RPG-III Language Support

VSCode extension providing language support for IBM RPG-III (fixed-format) source files.

Features

Full tokenization of the RPG-III 80-column fixed-format spec structure:

Spec type letters — H, F, E, L, I, C, O in column 6
F-spec — filename, file type/designation, device keyword (DISK, WORKSTN, PRINTER, etc.)
E-spec — array/table names
I-spec — data structure names, field names, data type codes (P, B, L, R)
C-spec — control level indicators, opcodes (structured control flow, operators), factor 1/2, result field, resulting indicators
Opcodes — structured operations (IFEQ, DOWGT, etc.) and all standard RPG-III opcodes highlighted by kind (control, operator). Correctly tokenized even when a 5-character opcode fills its field with no trailing space (MOVEAHIND, CHAINSUBFL)
Numeric literals — in factor 1 and factor 2 positions get constant.numeric scope, taking priority over the variable scope
System constants — *BLANKS, *ZERO, *HIVAL, *LOVAL, *ON, *OFF, *IN, UDATE, etc.
Indicators — *IN, *IN01–*IN99
Strings — single-quoted literals and hex (X'...') literals
Comments — spec comment lines (col 7 = *) and trailing comments past the usable columns
Embedded SQL — /EXEC SQL ... /END-EXEC blocks with inner SQL syntax highlighting
Compile-time data — ** delimited array data blocks
Precompiler directives — /COPY, /TITLE, /EJECT, /SPACE

Context-aware navigation understands which fixed-column field the cursor is in and what the opcode expects:

Cursor location	Resolves to
Subroutine name in `EXSR` / `CAS*` Factor 2	`BEGSR` line
Subroutine name in `BEGSR` / `ENDSR` Factor 1	`BEGSR` line
Tag name in `GOTO` / `CAB*` Factor 2	`TAG` line
File name in `CHAIN`, `READ`, `WRITE`, `SETLL`, etc.	F-spec line
Array name (e.g. `PATH` in `PATH,X`)	E-spec line
Array index (e.g. `X` in `PATH,X`)	Variable declaration
DS field or record field	I-spec definition line
C-spec variable (result field with a field length)	Most recent assignment at or before the cursor line

Hovering over any recognized symbol shows a tooltip:

Files — type (Input/Output/Update/Combined), device, designation, format
Arrays — entry count, entry length, decimal positions, data type
Fields (I-spec) — parent data structure, from/to positions, length, data type
Variables (C-spec) — declared at line N, declaring opcode
Subroutines — defined at / ends at line number
Tags — defined at line number

Click the fold gutter to collapse:

Structured blocks — IF/ENDIF, DO/ENDDO, DOW/ENDDO, DOU/ENDDO, SELEC/ENDSL
Subroutines — BEGSR/ENDSR pairs

The Explorer Outline panel is populated with all symbols extracted from the file, grouped by kind:

Files with the .rpg or .RPG extension are automatically associated with the rpg language.

The parser uses the standard RPG-III 80-column spec layout (0-based columns):

Columns	F-spec	E-spec	I-spec	C-spec
0–4	Sequence/page	Sequence/page	Sequence/page	Sequence/page
5	`F`	`E`	`I`	`C`
6–13	Filename (8)	Related file (8)	Filename (8)	—
6–7	—	—	—	Control level (2)
8–16	—	—	—	Conditioning indicators N01/N02/N03
17–26	—	—	—	Factor 1 (10)
26–31	—	Array name (6)	—	—
27–31	—	—	—	Opcode (5)
32–41	—	—	—	Factor 2 (10)
36–38	—	Entries per table (3)	—	—
39–41	—	Entry length (3)	—	—
42–47	—	—	—	Result field (6)
48–50	—	—	—	Field length (3)
52–57	—	—	Field name (6)	—
53–58	—	—	—	Resulting indicators (HI/LO/EQ)