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"""Base class to manage the interaction with a running kernel"""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from __future__ import absolute_import
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from IPython.kernel.channels import major_protocol_version
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from IPython.utils.py3compat import string_types, iteritems
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import zmq
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from IPython.utils.traitlets import (
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Any, Instance, Type,
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)
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from .channelsabc import (ChannelABC, HBChannelABC)
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from .clientabc import KernelClientABC
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from .connect import ConnectionFileMixin
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# some utilities to validate message structure, these might get moved elsewhere
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# if they prove to have more generic utility
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def validate_string_dict(dct):
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"""Validate that the input is a dict with string keys and values.
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Raises ValueError if not."""
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for k,v in iteritems(dct):
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if not isinstance(k, string_types):
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raise ValueError('key %r in dict must be a string' % k)
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if not isinstance(v, string_types):
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raise ValueError('value %r in dict must be a string' % v)
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class KernelClient(ConnectionFileMixin):
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"""Communicates with a single kernel on any host via zmq channels.
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There are four channels associated with each kernel:
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* shell: for request/reply calls to the kernel.
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* iopub: for the kernel to publish results to frontends.
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* hb: for monitoring the kernel's heartbeat.
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* stdin: for frontends to reply to raw_input calls in the kernel.
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The methods of the channels are exposed as methods of the client itself
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(KernelClient.execute, complete, history, etc.).
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See the channels themselves for documentation of these methods.
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"""
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# The PyZMQ Context to use for communication with the kernel.
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context = Instance(zmq.Context)
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def _context_default(self):
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return zmq.Context.instance()
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# The classes to use for the various channels
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shell_channel_class = Type(ChannelABC)
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iopub_channel_class = Type(ChannelABC)
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stdin_channel_class = Type(ChannelABC)
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hb_channel_class = Type(HBChannelABC)
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# Protected traits
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_shell_channel = Any
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_iopub_channel = Any
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_stdin_channel = Any
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_hb_channel = Any
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# flag for whether execute requests should be allowed to call raw_input:
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allow_stdin = True
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#--------------------------------------------------------------------------
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# Channel proxy methods
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#--------------------------------------------------------------------------
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def _get_msg(channel, *args, **kwargs):
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return channel.get_msg(*args, **kwargs)
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def get_shell_msg(self, *args, **kwargs):
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"""Get a message from the shell channel"""
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return self.shell_channel.get_msg(*args, **kwargs)
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def get_iopub_msg(self, *args, **kwargs):
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"""Get a message from the iopub channel"""
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return self.iopub_channel.get_msg(*args, **kwargs)
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def get_stdin_msg(self, *args, **kwargs):
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"""Get a message from the stdin channel"""
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return self.stdin_channel.get_msg(*args, **kwargs)
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#--------------------------------------------------------------------------
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# Channel management methods
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#--------------------------------------------------------------------------
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def start_channels(self, shell=True, iopub=True, stdin=True, hb=True):
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"""Starts the channels for this kernel.
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This will create the channels if they do not exist and then start
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them (their activity runs in a thread). If port numbers of 0 are
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being used (random ports) then you must first call
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:meth:`start_kernel`. If the channels have been stopped and you
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call this, :class:`RuntimeError` will be raised.
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"""
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if shell:
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self.shell_channel.start()
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self.kernel_info()
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if iopub:
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self.iopub_channel.start()
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if stdin:
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self.stdin_channel.start()
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self.allow_stdin = True
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else:
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self.allow_stdin = False
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if hb:
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self.hb_channel.start()
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def stop_channels(self):
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"""Stops all the running channels for this kernel.
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This stops their event loops and joins their threads.
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"""
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if self.shell_channel.is_alive():
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self.shell_channel.stop()
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if self.iopub_channel.is_alive():
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self.iopub_channel.stop()
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if self.stdin_channel.is_alive():
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self.stdin_channel.stop()
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if self.hb_channel.is_alive():
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self.hb_channel.stop()
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@property
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def channels_running(self):
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"""Are any of the channels created and running?"""
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return (self.shell_channel.is_alive() or self.iopub_channel.is_alive() or
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self.stdin_channel.is_alive() or self.hb_channel.is_alive())
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ioloop = None # Overridden in subclasses that use pyzmq event loop
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@property
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def shell_channel(self):
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"""Get the shell channel object for this kernel."""
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if self._shell_channel is None:
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url = self._make_url('shell')
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self.log.debug("connecting shell channel to %s", url)
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socket = self.connect_shell(identity=self.session.bsession)
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self._shell_channel = self.shell_channel_class(
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socket, self.session, self.ioloop
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)
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return self._shell_channel
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@property
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def iopub_channel(self):
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"""Get the iopub channel object for this kernel."""
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if self._iopub_channel is None:
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url = self._make_url('iopub')
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self.log.debug("connecting iopub channel to %s", url)
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socket = self.connect_iopub()
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self._iopub_channel = self.iopub_channel_class(
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socket, self.session, self.ioloop
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)
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return self._iopub_channel
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@property
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def stdin_channel(self):
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"""Get the stdin channel object for this kernel."""
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if self._stdin_channel is None:
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url = self._make_url('stdin')
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self.log.debug("connecting stdin channel to %s", url)
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socket = self.connect_stdin(identity=self.session.bsession)
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self._stdin_channel = self.stdin_channel_class(
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socket, self.session, self.ioloop
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)
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return self._stdin_channel
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@property
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def hb_channel(self):
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"""Get the hb channel object for this kernel."""
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if self._hb_channel is None:
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url = self._make_url('hb')
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self.log.debug("connecting heartbeat channel to %s", url)
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self._hb_channel = self.hb_channel_class(
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self.context, self.session, url
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)
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return self._hb_channel
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def is_alive(self):
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"""Is the kernel process still running?"""
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if self._hb_channel is not None:
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# We didn't start the kernel with this KernelManager so we
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# use the heartbeat.
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return self._hb_channel.is_beating()
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else:
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# no heartbeat and not local, we can't tell if it's running,
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# so naively return True
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return True
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# Methods to send specific messages on channels
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def execute(self, code, silent=False, store_history=True,
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user_expressions=None, allow_stdin=None, stop_on_error=True):
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"""Execute code in the kernel.
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Parameters
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----------
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code : str
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A string of Python code.
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silent : bool, optional (default False)
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If set, the kernel will execute the code as quietly possible, and
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will force store_history to be False.
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store_history : bool, optional (default True)
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If set, the kernel will store command history. This is forced
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to be False if silent is True.
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user_expressions : dict, optional
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A dict mapping names to expressions to be evaluated in the user's
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dict. The expression values are returned as strings formatted using
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:func:`repr`.
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allow_stdin : bool, optional (default self.allow_stdin)
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Flag for whether the kernel can send stdin requests to frontends.
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Some frontends (e.g. the Notebook) do not support stdin requests.
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If raw_input is called from code executed from such a frontend, a
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StdinNotImplementedError will be raised.
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stop_on_error: bool, optional (default True)
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Flag whether to abort the execution queue, if an exception is encountered.
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Returns
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-------
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The msg_id of the message sent.
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"""
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if user_expressions is None:
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user_expressions = {}
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if allow_stdin is None:
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allow_stdin = self.allow_stdin
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# Don't waste network traffic if inputs are invalid
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if not isinstance(code, string_types):
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raise ValueError('code %r must be a string' % code)
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validate_string_dict(user_expressions)
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# Create class for content/msg creation. Related to, but possibly
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# not in Session.
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content = dict(code=code, silent=silent, store_history=store_history,
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user_expressions=user_expressions,
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allow_stdin=allow_stdin, stop_on_error=stop_on_error
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)
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msg = self.session.msg('execute_request', content)
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self.shell_channel.send(msg)
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return msg['header']['msg_id']
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def complete(self, code, cursor_pos=None):
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"""Tab complete text in the kernel's namespace.
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Parameters
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----------
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code : str
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The context in which completion is requested.
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Can be anything between a variable name and an entire cell.
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cursor_pos : int, optional
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The position of the cursor in the block of code where the completion was requested.
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Default: ``len(code)``
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Returns
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-------
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The msg_id of the message sent.
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"""
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if cursor_pos is None:
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cursor_pos = len(code)
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content = dict(code=code, cursor_pos=cursor_pos)
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msg = self.session.msg('complete_request', content)
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self.shell_channel.send(msg)
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return msg['header']['msg_id']
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def inspect(self, code, cursor_pos=None, detail_level=0):
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"""Get metadata information about an object in the kernel's namespace.
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It is up to the kernel to determine the appropriate object to inspect.
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Parameters
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----------
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code : str
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The context in which info is requested.
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Can be anything between a variable name and an entire cell.
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cursor_pos : int, optional
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The position of the cursor in the block of code where the info was requested.
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Default: ``len(code)``
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detail_level : int, optional
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The level of detail for the introspection (0-2)
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Returns
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-------
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The msg_id of the message sent.
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"""
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if cursor_pos is None:
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cursor_pos = len(code)
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content = dict(code=code, cursor_pos=cursor_pos,
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detail_level=detail_level,
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)
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msg = self.session.msg('inspect_request', content)
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self.shell_channel.send(msg)
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return msg['header']['msg_id']
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def history(self, raw=True, output=False, hist_access_type='range', **kwargs):
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"""Get entries from the kernel's history list.
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Parameters
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----------
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raw : bool
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If True, return the raw input.
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output : bool
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If True, then return the output as well.
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hist_access_type : str
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'range' (fill in session, start and stop params), 'tail' (fill in n)
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or 'search' (fill in pattern param).
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session : int
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For a range request, the session from which to get lines. Session
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numbers are positive integers; negative ones count back from the
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current session.
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start : int
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The first line number of a history range.
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stop : int
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The final (excluded) line number of a history range.
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n : int
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The number of lines of history to get for a tail request.
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pattern : str
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The glob-syntax pattern for a search request.
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Returns
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-------
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The msg_id of the message sent.
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"""
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content = dict(raw=raw, output=output, hist_access_type=hist_access_type,
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**kwargs)
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msg = self.session.msg('history_request', content)
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self.shell_channel.send(msg)
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return msg['header']['msg_id']
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def kernel_info(self):
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"""Request kernel info."""
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msg = self.session.msg('kernel_info_request')
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self.shell_channel.send(msg)
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return msg['header']['msg_id']
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def _handle_kernel_info_reply(self, msg):
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"""handle kernel info reply
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sets protocol adaptation version. This might
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be run from a separate thread.
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"""
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adapt_version = int(msg['content']['protocol_version'].split('.')[0])
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if adapt_version != major_protocol_version:
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self.session.adapt_version = adapt_version
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def shutdown(self, restart=False):
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"""Request an immediate kernel shutdown.
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Upon receipt of the (empty) reply, client code can safely assume that
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the kernel has shut down and it's safe to forcefully terminate it if
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it's still alive.
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The kernel will send the reply via a function registered with Python's
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atexit module, ensuring it's truly done as the kernel is done with all
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normal operation.
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"""
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# Send quit message to kernel. Once we implement kernel-side setattr,
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# this should probably be done that way, but for now this will do.
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msg = self.session.msg('shutdown_request', {'restart':restart})
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self.shell_channel.send(msg)
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return msg['header']['msg_id']
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def is_complete(self, code):
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msg = self.session.msg('is_complete_request', {'code': code})
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self.shell_channel.send(msg)
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return msg['header']['msg_id']
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def input(self, string):
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"""Send a string of raw input to the kernel."""
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content = dict(value=string)
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msg = self.session.msg('input_reply', content)
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self.stdin_channel.send(msg)
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KernelClientABC.register(KernelClient)
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