Defining the val construct.

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

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

void ValInstruction::define_construct?Usage of ValInstruction::define_construct:
Inter Constructs - §15(void) {
    inter_construct *IC = InterInstruction::create_construct(VAL_IST, I"val");
    InterInstruction::specify_syntax(IC, I"val 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, ValInstruction::read);
    METHOD_ADD(IC, CONSTRUCT_TRANSPOSE_MTID, ValInstruction::transpose);
    METHOD_ADD(IC, CONSTRUCT_VERIFY_MTID, ValInstruction::verify);
    METHOD_ADD(IC, CONSTRUCT_WRITE_MTID, ValInstruction::write);
}

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

define TYPE_VAL_IFLD (DATA_IFLD + 0)
define VAL1_VAL_IFLD (DATA_IFLD + 1)
define VAL2_VAL_IFLD (DATA_IFLD + 2)

inter_error_message *ValInstruction::new?Usage of ValInstruction::new:
§4(inter_bookmark *IBM, inter_type val_type,
    int level, inter_pair val, inter_error_location *eloc) {
    inter_tree_node *P = Inode::new_with_3_data_fields(IBM, VAL_IST,
        /* TYPE_VAL_IFLD: */ InterTypes::to_TID_at(IBM, val_type),
        /* VAL1_VAL_IFLD: */ InterValuePairs::to_word1(val),
        /* VAL2_VAL_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;
}

void ValInstruction::transpose?Usage of ValInstruction::transpose:
§1(inter_construct *IC, inter_tree_node *P, inter_ti *grid,
    inter_ti grid_extent, inter_error_message **E) {
    InterValuePairs::set(P, VAL1_VAL_IFLD,
        InterValuePairs::transpose(InterValuePairs::get(P, VAL1_VAL_IFLD),
            grid, grid_extent, E));
}

§3. Verification consists only of sanity checks.

void ValInstruction::verify?Usage of ValInstruction::verify:
§1(inter_construct *IC, inter_tree_node *P,
    inter_package *owner, inter_error_message **E) {
    *E = VerifyingInter::TID_field(owner, P, TYPE_VAL_IFLD);
    if (*E) return;
    inter_type type = InterTypes::from_TID_in_field(P, TYPE_VAL_IFLD);
    *E = VerifyingInter::data_pair_fields(owner, P, VAL1_VAL_IFLD, type);
    if (*E) return;
}

§4. Creating from textual Inter syntax. Note that a val can legally hold a typename as a value.

void ValInstruction::read?Usage of ValInstruction::read:
§1(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 val_type =
        InterTypes::parse_simple(InterBookmark::scope(IBM), eloc, type_text, E);
    if (*E == NULL) {
        inter_symbol *typename_as_value =
            TextualInter::find_symbol(IBM, eloc, value_text, TYPENAME_IST, E);
        if (typename_as_value) {
            *E = NULL;
            val = InterValuePairs::symbolic(IBM, typename_as_value);
        } else {
            *E = TextualInter::parse_pair(ilp->line, eloc, IBM, val_type, value_text, &val);
        }
    }
    Regexp::dispose_of(&mr);
    if (*E) return;

    *E = ValInstruction::new(IBM, val_type, ilp->indent_level, val, eloc);
}

§5. Writing to textual Inter syntax.

void ValInstruction::write?Usage of ValInstruction::write:
§1(inter_construct *IC, OUTPUT_STREAM, inter_tree_node *P) {
    WRITE("val ");
    TextualInter::write_optional_type_marker(OUT, P, TYPE_VAL_IFLD);
    TextualInter::write_pair(OUT, P, ValInstruction::value(P));
}

§6. Access function.

inter_pair ValInstruction::value?Usage of ValInstruction::value:
§5(inter_tree_node *P) {
    if (P == NULL) return InterValuePairs::undef();
    if (Inode::isnt(P, VAL_IST)) return InterValuePairs::undef();
    return InterValuePairs::get(P, VAL1_VAL_IFLD);
}