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90 lines
3.2 KiB
OpenEdge ABL
90 lines
3.2 KiB
OpenEdge ABL
[LabelInstruction::] The Label Construct.
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Defining the label construct.
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@h Definition.
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For what this does and why it is used, see //inter: Textual Inter//.
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=
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void LabelInstruction::define_construct(void) {
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inter_construct *IC = InterInstruction::create_construct(LABEL_IST, I"label");
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InterInstruction::defines_symbol_in_fields(IC, DEFN_LABEL_IFLD, -1);
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InterInstruction::specify_syntax(IC, I".IDENTIFIER");
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InterInstruction::data_extent_always(IC, 1);
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InterInstruction::allow_in_depth_range(IC, 0, INFINITELY_DEEP);
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InterInstruction::permit(IC, INSIDE_CODE_PACKAGE_ICUP);
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InterInstruction::permit(IC, CAN_HAVE_CHILDREN_ICUP);
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METHOD_ADD(IC, CONSTRUCT_READ_MTID, LabelInstruction::read);
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METHOD_ADD(IC, CONSTRUCT_VERIFY_MTID, LabelInstruction::verify);
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METHOD_ADD(IC, CONSTRUCT_WRITE_MTID, LabelInstruction::write);
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}
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@h Instructions.
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In bytecode, the frame of a |label| instruction is laid out with the
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compulsory words -- see //Inter Nodes// -- followed by:
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@d DEFN_LABEL_IFLD (DATA_IFLD + 0)
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=
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inter_error_message *LabelInstruction::new(inter_bookmark *IBM, inter_symbol *lab_name,
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inter_ti level, inter_error_location *eloc) {
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inter_tree_node *P = Inode::new_with_1_data_field(IBM, LABEL_IST,
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/* DEFN_LABEL_IFLD: */ InterSymbolsTable::id_at_bookmark(IBM, lab_name),
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eloc, level);
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inter_error_message *E = VerifyingInter::instruction(InterBookmark::package(IBM), P);
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if (E) return E;
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NodePlacement::move_to_moving_bookmark(P, IBM);
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return NULL;
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}
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@ Verification consists only of sanity checks.
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=
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void LabelInstruction::verify(inter_construct *IC, inter_tree_node *P, inter_package *owner,
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inter_error_message **E) {
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inter_symbol *lab_name = LabelInstruction::label_symbol(P);
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if (InterSymbol::is_label(lab_name) == FALSE) {
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*E = Inode::error(P, I"not a label",
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(lab_name)?(InterSymbol::identifier(lab_name)):NULL);
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return;
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}
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}
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@h Creating from textual Inter syntax.
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Note that a |.LABEL| can occur either before or after it is used in |lab| instructions,
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so that the label name might already have been created: see //LabInstruction::read//.
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=
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void LabelInstruction::read(inter_construct *IC, inter_bookmark *IBM, inter_line_parse *ilp,
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inter_error_location *eloc, inter_error_message **E) {
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text_stream *label_name = ilp->mr.exp[0];
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inter_symbol *label_s =
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InterSymbolsTable::symbol_from_name(InterBookmark::scope(IBM), label_name);
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if (label_s == NULL) {
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label_s = TextualInter::new_symbol(eloc, InterBookmark::scope(IBM), label_name, E);
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if (*E) return;
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} else if (InterSymbol::is_defined(label_s)) {
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*E = InterErrors::plain(I"label_s defined in function once already", eloc);
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return;
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}
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InterSymbol::make_label(label_s);
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*E = LabelInstruction::new(IBM, label_s, (inter_ti) ilp->indent_level, eloc);
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}
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@h Writing to textual Inter syntax.
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=
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void LabelInstruction::write(inter_construct *IC, OUTPUT_STREAM, inter_tree_node *P) {
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inter_symbol *label_s = LabelInstruction::label_symbol(P);
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WRITE("%S", InterSymbol::identifier(label_s));
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}
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@h Access function.
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=
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inter_symbol *LabelInstruction::label_symbol(inter_tree_node *P) {
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if (P == NULL) return NULL;
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if (Inode::isnt(P, LABEL_IST)) return NULL;
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return InterSymbolsTable::symbol_from_ID_at_node(P, DEFN_LABEL_IFLD);
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}
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