Defining the variable construct.

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

void VariableInstruction::define_construct(void) {
    inter_construct *IC = InterInstruction::create_construct(VARIABLE_IST, I"variable");
    InterInstruction::defines_symbol_in_fields(IC, DEFN_VAR_IFLD, TYPE_VAR_IFLD);
    InterInstruction::specify_syntax(IC, I"variable TOKENS = TOKENS");
    InterInstruction::data_extent_always(IC, 4);
    InterInstruction::permit(IC, INSIDE_PLAIN_PACKAGE_ICUP);
    METHOD_ADD(IC, CONSTRUCT_READ_MTID, VariableInstruction::read);
    METHOD_ADD(IC, CONSTRUCT_TRANSPOSE_MTID, VariableInstruction::transpose);
    METHOD_ADD(IC, CONSTRUCT_VERIFY_MTID, VariableInstruction::verify);
    METHOD_ADD(IC, CONSTRUCT_WRITE_MTID, VariableInstruction::write);
}

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

define DEFN_VAR_IFLD (DATA_IFLD + 0)
define TYPE_VAR_IFLD (DATA_IFLD + 1)
define VAL1_VAR_IFLD (DATA_IFLD + 2)
define VAL2_VAR_IFLD (DATA_IFLD + 3)

inter_error_message *VariableInstruction::new(inter_bookmark *IBM, inter_symbol *var_s,
    inter_type var_type, inter_pair val, inter_ti level, inter_error_location *eloc) {
    inter_tree_node *P = Inode::new_with_4_data_fields(IBM, VARIABLE_IST,
        /* DEFN_VAR_IFLD: */ InterSymbolsTable::id_at_bookmark(IBM, var_s),
        /* TYPE_VAR_IFLD: */ InterTypes::to_TID_at(IBM, var_type),
        /* VAL1_VAR_IFLD: */ InterValuePairs::to_word1(val),
        /* VAL2_VAR_IFLD: */ InterValuePairs::to_word2(val),
        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 VariableInstruction::transpose(inter_construct *IC, inter_tree_node *P,
    inter_ti *grid, inter_ti grid_extent, inter_error_message **E) {
    InterValuePairs::set(P, VAL1_PVAL_IFLD,
        InterValuePairs::transpose(InterValuePairs::get(P, VAL1_PVAL_IFLD), grid, grid_extent, E));
}

§3. Verification consists only of sanity checks. 

void VariableInstruction::verify(inter_construct *IC, inter_tree_node *P,
    inter_package *owner, inter_error_message **E) {
    *E = VerifyingInter::TID_field(owner, P, TYPE_VAR_IFLD);
    if (*E) return;
    inter_type type = InterTypes::from_TID_in_field(P, TYPE_VAR_IFLD);
    *E = VerifyingInter::data_pair_fields(owner, P, VAL1_VAR_IFLD, type);
    if (*E) return;
}

§4. Creating from textual Inter syntax. 

void VariableInstruction::read(inter_construct *IC, inter_bookmark *IBM,
    inter_line_parse *ilp, inter_error_location *eloc, inter_error_message **E) {
    text_stream *type_text = NULL, *name_text = ilp->mr.exp[0];
    match_results mr = Regexp::create_mr();
    if (Regexp::match(&mr, name_text, U"%((%c+)%) (%c+)")) {
        type_text = mr.exp[0]; name_text = mr.exp[1];
    }
    inter_type var_type =
        InterTypes::parse_simple(InterBookmark::scope(IBM), eloc, type_text, E);
    inter_symbol *var_s = NULL;
    if (*E == NULL)
        var_s = TextualInter::new_symbol(eloc, InterBookmark::scope(IBM), name_text, E);
    Regexp::dispose_of(&mr);
    if (*E) return;

    SymbolAnnotation::copy_set_to_symbol(&(ilp->set), var_s);

    inter_pair val = InterValuePairs::undef();
    *E = TextualInter::parse_pair(ilp->line, eloc, IBM, var_type, ilp->mr.exp[1], &val);
    if (*E) return;

    *E = VariableInstruction::new(IBM, var_s, var_type, val,
        (inter_ti) ilp->indent_level, eloc);
}

§5. Writing to textual Inter syntax. 

void VariableInstruction::write(inter_construct *IC, OUTPUT_STREAM, inter_tree_node *P) {
    inter_symbol *var_s = VariableInstruction::variable(P);
    WRITE("variable ");
    TextualInter::write_optional_type_marker(OUT, P, TYPE_VAR_IFLD);
    WRITE("%S = ", InterSymbol::identifier(var_s));
    TextualInter::write_pair(OUT, P, VariableInstruction::value(P));
}

§6. Access functions. 

inter_symbol *VariableInstruction::variable(inter_tree_node *P) {
    if (P == NULL) return NULL;
    if (Inode::isnt(P, VARIABLE_IST)) return NULL;
    return InterSymbolsTable::symbol_from_ID_at_node(P, DEFN_VAR_IFLD);
}

inter_pair VariableInstruction::value(inter_tree_node *P) {
    if (P == NULL) return InterValuePairs::undef();
    if (Inode::isnt(P, VARIABLE_IST)) return InterValuePairs::undef();
    return InterValuePairs::get(P, VAL1_VAR_IFLD);
}