Adding a new language

If you want to add a new language to the site, you should follow this steps:

• Add the new language to the exported languages variable in lib/languages.js:

  • The syntax is as follows:

  'language-key': {
    name: YOUR_LANGUAGE_DISPLAY_NAME,
    monaco: MONACO_MODE_ID,
    extensions: ARRAY_OF_FILE_EXTENSIONS_OF_YOUR_LANGUAGE,
    alias: [], // Leave empty unless needed
  }
  

  • If the language is supported by Monaco Editor (You can find the list here), you should add it to the list of languages inside the MonacoEditorWebpackPlugin config in webpack.config.js
  • If not, you should implement your own language mode; see static/modes/asm-mode.js as an example. Don't forget to require your mode file in static/modes/_all.js, in alphabetical order
  • language-key is how your language will be referred internally by the code. In the rest of this document, replace {language-key} by the corresponding value in the real files.

• Add a lib/compilers/{language-key}.js file using the template below:

  import { BaseCompiler } from '../base-compiler';
  
  export class LanguageCompiler extends BaseCompiler {
      static get key() { return 'language'; }
  }
  

  • The value returned by key above corresponds to the compilerType value in etc/config/{lenguage-key}.defaults.properties (Explained below). This is usually {language-key}, but you can use whatever fits best
  • Override the OptionsForFilter method from the base class
  • Comment out the line saying fs.remove(result.dirPath); in base-compiler.js, so the latest CE compile attempt remains on disk for you to review
    • Remember to undo this change before opening a PR!
  • For reference, the basic behaviour of BaseCompiler is:
    • make a random temporary folder
    • save example.extension to the new folder, the full path to this is the inputFilename
    • the outputFilename is determined by the getOutputFilename() method
    • execute the compiler.exe with the arguments from OptionsForFilter() and adding inputFilename
    • be aware that the language class is only instanced once, so storing state is not possible
  • If the compiler has problems with the defaults, you will have to override the runCompiler() method too. When overriding it, here are some ideas
    • set execOptions.customCwd parameter if the working directory needs to be somewhere else
    • set execOptions.env parameter if the compiler requires special environment variables
    • manipulate options, but make sure the user can still add their own arguments in CE

• Add your LanguageCompiler to lib/compilers/_all.js, in alphabetical order

• Add a etc/config/{language-key}.local.properties file:

  • The syntax for its basic contents is documented in AddingACompiler.md
  • This file is ignored by Git, so that you can test the config locally
  • You should add 1 compiler for the language you want to test
  • Test the command line options of the language compilers outside CE

• Add a new file etc/config/{language-key}.defaults.properties. This is where a default configuration will live.

  • Usually, this loads default compilers from their usual paths on a normal installation (Check etc/config/c++.defaults.properties for an example)

• Of important note, for both files, is to properly define compilerType property in the newly added compilers. This should equal the value returned by your LanguageCompiler.key function

• Running make dev EXTRA_ARGS="--debug --language {language-key}" to tell CE to only load your new language

• You can check http://127.0.0.1:10240/api/compilers to be sure your language and compilers are there

• Make an installer in the infra repository

• Add your language files ({language-key}.*.properties and lib/compilers/{language-key}.js) to the list in .github/labeler.yml