PL/SQL Block Highlighter

A VS Code extension that highlights the structural keywords — DECLARE, BEGIN, EXCEPTION, and END — of the innermost PL/SQL block containing the cursor.

When you move the cursor inside any block, all four boundary keywords light up instantly, making it easy to see where a block starts and ends inside deeply nested code.

Features

• Highlights DECLARE, BEGIN, EXCEPTION, END of the block under the cursor
• Tracks nesting: always highlights the innermost block
• Three visual styles: border (default), background, bold
• Respects END IF, END LOOP, END CASE — does not confuse them with block ends
• Skips string literals and comments during parsing (no false positives)
• Works on .sql, .pls, .pkb, .pks, .pck, .fnc, .prc, .trg files
• Configurable language list, style, and enable/disable toggle

Quick demo

DECLARE                     -- highlighted (cursor is inside this block)
  v_count NUMBER;
BEGIN                       -- highlighted
  IF v_count > 0 THEN
    BEGIN                   -- NOT highlighted (inner block, cursor not here)
      NULL;
    END;
  END IF;
EXCEPTION                   -- highlighted
  WHEN OTHERS THEN NULL;
END;                        -- highlighted

Installation (development)

Prerequisites

Steps

# 1. Clone the repo
git clone <repo-url>
cd plsql-block-highlighter

# 2. Install dependencies
npm install

# 3. Compile TypeScript
npm run compile

Testing in VS Code (Extension Development Host)

The fastest way to try the extension is with the built-in Extension Development Host.

Option A — via the Run & Debug panel (recommended)

1. Open the project folder in VS Code: File > Open Folder…
2. Press F5 (or go to Run > Start Debugging)
3. VS Code opens a second window titled [Extension Development Host]
4. In that second window, open any .sql or .pls file
5. Move the cursor inside a PL/SQL block — the boundary keywords highlight automatically

The task watch runs automatically before launch, so any change you make to src/ is recompiled live. Just reload the Extension Development Host window with Ctrl+R / Cmd+R to pick up the change.

Option B — via the command line

# Compile once
npm run compile

# Then open VS Code pointing at the extension folder
code --extensionDevelopmentPath=$(pwd) .

Running the tests

Unit tests (fast, no VS Code required)

npm test
# or with watch mode:
npm run test:unit:watch
# or with coverage report:
npm run test:unit:coverage

Output example:

 ✓ test/unit/parser/tokenizer.test.ts        (7 tests)
 ✓ test/unit/parser/blockParser.test.ts      (8 tests)
 ✓ test/unit/parser/highlightService.test.ts (6 tests)

 Test Files  3 passed (3)
      Tests  21 passed (21)

Lint & format

npm run lint          # check for lint errors
npm run lint:fix      # auto-fix lint errors
npm run format:check  # check Prettier formatting
npm run format        # auto-format all files

Configuration

All settings live under plsqlBlockHighlighter.* in VS Code settings (Ctrl+, / Cmd+,, search for PL/SQL Block Highlighter).

Changing the style

Open your settings.json and add:

"plsqlBlockHighlighter.decorationStyle": "background"

Or use the Settings UI: search for PL/SQL Block Highlighter and pick a style from the dropdown.

Project structure

plsql-block-highlighter/
├── src/
│   ├── extension.ts                  # activate / deactivate entry point
│   ├── domain/
│   │   └── models.ts                 # Position, BlockKeyword, PlsqlBlock
│   ├── parser/
│   │   ├── tokenizer.ts              # hand-written lexer (strips comments/strings)
│   │   └── blockParser.ts            # stack-based block parser
│   ├── application/
│   │   └── highlightService.ts       # cursor → keywords service (pure, no VS Code)
│   └── editor/
│       ├── decorationManager.ts      # manages VS Code TextEditorDecorationType
│       └── editorEventHandler.ts     # wires selection / document / config events
├── test/
│   └── unit/
│       └── parser/
│           ├── tokenizer.test.ts
│           ├── blockParser.test.ts
│           └── highlightService.test.ts
├── .vscode/
│   ├── launch.json                   # F5 launch configs
│   └── tasks.json                    # build tasks
├── package.json
├── tsconfig.json
└── vitest.config.ts

How it works

1. Tokenizer (tokenizer.ts) — walks the raw text character by character, emitting keyword tokens while skipping string literals, single-line comments (--), and block comments (/* */).

2. Block parser (blockParser.ts) — maintains a stack of open BEGIN blocks. When it sees END IF, END LOOP, or END CASE it pops a separate non-block counter so those END tokens never close a real block.

3. Highlight service (highlightService.ts) — filters all parsed blocks to those whose range contains the cursor, then picks the deepest one and returns its keyword list.

4. Editor layer — EditorEventHandler listens to onDidChangeTextEditorSelection, onDidChangeTextDocument, and onDidChangeConfiguration, calling the service on every change and applying VS Code decorations via DecorationManager.

Supported file extensions

License

MIT