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"""Generic wrapper for read-eval-print-loops, a.k.a. interactive shells
"""
import os.path
import signal
import sys
import pexpect
PY3 = (sys.version_info[0] >= 3)
if PY3:
basestring = str
PEXPECT_PROMPT = u'[PEXPECT_PROMPT>'
PEXPECT_CONTINUATION_PROMPT = u'[PEXPECT_PROMPT+'
class REPLWrapper(object):
"""Wrapper for a REPL.
:param cmd_or_spawn: This can either be an instance of :class:`pexpect.spawn`
in which a REPL has already been started, or a str command to start a new
REPL process.
:param str orig_prompt: The prompt to expect at first.
:param str prompt_change: A command to change the prompt to something more
unique. If this is ``None``, the prompt will not be changed. This will
be formatted with the new and continuation prompts as positional
parameters, so you can use ``{}`` style formatting to insert them into
the command.
:param str new_prompt: The more unique prompt to expect after the change.
:param str extra_init_cmd: Commands to do extra initialisation, such as
disabling pagers.
"""
def __init__(self, cmd_or_spawn, orig_prompt, prompt_change,
new_prompt=PEXPECT_PROMPT,
continuation_prompt=PEXPECT_CONTINUATION_PROMPT,
extra_init_cmd=None):
if isinstance(cmd_or_spawn, basestring):
self.child = pexpect.spawn(cmd_or_spawn, echo=False, encoding='utf-8')
else:
self.child = cmd_or_spawn
if self.child.echo:
# Existing spawn instance has echo enabled, disable it
# to prevent our input from being repeated to output.
self.child.setecho(False)
self.child.waitnoecho()
if prompt_change is None:
self.prompt = orig_prompt
else:
self.set_prompt(orig_prompt,
prompt_change.format(new_prompt, continuation_prompt))
self.prompt = new_prompt
self.continuation_prompt = continuation_prompt
self._expect_prompt()
if extra_init_cmd is not None:
self.run_command(extra_init_cmd)
def set_prompt(self, orig_prompt, prompt_change):
self.child.expect(orig_prompt)
self.child.sendline(prompt_change)
def _expect_prompt(self, timeout=-1, async_=False):
return self.child.expect_exact([self.prompt, self.continuation_prompt],
timeout=timeout, async_=async_)
def run_command(self, command, timeout=-1, async_=False):
"""Send a command to the REPL, wait for and return output.
:param str command: The command to send. Trailing newlines are not needed.
This should be a complete block of input that will trigger execution;
if a continuation prompt is found after sending input, :exc:`ValueError`
will be raised.
:param int timeout: How long to wait for the next prompt. -1 means the
default from the :class:`pexpect.spawn` object (default 30 seconds).
None means to wait indefinitely.
:param bool async_: On Python 3.4, or Python 3.3 with asyncio
installed, passing ``async_=True`` will make this return an
:mod:`asyncio` Future, which you can yield from to get the same
result that this method would normally give directly.
"""
# Split up multiline commands and feed them in bit-by-bit
cmdlines = command.splitlines()
# splitlines ignores trailing newlines - add it back in manually
if command.endswith('\n'):
cmdlines.append('')
if not cmdlines:
raise ValueError("No command was given")
if async_:
from ._async import repl_run_command_async
return repl_run_command_async(self, cmdlines, timeout)
res = []
self.child.sendline(cmdlines[0])
for line in cmdlines[1:]:
self._expect_prompt(timeout=timeout)
res.append(self.child.before)
self.child.sendline(line)
# Command was fully submitted, now wait for the next prompt
if self._expect_prompt(timeout=timeout) == 1:
# We got the continuation prompt - command was incomplete
self.child.kill(signal.SIGINT)
self._expect_prompt(timeout=1)
raise ValueError("Continuation prompt found - input was incomplete:\n"
+ command)
return u''.join(res + [self.child.before])
def python(command=sys.executable):
"""Start a Python shell and return a :class:`REPLWrapper` object."""
return REPLWrapper(command, u">>> ", u"import sys; sys.ps1={0!r}; sys.ps2={1!r}")
def bash(command="bash"):
"""Start a bash shell and return a :class:`REPLWrapper` object."""
bashrc = os.path.join(os.path.dirname(__file__), 'bashrc.sh')
child = pexpect.spawn(command, ['--rcfile', bashrc], echo=False,
encoding='utf-8')
# If the user runs 'env', the value of PS1 will be in the output. To avoid
# replwrap seeing that as the next prompt, we'll embed the marker characters
# for invisible characters in the prompt; these show up when inspecting the
# environment variable, but not when bash displays the prompt.
ps1 = PEXPECT_PROMPT[:5] + u'\\[\\]' + PEXPECT_PROMPT[5:]
ps2 = PEXPECT_CONTINUATION_PROMPT[:5] + u'\\[\\]' + PEXPECT_CONTINUATION_PROMPT[5:]
prompt_change = u"PS1='{0}' PS2='{1}' PROMPT_COMMAND=''".format(ps1, ps2)
return REPLWrapper(child, u'\\$', prompt_change,
extra_init_cmd="export PAGER=cat")
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