Peggy Language Support

Syntax highlighting and error reporting for Peggy in Visual Studio Code.

Install

See the Marketplace.

Preferences

• peggyLanguageServer.consoleInfo [default: false]: Show info messages that don't have locations in the console. Examples include diagnostics about which compiler passes have been run. This is mostly useful for debugging the extension.
• peggyLanguageServer.markInfo [default: true]: Mark all diagnostics, even merely informative ones. Some grammar compiler passes will give informative messages about optimizations. Those may be more annoying to you than helpful, depending on your approach to grammar writing.
• peggyLanguageServer.debounceMS [default: 200] Amount of time to wait after a file has changed before running. Longer times use less CPU but are less responsive.
• peggyLanguageServer.filePattern [default: %s/%s.js] Convert a grammar name to a JS file to output, using this first %s as the directory and the second %s as the unsuffixed name of the grammar. This is useful in a per- workspace configuration file so that import and require work from the correct output directory.

Syntax Highlighting

Error Reporting

Errors in the grammar are highlighted.

Go to / Peek Definition

Right-click a rule name, and go to its definition.

Go to / Peek References

Right click a rule name, and see all of the places it is used.

Rename Symbol

Rename a rule and all of the places that it is used.

Outline / Symbol Support

See the current rule in the breadcrumbs at the top of the editor, and a list of all of the rules in the Outline view.

Live Preview

Live edit and test your Grammars, optionally starting at the rule under cursor.

Problem Matchers

Report problems of your code in the Problems view when peggy is run in a task. The extension provides two problem matchers: $peggy and $peggy-watch.

Configure them like the following in your .vscode/tasks.json:

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "npm: compile (peggy)",
      "type": "npm",
      "group": {
        "kind": "build",
        "isDefault": true
      },
      "script": "compile",
      "problemMatcher": "$peggy"
    },
    {
      "label": "npm: watch (peggy)",
      "type": "npm",
      "group": "build",
      "script": "watch",
      "isBackground": true,
      "problemMatcher": "$peggy-watch"
    }
  ]
}

and in your package.json:

{
  "scripts": {
    "compile": "peggy grammar.peggy",
    "watch": "peggy --watch grammar.peggy"
  },
  "devDependencies": {
    "peggy": "^5.0.3"
  }
}

Then you can compile your grammar via the command palette with "Tasks: Run Task". See Task / VS Code Extension API for more details.

Tips

Name your grammar like this for optimal experience: grammar_name.language_extension.peggy. Where language_extension is the extension of the language you're parsing. This will provide syntax highlighting if you have a matching language server installed.

Contributing

Feel free to contribute to this extension here. Please read the CONTRIBUTING.md.

Origins

Based on code-pegjs-language by Tobias Kahlert