rasa/core/trackers.py
import typing
from collections import deque
import copy
import io
import logging
from enum import Enum
from typing import Generator, Dict, Text, Any, Optional, Iterator, Type
from typing import List
from rasa.core import events
from rasa.core.actions.action import ACTION_LISTEN_NAME
from rasa.core.conversation import Dialogue
from rasa.core.events import (
UserUttered, ActionExecuted,
Event, SlotSet, Restarted, ActionReverted, UserUtteranceReverted,
BotUttered, Form)
from rasa.core.slots import Slot
logger = logging.getLogger(__name__)
if typing.TYPE_CHECKING:
from rasa.core.domain import Domain
class EventVerbosity(Enum):
"""Filter on which events to include in tracker dumps."""
# no events will be included
NONE = 1
# all events, that contribute to the trackers state are included
# these are all you need to reconstruct the tracker state
APPLIED = 2
# include even more events, in this case everything that comes
# after the most recent restart event. this will also include
# utterances that got reverted and actions that got undone.
AFTER_RESTART = 3
# include every logged event
ALL = 4
class DialogueStateTracker(object):
"""Maintains the state of a conversation.
The field max_event_history will only give you these last events,
it can be set in the tracker_store"""
@classmethod
def from_dict(cls,
sender_id: Text,
events_as_dict: List[Dict[Text, Any]],
slots: List[Slot],
max_event_history: Optional[int] = None
) -> 'DialogueStateTracker':
"""Create a tracker from dump.
The dump should be an array of dumped events. When restoring
the tracker, these events will be replayed to recreate the state."""
evts = events.deserialise_events(events_as_dict)
return cls.from_events(sender_id, evts, slots, max_event_history)
@classmethod
def from_events(cls,
sender_id: Text,
evts: List[Event],
slots: List[Slot],
max_event_history: Optional[int] = None
):
tracker = cls(sender_id, slots, max_event_history)
for e in evts:
tracker.update(e)
return tracker
def __init__(self, sender_id, slots,
max_event_history=None):
"""Initialize the tracker.
A set of events can be stored externally, and we will run through all
of them to get the current state. The tracker will represent all the
information we captured while processing messages of the dialogue."""
# maximum number of events to store
self._max_event_history = max_event_history
# list of previously seen events
self.events = self._create_events([])
# id of the source of the messages
self.sender_id = sender_id
# slots that can be filled in this domain
self.slots = {slot.name: copy.deepcopy(slot) for slot in slots}
###
# current state of the tracker - MUST be re-creatable by processing
# all the events. This only defines the attributes, values are set in
# `reset()`
###
# if tracker is paused, no actions should be taken
self._paused = False
# A deterministically scheduled action to be executed next
self.followup_action = ACTION_LISTEN_NAME
self.latest_action_name = None
# Stores the most recent message sent by the user
self.latest_message = None
self.latest_bot_utterance = None
self._reset()
self.active_form = {}
###
# Public tracker interface
###
def current_state(self,
event_verbosity: EventVerbosity = EventVerbosity.NONE
) -> Dict[Text, Any]:
"""Return the current tracker state as an object."""
if event_verbosity == EventVerbosity.ALL:
evts = [e.as_dict() for e in self.events]
elif event_verbosity == EventVerbosity.AFTER_RESTART:
evts = [e.as_dict() for e in self.events_after_latest_restart()]
elif event_verbosity == EventVerbosity.APPLIED:
evts = [e.as_dict() for e in self.applied_events()]
else:
evts = None
latest_event_time = None
if len(self.events) > 0:
latest_event_time = self.events[-1].timestamp
return {
"sender_id": self.sender_id,
"slots": self.current_slot_values(),
"latest_message": self.latest_message.parse_data,
"latest_event_time": latest_event_time,
"followup_action": self.followup_action,
"paused": self.is_paused(),
"events": evts,
"latest_input_channel": self.get_latest_input_channel(),
"active_form": self.active_form,
"latest_action_name": self.latest_action_name
}
def past_states(self, domain: 'Domain') -> deque:
"""Generate the past states of this tracker based on the history."""
generated_states = domain.states_for_tracker_history(self)
return deque((frozenset(s.items()) for s in generated_states))
def change_form_to(self, form_name: Text) -> None:
"""Activate or deactivate a form"""
if form_name is not None:
self.active_form = {
'name': form_name,
'validate': True,
'rejected': False,
'trigger_message': self.latest_message.parse_data
}
else:
self.active_form = {}
def set_form_validation(self, validate: bool) -> None:
"""Toggle form validation"""
self.active_form['validate'] = validate
def reject_action(self, action_name: Text) -> None:
"""Notify active form that it was rejected"""
if action_name == self.active_form.get('name'):
self.active_form['rejected'] = True
def set_latest_action_name(self, action_name: Text) -> None:
"""Set latest action name
and reset form validation and rejection parameters
"""
self.latest_action_name = action_name
if self.active_form.get('name'):
# reset form validation if some form is active
self.active_form['validate'] = True
if action_name == self.active_form.get('name'):
# reset form rejection if it was predicted again
self.active_form['rejected'] = False
def current_slot_values(self):
# type: () -> Dict[Text, Any]
"""Return the currently set values of the slots"""
return {key: slot.value for key, slot in self.slots.items()}
def get_slot(self, key: Text) -> Optional[Any]:
"""Retrieves the value of a slot."""
if key in self.slots:
return self.slots[key].value
else:
logger.info("Tried to access non existent slot '{}'".format(key))
return None
def get_latest_entity_values(self, entity_type: Text) -> Iterator[Text]:
"""Get entity values found for the passed entity name in latest msg.
If you are only interested in the first entity of a given type use
`next(tracker.get_latest_entity_values("my_entity_name"), None)`.
If no entity is found `None` is the default result."""
return (x.get("value")
for x in self.latest_message.entities
if x.get("entity") == entity_type)
def get_latest_input_channel(self) -> Optional[Text]:
"""Get the name of the input_channel of the latest UserUttered event"""
for e in reversed(self.events):
if isinstance(e, UserUttered):
return e.input_channel
def is_paused(self) -> bool:
"""State whether the tracker is currently paused."""
return self._paused
def idx_after_latest_restart(self):
# type: () -> int
"""Return the idx of the most recent restart in the list of events.
If the conversation has not been restarted, ``0`` is returned."""
idx = 0
for i, event in enumerate(self.events):
if isinstance(event, Restarted):
idx = i + 1
return idx
def events_after_latest_restart(self):
# type: () -> List[Event]
"""Return a list of events after the most recent restart."""
return list(self.events)[self.idx_after_latest_restart():]
def init_copy(self):
# type: () -> DialogueStateTracker
"""Creates a new state tracker with the same initial values."""
from rasa.core.channels import UserMessage
return DialogueStateTracker(UserMessage.DEFAULT_SENDER_ID,
self.slots.values(),
self._max_event_history)
def generate_all_prior_trackers(self):
# type: () -> Generator[DialogueStateTracker, None, None]
"""Returns a generator of the previous trackers of this tracker.
The resulting array is representing
the trackers before each action."""
tracker = self.init_copy()
ignored_trackers = []
latest_message = tracker.latest_message
for i, event in enumerate(self.applied_events()):
if isinstance(event, UserUttered):
if tracker.active_form.get('name') is None:
# store latest user message before the form
latest_message = event
elif isinstance(event, Form):
# form got either activated or deactivated, so override
# tracker's latest message
tracker.latest_message = latest_message
elif isinstance(event, ActionExecuted):
# yields the intermediate state
if tracker.active_form.get('name') is None:
yield tracker
elif tracker.active_form.get('rejected'):
for tr in ignored_trackers:
yield tr
ignored_trackers = []
if (not tracker.active_form.get('validate') or
event.action_name !=
tracker.active_form.get('name')):
# persist latest user message
# that was rejected by the form
latest_message = tracker.latest_message
else:
# form was called with validation, so
# override tracker's latest message
tracker.latest_message = latest_message
yield tracker
elif event.action_name != tracker.active_form.get('name'):
# it is not known whether the form will be
# successfully executed, so store this tracker for later
tr = tracker.copy()
# form was called with validation, so
# override tracker's latest message
tr.latest_message = latest_message
ignored_trackers.append(tr)
if event.action_name == tracker.active_form.get('name'):
# the form was successfully executed, so
# remove all stored trackers
ignored_trackers = []
tracker.update(event)
# yields the final state
if tracker.active_form.get('name') is None:
yield tracker
elif tracker.active_form.get('rejected'):
for tr in ignored_trackers:
yield tr
yield tracker
def applied_events(self) -> List[Event]:
"""Returns all actions that should be applied - w/o reverted events."""
def undo_till_previous(event_type, done_events):
"""Removes events from `done_events` until `event_type` is
found."""
# list gets modified - hence we need to copy events!
for e in reversed(done_events[:]):
del done_events[-1]
if isinstance(e, event_type):
break
applied_events = []
for event in self.events:
if isinstance(event, Restarted):
applied_events = []
elif isinstance(event, ActionReverted):
undo_till_previous(ActionExecuted, applied_events)
elif isinstance(event, UserUtteranceReverted):
# Seeing a user uttered event automatically implies there was
# a listen event right before it, so we'll first rewind the
# user utterance, then get the action right before it (the
# listen action).
undo_till_previous(UserUttered, applied_events)
undo_till_previous(ActionExecuted, applied_events)
else:
applied_events.append(event)
return applied_events
def replay_events(self):
# type: () -> None
"""Update the tracker based on a list of events."""
applied_events = self.applied_events()
for event in applied_events:
event.apply_to(self)
def recreate_from_dialogue(self, dialogue: Dialogue) -> None:
"""Use a serialised `Dialogue` to update the trackers state.
This uses the state as is persisted in a ``TrackerStore``. If the
tracker is blank before calling this method, the final state will be
identical to the tracker from which the dialogue was created."""
if not isinstance(dialogue, Dialogue):
raise ValueError("story {0} is not of type Dialogue. "
"Have you deserialized it?".format(dialogue))
self._reset()
self.events.extend(dialogue.events)
self.replay_events()
def copy(self):
"""Creates a duplicate of this tracker"""
return self.travel_back_in_time(float("inf"))
def travel_back_in_time(self,
target_time: float) -> 'DialogueStateTracker':
"""Creates a new tracker with a state at a specific timestamp.
A new tracker will be created and all events previous to the
passed time stamp will be replayed. Events that occur exactly
at the target time will be included."""
tracker = self.init_copy()
for event in self.events:
if event.timestamp <= target_time:
tracker.update(event)
else:
break
return tracker # yields the final state
def as_dialogue(self):
# type: () -> Dialogue
"""Return a ``Dialogue`` object containing all of the turns.
This can be serialised and later used to recover the state
of this tracker exactly."""
return Dialogue(self.sender_id, list(self.events))
def update(self, event: Event) -> None:
"""Modify the state of the tracker according to an ``Event``. """
if not isinstance(event, Event): # pragma: no cover
raise ValueError("event to log must be an instance "
"of a subclass of Event.")
self.events.append(event)
event.apply_to(self)
def export_stories(self, e2e=False) -> Text:
"""Dump the tracker as a story in the Rasa Core story format.
Returns the dumped tracker as a string."""
from rasa.core.training.structures import Story
story = Story.from_events(self.applied_events(), self.sender_id)
return story.as_story_string(flat=True, e2e=e2e)
def export_stories_to_file(self, export_path: Text = "debug.md") -> None:
"""Dump the tracker as a story to a file."""
with open(export_path, 'a', encoding="utf-8") as f:
f.write(self.export_stories() + "\n")
def get_last_event_for(self,
event_type: Type[Event],
action_names_to_exclude: List[Text] = None,
skip: int = 0) -> Optional[Event]:
"""Gets the last event of a given type which was actually applied.
Args:
event_type: The type of event you want to find.
action_names_to_exclude: Events of type `ActionExecuted` which
should be excluded from the results. Can be used to skip
`action_listen` events.
skip: Skips n possible results before return an event.
Returns:
event which matched the query or `None` if no event matched.
"""
to_exclude = action_names_to_exclude or []
def filter_function(e: Event):
has_instance = isinstance(e, event_type)
excluded = (isinstance(e, ActionExecuted) and
e.action_name in to_exclude)
return has_instance and not excluded
filtered = filter(filter_function, reversed(self.applied_events()))
for i in range(skip):
next(filtered, None)
return next(filtered, None)
def last_executed_action_has(self, name: Text, skip=0) -> bool:
"""Returns whether last `ActionExecuted` event had a specific name.
Args:
name: Name of the event which should be matched.
skip: Skips n possible results in between.
Returns:
`True` if last executed action had name `name`, otherwise `False`.
"""
last = self.get_last_event_for(ActionExecuted,
action_names_to_exclude=[
ACTION_LISTEN_NAME],
skip=skip)
return last is not None and last.action_name == name
###
# Internal methods for the modification of the trackers state. Should
# only be called by events, not directly. Rather update the tracker
# with an event that in its ``apply_to`` method modifies the tracker.
###
def _reset(self):
# type: () -> None
"""Reset tracker to initial state - doesn't delete events though!."""
self._reset_slots()
self._paused = False
self.latest_action_name = None
self.latest_message = UserUttered.empty()
self.latest_bot_utterance = BotUttered.empty()
self.followup_action = ACTION_LISTEN_NAME
self.active_form = {}
def _reset_slots(self):
# type: () -> None
"""Set all the slots to their initial value."""
for slot in self.slots.values():
slot.reset()
def _set_slot(self, key: Text, value: Any) -> None:
"""Set the value of a slot if that slot exists."""
if key in self.slots:
self.slots[key].value = value
else:
logger.error("Tried to set non existent slot '{}'. Make sure you "
"added all your slots to your domain file."
"".format(key))
def _create_events(self, evts: List[Event]) -> deque:
if evts and not isinstance(evts[0], Event): # pragma: no cover
raise ValueError("events, if given, must be a list of events")
return deque(evts, self._max_event_history)
def __eq__(self, other):
if isinstance(self, type(other)):
return (other.events == self.events and
self.sender_id == other.sender_id)
else:
return False
def __ne__(self, other):
return not self.__eq__(other)
def trigger_followup_action(self, action: Text) -> None:
"""Triggers another action following the execution of the current."""
self.followup_action = action
def clear_followup_action(self):
# type: () -> None
"""Clears follow up action when it was executed."""
self.followup_action = None
def _merge_slots(self,
entities: Optional[List[Dict[Text, Any]]] = None
) -> List[SlotSet]:
"""Take a list of entities and create tracker slot set events.
If an entity type matches a slots name, the entities value is set
as the slots value by creating a ``SlotSet`` event.
"""
entities = entities if entities else self.latest_message.entities
new_slots = [SlotSet(e["entity"], e["value"]) for e in entities if
e["entity"] in self.slots.keys()]
return new_slots