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# -*- coding: utf-8 -*-

""" Imports and provides the 'correct' version of readline for the platform.

Readline is used throughout IPython as::

import IPython.utils.rlineimpl as readline

In addition to normal readline stuff, this module provides have_readline

boolean and _outputfile variable used in IPython.utils.

"""

import sys

import warnings

if sys.platform == 'darwin':

# dirty trick, to skip the system readline, because pip-installed readline

# will never be found on OSX, since lib-dynload always comes ahead of site-packages

from distutils import sysconfig

lib_dynload = sysconfig.get_config_var('DESTSHARED')

del sysconfig

try:

dynload_idx = sys.path.index(lib_dynload)

except ValueError:

dynload_idx = None

else:

sys.path.pop(dynload_idx)

try:

from readline import *

import readline as _rl

have_readline = True

except ImportError:

try:

from pyreadline import *

import pyreadline as _rl

have_readline = True

except ImportError:

have_readline = False

if sys.platform == 'darwin':

# dirty trick, part II:

if dynload_idx is not None:

# restore path

sys.path.insert(dynload_idx, lib_dynload)

if not have_readline:

# *only* have system readline, try import again

try:

from readline import *

import readline as _rl

have_readline = True

except ImportError:

have_readline = False

else:

# if we want to warn about EPD / Fink having bad readline

# we would do it here

pass

# cleanup dirty trick vars

del dynload_idx, lib_dynload

if (sys.platform == 'win32' or sys.platform == 'cli') and have_readline:

try:

_outputfile=_rl.GetOutputFile()

except AttributeError:

warnings.warn("Failed GetOutputFile")

have_readline = False

# Test to see if libedit is being used instead of GNU readline.

# Thanks to Boyd Waters for the original patch.

uses_libedit = False

if have_readline:

# Official Python docs state that 'libedit' is in the docstring for libedit readline:

uses_libedit = _rl.__doc__ and 'libedit' in _rl.__doc__

# Note that many non-System Pythons also do not use proper readline,

# but do not report libedit at all, nor are they linked dynamically against libedit.

# known culprits of this include: EPD, Fink

# There is not much we can do to detect this, until we find a specific failure

# case, rather than relying on the readline module to self-identify as broken.

if uses_libedit and sys.platform == 'darwin':

_rl.parse_and_bind("bind ^I rl_complete")

warnings.warn('\n'.join(['', "*"*78,

"libedit detected - readline will not be well behaved, including but not limited to:",

" * crashes on tab completion",

" * incorrect history navigation",

" * corrupting long-lines",

" * failure to wrap or indent lines properly",

"It is highly recommended that you install readline, which is easy_installable:",

" easy_install readline",

"Note that `pip install readline` generally DOES NOT WORK, because",

"it installs to site-packages, which come *after* lib-dynload in sys.path,",

"where readline is located. It must be `easy_install readline`, or to a custom",

"location on your PYTHONPATH (even --user comes after lib-dyload).",

"*"*78]),

RuntimeWarning)

# the clear_history() function was only introduced in Python 2.4 and is

# actually optional in the readline API, so we must explicitly check for its

# existence. Some known platforms actually don't have it. This thread:

# http://mail.python.org/pipermail/python-dev/2003-August/037845.html

# has the original discussion.

if have_readline:

try:

_rl.clear_history

except AttributeError:

def clear_history(): pass

_rl.clear_history = clear_history