RDN VS Code Extension

Syntax highlighting, diagnostics, and smart completions for RDN (Rich Data Notation) files in Visual Studio Code.

Features

Syntax Highlighting

Full TextMate grammar for all RDN types:

• JSON-compatible: strings, numbers, booleans, null, arrays, objects
• Dates & times: @2024-01-15T10:30:00.000Z, @14:30:00, @P1Y2M3DT4H5M6S
• BigInt: 42n, -999n
• Special numbers: NaN, Infinity, -Infinity
• RegExp: /^test$/gi
• Binary data: b"SGVsbG8=", x"48656C6C6F"
• Map: Map{"a" => 1}, {"a" => 1}
• Set: Set{1, 2, 3}, {"a", "b"}
• Tuple: (1, 2, 3)

Full File Validation

The extension bundles the reference RDN parser and validates your .rdn files on every edit (with 300ms debounce), just like the built-in JSON validation. Any parse error — missing commas, unterminated strings, invalid literals, bad escape sequences, malformed dates, etc. — is shown as a red squiggle with a clear error message.

Unquoted Key Detection + Quick Fixes

RDN requires all object keys to be quoted strings (just like JSON). A dedicated scanner finds all unquoted keys in the file and flags them with quick fixes:

{foo: 1, bar: "test"}   ← "foo" and "bar" flagged as errors
{"foo": 1, "bar": "test"}  ← valid

The scanner correctly handles brace disambiguation — Maps ({"a" => 1}), Sets ({"a", "b"}), explicit Map{...} / Set{...}, and RDN literals (@dates, /regex/, b"...") are not false-positived.

When an unquoted key is detected:

• Wrap in quotes — fixes a single key (foo → "foo")
• Wrap all unquoted keys in quotes — fixes all unquoted keys in the file at once

Binary Character Validation

A dedicated scanner validates the content of b"..." (base64) and x"..." (hex) binary literals:

• Base64: flags characters outside the base64 alphabet (A-Z, a-z, 0-9, +, /, =) and data after padding
• Hex: flags characters outside the hex alphabet (0-9, A-F, a-f)

Each invalid character is highlighted individually with a red squiggle and a clear error message.

$schema Completion

When typing " inside a top-level object, the extension suggests "$schema" as a completion item for adding a JSON Schema reference.

RDN Keywords & Snippets

The extension provides two layers of completions in value positions:

Keywords — type the keyword and insert it directly:

Snippets — type the name and expand into full RDN syntax with tab stops:

For example, typing Map shows both the Map keyword and the Map{} snippet — pick the keyword to just insert Map, or the snippet to get Map{key => value} with tab stops.

Document Formatting

Built-in formatting support — use Format Document (Shift+Alt+F) or enable Format on Save to auto-format .rdn files. The formatter uses a CST-based approach that preserves RDN-specific syntax:

• Preserves tuples (1, 2, 3) (not collapsed to arrays)
• Preserves literal representations (dates, times, durations, regex, binary, bigints)
• Re-escapes strings with canonical escape sequences
• Smart line-breaking: keeps short collections on one line, expands long ones to multi-line with proper indentation
• Respects your editor's tab size and spaces/tabs preference
• Leaves invalid RDN files unchanged (no destructive formatting)

Formatting Settings

Hover Information

Hover over any RDN-specific literal to see contextual information:

• DateTime — formatted date with variant label (full ISO, date-only, no milliseconds)
• Unix Timestamp — converted date with seconds/milliseconds detection
• TimeOnly — formatted time display
• Duration — plain English expansion (e.g. @P1Y2M3D → "1 year, 2 months, 3 days")
• BigInt — comma-grouped digits with bit length
• Binary — byte count with optional ASCII preview; image preview when the data starts with recognized image magic bytes (PNG, JPEG, GIF, WebP, BMP, ICO)
• RegExp — expanded flag names (e.g. gi → "global, ignoreCase")
• Special Numbers — IEEE 754 description for NaN, Infinity, -Infinity
• Collections — element/entry count for Map, Set, and Tuple (both explicit and implicit)
• => — Map entry separator hint

Hover diagnostics:

• Hex binary with odd digit count
• BigInt values that fit in a regular Number
• Ambiguous 10-digit Unix timestamps (seconds vs milliseconds)

Editor diagnostics (red squiggles):

• Invalid characters in base64 binary literals
• Invalid characters in hex binary literals

Hover Settings

All hover features are individually toggleable:

Date format strings support the following tokens: YYYY, YY, MMMM, MMM, MM, M, DD, D, HH, H, hh, h, mm, m, ss, s, SSS, SS, S, A, a. Use [brackets] for literal text.

Other

• Bracket matching and auto-closing for {}, [], ()
• Auto-closing for double quotes
• Indentation support for bracket blocks
• Invalid escape sequence highlighting
• Object key vs. value distinction (keys get support.type.property-name scope)

Installation

From source (development)

1. Open tools/vscode-extension/ in VS Code
2. Run npm install and npm run compile
3. Press F5 to launch the Extension Development Host
4. Open any .rdn file to see all features in action

Manual install

cd tools/vscode-extension
npm install
npm run package
code --install-extension rdn-0.2.0.vsix

Scope Reference

Use Developer: Inspect Editor Tokens and Scopes in VS Code to verify assignments.

Limitations

• Implicit Map/Set vs Object disambiguation is not possible at the TextMate grammar level. Implicit maps ({"a" => 1}) and sets ({"a", "b"}) are parsed as brace blocks — the =>, :, and , punctuation conveys the type visually.
• RegExp body is highlighted as a single token. Sub-pattern highlighting (character classes, quantifiers, etc.) is not provided.
• Unquoted key detection uses a lightweight scanner separate from the parser. Edge cases in deeply malformed documents may not be caught by the scanner, but the parser will still flag them.
• Parser errors are one-at-a-time — like JSON validation, the parser stops at the first error. Fix it and the next error (if any) will appear.