"""
A Command Set (CmdSet) holds a set of commands. The Cmdsets can be
merged and combined to create new sets of commands in a
non-destructive way. This makes them very powerful for implementing
custom game states where different commands (or different variations
of commands) are available to the accounts depending on circumstance.
The available merge operations are partly borrowed from mathematical
Set theory.
* Union The two command sets are merged so that as many commands as
possible of each cmdset ends up in the merged cmdset. Same-name
commands are merged by priority. This is the most common default.
Ex: A1,A3 + B1,B2,B4,B5 = A1,B2,A3,B4,B5
* Intersect - Only commands found in *both* cmdsets (i.e. which have
same names) end up in the merged cmdset, with the higher-priority
cmdset replacing the lower one. Ex: A1,A3 + B1,B2,B4,B5 = A1
* Replace - The commands of this cmdset completely replaces the
lower-priority cmdset's commands, regardless of if same-name commands
exist. Ex: A1,A3 + B1,B2,B4,B5 = A1,A3
* Remove - This removes the relevant commands from the
lower-priority cmdset completely. They are not replaced with
anything, so this in effects uses the high-priority cmdset as a filter
to affect the low-priority cmdset. Ex: A1,A3 + B1,B2,B4,B5 = B2,B4,B5
"""
from weakref import WeakKeyDictionary
from django.utils.translation import gettext as _
from evennia.utils.utils import inherits_from, is_iter
__all__ = ("CmdSet",)
class _CmdSetMeta(type):
"""
This metaclass makes some minor on-the-fly convenience fixes to
the cmdset class.
"""
def __init__(cls, *args, **kwargs):
"""
Fixes some things in the cmdclass
"""
# by default we key the cmdset the same as the
# name of its class.
if not hasattr(cls, "key") or not cls.key:
cls.key = cls.__name__
cls.path = "%s.%s" % (cls.__module__, cls.__name__)
if not isinstance(cls.key_mergetypes, dict):
cls.key_mergetypes = {}
super().__init__(*args, **kwargs)
[docs]class CmdSet(object, metaclass=_CmdSetMeta):
"""
This class describes a unique cmdset that understands priorities.
CmdSets can be merged and made to perform various set operations
on each other. CmdSets have priorities that affect which of their
ingoing commands gets used.
In the examples, cmdset A always have higher priority than cmdset B.
key - the name of the cmdset. This can be used on its own for game
operations
mergetype (partly from Set theory):
Union - The two command sets are merged so that as many
commands as possible of each cmdset ends up in the
merged cmdset. Same-name commands are merged by
priority. This is the most common default.
Ex: A1,A3 + B1,B2,B4,B5 = A1,B2,A3,B4,B5
Intersect - Only commands found in *both* cmdsets
(i.e. which have same names) end up in the merged
cmdset, with the higher-priority cmdset replacing the
lower one. Ex: A1,A3 + B1,B2,B4,B5 = A1
Replace - The commands of this cmdset completely replaces
the lower-priority cmdset's commands, regardless
of if same-name commands exist.
Ex: A1,A3 + B1,B2,B4,B5 = A1,A3
Remove - This removes the relevant commands from the
lower-priority cmdset completely. They are not
replaced with anything, so this in effects uses the
high-priority cmdset as a filter to affect the
low-priority cmdset.
Ex: A1,A3 + B1,B2,B4,B5 = B2,B4,B5
Note: Commands longer than 2 characters and starting
with double underscrores, like '__noinput_command'
are considered 'system commands' and are
excempt from all merge operations - they are
ALWAYS included across mergers and only affected
if same-named system commands replace them.
priority- All cmdsets are always merged in pairs of two so that
the higher set's mergetype is applied to the
lower-priority cmdset. Default commands have priority 0,
high-priority ones like Exits and Channels have 10 and 9.
Priorities can be negative as well to give default
commands preference.
duplicates - determines what happens when two sets of equal
priority merge (only). Defaults to None and has the first of them in the
merger (i.e. A above) automatically taking
precedence. But if `duplicates` is true, the
result will be a merger with more than one of each
name match. This will usually lead to the account
receiving a multiple-match error higher up the road,
but can be good for things like cmdsets on non-account
objects in a room, to allow the system to warn that
more than one 'ball' in the room has the same 'kick'
command defined on it, so it may offer a chance to
select which ball to kick ... Allowing duplicates
only makes sense for Union and Intersect, the setting
is ignored for the other mergetypes.
Note that the `duplicates` flag is *not* propagated in
a cmdset merger. So `A + B = C` will result in
a cmdset with duplicate commands, but C.duplicates will
be `None`. For duplication to apply to a whole cmdset
stack merge, _all_ cmdsets in the stack must have
`.duplicates=True` set.
Finally, if a final cmdset has `.duplicates=None` (the normal
unless created alone with another value), the cmdhandler
will assume True for object-based cmdsets and False for
all other. This is usually the most intuitive outcome.
key_mergetype (dict) - allows the cmdset to define a unique
mergetype for particular cmdsets. Format is
{CmdSetkeystring:mergetype}. Priorities still apply.
Example: {'Myevilcmdset','Replace'} which would make
sure for this set to always use 'Replace' on
Myevilcmdset no matter what overall mergetype this set
has.
no_objs - don't include any commands from nearby objects
when searching for suitable commands
no_exits - ignore the names of exits when matching against
commands
no_channels - ignore the name of channels when matching against
commands (WARNING- this is dangerous since the
account can then not even ask staff for help if
something goes wrong)
"""
key = "Unnamed CmdSet"
mergetype = "Union"
priority = 0
# These flags, if set to None should be interpreted as 'I don't care' and,
# will allow "pass-through" even of lower-prio cmdsets' explicitly True/False
# options. If this is set to True/False however, priority matters.
no_exits = None
no_objs = None
no_channels = None
# The .duplicates setting does not propagate and since duplicates can only happen
# on same-prio cmdsets, there is no concept of passthrough on `None`.
# The merger of two cmdsets always return in a cmdset with `duplicates=None`
# (even if the result may have duplicated commands).
# If a final cmdset has `duplicates=None` (normal, unless the cmdset is
# created on its own with the flag set), the cmdhandler will auto-assume it to be
# True for Object-based cmdsets and stay None/False for all other entities.
#
# Example:
# A and C has .duplicates=True, B has .duplicates=None (or False)
# B + A = BA, where BA will have duplicate cmds, but BA.duplicates = None
# BA + C = BAC, where BAC will have more duplication, but BAC.duplicates = None
#
# Basically, for the `.duplicate` setting to survive throughout a
# merge-stack, every cmdset in the stack must have `duplicates` set explicitly.
duplicates = None
persistent = False
key_mergetypes = {}
errmessage = ""
# pre-store properties to duplicate straight off
to_duplicate = (
"key",
"cmdsetobj",
"no_exits",
"no_objs",
"no_channels",
"persistent",
"mergetype",
"priority",
"duplicates",
"errmessage",
)
[docs] def __init__(self, cmdsetobj=None, key=None):
"""
Creates a new CmdSet instance.
Args:
cmdsetobj (Session, Account, Object, optional): This is the database object
to which this particular instance of cmdset is related. It
is often a character but may also be a regular object, Account
or Session.
key (str, optional): The idenfier for this cmdset. This
helps if wanting to selectively remov cmdsets.
"""
if key:
self.key = key
self.commands = []
self.system_commands = []
self.actual_mergetype = self.mergetype
self.cmdsetobj = cmdsetobj
# this is set only on merged sets, in cmdhandler.py, in order to
# track, list and debug mergers correctly.
self.merged_from = []
# initialize system
self.at_cmdset_creation()
self._contains_cache = WeakKeyDictionary() # {}
# Priority-sensitive merge operations for cmdsets
def _union(self, cmdset_a, cmdset_b):
"""
Merge two sets using union merger
Args:
cmdset_a (Cmdset): Cmdset given higher priority in the case of a tie.
cmdset_b (Cmdset): Cmdset given lower priority in the case of a tie.
Returns:
cmdset_c (Cmdset): The result of A U B operation.
Notes:
Union, C = A U B, means that C gets all elements from both A and B.
"""
cmdset_c = cmdset_a._duplicate()
# we make copies, not refs by use of [:]
cmdset_c.commands = cmdset_a.commands[:]
if cmdset_a.duplicates and cmdset_a.priority == cmdset_b.priority:
cmdset_c.commands.extend(cmdset_b.commands)
else:
cmdset_c.commands.extend([cmd for cmd in cmdset_b if cmd not in cmdset_a])
return cmdset_c
def _intersect(self, cmdset_a, cmdset_b):
"""
Merge two sets using intersection merger
Args:
cmdset_a (Cmdset): Cmdset given higher priority in the case of a tie.
cmdset_b (Cmdset): Cmdset given lower priority in the case of a tie.
Returns:
cmdset_c (Cmdset): The result of A (intersect) B operation.
Notes:
Intersection, C = A (intersect) B, means that C only gets the
parts of A and B that are the same (that is, the commands
of each set having the same name. Only the one of these
having the higher prio ends up in C).
"""
cmdset_c = cmdset_a._duplicate()
if cmdset_a.duplicates and cmdset_a.priority == cmdset_b.priority:
for cmd in [cmd for cmd in cmdset_a if cmd in cmdset_b]:
cmdset_c.add(cmd)
cmdset_c.add(cmdset_b.get(cmd))
else:
cmdset_c.commands = [cmd for cmd in cmdset_a if cmd in cmdset_b]
return cmdset_c
def _replace(self, cmdset_a, cmdset_b):
"""
Replace the contents of one set with another
Args:
cmdset_a (Cmdset): Cmdset replacing
cmdset_b (Cmdset): Cmdset to replace
Returns:
cmdset_c (Cmdset): This is indentical to cmdset_a.
Notes:
C = A, where B is ignored.
"""
cmdset_c = cmdset_a._duplicate()
cmdset_c.commands = cmdset_a.commands[:]
return cmdset_c
def _remove(self, cmdset_a, cmdset_b):
"""
Filter a set by another.
Args:
cmdset_a (Cmdset): Cmdset acting as a removal filter.
cmdset_b (Cmdset): Cmdset to filter
Returns:
cmdset_c (Cmdset): B, with all matching commands from A removed.
Notes:
C = B - A, where A is used to remove the commands of B.
"""
cmdset_c = cmdset_a._duplicate()
cmdset_c.commands = [cmd for cmd in cmdset_b if cmd not in cmdset_a]
return cmdset_c
def _instantiate(self, cmd):
"""
checks so that object is an instantiated command and not, say
a cmdclass. If it is, instantiate it. Other types, like
strings, are passed through.
Args:
cmd (any): Entity to analyze.
Returns:
result (any): An instantiated Command or the input unmodified.
"""
if callable(cmd):
return cmd()
else:
return cmd
def _duplicate(self):
"""
Returns a new cmdset with the same settings as this one (no
actual commands are copied over)
Returns:
cmdset (Cmdset): A copy of the current cmdset.
"""
cmdset = CmdSet()
for key, val in ((key, getattr(self, key)) for key in self.to_duplicate):
if val != getattr(cmdset, key):
# only copy if different from default; avoid turning
# class-vars into instance vars
setattr(cmdset, key, val)
cmdset.key_mergetypes = self.key_mergetypes.copy()
return cmdset
def __str__(self):
"""
Show all commands in cmdset when printing it.
Returns:
commands (str): Representation of commands in Cmdset.
"""
perm = "perm" if self.persistent else "non-perm"
options = ", ".join(
[
"{}:{}".format(opt, "T" if getattr(self, opt) else "F")
for opt in ("no_exits", "no_objs", "no_channels", "duplicates")
if getattr(self, opt) is not None
]
)
options = (", " + options) if options else ""
return (
f"<CmdSet {self.key}, {self.mergetype}, {perm}, prio {self.priority}{options}>: "
+ ", ".join([str(cmd) for cmd in sorted(self.commands, key=lambda o: o.key)])
)
def __iter__(self):
"""
Allows for things like 'for cmd in cmdset':
Returns:
iterable (iter): Commands in Cmdset.
"""
return iter(self.commands)
def __contains__(self, othercmd):
"""
Returns True if this cmdset contains the given command (as
defined by command name and aliases). This allows for things
like 'if cmd in cmdset'
"""
ret = self._contains_cache.get(othercmd)
if ret is None:
ret = othercmd in self.commands
self._contains_cache[othercmd] = ret
return ret
def __add__(self, cmdset_a):
"""
Merge this cmdset (B) with another cmdset (A) using the + operator,
C = B + A
Here, we (by convention) say that 'A is merged onto B to form
C'. The actual merge operation used in the 'addition' depends
on which priorities A and B have. The one of the two with the
highest priority will apply and give its properties to C. In
the case of a tie, A takes priority and replaces the
same-named commands in B unless A has the 'duplicate' variable
set (which means both sets' commands are kept).
"""
# It's okay to merge with None
if not cmdset_a:
return self
sys_commands_a = cmdset_a.get_system_cmds()
sys_commands_b = self.get_system_cmds()
if self.priority <= cmdset_a.priority:
# A higher or equal priority to B
# preserve system __commands
sys_commands = sys_commands_a + [
cmd for cmd in sys_commands_b if cmd not in sys_commands_a
]
mergetype = cmdset_a.key_mergetypes.get(self.key, cmdset_a.mergetype)
if mergetype == "Intersect":
cmdset_c = self._intersect(cmdset_a, self)
elif mergetype == "Replace":
cmdset_c = self._replace(cmdset_a, self)
elif mergetype == "Remove":
cmdset_c = self._remove(cmdset_a, self)
else: # Union
cmdset_c = self._union(cmdset_a, self)
# pass through options whenever they are set, unless the merging or higher-prio
# set changes the setting (i.e. has a non-None value). We don't pass through
# the duplicates setting; that is per-merge; the resulting .duplicates value
# is always None (so merging cmdsets must all have explicit values if wanting
# to cause duplicates).
cmdset_c.no_channels = (
self.no_channels if cmdset_a.no_channels is None else cmdset_a.no_channels
)
cmdset_c.no_exits = self.no_exits if cmdset_a.no_exits is None else cmdset_a.no_exits
cmdset_c.no_objs = self.no_objs if cmdset_a.no_objs is None else cmdset_a.no_objs
cmdset_c.duplicates = None
else:
# B higher priority than A
# preserver system __commands
sys_commands = sys_commands_b + [
cmd for cmd in sys_commands_a if cmd not in sys_commands_b
]
mergetype = self.key_mergetypes.get(cmdset_a.key, self.mergetype)
if mergetype == "Intersect":
cmdset_c = self._intersect(self, cmdset_a)
elif mergetype == "Replace":
cmdset_c = self._replace(self, cmdset_a)
elif mergetype == "Remove":
cmdset_c = self._remove(self, cmdset_a)
else: # Union
cmdset_c = self._union(self, cmdset_a)
# pass through options whenever they are set, unless the higher-prio
# set changes the setting (i.e. has a non-None value). We don't pass through
# the duplicates setting; that is per-merge; the resulting .duplicates value#
# is always None (so merging cmdsets must all have explicit values if wanting
# to cause duplicates).
cmdset_c.no_channels = (
cmdset_a.no_channels if self.no_channels is None else self.no_channels
)
cmdset_c.no_exits = cmdset_a.no_exits if self.no_exits is None else self.no_exits
cmdset_c.no_objs = cmdset_a.no_objs if self.no_objs is None else self.no_objs
cmdset_c.duplicates = None
# we store actual_mergetype since key_mergetypes
# might be different from the main mergetype.
# This is used for diagnosis.
cmdset_c.actual_mergetype = mergetype
# print "__add__ for %s (prio %i) called with %s (prio %i)." % (self.key, self.priority,
# cmdset_a.key, cmdset_a.priority)
# return the system commands to the cmdset
cmdset_c.add(sys_commands, allow_duplicates=True)
return cmdset_c
[docs] def add(self, cmd, allow_duplicates=False):
"""
Add a new command or commands to this CmdSet, a list of
commands or a cmdset to this cmdset. Note that this is *not*
a merge operation (that is handled by the + operator).
Args:
cmd (Command, list, Cmdset): This allows for adding one or
more commands to this Cmdset in one go. If another Cmdset
is given, all its commands will be added.
allow_duplicates (bool, optional): If set, will not try to remove
duplicate cmds in the set. This is needed during the merge process
to avoid wiping commands coming from cmdsets with duplicate=True.
Notes:
If cmd already exists in set, it will replace the old one
(no priority checking etc happens here). This is very useful
when overloading default commands).
If cmd is another cmdset class or -instance, the commands of
that command set is added to this one, as if they were part of
the original cmdset definition. No merging or priority checks
are made, rather later added commands will simply replace
existing ones to make a unique set.
"""
if inherits_from(cmd, "evennia.commands.cmdset.CmdSet"):
# cmd is a command set so merge all commands in that set
# to this one. We raise a visible error if we created
# an infinite loop (adding cmdset to itself somehow)
cmdset = cmd
try:
cmdset = self._instantiate(cmdset)
except RuntimeError:
err = (
"Adding cmdset {cmdset} to {cls} lead to an "
"infinite loop. When adding a cmdset to another, "
"make sure they are not themself cyclically added to "
"the new cmdset somewhere in the chain."
)
raise RuntimeError(_(err.format(cmdset=cmdset, cls=self.__class__)))
cmds = cmdset.commands
elif is_iter(cmd):
cmds = [self._instantiate(c) for c in cmd]
else:
cmds = [self._instantiate(cmd)]
commands = self.commands
system_commands = self.system_commands
for cmd in cmds:
# Ensure commands know their source cmdset.
cmd.cmdset_source = self
# add all commands
if not hasattr(cmd, "obj") or cmd.obj is None:
cmd.obj = self.cmdsetobj
# remove duplicates and add new
for _dum in range(commands.count(cmd)):
commands.remove(cmd)
commands.append(cmd)
# add system_command to separate list as well,
# for quick look-up. These have no
if cmd.key.startswith("__"):
# remove same-matches and add new
for _dum in range(system_commands.count(cmd)):
system_commands.remove(cmd)
system_commands.append(cmd)
if not allow_duplicates:
# extra run to make sure to avoid doublets
commands = list(set(commands))
self.commands = commands
[docs] def remove(self, cmd):
"""
Remove a command instance from the cmdset.
Args:
cmd (Command or str): Either the Command object to remove
or the key of such a command.
"""
if isinstance(cmd, str):
_cmd = next((_cmd for _cmd in self.commands if _cmd.key == cmd), None)
if _cmd is None:
if not cmd.startswith("__"):
# if a syscommand, keep the original string and instantiate on it
return None
else:
cmd = _cmd
cmd = self._instantiate(cmd)
if cmd.key.startswith("__"):
try:
ic = self.system_commands.index(cmd)
del self.system_commands[ic]
except ValueError:
# ignore error
pass
else:
self.commands = [oldcmd for oldcmd in self.commands if oldcmd != cmd]
[docs] def get(self, cmd):
"""
Get a command from the cmdset. This is mostly useful to
check if the command is part of this cmdset or not.
Args:
cmd (Command or str): Either the Command object or its key.
Returns:
cmd (Command): The first matching Command in the set.
"""
if isinstance(cmd, str):
_cmd = next((_cmd for _cmd in self.commands if _cmd.key == cmd), None)
if _cmd is None:
if not cmd.startswith("__"):
# if a syscommand, keep the original string and instantiate on it
return None
else:
cmd = _cmd
cmd = self._instantiate(cmd)
for thiscmd in self.commands:
if thiscmd == cmd:
return thiscmd
return None
[docs] def count(self):
"""
Number of commands in set.
Returns:
N (int): Number of commands in this Cmdset.
"""
return len(self.commands)
[docs] def get_system_cmds(self):
"""
Get system commands in cmdset
Returns:
sys_cmds (list): The system commands in the set.
Notes:
As far as the Cmdset is concerned, system commands are any
commands with a key starting with double underscore __.
These are excempt from merge operations.
"""
return self.system_commands
[docs] def make_unique(self, caller):
"""
Remove duplicate command-keys (unsafe)
Args:
caller (object): Commands on this object will
get preference in the duplicate removal.
Notes:
This is an unsafe command meant to clean out a cmdset of
doublet commands after it has been created. It is useful
for commands inheriting cmdsets from the cmdhandler where
obj-based cmdsets always are added double. Doublets will
be weeded out with preference to commands defined on
caller, otherwise just by first-come-first-served.
"""
unique = {}
for cmd in self.commands:
if cmd.key in unique:
ocmd = unique[cmd.key]
if (hasattr(cmd, "obj") and cmd.obj == caller) and not (
hasattr(ocmd, "obj") and ocmd.obj == caller
):
unique[cmd.key] = cmd
else:
unique[cmd.key] = cmd
self.commands = list(unique.values())
[docs] def get_all_cmd_keys_and_aliases(self, caller=None):
"""
Collects keys/aliases from commands
Args:
caller (Object, optional): If set, this is used to check access permissions
on each command. Only commands that pass are returned.
Returns:
names (list): A list of all command keys and aliases in this cmdset. If `caller`
was given, this list will only contain commands to which `caller` passed
the `call` locktype check.
"""
names = []
if caller:
[names.extend(cmd._keyaliases) for cmd in self.commands if cmd.access(caller)]
else:
[names.extend(cmd._keyaliases) for cmd in self.commands]
return names
[docs] def at_cmdset_creation(self):
"""
Hook method - this should be overloaded in the inheriting
class, and should take care of populating the cmdset by use of
self.add().
"""
pass
