Defining the ref construct.

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

void RefInstruction::define_construct(void) {
    inter_construct *IC = InterInstruction::create_construct(REF_IST, I"ref");
    InterInstruction::specify_syntax(IC, I"ref TOKENS");
    InterInstruction::data_extent_always(IC, 3);
    InterInstruction::allow_in_depth_range(IC, 1, INFINITELY_DEEP);
    InterInstruction::permit(IC, INSIDE_CODE_PACKAGE_ICUP);
    METHOD_ADD(IC, CONSTRUCT_READ_MTID, RefInstruction::read);
    METHOD_ADD(IC, CONSTRUCT_VERIFY_MTID, RefInstruction::verify);
    METHOD_ADD(IC, CONSTRUCT_WRITE_MTID, RefInstruction::write);

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

define VAL1_REF_IFLD (DATA_IFLD + 1)
define VAL2_REF_IFLD (DATA_IFLD + 2)
inter_error_message *RefInstruction::new(inter_bookmark *IBM, inter_type ref_type,
    int level, inter_pair val, inter_error_location *eloc) {
    inter_tree_node *P = Inode::new_with_3_data_fields(IBM, REF_IST,
        /* TYPE_REF_IFLD: */ InterTypes::to_TID_at(IBM, ref_type),
        /* VAL1_REF_IFLD: */ InterValuePairs::to_word1(val),
        /* VAL2_REF_IFLD: */ InterValuePairs::to_word2(val),
        eloc, (inter_ti) level);
    inter_error_message *E = VerifyingInter::instruction(InterBookmark::package(IBM), P);
    if (E) return E;
    NodePlacement::move_to_moving_bookmark(P, IBM);
    return NULL;

§3. Verification consists only of sanity checks.

void RefInstruction::verify(inter_construct *IC, inter_tree_node *P, inter_package *owner,
    inter_error_message **E) {
    *E = VerifyingInter::TID_field(owner, P, TYPE_REF_IFLD);
    if (*E) return;
    inter_type type = InterTypes::from_TID_in_field(P, TYPE_REF_IFLD);
    *E = VerifyingInter::data_pair_fields(owner, P, VAL1_REF_IFLD, type);
    if (*E) return;

§4. Creating from textual Inter syntax.

void RefInstruction::read(inter_construct *IC, inter_bookmark *IBM, inter_line_parse *ilp,
    inter_error_location *eloc, inter_error_message **E) {
    text_stream *type_text = NULL, *value_text = ilp->mr.exp[0];
    match_results mr = Regexp::create_mr();
    if (Regexp::match(&mr, value_text, U"%((%c+)%) (%c+)")) {
        type_text = mr.exp[0];
        value_text = mr.exp[1];
    inter_pair val = InterValuePairs::undef();
    inter_type ref_type = InterTypes::parse_simple(InterBookmark::scope(IBM), eloc, type_text, E);
    if (*E == NULL)
        *E = TextualInter::parse_pair(ilp->line, eloc, IBM, ref_type, value_text, &val);
    if (*E) return;

    *E = RefInstruction::new(IBM, ref_type, ilp->indent_level, val, eloc);

§5. Writing to textual Inter syntax.

void RefInstruction::write(inter_construct *IC, OUTPUT_STREAM, inter_tree_node *P) {
    WRITE("ref ");
    TextualInter::write_optional_type_marker(OUT, P, TYPE_REF_IFLD);
    TextualInter::write_pair(OUT, P, RefInstruction::value(P));

§6. Access function.

inter_pair RefInstruction::value(inter_tree_node *P) {
    if (P == NULL) return InterValuePairs::undef();
    if (Inode::isnt(P, REF_IST)) return InterValuePairs::undef();
    return InterValuePairs::get(P, VAL1_REF_IFLD);