/** * @param {object} exports * @param {Set} keys */ function loop(exports, keys) { if (typeof exports === 'string') { return exports; } if (exports) { let idx, tmp; if (Array.isArray(exports)) { for (idx=0; idx < exports.length; idx++) { if (tmp = loop(exports[idx], keys)) return tmp; } } else { for (idx in exports) { if (keys.has(idx)) { return loop(exports[idx], keys); } } } } } /** * @param {string} name The package name * @param {string} entry The target entry, eg "." * @param {number} [condition] Unmatched condition? */ function bail(name, entry, condition) { throw new Error( condition ? `No known conditions for "${entry}" entry in "${name}" package` : `Missing "${entry}" export in "${name}" package` ); } /** * @param {string} name the package name * @param {string} entry the target path/import */ function toName(name, entry) { return entry === name ? '.' : entry[0] === '.' ? entry : entry.replace(new RegExp('^' + name + '\/'), './'); } /** * @param {object} pkg package.json contents * @param {string} [entry] entry name or import path * @param {object} [options] * @param {boolean} [options.browser] * @param {boolean} [options.require] * @param {string[]} [options.conditions] * @param {boolean} [options.unsafe] */ function resolve(pkg, entry='.', options={}) { let { name, exports } = pkg; if (exports) { let { browser, require, unsafe, conditions=[] } = options; let target = toName(name, entry); if (target[0] !== '.') target = './' + target; if (typeof exports === 'string') { return target === '.' ? exports : bail(name, target); } let allows = new Set(['default', ...conditions]); unsafe || allows.add(require ? 'require' : 'import'); unsafe || allows.add(browser ? 'browser' : 'node'); let key, tmp, isSingle=false; for (key in exports) { isSingle = key[0] !== '.'; break; } if (isSingle) { return target === '.' ? loop(exports, allows) || bail(name, target, 1) : bail(name, target); } if (tmp = exports[target]) { return loop(tmp, allows) || bail(name, target, 1); } for (key in exports) { tmp = key[key.length - 1]; if (tmp === '/' && target.startsWith(key)) { return (tmp = loop(exports[key], allows)) ? (tmp + target.substring(key.length)) : bail(name, target, 1); } if (tmp === '*' && target.startsWith(key.slice(0, -1))) { // do not trigger if no *content* to inject if (target.substring(key.length - 1).length > 0) { return (tmp = loop(exports[key], allows)) ? tmp.replace('*', target.substring(key.length - 1)) : bail(name, target, 1); } } } return bail(name, target); } } /** * @param {object} pkg * @param {object} [options] * @param {string|boolean} [options.browser] * @param {string[]} [options.fields] */ function legacy(pkg, options={}) { let i=0, value, browser = options.browser, fields = options.fields || ['module', 'main']; if (browser && !fields.includes('browser')) { fields.unshift('browser'); } for (; i < fields.length; i++) { if (value = pkg[fields[i]]) { if (typeof value == 'string') { // } else if (typeof value == 'object' && fields[i] == 'browser') { if (typeof browser == 'string') { value = value[browser=toName(pkg.name, browser)]; if (value == null) return browser; } } else { continue; } return typeof value == 'string' ? ('./' + value.replace(/^\.?\//, '')) : value; } } } exports.legacy = legacy; exports.resolve = resolve;