Providing a sense of meaning for relationships.

§1. This test tool uses the linguistics module, and it needs to have some concept of what relationships are — that is, of what might be meant by "X sees Y" or "X is on top of Y".

Inform uses a class called binary_predicate for this, but we will use a class simply called rel.

enum rel_CLASS
define VERB_MEANING_LINGUISTICS_TYPE struct rel

§2. linguistics also needs us to make annotation functions for one special annotation it uses. (It can't do this itself without knowing the type.) But we don't need to create the annotation or give it permissions.

DECLARE_ANNOTATION_FUNCTIONS(relationship, rel)

§3.

DECLARE_CLASS(rel)
MAKE_ANNOTATION_FUNCTIONS(relationship, rel)

§4. There isn't much to this, since all we want to be able to do is to print out a name.

typedef struct rel {
    struct text_stream *debugging_log_name;
    struct rel *reversed;
    CLASS_DEFINITION
} rel;

• The structure rel is accessed in 1/dgr, 3/vm and here.

§5. linguistics requires that whatever this is, it has to be "reversible". (This transposes the two terms. The reversal of "X sees Y" is "X is seen by Y".)

define VERB_MEANING_REVERSAL_LINGUISTICS_CALLBACK Relating::reverse_rel

rel *Relating::reverse_rel(rel *R) {
    return R->reversed;
}

§6. linguistics also wants to know the identities of two special meanings, roughly those of the verbs "to be" and "to have". So it requires us to define these two macros:

define VERB_MEANING_EQUALITY R_equality
define VERB_MEANING_POSSESSION R_possession

rel *R_equality = NULL;
rel *R_possession = NULL;

§7. And so we will create rels in pairs, and the first two (pairs) to be created must be for equality and possession:

rel *Relating::new(wording W) {
    TEMPORARY_TEXT(name)
    WRITE_TO(name, "%W", W);
    rel *R = CREATE(rel), *RR = CREATE(rel);
    R->debugging_log_name = Str::duplicate(name);
    WRITE_TO(name, "-reversed");
    RR->debugging_log_name = Str::duplicate(name);
    R->reversed = RR; RR->reversed = R;
    if (R_equality == NULL) R_equality = R;
    else if (R_possession == NULL) R_possession = R;
    DISCARD_TEXT(name)
    return R;
}

§8. This function finds a rel by name.

rel *Relating::find(wording W) {
    TEMPORARY_TEXT(name)
    WRITE_TO(name, "%W", W);
    rel *T;
    LOOP_OVER(T, rel)
        if (Str::eq_insensitive(T->debugging_log_name, name))
            break;
    DISCARD_TEXT(name)
    return T;
}