pexpect.replwrap — Pexpect 4.2.1 documentation

# Source code for pexpect.replwrap

    """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="/usr/local/bin/python2.7"):
        """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")