zmqshell.py

"""A ZMQ-based subclass of InteractiveShell.

This code is meant to ease the refactoring of the base InteractiveShell into
something with a cleaner architecture for 2-process use, without actually
breaking InteractiveShell itself.  So we're doing something a bit ugly, where
we subclass and override what we want to fix.  Once this is working well, we
can go back to the base class and refactor the code for a cleaner inheritance
implementation that doesn't rely on so much monkeypatching.

But this lets us maintain a fully working IPython as we develop the new
machinery.  This should thus be thought of as scaffolding.
"""
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from __future__ import print_function

# Stdlib
import inspect
import os

# Our own
from IPython.core.interactiveshell import (
    InteractiveShell, InteractiveShellABC
)
from IPython.core import page
from IPython.core.autocall import ZMQExitAutocall
from IPython.core.displaypub import DisplayPublisher
from IPython.core.macro import Macro
from IPython.core.magic import MacroToEdit
from IPython.core.payloadpage import install_payload_page
from IPython.utils import io
from IPython.utils.jsonutil import json_clean
from IPython.utils.path import get_py_filename
from IPython.utils.traitlets import Instance, Type, Dict, CBool
from IPython.utils.warn import warn
from IPython.zmq.displayhook import ZMQShellDisplayHook, _encode_binary
from IPython.zmq.session import extract_header
from session import Session

#-----------------------------------------------------------------------------
# Globals and side-effects
#-----------------------------------------------------------------------------

# Install the payload version of page.
install_payload_page()

#-----------------------------------------------------------------------------
# Functions and classes
#-----------------------------------------------------------------------------

class ZMQDisplayPublisher(DisplayPublisher):
    """A display publisher that publishes data using a ZeroMQ PUB socket."""

    session = Instance(Session)
    pub_socket = Instance('zmq.Socket')
    parent_header = Dict({})

    def set_parent(self, parent):
        """Set the parent for outbound messages."""
        self.parent_header = extract_header(parent)

    def publish(self, source, data, metadata=None):
        if metadata is None:
            metadata = {}
        self._validate_data(source, data, metadata)
        content = {}
        content['source'] = source
        _encode_binary(data)
        content['data'] = data
        content['metadata'] = metadata
        self.session.send(
            self.pub_socket, u'display_data', json_clean(content),
            parent=self.parent_header
        )


class ZMQInteractiveShell(InteractiveShell):
    """A subclass of InteractiveShell for ZMQ."""

    displayhook_class = Type(ZMQShellDisplayHook)
    display_pub_class = Type(ZMQDisplayPublisher)
    
    # Override the traitlet in the parent class, because there's no point using
    # readline for the kernel. Can be removed when the readline code is moved
    # to the terminal frontend.
    colors_force = CBool(True)
    readline_use = CBool(False)
    # autoindent has no meaning in a zmqshell, and attempting to enable it
    # will print a warning in the absence of readline.
    autoindent = CBool(False)
    
    exiter = Instance(ZMQExitAutocall)
    def _exiter_default(self):
        return ZMQExitAutocall(self)

    keepkernel_on_exit = None

    def init_environment(self):
        """Configure the user's environment.

        """
        env = os.environ
        # These two ensure 'ls' produces nice coloring on BSD-derived systems
        env['TERM'] = 'xterm-color'
        env['CLICOLOR'] = '1'
        # Since normal pagers don't work at all (over pexpect we don't have
        # single-key control of the subprocess), try to disable paging in
        # subprocesses as much as possible.
        env['PAGER'] = 'cat'
        env['GIT_PAGER'] = 'cat'

    def auto_rewrite_input(self, cmd):
        """Called to show the auto-rewritten input for autocall and friends.

        FIXME: this payload is currently not correctly processed by the
        frontend.
        """
        new = self.displayhook.prompt1.auto_rewrite() + cmd
        payload = dict(
            source='IPython.zmq.zmqshell.ZMQInteractiveShell.auto_rewrite_input',
            transformed_input=new,
            )
        self.payload_manager.write_payload(payload)
        
    def ask_exit(self):
        """Engage the exit actions."""
        payload = dict(
            source='IPython.zmq.zmqshell.ZMQInteractiveShell.ask_exit',
            exit=True,
            keepkernel=self.keepkernel_on_exit,
            )
        self.payload_manager.write_payload(payload)

    def _showtraceback(self, etype, evalue, stb):

        exc_content = {
            u'traceback' : stb,
            u'ename' : unicode(etype.__name__),
            u'evalue' : unicode(evalue)
        }

        dh = self.displayhook
        # Send exception info over pub socket for other clients than the caller
        # to pick up
        exc_msg = dh.session.send(dh.pub_socket, u'pyerr', json_clean(exc_content), dh.parent_header)

        # FIXME - Hack: store exception info in shell object.  Right now, the
        # caller is reading this info after the fact, we need to fix this logic
        # to remove this hack.  Even uglier, we need to store the error status
        # here, because in the main loop, the logic that sets it is being
        # skipped because runlines swallows the exceptions.
        exc_content[u'status'] = u'error'
        self._reply_content = exc_content
        # /FIXME
        
        return exc_content

    #------------------------------------------------------------------------
    # Magic overrides
    #------------------------------------------------------------------------
    # Once the base class stops inheriting from magic, this code needs to be
    # moved into a separate machinery as well.  For now, at least isolate here
    # the magics which this class needs to implement differently from the base
    # class, or that are unique to it.

    def magic_doctest_mode(self,parameter_s=''):
        """Toggle doctest mode on and off.

        This mode is intended to make IPython behave as much as possible like a
        plain Python shell, from the perspective of how its prompts, exceptions
        and output look.  This makes it easy to copy and paste parts of a
        session into doctests.  It does so by:

        - Changing the prompts to the classic ``>>>`` ones.
        - Changing the exception reporting mode to 'Plain'.
        - Disabling pretty-printing of output.

        Note that IPython also supports the pasting of code snippets that have
        leading '>>>' and '...' prompts in them.  This means that you can paste
        doctests from files or docstrings (even if they have leading
        whitespace), and the code will execute correctly.  You can then use
        '%history -t' to see the translated history; this will give you the
        input after removal of all the leading prompts and whitespace, which
        can be pasted back into an editor.

        With these features, you can switch into this mode easily whenever you
        need to do testing and changes to doctests, without having to leave
        your existing IPython session.
        """

        from IPython.utils.ipstruct import Struct

        # Shorthands
        shell = self.shell
        disp_formatter = self.shell.display_formatter
        ptformatter = disp_formatter.formatters['text/plain']
        # dstore is a data store kept in the instance metadata bag to track any
        # changes we make, so we can undo them later.
        dstore = shell.meta.setdefault('doctest_mode', Struct())
        save_dstore = dstore.setdefault

        # save a few values we'll need to recover later
        mode = save_dstore('mode', False)
        save_dstore('rc_pprint', ptformatter.pprint)
        save_dstore('rc_plain_text_only',disp_formatter.plain_text_only)
        save_dstore('xmode', shell.InteractiveTB.mode)
        
        if mode == False:
            # turn on
            ptformatter.pprint = False
            disp_formatter.plain_text_only = True
            shell.magic_xmode('Plain')
        else:
            # turn off
            ptformatter.pprint = dstore.rc_pprint
            disp_formatter.plain_text_only = dstore.rc_plain_text_only
            shell.magic_xmode(dstore.xmode)

        # Store new mode and inform on console
        dstore.mode = bool(1-int(mode))
        mode_label = ['OFF','ON'][dstore.mode]
        print('Doctest mode is:', mode_label)
        
        # Send the payload back so that clients can modify their prompt display
        payload = dict(
            source='IPython.zmq.zmqshell.ZMQInteractiveShell.magic_doctest_mode',
            mode=dstore.mode)
        self.payload_manager.write_payload(payload)

    def magic_edit(self,parameter_s='',last_call=['','']):
        """Bring up an editor and execute the resulting code.

        Usage:
          %edit [options] [args]

        %edit runs an external text editor. You will need to set the command for
        this editor via the ``TerminalInteractiveShell.editor`` option in your
        configuration file before it will work.

        This command allows you to conveniently edit multi-line code right in
        your IPython session.
        
        If called without arguments, %edit opens up an empty editor with a
        temporary file and will execute the contents of this file when you
        close it (don't forget to save it!).


        Options:

        -n <number>: open the editor at a specified line number.  By default,
        the IPython editor hook uses the unix syntax 'editor +N filename', but
        you can configure this by providing your own modified hook if your
        favorite editor supports line-number specifications with a different
        syntax.
        
        -p: this will call the editor with the same data as the previous time
        it was used, regardless of how long ago (in your current session) it
        was.

        -r: use 'raw' input.  This option only applies to input taken from the
        user's history.  By default, the 'processed' history is used, so that
        magics are loaded in their transformed version to valid Python.  If
        this option is given, the raw input as typed as the command line is
        used instead.  When you exit the editor, it will be executed by
        IPython's own processor.
        
        -x: do not execute the edited code immediately upon exit. This is
        mainly useful if you are editing programs which need to be called with
        command line arguments, which you can then do using %run.


        Arguments:

        If arguments are given, the following possibilites exist:

        - The arguments are numbers or pairs of colon-separated numbers (like
        1 4:8 9). These are interpreted as lines of previous input to be
        loaded into the editor. The syntax is the same of the %macro command.

        - If the argument doesn't start with a number, it is evaluated as a
        variable and its contents loaded into the editor. You can thus edit
        any string which contains python code (including the result of
        previous edits).

        - If the argument is the name of an object (other than a string),
        IPython will try to locate the file where it was defined and open the
        editor at the point where it is defined. You can use `%edit function`
        to load an editor exactly at the point where 'function' is defined,
        edit it and have the file be executed automatically.

        If the object is a macro (see %macro for details), this opens up your
        specified editor with a temporary file containing the macro's data.
        Upon exit, the macro is reloaded with the contents of the file.

        Note: opening at an exact line is only supported under Unix, and some
        editors (like kedit and gedit up to Gnome 2.8) do not understand the
        '+NUMBER' parameter necessary for this feature. Good editors like
        (X)Emacs, vi, jed, pico and joe all do.

        - If the argument is not found as a variable, IPython will look for a
        file with that name (adding .py if necessary) and load it into the
        editor. It will execute its contents with execfile() when you exit,
        loading any code in the file into your interactive namespace.

        After executing your code, %edit will return as output the code you
        typed in the editor (except when it was an existing file). This way
        you can reload the code in further invocations of %edit as a variable,
        via _<NUMBER> or Out[<NUMBER>], where <NUMBER> is the prompt number of
        the output.

        Note that %edit is also available through the alias %ed.

        This is an example of creating a simple function inside the editor and
        then modifying it. First, start up the editor:

        In [1]: ed
        Editing... done. Executing edited code...
        Out[1]: 'def foo():n    print "foo() was defined in an editing session"n'

        We can then call the function foo():
        
        In [2]: foo()
        foo() was defined in an editing session

        Now we edit foo.  IPython automatically loads the editor with the
        (temporary) file where foo() was previously defined:
        
        In [3]: ed foo
        Editing... done. Executing edited code...

        And if we call foo() again we get the modified version:
        
        In [4]: foo()
        foo() has now been changed!

        Here is an example of how to edit a code snippet successive
        times. First we call the editor:

        In [5]: ed
        Editing... done. Executing edited code...
        hello
        Out[5]: "print 'hello'n"

        Now we call it again with the previous output (stored in _):

        In [6]: ed _
        Editing... done. Executing edited code...
        hello world
        Out[6]: "print 'hello world'n"

        Now we call it with the output #8 (stored in _8, also as Out[8]):

        In [7]: ed _8
        Editing... done. Executing edited code...
        hello again
        Out[7]: "print 'hello again'n"
        """
        
        opts,args = self.parse_options(parameter_s,'prn:')
        
        try:
            filename, lineno, _ = self._find_edit_target(args, opts, last_call)
        except MacroToEdit as e:
            # TODO: Implement macro editing over 2 processes.
            print("Macro editing not yet implemented in 2-process model.")
            return

        # Make sure we send to the client an absolute path, in case the working
        # directory of client and kernel don't match
        filename = os.path.abspath(filename)

        payload = {
            'source' : 'IPython.zmq.zmqshell.ZMQInteractiveShell.edit_magic',
            'filename' : filename,
            'line_number' : lineno
        }
        self.payload_manager.write_payload(payload)

    def magic_gui(self, *args, **kwargs):
        raise NotImplementedError(
            'Kernel GUI support is not implemented yet, except for --pylab.')

    def magic_pylab(self, *args, **kwargs):
        raise NotImplementedError(
            'pylab support must be enabled in command line options.')

    # A few magics that are adapted to the specifics of using pexpect and a
    # remote terminal

    def magic_clear(self, arg_s):
        """Clear the terminal."""
        if os.name == 'posix':
            self.shell.system("clear")
        else:
            self.shell.system("cls")

    if os.name == 'nt':
        # This is the usual name in windows
        magic_cls = magic_clear

    # Terminal pagers won't work over pexpect, but we do have our own pager
    
    def magic_less(self, arg_s):
        """Show a file through the pager.

        Files ending in .py are syntax-highlighted."""
        cont = open(arg_s).read()
        if arg_s.endswith('.py'):
            cont = self.shell.pycolorize(cont)
        page.page(cont)

    magic_more = magic_less

    # Man calls a pager, so we also need to redefine it
    if os.name == 'posix':
        def magic_man(self, arg_s):
            """Find the man page for the given command and display in pager."""
            page.page(self.shell.getoutput('man %s | col -b' % arg_s,
                                           split=False))

    # FIXME: this is specific to the GUI, so we should let the gui app load
    # magics at startup that are only for the gui.  Once the gui app has proper
    # profile and configuration management, we can have it initialize a kernel
    # with a special config file that provides these.
    def magic_guiref(self, arg_s):
        """Show a basic reference about the GUI console."""
        from IPython.core.usage import gui_reference
        page.page(gui_reference, auto_html=True)
    
    def set_next_input(self, text):
        """Send the specified text to the frontend to be presented at the next
        input cell."""
        payload = dict(
            source='IPython.zmq.zmqshell.ZMQInteractiveShell.set_next_input', 
            text=text
        )
        self.payload_manager.write_payload(payload)

InteractiveShellABC.register(ZMQInteractiveShell)