A plugin to support the maximum score variable.

§1. Initialisation. 

void PL::Score::start(void) {
    PluginManager::plug(PRODUCTION_LINE_PLUG, PL::Score::production_line);
    PluginManager::plug(NEW_VARIABLE_NOTIFY_PLUG, PL::Score::new_variable_notify);
}

int PL::Score::production_line(int stage, int debugging, stopwatch_timer *sequence_timer) {
    if (stage == INTER1_CSEQ) {
        BENCH(PL::Score::compile_max_score);
    }
    return FALSE;
}

§2. For many years this was a defined I6 constant, but then people sent in bug reports asking why it wouldn't change in play. 

nonlocal_variable *score_VAR = NULL;
nonlocal_variable *max_score_VAR = NULL;

§3. 

<notable-scoring-variables> ::=
    score |
    maximum score

§4. 

int PL::Score::new_variable_notify(nonlocal_variable *var) {
    if (<notable-scoring-variables>(var->name)) {
        switch(<<r>>) {
            case 0:
                score_VAR = var;
                RTVariables::make_initialisable(score_VAR);
                break;
            case 1:
                max_score_VAR = var;
                RTVariables::make_initialisable(max_score_VAR);
                break;
        }
    }
    return FALSE;
}

§5. The maximum score and rankings table. A special rule is that if a table is called "Rankings" and contains a column of numbers followed by a column of text, then it is used by the run-time scoring system. In retrospect, Inform really shouldn't support this at the compiler level (not that it does much), and in any case it's a very old-school idea of IF. Still, it does little harm. 

<rankings-table-name> ::=
    rankings

§6. This can only happen if we declare it somehow in I6 code, which we do with the constant RANKING_TABLE. We also set the MAX_SCORE variable equal to the number in the bottom row of the table, which is assumed to be the score corresponding to successful completion and the highest rank. 

void PL::Score::compile_max_score(void) {
    int rt_made = FALSE;
    table *t;
    LOOP_OVER(t, table) {
        if ((<rankings-table-name>(t->table_name_text)) &&
            (Tables::get_no_columns(t) >= 2) &&
            (Kinds::eq(Tables::kind_of_ith_column(t, 0), K_number)) &&
            (Kinds::eq(Tables::kind_of_ith_column(t, 1), K_text))) {
            inter_name *iname = Hierarchy::find(RANKING_TABLE_HL);
            Emit::named_iname_constant(iname, K_value, RTTables::identifier(t));
            parse_node *PN = Tables::cells_in_ith_column(t, 0);
            while ((PN != NULL) && (PN->next != NULL)) PN = PN->next;
            if ((PN != NULL) && (max_score_VAR) &&
                (VariableSubjects::has_initial_value_set(max_score_VAR) == FALSE))
                Assertions::PropertyKnowledge::initialise_global_variable(
                    max_score_VAR, Node::get_evaluation(PN));
            Hierarchy::make_available(Emit::tree(), iname);
            global_compilation_settings.ranking_table_given = TRUE;
            rt_made = TRUE;
            break;
        }
    }
    if (rt_made == FALSE) {
        inter_name *iname = Hierarchy::find(RANKING_TABLE_HL);
        Emit::named_generic_constant(iname, LITERAL_IVAL, 0);
        Hierarchy::make_available(Emit::tree(), iname);
    }
    inter_name *iname = Hierarchy::find(INITIAL_MAX_SCORE_HL);
    Hierarchy::make_available(Emit::tree(), iname);
    if (VariableSubjects::has_initial_value_set(max_score_VAR)) {
        inter_ti v1 = 0, v2 = 0;
        RTVariables::seek_initial_value(iname, &v1, &v2, max_score_VAR);
        Emit::named_generic_constant(iname, v1, v2);
    } else {
        Emit::named_numeric_constant(iname, 0);
    }
}