Function parse_preferences

Core/SoarKernel/src/parser.cpp:1704–1780

----------------------------------------------------------------- */

action* parse_preferences(agent* thisAgent, Symbol* id,
                          rhs_value attr, rhs_value value)
{
    action* a;
    action* prev_a;
    rhs_value referent;
    byte preference_type;
    bool saw_plus_sign;
    
    /* --- Note: this routine is set up so if there's not preference type
       indicator at all, we return a single acceptable preference make --- */
    
    prev_a = NIL;
    
    saw_plus_sign = (thisAgent->lexeme.type == PLUS_LEXEME);
    preference_type = parse_preference_specifier_without_referent(thisAgent);
    if ((preference_type == ACCEPTABLE_PREFERENCE_TYPE) && (! saw_plus_sign))
    {
        /* If the routine gave us a + pref without seeing a + sign, then it's
           just giving us the default acceptable preference.  Look for optional
           comma. */
        if (thisAgent->lexeme.type == COMMA_LEXEME)
        {
            get_lexeme(thisAgent);
        }
    }
    
    while (true)
    {
        /* --- read referent --- */
        if (preference_is_binary(preference_type))
        {
            referent = parse_rhs_value(thisAgent);
            if (! referent)
            {
                deallocate_action_list(thisAgent, prev_a);
                return NIL;
            }
            if (thisAgent->lexeme.type == COMMA_LEXEME)
            {
                get_lexeme(thisAgent);
            }
        }
        else
        {
            referent = NIL; /* unnecessary, but gcc -Wall warns without it */
        }
        
        /* --- create the appropriate action --- */
        allocate_with_pool(thisAgent, &thisAgent->action_pool,  &a);
        a->next = prev_a;
        prev_a = a;
        a->type = MAKE_ACTION;
        a->preference_type = preference_type;
        a->id = symbol_to_rhs_value(id);
        symbol_add_ref(thisAgent, id);
        a->attr = copy_rhs_value(thisAgent, attr);
        a->value = copy_rhs_value(thisAgent, value);