Defining the instance construct.

• §1. Definition
• §2. Instructions
• §4. Creating from textual Inter syntax
• §5. Writing to textual Inter syntax
• §6. Access functions

§1. Definition. For what this does and why it is used, see Textual Inter (in inter).

void InstanceInstruction::define_construct?Usage of InstanceInstruction::define_construct:
Inter Constructs - §15(void) {
    inter_construct *IC = InterInstruction::create_construct(INSTANCE_IST, I"instance");
    InterInstruction::defines_symbol_in_fields(IC, DEFN_INST_IFLD, TYPE_INST_IFLD);
    InterInstruction::specify_syntax(IC, I"instance TOKEN TOKENS");
    InterInstruction::data_extent_always(IC, 6);
    InterInstruction::permit(IC, INSIDE_PLAIN_PACKAGE_ICUP);
    METHOD_ADD(IC, CONSTRUCT_READ_MTID, InstanceInstruction::read);
    METHOD_ADD(IC, CONSTRUCT_TRANSPOSE_MTID, InstanceInstruction::transpose);
    METHOD_ADD(IC, CONSTRUCT_VERIFY_MTID, InstanceInstruction::verify);
    METHOD_ADD(IC, CONSTRUCT_XREF_MTID, InstanceInstruction::xref);
    METHOD_ADD(IC, CONSTRUCT_WRITE_MTID, InstanceInstruction::write);
}

§2. Instructions. In bytecode, the frame of an instance instruction is laid out with the compulsory words — see Inter Nodes — followed by:

define DEFN_INST_IFLD      (DATA_IFLD + 0)
define TYPE_INST_IFLD      (DATA_IFLD + 1)
define VAL1_INST_IFLD      (DATA_IFLD + 2)
define VAL2_INST_IFLD      (DATA_IFLD + 3)
define PROP_LIST_INST_IFLD (DATA_IFLD + 4)
define PERM_LIST_INST_IFLD (DATA_IFLD + 5)

inter_error_message *InstanceInstruction::new?Usage of InstanceInstruction::new:
§4(inter_bookmark *IBM, inter_symbol *S,
    inter_symbol *typename_s, inter_pair val, inter_ti level, inter_error_location *eloc) {
    inter_warehouse *warehouse = InterBookmark::warehouse(IBM);
    inter_package *pack = InterBookmark::package(IBM);
    inter_tree_node *P = Inode::new_with_6_data_fields(IBM, INSTANCE_IST,
        /* DEFN_INST_IFLD: */      InterSymbolsTable::id_at_bookmark(IBM, S),
        /* TYPE_INST_IFLD: */      InterSymbolsTable::id_at_bookmark(IBM, typename_s),
        /* VAL1_INST_IFLD: */      InterValuePairs::to_word1(val),
        /* VAL2_INST_IFLD: */      InterValuePairs::to_word2(val),
        /* PROP_LIST_INST_IFLD: */ InterWarehouse::create_node_list(warehouse, pack),
        /* PERM_LIST_INST_IFLD: */ InterWarehouse::create_node_list(warehouse, pack),
        eloc, level);
    inter_error_message *E = VerifyingInter::instruction(InterBookmark::package(IBM), P);
    if (E) return E;
    NodePlacement::move_to_moving_bookmark(P, IBM);
    return NULL;
}

void InstanceInstruction::transpose?Usage of InstanceInstruction::transpose:
§1(inter_construct *IC, inter_tree_node *P,
    inter_ti *grid, inter_ti grid_extent, inter_error_message **E) {
    P->W.instruction[PROP_LIST_INST_IFLD] = grid[P->W.instruction[PROP_LIST_INST_IFLD]];
    P->W.instruction[PERM_LIST_INST_IFLD] = grid[P->W.instruction[PERM_LIST_INST_IFLD]];
    InterValuePairs::set(P, VAL1_INST_IFLD,
        InterValuePairs::transpose(InterValuePairs::get(P, VAL1_INST_IFLD), grid, grid_extent, E));
}

§3. Verification does more than making sanity checks: it also calculates and sets the enumerated value of the instance (if it is not already set), and notifies the typename_s that it has a new instance.

void InstanceInstruction::verify?Usage of InstanceInstruction::verify:
§1(inter_construct *IC, inter_tree_node *P, inter_package *owner,
    inter_error_message **E) {
    *E = VerifyingInter::SID_field(owner, P, TYPE_INST_IFLD, TYPENAME_IST);
    if (*E) return;
    *E = VerifyingInter::node_list_field(owner, P, PROP_LIST_INST_IFLD);
    if (*E) return;
    *E = VerifyingInter::node_list_field(owner, P, PERM_LIST_INST_IFLD);
    if (*E) return;
}

void InstanceInstruction::xref?Usage of InstanceInstruction::xref:
§1(inter_construct *IC, inter_tree_node *P,
    inter_error_message **E) {
    inter_symbol *typename_s = InterSymbolsTable::symbol_from_ID_at_node(P, TYPE_INST_IFLD);
    inter_type inst_type = InterTypes::from_type_name(typename_s);
    if (InterTypes::is_enumerated(inst_type)) {
        if (InterValuePairs::is_undef(InterValuePairs::get(P, VAL1_INST_IFLD)))
            InterValuePairs::set(P, VAL1_INST_IFLD,
                InterValuePairs::number(TypenameInstruction::next_enumerated_value(typename_s)));
    } else {
        *E = Inode::error(P, I"not a kind which has instances", NULL); return;
    }
    inter_package *owner = Inode::get_package(P);
    *E = VerifyingInter::data_pair_fields(owner, P, VAL1_INST_IFLD, inst_type);
    if (*E) return;

    inter_symbol *instance_s = InstanceInstruction::instance(P);
    TypenameInstruction::new_instance(typename_s, instance_s);
}

§4. Creating from textual Inter syntax.

void InstanceInstruction::read?Usage of InstanceInstruction::read:
§1(inter_construct *IC, inter_bookmark *IBM, inter_line_parse *ilp,
    inter_error_location *eloc, inter_error_message **E) {
    text_stream *type_text = ilp->mr.exp[0];
    text_stream *instance_text = ilp->mr.exp[1];

    inter_type inst_type = InterTypes::unchecked();
    Find the enumerated type this will belong to4.1;

    inter_symbol *instance_s = NULL;
    inter_pair val = InterValuePairs::undef();
    Find the instance name and enumerated value, if given4.2;

    *E = InstanceInstruction::new(IBM, instance_s, InterTypes::type_name(inst_type),
        val, (inter_ti) ilp->indent_level, eloc);
}

§4.1. Find the enumerated type this will belong to4.1 =

    match_results mr = Regexp::create_mr();
    if (Regexp::match(&mr, type_text, U"%((%c+)%)"))
        inst_type = InterTypes::parse_simple(InterBookmark::scope(IBM), eloc, mr.exp[0], E);
    Regexp::dispose_of(&mr);
    if (*E) return;

• This code is used in §4.

§4.2. Find the instance name and enumerated value, if given4.2 =

    text_stream *value_text = NULL;
    match_results mr = Regexp::create_mr();
    if (Regexp::match(&mr, instance_text, U"(%i+) = (%c+)")) {
        instance_text = mr.exp[0]; value_text = mr.exp[1];
    }
    instance_s =
        TextualInter::new_symbol(eloc, InterBookmark::scope(IBM), instance_text, E);
    if ((*E == NULL) && (Str::len(value_text) > 0))
        *E = TextualInter::parse_pair(ilp->line, eloc, IBM, InterTypes::unchecked(),
            value_text, &val);
    Regexp::dispose_of(&mr);
    if (*E) return;

• This code is used in §4.

§5. Writing to textual Inter syntax.

void InstanceInstruction::write?Usage of InstanceInstruction::write:
§1(inter_construct *IC, OUTPUT_STREAM, inter_tree_node *P) {
    inter_symbol *instance_s = InstanceInstruction::instance(P);
    WRITE("instance (");
    TextualInter::write_symbol_from(OUT, P, TYPE_INST_IFLD);
    WRITE(") %S = ", InterSymbol::identifier(instance_s));
    TextualInter::write_pair(OUT, P, InterValuePairs::get(P, VAL1_INST_IFLD));
}

§6. Access functions.

inter_symbol *InstanceInstruction::instance?Usage of InstanceInstruction::instance:
§3, §5(inter_tree_node *P) {
    if (P == NULL) return NULL;
    if (Inode::isnt(P, INSTANCE_IST)) return NULL;
    return InterSymbolsTable::symbol_from_ID_at_node(P, DEFN_INST_IFLD);
}

int InstanceInstruction::is?Usage of InstanceInstruction::is:
The Permission Construct - §3
The PropertyValue Construct - §3(inter_symbol *instance_s) {
    if (instance_s == NULL) return FALSE;
    inter_tree_node *D = InterSymbol::definition(instance_s);
    if (Inode::is(D, INSTANCE_IST)) return TRUE;
    return FALSE;
}

inter_symbol *InstanceInstruction::typename?Usage of InstanceInstruction::typename:
The PropertyValue Construct - §3(inter_symbol *instance_s) {
    return InterTypes::type_name(InterTypes::of_symbol(instance_s));
}

inter_pair InstanceInstruction::enumerated_value(inter_symbol *instance_s) {
    if (instance_s == NULL) return InterValuePairs::undef();
    inter_tree_node *D = InterSymbol::definition(instance_s);
    if (D == NULL) return InterValuePairs::undef();
    return InterValuePairs::get(D, VAL1_INST_IFLD);
}

inter_node_list *InstanceInstruction::permissions_list?Usage of InstanceInstruction::permissions_list:
The Permission Construct - §3
The PropertyValue Construct - §3(inter_symbol *instance_s) {
    if (instance_s == NULL) return NULL;
    inter_tree_node *D = InterSymbol::definition(instance_s);
    if (D == NULL) return NULL;
    return Inode::ID_to_frame_list(D, D->W.instruction[PERM_LIST_INST_IFLD]);
}

inter_node_list *InstanceInstruction::properties_list?Usage of InstanceInstruction::properties_list:
The PropertyValue Construct - §3(inter_symbol *instance_s) {
    if (instance_s == NULL) return NULL;
    inter_tree_node *D = InterSymbol::definition(instance_s);
    if (D == NULL) return NULL;
    return Inode::ID_to_frame_list(D, D->W.instruction[PROP_LIST_INST_IFLD]);
}