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/**
* @param {object} exports
* @param {Set<string>} 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;