Narrative planning problems parsing

[MFaisalZaki]

User Story

Narrative planning problems have a modified action format (e.g., :fail, ':agents') and keyword predicates such as believes and 'intends'.

Here is an example of an action:

(:action search-for
        :parameters  (?character - character ?thing - thing ?room - room)
        :precondition
            (and
                (at ?character ?room)
                (in ?thing ?room)
            )
        :effect
            (and
                (has ?character ?thing)
                (not (in ?thing ?room))

                (believes ?character (has ?character ?thing))
                (believes ?character (not (in ?thing ?room)))
                (not (believes ?character (not (has ?character ?thing))))
                (not (believes ?character (in ?thing ?room)))
            )
        :fail
            (when (and (not (in ?thing ?room)) (at ?character ?room))
                (and
                    (not (believes ?character (in ?thing ?room)))
                    (believes ?character (not (in ?thing ?room)))
                )
            )
        :agents (?character)
    )

I have modified the PDDLGrammar to parse the :fail and :agents by changing action_def in PDDLGrammar:

agents = set_results_name(
            Suppress("(")
            - ZeroOrMore(
                Group(
                    Located(Group(OneOrMore(variable)) + Optional(Suppress("-") + name))
                )
            )
            + Suppress(")"),
            "agents",
        )

action_def = Group(
            Suppress("(")
            + ":action"
            - set_results_name(name, "name")
            + ":parameters"
            - Suppress("(")
            + parameters
            + Suppress(")")
            + Optional(":precondition" - set_results_name(nested_expr(), "pre"))
            + Optional(":effect" - set_results_name(nested_expr(), "eff"))
            + Optional(":observe" - set_results_name(nested_expr(), "obs"))
            + Optional(":fail" - set_results_name(nested_expr(), "fail"))
            + Optional(":agents" - agents)
            + Suppress(")")
        )

Also modified the requirements:

require_def = (
            Suppress("(")
            + ":requirements"
            + OneOrMore(
                one_of(
                    ":strips :typing :negative-preconditions :disjunctive-preconditions :equality :existential-preconditions :universal-preconditions :quantified-preconditions :conditional-effects :fluents :numeric-fluents :adl :durative-actions :duration-inequalities :timed-initial-literals :timed-initial-effects :action-costs :hierarchy :method-preconditions :constraints :contingent :preferences :expression-variables :intentionality :belief"
                )
            )
            + Suppress(")")
        )

Now I am facing a problem when parsing the believes predicate since such predicate's args are (believes <agent> <fact>) (e.g., (not (believes ?character (not (has ?character ?thing))))).

Any advice on parsing this since I am getting the well-formed exception?

rooms-domain-example