lib/util/templateString.js

const cache = {};

/**
 * Produces a function which uses template strings to do simple interpolation from objects.
 *
 * Usage:
 *    const makeMeKing = generateTemplateString('${name} is now the king of ${country}!');
 *
 *    console.log(makeMeKing({ name: 'Bryan', country: 'Scotland'}));
 *    // Logs 'Bryan is now the king of Scotland!'
 * @memberof module:util
 */
const templateString = (template) => {
    let fn = cache[template];

    if (!fn) {
        // Replace ${expressions} (etc) with ${map.expressions}.

        const sanitized = template
            .replace(/\$\{([\s]*[^;\s{]+[\s]*)\}/g, (_, match) => `$\{map.${match.trim()}}`)
            // Afterwards, replace anything that's not ${map.expressions}' (etc) with a blank string.
            .replace(/(\$\{(?!map\.)[^}]+\})/g, '');

        // eslint-disable-next-line no-new-func
        fn = Function('map', `return \`${sanitized}\``);
    }

    return fn;
};

module.exports = templateString;