Silly morse code inventory plugin

morse.py

# A super simple morse-code inventory plugin for demonstration and learning
# purposes.
#
# It takes files with lines like this:
# ! -- -.-- ..--.- --. .-. --- ..- .--. // the "my_group" group
# .- -.. -.-. ----- .---- ansible_user=nonroot // and some comment here

from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

from ansible.inventory.group import to_safe_group_name
from ansible.plugins.inventory import BaseFileInventoryPlugin
from ansible.module_utils._text import to_bytes, to_text
import itertools

morse = {
    ".-": "a", "-...": "b", "-.-.": "c", "-..": "d", ".": "e", "..-.": "f",
    "--.": "g", "....": "h", "..": "i", ".---": "j", "-.-": "k", ".-..": "l",
    "--": "m", "-.": "n", "---": "o", ".--.": "p", "--.-": "q", ".-.": "r",
    "...": "s", "-": "t", "..-": "u", "...-": "v", ".--": "w", "-..-": "x",
    "-.--": "y", "--..": "z",
    ".-.-.-": ".", "..--.-": "_", "-....-": "-",
    "-----": "0", ".----": "1", "..---": "2", "...--": "3", "....-": "4",
    ".....": "5", "-....": "6", "--...": "7", "---..": "8", "----.": "9",
}

def decode_morse(morse_str):
    return ''.join(morse[s] for s in morse_str.split())

class InventoryModule(BaseFileInventoryPlugin):
    """
    Takes a morse code inventory file and builds a list of hosts and groups.
    Subgroups, caching, and host patterns are left as an exercise to the very
    bored or very curious reader.
    """
    NAME = 'morse'

    def parse(self, inventory, loader, path, cache=True):
        """
        Figure out if the line is introducing a group, a host, or a comment,
        then if necessary add it to the InventoryData.
        """

        super(InventoryModule, self).parse(inventory, loader, path)

        # We assume there is a DataLoader
        (data, private) = self.loader._get_file_contents(path)
        data = to_text(data)
        lines = data.splitlines()

        # Default group if we're only given a list of hosts
        groupname = 'ungrouped'
        for line in lines:
            # Strip comments
            line = line.strip().split('//', 1)[0]

            # If it's a comment line, ignore it and move on.
            if not line:
                continue

            # If it starts with !, it's a group.
            if line.startswith('!'):
                groupname = to_safe_group_name(decode_morse(line[1:].strip()))
                self.inventory.add_group(groupname)
                continue

            # Otherwise it's a host.
            # Yes, there are more efficient ways to do this.
            host = itertools.takewhile(lambda x: x in ('-', '.', ' '), line)
            host = decode_morse(''.join(host))
            vrs = itertools.dropwhile(lambda x: x in ('-', '.', ' '), line)
            vrs = ''.join(vrs).split()
            vrs_hash = {}
            for var in vrs:
                (k, v) = var.split('=', 1)
                # See how the built-in 'ini' inventory plugin uses 'ast' for an
                # example of how to coerce values into Python types. Here we
                # just keep strings.
                vrs_hash[k] = v
            self._populate_host_vars([host], vrs_hash, groupname)