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# coding=utf-8
"""
Bridges calls made inside of pyscript with the Cmd2 host app while maintaining a reasonable
degree of isolation between the two
Copyright 2018 Eric Lin <anselor@gmail.com>
Released under MIT license, see LICENSE file
"""
import sys
from typing import Optional
from .utils import namedtuple_with_defaults, StdSim
# Python 3.4 require contextlib2 for temporarily redirecting stderr and stdout
if sys.version_info < (3, 5):
from contextlib2 import redirect_stdout, redirect_stderr
else:
from contextlib import redirect_stdout, redirect_stderr
class CommandResult(namedtuple_with_defaults('CommandResult', ['stdout', 'stderr', 'data'])):
"""Encapsulates the results from a command.
Named tuple attributes
----------------------
stdout: str - Output captured from stdout while this command is executing
stderr: str - Output captured from stderr while this command is executing. None if no error captured
data - Data returned by the command.
NOTE: Named tuples are immutable. So the contents are there for access, not for modification.
"""
def __bool__(self) -> bool:
"""Returns True if the command succeeded, otherwise False"""
# If data has a __bool__ method, then call it to determine success of command
if self.data is not None and callable(getattr(self.data, '__bool__', None)):
return bool(self.data)
# Otherwise check if stderr was filled out
else:
return not self.stderr
class PyscriptBridge(object):
"""Preserves the legacy 'cmd' interface for pyscript while also providing a new python API wrapper for
application commands."""
def __init__(self, cmd2_app):
self._cmd2_app = cmd2_app
self._last_result = None
self.cmd_echo = False
def __dir__(self):
"""Return a custom set of attribute names"""
attributes = []
attributes.insert(0, 'cmd_echo')
return attributes
def __call__(self, command: str, echo: Optional[bool]=None) -> CommandResult:
"""
Provide functionality to call application commands by calling PyscriptBridge
ex: app('help')
:param command: command line being run
:param echo: if True, output will be echoed to stdout/stderr while the command runs
this temporarily overrides the value of self.cmd_echo
"""
if echo is None:
echo = self.cmd_echo
copy_stdout = StdSim(sys.stdout, echo)
copy_stderr = StdSim(sys.stderr, echo)
copy_cmd_stdout = StdSim(self._cmd2_app.stdout, echo)
self._cmd2_app._last_result = None
try:
self._cmd2_app.stdout = copy_cmd_stdout
with redirect_stdout(copy_stdout):
with redirect_stderr(copy_stderr):
# Include a newline in case it's a multiline command
self._cmd2_app.onecmd_plus_hooks(command + '\n')
finally:
self._cmd2_app.stdout = copy_cmd_stdout.inner_stream
# if stderr is empty, set it to None
stderr = copy_stderr.getvalue() if copy_stderr.getvalue() else None
outbuf = copy_cmd_stdout.getvalue() if copy_cmd_stdout.getvalue() else copy_stdout.getvalue()
result = CommandResult(stdout=outbuf, stderr=stderr, data=self._cmd2_app._last_result)
return result
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