Names of either-or properties when used as adjectives.

§1. Names of either-or properties can be used adjectivally in Inform: thus, "an open door", or "a transparent container". They form the either_or_property_amf family of adjectives, which we now declare.

adjective_meaning_family *either_or_property_amf = NULL;

void EitherOrPropertyAdjectives::start?Usage of EitherOrPropertyAdjectives::start:
Knowledge Module - §3(void) {
    either_or_property_amf = AdjectiveMeanings::new_family(1);
    METHOD_ADD(either_or_property_amf, ASSERT_ADJM_MTID,
        EitherOrPropertyAdjectives::assert);
    METHOD_ADD(either_or_property_amf, PREPARE_SCHEMAS_ADJM_MTID,
        EitherOrPropertyAdjectives::prepare_schemas);
    METHOD_ADD(either_or_property_amf, INDEX_ADJM_MTID,
        EitherOrPropertyAdjectives::index);
}

int EitherOrPropertyAdjectives::is(adjective_meaning *am) {
    if ((am) && (am->family == either_or_property_amf)) return TRUE;
    return FALSE;
}

§2. This tells us that the property should now be used adjectivally over a given kind. Note that it creates the adjective if it doesn't already exist, and also that it does nothing if the adjective can already be used in this way. So, for example, the either-or property "empty" has an associated adjective "empty", but it can apply to both rulebooks and containers. These are two different adjective meanings, one for each kind the adjective applies to.

void EitherOrPropertyAdjectives::create_for_property?Usage of EitherOrPropertyAdjectives::create_for_property:
Either-Or Properties - §3, §4(property *prn, wording W, kind *K) {
    if ((prn == NULL) || (prn->either_or_data == NULL)) internal_error("not either-or");
    adjective *adj = EitherOrProperties::as_adjective(prn);
    if (adj) {
        if (AdjectiveAmbiguity::can_be_applied_to(adj, K)) return;
    } else {
        adj = Adjectives::declare(W, NULL);
        prn->either_or_data->as_adjective = adj;
    }
    adjective_meaning *am =
        AdjectiveMeanings::new(either_or_property_amf, STORE_POINTER_property(prn), W);
    AdjectiveAmbiguity::add_meaning_to_adjective(am, adj);
    AdjectiveMeaningDomains::set_from_kind(am, K);
}

§3. That just leaves three methods, all of which pass out work elsewhere:

int EitherOrPropertyAdjectives::assert?Usage of EitherOrPropertyAdjectives::assert:
§1(adjective_meaning_family *f,
    adjective_meaning *am, inference_subject *infs_to_assert_on, int parity) {
    property *prn = RETRIEVE_POINTER_property(am->family_specific_data);
    if (parity == FALSE) PropertyInferences::draw_negated(infs_to_assert_on, prn, NULL);
    else PropertyInferences::draw(infs_to_assert_on, prn, NULL);
    return TRUE;
}

void EitherOrPropertyAdjectives::prepare_schemas?Usage of EitherOrPropertyAdjectives::prepare_schemas:
§1(adjective_meaning_family *family,
    adjective_meaning *am, int T) {
    property *prn = RETRIEVE_POINTER_property(am->family_specific_data);
    if (am->schemas_prepared == FALSE)
        RTProperties::write_either_or_schemas(am, prn, T);
}

int EitherOrPropertyAdjectives::index?Usage of EitherOrPropertyAdjectives::index:
§1(adjective_meaning_family *f, text_stream *OUT,
    adjective_meaning *am) {
    property *prn = RETRIEVE_POINTER_property(am->family_specific_data);
    RTInferences::index_either_or(OUT, prn);
    return TRUE;
}