source: node_modules/prismjs/components/index.js

const components = require('../components.js');
const getLoader = require('../dependencies');


/**
 * The set of all languages which have been loaded using the below function.
 *
 * @type {Set<string>}
 */
const loadedLanguages = new Set();

/**
 * Loads the given languages and adds them to the current Prism instance.
 *
 * If no languages are provided, __all__ Prism languages will be loaded.
 *
 * @param {string|string[]} [languages]
 * @returns {void}
 */
function loadLanguages(languages) {
        if (languages === undefined) {
                languages = Object.keys(components.languages).filter(l => l != 'meta');
        } else if (!Array.isArray(languages)) {
                languages = [languages];
        }

        // the user might have loaded languages via some other way or used `prism.js` which already includes some
        // we don't need to validate the ids because `getLoader` will ignore invalid ones
        const loaded = [...loadedLanguages, ...Object.keys(Prism.languages)];

        getLoader(components, languages, loaded).load(lang => {
                if (!(lang in components.languages)) {
                        if (!loadLanguages.silent) {
                                console.warn('Language does not exist: ' + lang);
                        }
                        return;
                }

                const pathToLanguage = './prism-' + lang;

                // remove from require cache and from Prism
                delete require.cache[require.resolve(pathToLanguage)];
                delete Prism.languages[lang];

                require(pathToLanguage);

                loadedLanguages.add(lang);
        });
}

/**
 * Set this to `true` to prevent all warning messages `loadLanguages` logs.
 */
loadLanguages.silent = false;

module.exports = loadLanguages;