Source code for evennia.commands.cmdset

"""

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