Sequence Diagram Generator (sdg)

Sequence Diagram Generator (display name: Sequence-Diagram-Generator) is a Visual Studio Code extension that helps you generate PlantUML sequence diagrams from C++ source code.

It parses your workspace C++ files, extracts callable declarations, and generates a PlantUML (.puml) diagram that is rendered to SVG. The extension also provides a live preview panel with pan/zoom and highlights participants when you select them in the editor.

Key features

• Generate a PlantUML sequence diagram for a selected function in a C++ file.
• Pre-render a base diagram and per-participant diagrams (SVG) into docs/diagrams.
• Interactive preview panel with zoom, pan and double-click-to-reset.
• Editor decorations that underline participant names and allow quick highlighting of participant-specific diagrams by selecting names in the code.

Commands

• sdg.helloWorld — "Generate Sequence Diagram"
  • Run via the Command Palette (Ctrl+Shift+P) and choose "Generate Sequence Diagram". The command generates a diagram for the function at the top of your current selection.

Usage notes:

• Make a non-empty selection in a C++ file (the extension filters for languageId cpp) and run the command.
• If nothing is selected, the command will prompt you to select text.

How it works (implementation details)

• The extension uses the customastparser package to find callable declarations and generate PlantUML source via generatePlantUMLAsync.

• The generated .puml file is written to docs/diagrams/diagram.puml and the extension invokes PlantUML (bundled as lib/plantuml.jar) to render SVGs using:

  java -jar lib/plantuml.jar -tsvg docs/diagrams/diagram.puml

• A preview webview renders the produced SVG (base.svg by default) and the extension pre-renders one SVG per participant (naming: docs/diagrams/<participant>.svg).

Requirements

• Java runtime available on PATH (required to run plantuml.jar).
• lib/plantuml.jar should exist in the extension folder (the extension expects it at lib/plantuml.jar).
• A C/C++ compilation database (optional) if you use the helper that generates config for external tools — the extension includes configSetupAlt.ts which emits a YAML-style minimal config.

The extension lists the following extension dependency in package.json:

• vstirbu.vscode-mermaid-preview (optional helper for rendering mermaid if you use that in your workflow).

Configuration and output

• Generated diagrams and intermediate files are written to docs/diagrams in the workspace root.

Troubleshooting

• "No text selected" or "Please select some text": ensure you have an active text editor, a non-empty selection, and the file language is set to C++ (cpp).
• PlantUML errors / no SVGs produced: verify java is on PATH and that lib/plantuml.jar is present.
• If diagrams are not updating, check and clear docs/diagrams — the extension clears the folder before writing a new diagram.puml.

Development

Install dependencies and build the extension:

# from the extension root
npm install
npm run compile

Run a TypeScript watcher during development:

npm run watch

Run tests (uses the VS Code test runner configured in package.json):

npm test

Linting:

npm run lint

To debug the extension in VS Code, press F5 to open a new Extension Development Host.

Project structure (relevant files)

• src/extension.ts — activation, command registration (sdg.helloWorld), selection handling and wiring to the parser and preview.
• src/presentation.ts — creates the webview preview, pre-renders SVGs using PlantUML, and applies editor decorations.
• src/functionExtractor.ts — helper (currently minimal) for extracting selected text / functions.
• src/configSetupAlt.ts — helper to generate a minimal YAML config for diagram generation.
• lib/plantuml.jar — expected PlantUML JAR used to render .puml to .svg.

Contributing

If you'd like to contribute improvements or fixes, please fork the repository and open a pull request. Ensure TypeScript compiles and tests pass before opening a PR.

License

See package.json for project metadata. Add a LICENSE file if you wish to specify a license.

If you want, I can also add a short example (sample C++ snippet and the generated PlantUML) or include a screenshot of the preview.