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usr
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lib
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python3
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dist-packages
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pexpect
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Filename :
replwrap.py
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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): return self.child.expect_exact([self.prompt, self.continuation_prompt], timeout=timeout) def run_command(self, command, timeout=-1): """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. """ # 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") 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="python"): """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")