"""
Command handler
This module contains the infrastructure for accepting commands on the
command line. The processing of a command works as follows:
1. The calling object (caller) is analyzed based on its callertype.
2. Cmdsets are gathered from different sources:
- object cmdsets: all objects at caller's location are scanned for non-empty
cmdsets. This includes cmdsets on exits.
- caller: the caller is searched for its own currently active cmdset.
- account: lastly the cmdsets defined on caller.account are added.
3. The collected cmdsets are merged together to a combined, current cmdset.
4. If the input string is empty -> check for CMD_NOINPUT command in
current cmdset or fallback to error message. Exit.
5. The Command Parser is triggered, using the current cmdset to analyze the
input string for possible command matches.
6. If multiple matches are found -> check for CMD_MULTIMATCH in current
cmdset, or fallback to error message. Exit.
7. If no match was found -> check for CMD_NOMATCH in current cmdset or
fallback to error message. Exit.
8. At this point we have found a normal command. We assign useful variables to it that
will be available to the command coder at run-time.
9. We have a unique cmdobject, primed for use. Call all hooks:
`at_pre_cmd()`, `cmdobj.parse()`, `cmdobj.func()` and finally `at_post_cmd()`.
10. Return deferred that will fire with the return from `cmdobj.func()` (unused by default).
"""
import types
from collections import defaultdict
from copy import copy
from itertools import chain
from traceback import format_exc
from weakref import WeakValueDictionary
from django.conf import settings
from django.utils.translation import gettext as _
from twisted.internet import reactor
from twisted.internet.defer import inlineCallbacks, returnValue
from twisted.internet.task import deferLater
from evennia.commands.command import InterruptCommand
from evennia.utils import logger, utils
from evennia.utils.utils import string_suggestions
_IN_GAME_ERRORS = settings.IN_GAME_ERRORS
__all__ = ("cmdhandler", "InterruptCommand")
_GA = object.__getattribute__
_CMDSET_MERGE_CACHE = WeakValueDictionary()
# tracks recursive calls by each caller
# to avoid infinite loops (commands calling themselves)
_COMMAND_NESTING = defaultdict(lambda: 0)
_COMMAND_RECURSION_LIMIT = 10
# This decides which command parser is to be used.
# You have to restart the server for changes to take effect.
_COMMAND_PARSER = utils.variable_from_module(*settings.COMMAND_PARSER.rsplit(".", 1))
# System command names - import these variables rather than trying to
# remember the actual string constants. If not defined, Evennia
# hard-coded defaults are used instead.
# command to call if user just presses <return> with no input
CMD_NOINPUT = "__noinput_command"
# command to call if no command match was found
CMD_NOMATCH = "__nomatch_command"
# command to call if multiple command matches were found
CMD_MULTIMATCH = "__multimatch_command"
# command to call as the very first one when the user connects.
# (is expected to display the login screen)
CMD_LOGINSTART = "__unloggedin_look_command"
# Function for handling multiple command matches.
_SEARCH_AT_RESULT = utils.variable_from_module(*settings.SEARCH_AT_RESULT.rsplit(".", 1))
# Output strings. The first is the IN_GAME_ERRORS return, the second
# is the normal "production message to echo to the account.
_ERROR_UNTRAPPED = (
_(
"""
An untrapped error occurred.
"""
),
_(
"""
An untrapped error occurred. Please file a bug report detailing the steps to reproduce.
"""
),
)
_ERROR_CMDSETS = (
_(
"""
A cmdset merger-error occurred. This is often due to a syntax
error in one of the cmdsets to merge.
"""
),
_(
"""
A cmdset merger-error occurred. Please file a bug report detailing the
steps to reproduce.
"""
),
)
_ERROR_NOCMDSETS = (
_(
"""
No command sets found! This is a critical bug that can have
multiple causes.
"""
),
_(
"""
No command sets found! This is a sign of a critical bug. If
disconnecting/reconnecting doesn't" solve the problem, try to contact
the server admin through" some other means for assistance.
"""
),
)
_ERROR_CMDHANDLER = (
_(
"""
A command handler bug occurred. If this is not due to a local change,
please file a bug report with the Evennia project, including the
traceback and steps to reproduce.
"""
),
_(
"""
A command handler bug occurred. Please notify staff - they should
likely file a bug report with the Evennia project.
"""
),
)
_ERROR_RECURSION_LIMIT = _(
"Command recursion limit ({recursion_limit}) reached for '{raw_cmdname}' ({cmdclass})."
)
# delayed imports
_GET_INPUT = None
# helper functions
def _msg_err(receiver, stringtuple):
"""
Helper function for returning an error to the caller.
Args:
receiver (Object): object to get the error message.
stringtuple (tuple): tuple with two strings - one for the
_IN_GAME_ERRORS mode (with the traceback) and one with the
production string (with a timestamp) to be shown to the user.
"""
string = _("{traceback}\n{errmsg}\n(Traceback was logged {timestamp}).")
timestamp = logger.timeformat()
tracestring = format_exc()
logger.log_trace()
if _IN_GAME_ERRORS:
receiver.msg(
string.format(
traceback=tracestring, errmsg=stringtuple[0].strip(), timestamp=timestamp
).strip()
)
else:
receiver.msg(
string.format(
traceback=tracestring.splitlines()[-1],
errmsg=stringtuple[1].strip(),
timestamp=timestamp,
).strip()
)
def _process_input(caller, prompt, result, cmd, generator):
"""
Specifically handle the get_input value to send to _progressive_cmd_run as
part of yielding from a Command's `func`.
Args:
caller (Character, Account or Session): the caller.
prompt (str): The sent prompt.
result (str): The unprocessed answer.
cmd (Command): The command itself.
generator (GeneratorType): The generator.
Returns:
result (bool): Always `False` (stop processing).
"""
# We call it using a Twisted deferLater to make sure the input is properly closed.
deferLater(reactor, 0, _progressive_cmd_run, cmd, generator, response=result)
return False
def _progressive_cmd_run(cmd, generator, response=None):
"""
Progressively call the command that was given in argument. Used
when `yield` is present in the Command's `func()` method.
Args:
cmd (Command): the command itself.
generator (GeneratorType): the generator describing the processing.
reponse (str, optional): the response to send to the generator.
Raises:
ValueError: If the func call yields something not identifiable as a
time-delay or a string prompt.
Note:
This function is responsible for executing the command, if
the func() method contains 'yield' instructions. The yielded
value will be accessible at each step and will affect the
process. If the value is a number, just delay the execution
of the command. If it's a string, wait for the user input.
"""
global _GET_INPUT
if not _GET_INPUT:
from evennia.utils.evmenu import get_input as _GET_INPUT
try:
if response is None:
value = next(generator)
else:
value = generator.send(response)
except StopIteration:
# duplicated from cmdhandler._run_command, to have these
# run in the right order while staying inside the deferred
cmd.at_post_cmd()
if cmd.save_for_next:
# store a reference to this command, possibly
# accessible by the next command.
cmd.caller.ndb.last_cmd = copy(cmd)
else:
cmd.caller.ndb.last_cmd = None
else:
if isinstance(value, (int, float)):
utils.delay(value, _progressive_cmd_run, cmd, generator)
elif isinstance(value, str):
_GET_INPUT(cmd.caller, value, _process_input, cmd=cmd, generator=generator)
else:
raise ValueError("unknown type for a yielded value in command: {}".format(type(value)))
# custom Exceptions
class NoCmdSets(Exception):
"No cmdsets found. Critical error."
pass
class ExecSystemCommand(Exception):
"Run a system command"
def __init__(self, syscmd, sysarg):
self.args = (syscmd, sysarg) # needed by exception error handling
self.syscmd = syscmd
self.sysarg = sysarg
class ErrorReported(Exception):
"Re-raised when a subsructure already reported the error"
def __init__(self, raw_string):
self.args = (raw_string,)
self.raw_string = raw_string
# Helper function
@inlineCallbacks
def get_and_merge_cmdsets(caller, session, account, obj, callertype, raw_string):
"""
Gather all relevant cmdsets and merge them.
Args:
caller (Session, Account or Object): The entity executing the command. Which
type of object this is depends on the current game state; for example
when the user is not logged in, this will be a Session, when being OOC
it will be an Account and when puppeting an object this will (often) be
a Character Object. In the end it depends on where the cmdset is stored.
session (Session or None): The Session associated with caller, if any.
account (Account or None): The calling Account associated with caller, if any.
obj (Object or None): The Object associated with caller, if any.
callertype (str): This identifies caller as either "account", "object" or "session"
to avoid having to do this check internally.
raw_string (str): The input string. This is only used for error reporting.
Returns:
cmdset (Deferred): This deferred fires with the merged cmdset
result once merger finishes.
Notes:
The cdmsets are merged in order or generality, so that the
Object's cmdset is merged last (and will thus take precedence
over same-named and same-prio commands on Account and Session).
"""
try:
@inlineCallbacks
def _get_local_obj_cmdsets(obj):
"""
Helper-method; Get Object-level cmdsets
"""
# Gather cmdsets from location, objects in location or carried
try:
local_obj_cmdsets = [None]
try:
location = obj.location
except Exception:
location = None
if location:
# Gather all cmdsets stored on objects in the room and
# also in the caller's inventory and the location itself
local_objlist = yield (
location.contents_get(exclude=obj) + obj.contents_get() + [location]
)
local_objlist = [o for o in local_objlist if not o._is_deleted]
for lobj in local_objlist:
try:
# call hook in case we need to do dynamic changing to cmdset
_GA(lobj, "at_cmdset_get")(caller=caller)
except Exception:
logger.log_trace()
# the call-type lock is checked here, it makes sure an account
# is not seeing e.g. the commands on a fellow account (which is why
# the no_superuser_bypass must be True)
local_obj_cmdsets = yield list(
chain.from_iterable(
lobj.cmdset.cmdset_stack
for lobj in local_objlist
if (
lobj.cmdset.current
and lobj.access(
caller, access_type="call", no_superuser_bypass=True
)
)
)
)
for cset in local_obj_cmdsets:
# This is necessary for object sets, or we won't be able to
# separate the command sets from each other in a busy room. We
# only keep the setting if duplicates were set to False/True
# explicitly.
cset.old_duplicates = cset.duplicates
cset.duplicates = True if cset.duplicates is None else cset.duplicates
returnValue(local_obj_cmdsets)
except Exception:
_msg_err(caller, _ERROR_CMDSETS)
raise ErrorReported(raw_string)
@inlineCallbacks
def _get_cmdsets(obj):
"""
Helper method; Get cmdset while making sure to trigger all
hooks safely. Returns the stack and the valid options.
"""
try:
yield obj.at_cmdset_get()
except Exception:
_msg_err(caller, _ERROR_CMDSETS)
raise ErrorReported(raw_string)
try:
returnValue((obj.cmdset.current, list(obj.cmdset.cmdset_stack)))
except AttributeError:
returnValue(((None, None, None), []))
local_obj_cmdsets = []
if callertype == "session":
# we are calling the command from the session level
report_to = session
current, cmdsets = yield _get_cmdsets(session)
if account: # this automatically implies logged-in
pcurrent, account_cmdsets = yield _get_cmdsets(account)
cmdsets += account_cmdsets
current = current + pcurrent
if obj:
ocurrent, obj_cmdsets = yield _get_cmdsets(obj)
current = current + ocurrent
cmdsets += obj_cmdsets
if not current.no_objs:
local_obj_cmdsets = yield _get_local_obj_cmdsets(obj)
if current.no_exits:
# filter out all exits
local_obj_cmdsets = [
cmdset for cmdset in local_obj_cmdsets if cmdset.key != "ExitCmdSet"
]
cmdsets += local_obj_cmdsets
elif callertype == "account":
# we are calling the command from the account level
report_to = account
current, cmdsets = yield _get_cmdsets(account)
if obj:
ocurrent, obj_cmdsets = yield _get_cmdsets(obj)
current = current + ocurrent
cmdsets += obj_cmdsets
if not current.no_objs:
local_obj_cmdsets = yield _get_local_obj_cmdsets(obj)
if current.no_exits:
# filter out all exits
local_obj_cmdsets = [
cmdset for cmdset in local_obj_cmdsets if cmdset.key != "ExitCmdSet"
]
cmdsets += local_obj_cmdsets
elif callertype == "object":
# we are calling the command from the object level
report_to = obj
current, cmdsets = yield _get_cmdsets(obj)
if not current.no_objs:
local_obj_cmdsets = yield _get_local_obj_cmdsets(obj)
if current.no_exits:
# filter out all exits
local_obj_cmdsets = [
cmdset for cmdset in local_obj_cmdsets if cmdset.key != "ExitCmdSet"
]
cmdsets += yield local_obj_cmdsets
else:
raise Exception("get_and_merge_cmdsets: callertype %s is not valid." % callertype)
# weed out all non-found sets
cmdsets = yield [cmdset for cmdset in cmdsets if cmdset and cmdset.key != "_EMPTY_CMDSET"]
# report cmdset errors to user (these should already have been logged)
yield [
report_to.msg(cmdset.errmessage) for cmdset in cmdsets if cmdset.key == "_CMDSET_ERROR"
]
if cmdsets:
# faster to do tuple on list than to build tuple directly
mergehash = tuple([id(cmdset) for cmdset in cmdsets])
if mergehash in _CMDSET_MERGE_CACHE:
# cached merge exist; use that
cmdset = _CMDSET_MERGE_CACHE[mergehash]
else:
# we group and merge all same-prio cmdsets separately (this avoids
# order-dependent clashes in certain cases, such as
# when duplicates=True)
tempmergers = {}
for cmdset in cmdsets:
prio = cmdset.priority
if prio in tempmergers:
# merge same-prio cmdset together separately
tempmergers[prio] = yield tempmergers[prio] + cmdset
else:
tempmergers[prio] = cmdset
# sort cmdsets after reverse priority (highest prio are merged in last)
sorted_cmdsets = yield sorted(list(tempmergers.values()), key=lambda x: x.priority)
# Merge all command sets into one, beginning with the lowest-prio one
cmdset = sorted_cmdsets[0]
for merging_cmdset in sorted_cmdsets[1:]:
cmdset = yield cmdset + merging_cmdset
# store the original, ungrouped set for diagnosis
cmdset.merged_from = cmdsets
# cache
_CMDSET_MERGE_CACHE[mergehash] = cmdset
else:
cmdset = None
for cset in (cset for cset in local_obj_cmdsets if cset):
cset.duplicates = cset.old_duplicates
# important - this syncs the CmdSetHandler's .current field with the
# true current cmdset!
# TODO - removed because this causes cmdset overlaps across sessions/accounts
# - see https://github.com/evennia/evennia/issues/2855
# if cmdset:
# caller.cmdset.current = cmdset
returnValue(cmdset)
except ErrorReported:
raise
except Exception:
_msg_err(caller, _ERROR_CMDSETS)
raise
# raise ErrorReported
# Main command-handler function
[docs]@inlineCallbacks
def cmdhandler(
called_by,
raw_string,
_testing=False,
callertype="session",
session=None,
cmdobj=None,
cmdobj_key=None,
**kwargs,
):
"""
This is the main mechanism that handles any string sent to the engine.
Args:
called_by (Session, Account or Object): Object from which this
command was called. which this was called from. What this is
depends on the game state.
raw_string (str): The command string as given on the command line.
_testing (bool, optional): Used for debug purposes and decides if we
should actually execute the command or not. If True, the
command instance will be returned.
callertype (str, optional): One of "session", "account" or
"object". These are treated in decending order, so when the
Session is the caller, it will merge its own cmdset into
cmdsets from both Account and eventual puppeted Object (and
cmdsets in its room etc). An Account will only include its own
cmdset and the Objects and so on. Merge order is the same
order, so that Object cmdsets are merged in last, giving them
precendence for same-name and same-prio commands.
session (Session, optional): Relevant if callertype is "account" - the session will help
retrieve the correct cmdsets from puppeted objects.
cmdobj (Command, optional): If given a command instance, this will be executed using
`called_by` as the caller, `raw_string` representing its arguments and (optionally)
`cmdobj_key` as its input command name. No cmdset lookup will be performed but
all other options apply as normal. This allows for running a specific Command
within the command system mechanism.
cmdobj_key (string, optional): Used together with `cmdobj` keyword to specify
which cmdname should be assigned when calling the specified Command instance. This
is made available as `self.cmdstring` when the Command runs.
If not given, the command will be assumed to be called as `cmdobj.key`.
Keyword Args:
kwargs (any): other keyword arguments will be assigned as named variables on the
retrieved command object *before* it is executed. This is unused
in default Evennia but may be used by code to set custom flags or
special operating conditions for a command as it executes.
Returns:
deferred (Deferred): This deferred is fired with the return
value of the command's `func` method. This is not used in
default Evennia.
"""
@inlineCallbacks
def _run_command(cmd, cmdname, args, raw_cmdname, cmdset, session, account):
"""
Helper function: This initializes and runs the Command
instance once the parser has identified it as either a normal
command or one of the system commands.
Args:
cmd (Command): Command object
cmdname (str): Name of command
args (str): extra text entered after the identified command
raw_cmdname (str): Name of Command, unaffected by eventual
prefix-stripping (if no prefix-stripping, this is the same
as cmdname).
cmdset (CmdSet): Command sert the command belongs to (if any)..
session (Session): Session of caller (if any).
account (Account): Account of caller (if any).
Returns:
deferred (Deferred): this will fire with the return of the
command's `func` method.
Raises:
RuntimeError: If command recursion limit was reached.
"""
global _COMMAND_NESTING
try:
# Assign useful variables to the instance
cmd.caller = caller
cmd.cmdname = cmdname
cmd.raw_cmdname = raw_cmdname
cmd.cmdstring = cmdname # deprecated
cmd.args = args
cmd.cmdset = cmdset
cmd.session = session
cmd.account = account
cmd.raw_string = unformatted_raw_string
# cmd.obj # set via on-object cmdset handler for each command,
# since this may be different for every command when
# merging multiple cmdsets
if _testing:
# only return the command instance
returnValue(cmd)
# assign custom kwargs to found cmd object
for key, val in kwargs.items():
setattr(cmd, key, val)
_COMMAND_NESTING[called_by] += 1
if _COMMAND_NESTING[called_by] > _COMMAND_RECURSION_LIMIT:
err = _ERROR_RECURSION_LIMIT.format(
recursion_limit=_COMMAND_RECURSION_LIMIT,
raw_cmdname=raw_cmdname,
cmdclass=cmd.__class__,
)
raise RuntimeError(err)
# pre-command hook
abort = yield cmd.at_pre_cmd()
if abort:
# abort sequence
returnValue(abort)
# Parse and execute
yield cmd.parse()
# main command code
# (return value is normally None)
ret = cmd.func()
if isinstance(ret, types.GeneratorType):
# cmd.func() is a generator, execute progressively
_progressive_cmd_run(cmd, ret)
ret = yield ret
# note that the _progressive_cmd_run will itself run
# the at_post_cmd etc as it finishes; this is a bit of
# code duplication but there seems to be no way to
# catch the StopIteration here (it's not in the same
# frame since this is in a deferred chain)
else:
ret = yield ret
# post-command hook
yield cmd.at_post_cmd()
if cmd.save_for_next:
# store a reference to this command, possibly
# accessible by the next command.
caller.ndb.last_cmd = yield copy(cmd)
else:
caller.ndb.last_cmd = None
# return result to the deferred
returnValue(ret)
except InterruptCommand:
# Do nothing, clean exit
pass
except Exception:
_msg_err(caller, _ERROR_UNTRAPPED)
raise ErrorReported(raw_string)
finally:
_COMMAND_NESTING[called_by] -= 1
session, account, obj = session, None, None
if callertype == "session":
session = called_by
account = session.account
obj = session.puppet
elif callertype == "account":
account = called_by
if session:
obj = yield session.puppet
elif callertype == "object":
obj = called_by
else:
raise RuntimeError("cmdhandler: callertype %s is not valid." % callertype)
# the caller will be the one to receive messages and excert its permissions.
# we assign the caller with preference 'bottom up'
caller = obj or account or session
# The error_to is the default recipient for errors. Tries to make sure an account
# does not get spammed for errors while preserving character mirroring.
error_to = obj or session or account
try: # catch bugs in cmdhandler itself
try: # catch special-type commands
if cmdobj:
# the command object is already given
cmd = cmdobj() if callable(cmdobj) else cmdobj
cmdname = cmdobj_key if cmdobj_key else cmd.key
args = raw_string
unformatted_raw_string = "%s%s" % (cmdname, args)
cmdset = None
raw_cmdname = cmdname
# session = session
# account = account
else:
# no explicit cmdobject given, figure it out
cmdset = yield get_and_merge_cmdsets(
caller, session, account, obj, callertype, raw_string
)
if not cmdset:
# this is bad and shouldn't happen.
raise NoCmdSets
# store the completely unmodified raw string - including
# whitespace and eventual prefixes-to-be-stripped.
unformatted_raw_string = raw_string
raw_string = raw_string.strip()
if not raw_string:
# Empty input. Test for system command instead.
syscmd = yield cmdset.get(CMD_NOINPUT)
sysarg = ""
raise ExecSystemCommand(syscmd, sysarg)
# Parse the input string and match to available cmdset.
# This also checks for permissions, so all commands in match
# are commands the caller is allowed to call.
matches = yield _COMMAND_PARSER(raw_string, cmdset, caller)
# Deal with matches
if len(matches) > 1:
# We have a multiple-match
syscmd = yield cmdset.get(CMD_MULTIMATCH)
sysarg = _("There were multiple matches.")
if syscmd:
# use custom CMD_MULTIMATCH
syscmd.matches = matches
else:
# fall back to default error handling
sysarg = yield _SEARCH_AT_RESULT(
[match[2] for match in matches], caller, query=matches[0][0]
)
raise ExecSystemCommand(syscmd, sysarg)
cmdname, args, cmd, raw_cmdname = "", "", None, ""
if len(matches) == 1:
# We have a unique command match. But it may still be invalid.
match = matches[0]
cmdname, args, cmd, raw_cmdname = (match[0], match[1], match[2], match[5])
if not matches:
# No commands match our entered command
syscmd = yield cmdset.get(CMD_NOMATCH)
if syscmd:
# use custom CMD_NOMATCH command
sysarg = raw_string
else:
# fallback to default error text
sysarg = _("Command '{command}' is not available.").format(
command=raw_string
)
suggestions = string_suggestions(
raw_string,
cmdset.get_all_cmd_keys_and_aliases(caller),
cutoff=0.7,
maxnum=3,
)
if suggestions:
sysarg += _(" Maybe you meant {command}?").format(
command=utils.list_to_string(
suggestions, endsep=_("or"), addquote=True
)
)
else:
sysarg += _(' Type "help" for help.')
raise ExecSystemCommand(syscmd, sysarg)
if not cmd.retain_instance:
# making a copy allows multiple users to share the command also when yield is used
cmd = copy(cmd)
# A normal command.
ret = yield _run_command(cmd, cmdname, args, raw_cmdname, cmdset, session, account)
returnValue(ret)
except ErrorReported as exc:
# this error was already reported, so we
# catch it here and don't pass it on.
logger.log_err("User input was: '%s'." % exc.raw_string)
except ExecSystemCommand as exc:
# Not a normal command: run a system command, if available,
# or fall back to a return string.
syscmd = exc.syscmd
sysarg = exc.sysarg
if syscmd:
ret = yield _run_command(
syscmd, syscmd.key, sysarg, unformatted_raw_string, cmdset, session, account
)
returnValue(ret)
elif sysarg:
# return system arg
error_to.msg(exc.sysarg)
except NoCmdSets:
# Critical error.
logger.log_err("No cmdsets found: %s" % caller)
error_to.msg(_ERROR_NOCMDSETS)
except Exception:
# We should not end up here. If we do, it's a programming bug.
_msg_err(error_to, _ERROR_UNTRAPPED)
except Exception:
# This catches exceptions in cmdhandler exceptions themselves
_msg_err(error_to, _ERROR_CMDHANDLER)
