                                        before_prompt=True)

                if not self.from_here(msg):
                    self._append_plain_text('\n', before_prompt=True)

    def _handle_display_data(self, msg):
        """The base handler for the ``display_data`` message."""
        # 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 self.include_output(msg):
            self.flush_clearoutput()
            data = msg['content']['data']
            metadata = msg['content']['metadata']
            # In the regular JupyterWidget, we simply print the plain text
            # representation.
            if 'text/plain' in data:
                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 _handle_kernel_info_reply(self, rep):
        """Handle kernel info replies."""
        content = rep['content']
        self.language_name = content['language_info']['name']
        pygments_lexer = content['language_info'].get('pygments_lexer', '')

        try:
            # Other kernels with pygments_lexer info will have to be
            # added here by hand.
            if pygments_lexer == 'ipython3':
                lexer = IPython3Lexer()
            elif pygments_lexer == 'ipython2':
                lexer = IPythonLexer()
            else:
                lexer = get_lexer_by_name(self.language_name)
            self._highlighter._lexer = lexer
        except ClassNotFound:
            pass

        self.kernel_banner = content.get('banner', '')
        if self._starting:
            # finish handling started channels
            self._starting = False
            super(JupyterWidget, self)._started_channels()

    def _started_channels(self):
        """Make a history request"""
        self._starting = True
        self.kernel_client.kernel_info()
        self.kernel_client.history(hist_access_type='tail', n=1000)

    #---------------------------------------------------------------------------
    # 'FrontendWidget' protected interface
    #---------------------------------------------------------------------------

    def _process_execute_error(self, msg):
        """Handle an execute_error message"""
        self.log.debug("execute_error: %s", msg.get('content', ''))

        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,
                                    before_prompt=not self.from_here(msg))

    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_client.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 _update_prompt(self, new_prompt_number):
        """Replace the last displayed prompt with a new one."""
        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(new_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())

            # Update the prompt cursor
            self._prompt_cursor.setPosition(cursor.position() - 1)

    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:
            self._update_prompt(previous_prompt_number)
            self._previous_prompt_obj = None

        # Show a new prompt with the kernel's estimated prompt number.
        self._show_interpreter_prompt(previous_prompt_number + 1)

    #---------------------------------------------------------------------------
    # 'JupyterWidget' 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 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)

    #---------------------------------------------------------------------------
    # 'JupyterWidget' 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 `JupyterWidget.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, remote=False):
        """ 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. '>>> '
            from xml.sax.saxutils import escape
            body = escape(self.in_prompt)
        if remote:
            body = self.other_output_prefix + body
        return '<span class="in-prompt">%s</span>' % body

    def _make_continuation_prompt(self, prompt, remote=False):
        """ 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)
        if remote:
            space_count += len(self.other_output_prefix.rsplit('\n')[-1])
        body = '&nbsp;' * space_count + end_chars
        return '<span class="in-prompt">%s</span>' % body

    def _make_out_prompt(self, number, remote=False):
        """ Given a prompt number, returns an HTML Out prompt.
        """
        try:
            body = self.out_prompt % number
        except TypeError:
            # allow out_prompt to leave out number, e.g. '<<< '
            from xml.sax.saxutils import escape
            body = escape(self.out_prompt)
        if remote:
            body = self.other_output_prefix + body
        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 = 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.
        data = item['data']
        if 'text/html' in data and self.kind == 'rich':
            self._page(data['text/html'], html=True)
        else:
            self._page(data['text/plain'], html=False)

    #------ Trait change handlers --------------------------------------------

    @observe('style_sheet')
    def _style_sheet_changed(self, changed=None):
        """ Set the style sheets of the underlying widgets.
        """
        self.setStyleSheet(self.style_sheet)
        if self._control is not None:
            self._control.document().setDefaultStyleSheet(self.style_sheet)

        if self._page_control is not None:
            self._page_control.document().setDefaultStyleSheet(
                self.style_sheet)

    @observe('syntax_style')
    def _syntax_style_changed(self, changed=None):
        """ 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)
            self._ansi_processor.set_background_color(self.syntax_style)
        else:
            self._highlighter.set_style_sheet(self.style_sheet)

    #------ Trait default initializers -----------------------------------------

    @default('banner')
    def _banner_default(self):
        return "Jupyter QtConsole {version}\n".format(version=__version__)
Exemplo n.º 8
0
class FrontendWidget(HistoryConsoleWidget, BaseFrontendMixin):
    """ A Qt frontend for a generic Python kernel.
    """

    # The text to show when the kernel is (re)started.
    banner = Unicode(config=True)
    kernel_banner = Unicode()
    # Whether to show the banner
    _display_banner = Bool(False)

    # 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.")

    clear_on_kernel_restart = Bool(
        True,
        config=True,
        help="Whether to clear the console when the kernel is restarted")

    confirm_restart = Bool(
        True,
        config=True,
        help="Whether to ask for user confirmation when restarting kernel")

    lexer_class = DottedObjectName(config=True,
                                   help="The pygments lexer class to use.")

    def _lexer_class_changed(self, name, old, new):
        lexer_class = import_item(new)
        self.lexer = lexer_class()

    def _lexer_class_default(self):
        if py3compat.PY3:
            return 'pygments.lexers.Python3Lexer'
        else:
            return 'pygments.lexers.PythonLexer'

    lexer = Any()

    def _lexer_default(self):
        lexer_class = import_item(self.lexer_class)
        return lexer_class()

    # 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)

    _CallTipRequest = namedtuple('_CallTipRequest', ['id', 'pos'])
    _CompletionRequest = namedtuple('_CompletionRequest', ['id', 'pos'])
    _ExecutionRequest = namedtuple('_ExecutionRequest', ['id', 'kind'])
    _local_kernel = False
    _highlighter = Instance(FrontendHighlighter, allow_none=True)

    #---------------------------------------------------------------------------
    # '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._copy_raw_action = QtGui.QAction('Copy (Raw Text)', None)
        self._hidden = False
        self._highlighter = FrontendHighlighter(self, lexer=self.lexer)
        self._kernel_manager = None
        self._kernel_client = None
        self._request_info = {}
        self._request_info['execute'] = {}
        self._callback_dict = {}
        self._display_banner = True

        # 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)

        # Whether or not a clear_output call is pending new output.
        self._pending_clearoutput = False

    #---------------------------------------------------------------------------
    # 'ConsoleWidget' public interface
    #---------------------------------------------------------------------------

    def copy(self):
        """ Copy the currently selected text to the clipboard, removing prompts.
        """
        if self._page_control is not None and self._page_control.hasFocus():
            self._page_control.copy()
        elif self._control.hasFocus():
            text = self._control.textCursor().selection().toPlainText()
            if text:
                # Remove prompts.
                lines = text.splitlines()
                lines = map(self._highlighter.transform_classic_prompt, lines)
                lines = map(self._highlighter.transform_ipy_prompt, lines)
                text = '\n'.join(lines)
                # Needed to prevent errors when copying the prompt.
                # See issue 264
                try:
                    was_newline = text[-1] == '\n'
                except IndexError:
                    was_newline = False
                if was_newline:  # user doesn't need newline
                    text = text[:-1]
                QtGui.QApplication.clipboard().setText(text)
        else:
            self.log.debug("frontend widget : unknown copy target")

    #---------------------------------------------------------------------------
    # 'ConsoleWidget' abstract interface
    #---------------------------------------------------------------------------

    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_client.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.
        """
        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.
        # 3) There is no active selection.
        text = self._get_input_buffer_cursor_line()
        if text is None:
            return False
        non_ws_before = bool(
            text[:self._get_input_buffer_cursor_column()].strip())
        complete = non_ws_before and self._get_cursor().selectedText() == ''
        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)

    #---------------------------------------------------------------------------
    # 'BaseFrontendMixin' abstract interface
    #---------------------------------------------------------------------------
    def _handle_clear_output(self, msg):
        """Handle clear output messages."""
        if self.include_output(msg):
            wait = msg['content'].get('wait', True)
            if wait:
                self._pending_clearoutput = True
            else:
                self.clear_output()

    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 argument, 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()` on the passed value.

        See Also
        --------
        _handle_exec_callback : private method, deal with calling callback with reply

        """

        # generate uuid, which would be used as an indication of whether or
        # not the unique request originated from here (can use msg id ?)
        local_uuid = str(uuid.uuid1())
        msg_id = self.kernel_client.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` corresponding 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 function 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'].get('user_expressions')
        if not user_exp:
            return
        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_reply: %s", msg.get('content', ''))
        msg_id = msg['parent_header']['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
        # Note:  If info is NoneType, this is ignored
        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_client.iopub_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 == 'aborted':
                self._process_execute_abort(msg)

            self._show_interpreter_prompt_for_reply(msg)
            self.executed.emit(msg)
            self._request_info['execute'].pop(msg_id)
        elif info and info.kind == 'silent_exec_callback' and not self._hidden:
            self._handle_exec_callback(msg)
            self._request_info['execute'].pop(msg_id)
        elif info and not self._hidden:
            raise RuntimeError("Unknown handler for %s" % info.kind)

    def _handle_error(self, msg):
        """ Handle error messages.
        """
        self._process_execute_error(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_client.iopub_channel.flush()

        def callback(line):
            self.kernel_client.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,
                       password=msg['content']['password'])

    def _kernel_restarted_message(self, died=True):
        msg = "Kernel died, restarting" if died else "Kernel restarting"
        self._append_html("<br>%s<hr><br>" % msg, before_prompt=False)

    def _handle_kernel_died(self, since_last_heartbeat):
        """Handle the kernel's death (if we do not own the kernel).
        """
        self.log.warn("kernel died: %s", since_last_heartbeat)
        if self.custom_restart:
            self.custom_restart_kernel_died.emit(since_last_heartbeat)
        else:
            self._kernel_restarted_message(died=True)
            self.reset()

    def _handle_kernel_restarted(self, died=True):
        """Notice that the autorestarter restarted the kernel.

        There's nothing to do but show a message.
        """
        self.log.warn("kernel restarted")
        self._kernel_restarted_message(died=died)
        self.reset()

    def _handle_inspect_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():
            content = rep['content']
            if content.get('status') == 'ok' and content.get('found', False):
                self._call_tip_widget.show_inspect_data(content)

    def _handle_execute_result(self, msg):
        """ Handle display hook output.
        """
        self.log.debug("execute_result: %s", msg.get('content', ''))
        if self.include_output(msg):
            self.flush_clearoutput()
            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 self.include_output(msg):
            self.flush_clearoutput()
            self.append_stream(msg['content']['text'])

    def _handle_shutdown_reply(self, msg):
        """ Handle shutdown signal, only if from other console.
        """
        self.log.debug("shutdown: %s", msg.get('content', ''))
        restart = msg.get('content', {}).get('restart', False)
        if not self._hidden and not self.from_here(msg):
            # got shutdown reply, request came from session other than ours
            if restart:
                # someone restarted the kernel, handle it
                self._handle_kernel_restarted(died=False)
            else:
                # kernel was shutdown permanently
                # this triggers exit_requested if the kernel was local,
                # and a dialog if the kernel was remote,
                # so we don't suddenly clear the qtconsole without asking.
                if self._local_kernel:
                    self.exit_requested.emit(self)
                else:
                    title = self.window().windowTitle()
                    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)

    def _handle_status(self, msg):
        """Handle status message"""
        # This is where a busy/idle indicator would be triggered,
        # when we make one.
        state = msg['content'].get('execution_state', '')
        if state == 'starting':
            # kernel started while we were running
            if self._executing:
                self._handle_kernel_restarted(died=True)
        elif state == 'idle':
            pass
        elif state == 'busy':
            pass

    def _started_channels(self):
        """ Called when the KernelManager channels have started listening or
            when the frontend is assigned an already listening KernelManager.
        """
        self.reset(clear=True)

    #---------------------------------------------------------------------------
    # '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 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:
            self._reading = False
            self.kernel_manager.interrupt_kernel()
        else:
            self._append_plain_text(
                'Cannot interrupt a kernel I did not start.\n')

    def reset(self, clear=False):
        """ Resets the widget to its initial state if ``clear`` parameter
        is True, otherwise
        prints a visual indication of the fact that the kernel restarted, but
        does not clear the traces from previous usage of the kernel before it
        was restarted.  With ``clear=True``, it is 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

        if clear:
            self._control.clear()
            if self._display_banner:
                self._append_plain_text(self.banner)
                if self.kernel_banner:
                    self._append_plain_text(self.kernel_banner)

        # update output marker for stdout/stderr, so that startup
        # messages appear after banner:
        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()
            return

        if self.kernel_manager:
            # Pause the heart beat channel to prevent further warnings.
            self.kernel_client.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.)
            if self.confirm_restart:
                buttons = QtGui.QMessageBox.Yes | QtGui.QMessageBox.No
                result = QtGui.QMessageBox.question(self, 'Restart kernel?',
                                                    message, buttons)
                do_restart = result == QtGui.QMessageBox.Yes
            else:
                # confirm_restart is False, so we don't need to ask user
                # anything, just do the restart
                do_restart = True
            if do_restart:
                try:
                    self.kernel_manager.restart_kernel(now=now)
                except RuntimeError as e:
                    self._append_plain_text('Error restarting kernel: %s\n' %
                                            e,
                                            before_prompt=True)
                else:
                    self._append_html(
                        "<br>Restarting kernel...\n<hr><br>",
                        before_prompt=True,
                    )
            else:
                self.kernel_client.hb_channel.unpause()

        else:
            self._append_plain_text(
                'Cannot restart a Kernel I did not start\n',
                before_prompt=True)

    def append_stream(self, text):
        """Appends text to the output stream."""
        # 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 = text.expandtabs(8)
        self._append_plain_text(text, before_prompt=True)
        self._control.moveCursor(QtGui.QTextCursor.End)

    def flush_clearoutput(self):
        """If a clearoutput is pending, execute it."""
        if self._pending_clearoutput:
            self._pending_clearoutput = False
            self.clear_output()

    def clear_output(self):
        """Clears the current line of output."""
        cursor = self._control.textCursor()
        cursor.beginEditBlock()
        cursor.movePosition(cursor.StartOfLine, cursor.KeepAnchor)
        cursor.insertText('')
        cursor.endEditBlock()

    #---------------------------------------------------------------------------
    # 'FrontendWidget' protected interface
    #---------------------------------------------------------------------------

    def _auto_call_tip(self):
        """Trigger call tip automatically on open parenthesis
        
        Call tips can be requested explcitly with `_call_tip`.
        """
        cursor = self._get_cursor()
        cursor.movePosition(QtGui.QTextCursor.Left)
        if cursor.document().characterAt(cursor.position()) == '(':
            # trigger auto call tip on open paren
            self._call_tip()

    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 or not self.kernel_client.shell_channel.is_alive(
        ):
            return False
        cursor_pos = self._get_input_buffer_cursor_pos()
        code = self.input_buffer
        # Send the metadata request to the kernel
        msg_id = self.kernel_client.inspect(code, cursor_pos)
        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.
        """
        # Send the completion request to the kernel
        msg_id = self.kernel_client.complete(
            code=self.input_buffer,
            cursor_pos=self._get_input_buffer_cursor_pos(),
        )
        pos = self._get_cursor().position()
        info = self._CompletionRequest(msg_id, pos)
        self._request_info['complete'] = info

    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 request.
        """
        payload = msg['content'].get('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._auto_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)
Exemplo n.º 9
0
class QtKernelManagerMixin(MetaQObjectHasTraits('NewBase', (HasTraits, SuperQObject), {})):
    """ A KernelClient that provides signals and slots.
    """

    kernel_restarted = QtCore.Signal()
Exemplo n.º 10
0
class Comm(
        MetaQObjectHasTraits('NewBase', (LoggingConfigurable, SuperQObject),
                             {})):
    """
    Comm base class
    """
    sig_is_closing = QtCore.Signal(object)

    def __init__(self,
                 target_name,
                 kernel_client,
                 comm_id=None,
                 msg_callback=None,
                 close_callback=None):
        """
        Create a new comm. Must call open to use.
        """
        super(Comm, self).__init__(target_name=target_name)
        self.target_name = target_name
        self.kernel_client = kernel_client
        if comm_id is None:
            comm_id = uuid.uuid1().hex
        self.comm_id = comm_id
        self._msg_callback = msg_callback
        self._close_callback = close_callback
        self._send_channel = self.kernel_client.shell_channel

    def __del__(self):
        self.close()

    def _send_msg(self, msg_type, content, data, metadata, buffers):
        """
        Send a message on the shell channel.
        """
        if data is None:
            data = {}
        if content is None:
            content = {}
        content['comm_id'] = self.comm_id
        content['data'] = data

        msg = self.kernel_client.session.msg(msg_type,
                                             content,
                                             metadata=metadata)
        if buffers:
            msg['buffers'] = buffers
        return self._send_channel.send(msg)

    # methods for sending messages
    def open(self, data=None, metadata=None, buffers=None):
        """Open the kernel-side version of this comm"""
        return self._send_msg('comm_open', {'target_name': self.target_name},
                              data, metadata, buffers)

    def send(self, data=None, metadata=None, buffers=None):
        """Send a message to the kernel-side version of this comm"""
        return self._send_msg('comm_msg', {}, data, metadata, buffers)

    def close(self, data=None, metadata=None, buffers=None):
        """Close the kernel-side version of this comm"""
        self.sig_is_closing.emit(self)
        return self._send_msg('comm_close', {}, data, metadata, buffers)

    # methods for registering callbacks for incoming messages

    def on_msg(self, callback):
        """Register a callback for comm_msg
        
        Will be called with the `data` of any comm_msg messages.
        
        Call `on_msg(None)` to disable an existing callback.
        """
        self._msg_callback = callback

    def on_close(self, callback):
        """Register a callback for comm_close
        
        Will be called with the `data` of the close message.
        
        Call `on_close(None)` to disable an existing callback.
        """
        self._close_callback = callback

    # methods for handling incoming messages
    def handle_msg(self, msg):
        """Handle a comm_msg message"""
        self.log.debug("handle_msg[%s](%s)", self.comm_id, msg)
        if self._msg_callback:
            return self._msg_callback(msg)

    def handle_close(self, msg):
        """Handle a comm_close message"""
        self.log.debug("handle_close[%s](%s)", self.comm_id, msg)
        if self._close_callback:
            return self._close_callback(msg)
Exemplo n.º 11
0
class MagicHelper(QtGui.QDockWidget):
    """MagicHelper - dockable widget for convenient search and running of
                     magic command for Jupyter QtConsole.
    """

    #---------------------------------------------------------------------------
    # signals
    #---------------------------------------------------------------------------

    pasteRequested = QtCore.Signal(str, name='pasteRequested')
    """This signal is emitted when user wants to paste selected magic 
       command into the command line.
    """

    runRequested = QtCore.Signal(str, name='runRequested')
    """This signal is emitted when user wants to execute selected magic command
    """

    readyForUpdate = QtCore.Signal(name='readyForUpdate')
    """This signal is emitted when MagicHelper is ready to be populated.
       Since kernel querying mechanisms are out of scope of this class,
       it expects its owner to invoke MagicHelper.populate_magic_helper()
       as a reaction on this event.
    """

    #---------------------------------------------------------------------------
    # constructor
    #---------------------------------------------------------------------------

    def __init__(self, name, parent):
        super(MagicHelper, self).__init__(name, parent)

        self.data = None

        class MinListWidget(QtGui.QListWidget):
            """Temp class to overide the default QListWidget size hint
               in order to make MagicHelper narrow
            """
            def sizeHint(self):
                s = QtCore.QSize()
                s.setHeight(super(MinListWidget, self).sizeHint().height())
                s.setWidth(self.sizeHintForColumn(0))
                return s

        # construct content
        self.frame = QtGui.QFrame()
        self.search_label = QtGui.QLabel("Search:")
        self.search_line = QtGui.QLineEdit()
        self.search_class = QtGui.QComboBox()
        self.search_list = MinListWidget()
        self.paste_button = QtGui.QPushButton("Paste")
        self.run_button = QtGui.QPushButton("Run")

        # layout all the widgets
        main_layout = QtGui.QVBoxLayout()
        search_layout = QtGui.QHBoxLayout()
        search_layout.addWidget(self.search_label)
        search_layout.addWidget(self.search_line, 10)
        main_layout.addLayout(search_layout)
        main_layout.addWidget(self.search_class)
        main_layout.addWidget(self.search_list, 10)
        action_layout = QtGui.QHBoxLayout()
        action_layout.addWidget(self.paste_button)
        action_layout.addWidget(self.run_button)
        main_layout.addLayout(action_layout)

        self.frame.setLayout(main_layout)
        self.setWidget(self.frame)

        # connect all the relevant signals to handlers
        self.visibilityChanged[bool].connect(self._update_magic_helper)
        self.search_class.activated[int].connect(self.class_selected)
        self.search_line.textChanged[str].connect(self.search_changed)
        self.search_list.itemDoubleClicked.connect(self.paste_requested)
        self.paste_button.clicked[bool].connect(self.paste_requested)
        self.run_button.clicked[bool].connect(self.run_requested)

    #---------------------------------------------------------------------------
    # implementation
    #---------------------------------------------------------------------------

    def _update_magic_helper(self, visible):
        """Start update sequence. 
           This method is called when MagicHelper becomes visible. It clears
           the content and emits readyForUpdate signal. The owner of the 
           instance is expected to invoke populate_magic_helper() when magic
           info is available.
        """
        if not visible or self.data is not None:
            return
        self.data = {}
        self.search_class.clear()
        self.search_class.addItem("Populating...")
        self.search_list.clear()
        self.readyForUpdate.emit()

    def populate_magic_helper(self, data):
        """Expects data returned by lsmagics query from kernel.
           Populates the search_class and search_list with relevant items.
        """
        self.search_class.clear()
        self.search_list.clear()

        self.data = data['data'].get('application/json', {})

        self.search_class.addItem('All Magics', 'any')
        classes = set()

        for mtype in sorted(self.data):
            subdict = self.data[mtype]
            for name in sorted(subdict):
                classes.add(subdict[name])

        for cls in sorted(classes):
            label = re.sub("([a-zA-Z]+)([A-Z][a-z])", "\g<1> \g<2>", cls)
            self.search_class.addItem(label, cls)

        self.filter_magic_helper('.', 'any')

    def class_selected(self, index):
        """Handle search_class selection changes
        """
        item = self.search_class.itemData(index)
        regex = self.search_line.text()
        self.filter_magic_helper(regex=regex, cls=item)

    def search_changed(self, search_string):
        """Handle search_line text changes.
           The text is interpreted as a regular expression
        """
        item = self.search_class.itemData(self.search_class.currentIndex())
        self.filter_magic_helper(regex=search_string, cls=item)

    def _get_current_search_item(self, item=None):
        """Retrieve magic command currently selected in the search_list
        """
        text = None
        if not isinstance(item, QtGui.QListWidgetItem):
            item = self.search_list.currentItem()
        text = item.text()
        return text

    def paste_requested(self, item=None):
        """Emit pasteRequested signal with currently selected item text
        """
        text = self._get_current_search_item(item)
        if text is not None:
            self.pasteRequested.emit(text)

    def run_requested(self, item=None):
        """Emit runRequested signal with currently selected item text
        """
        text = self._get_current_search_item(item)
        if text is not None:
            self.runRequested.emit(text)

    def filter_magic_helper(self, regex, cls):
        """Update search_list with magic commands whose text match
           regex and class match cls.
           If cls equals 'any' - any class matches.
        """
        if regex == "" or regex is None:
            regex = '.'
        if cls is None:
            cls = 'any'

        self.search_list.clear()
        for mtype in sorted(self.data):
            subdict = self.data[mtype]
            prefix = magic_escapes[mtype]

            for name in sorted(subdict):
                mclass = subdict[name]
                pmagic = prefix + name

                if (re.match(regex, name) or re.match(regex, pmagic)) and \
                   (cls == 'any' or cls == mclass):
                    self.search_list.addItem(pmagic)