baseimage-tutorial-framework/lib/tfw/components/terminal_commands.py

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import logging
from abc import ABC
from re import match
from shlex import split
LOG = logging.getLogger(__name__)
class TerminalCommands(ABC):
# pylint: disable=anomalous-backslash-in-string
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"""
A class you can use to define hooks for terminal commands. This means that you can
have python code executed when the user enters a specific command to the terminal on
our frontend.
To receive events you need to subscribe TerminalCommand.callback to a HistoryMonitor
instance.
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Inherit from this class and define methods which start with "command\_". When the user
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executes the command specified after the underscore, your method will be invoked. All
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such commands must expect the parameter \*args which will contain the arguments of the
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command.
For example to define a method that runs when someone starts vim in the terminal
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you have to define a method like: "def command_vim(self, \*args)"
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You can also use this class to create new commands similarly.
"""
def __init__(self, bashrc):
self._command_method_regex = r'^command_(.+)$'
self.command_implemetations = self._build_command_to_implementation_dict()
if bashrc is not None:
self._setup_bashrc_aliases(bashrc)
def _build_command_to_implementation_dict(self):
return {
self._parse_command_name(fun): getattr(self, fun)
for fun in dir(self)
if callable(getattr(self, fun))
and self._is_command_implementation(fun)
}
def _setup_bashrc_aliases(self, bashrc):
with open(bashrc, 'a') as ofile:
alias_template = 'type {0} &> /dev/null || alias {0}="{0} &> /dev/null"\n'
for command in self.command_implemetations.keys():
ofile.write(alias_template.format(command))
def _is_command_implementation(self, method_name):
return bool(self._match_command_regex(method_name))
def _parse_command_name(self, method_name):
try:
return self._match_command_regex(method_name).groups()[0]
except AttributeError:
return ''
def _match_command_regex(self, string):
return match(self._command_method_regex, string)
def callback(self, command):
parts = split(command)
command = parts[0]
if command in self.command_implemetations.keys():
try:
self.command_implemetations[command](*parts[1:])
except Exception: # pylint: disable=broad-except
LOG.exception('Command "%s" failed:', command)