babel-plugin-transform-import-meta
Version:
Transforms import.meta for nodejs environments
155 lines (150 loc) • 9.08 kB
JavaScript
;
Object.defineProperty(exports, '__esModule', { value: true });
var template = require('@babel/template');
/**
* Rewrites known `import.meta`[1] properties into equivalent non-module node.js
* expressions. In order to maintain compatibility with plugins transforming
* non-standard properties, this plugin transforms only known properties and
* does not touch expressions with unknown or without member property access.
* Properties known to this plugin:
*
* - `url`[2]
*
* [1]: https://github.com/tc39/proposal-import-meta
* [2]: https://html.spec.whatwg.org/#hostgetimportmetaproperties
*/
function index () {
return {
name: 'transform-import-meta',
visitor: {
// eslint-disable-next-line complexity -- I don't know how to do it better
Program(path, state) {
var _a;
const { module: target = 'CommonJS' } = (_a = state.opts) !== null && _a !== void 0 ? _a : {};
// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- user input may not match type
if (target !== 'CommonJS' && target !== 'ES6') {
throw new Error('Invalid target, must be one of: "CommonJS" or "ES6"');
}
const urlMetas = [];
const filenameMetas = [];
const dirnameMetas = [];
const resolveMetas = [];
const urlScopeIdentifiers = new Set();
const resolveScopeIdentifiers = new Set();
// Gather all of the relevant data for import.meta's that we're going to replace later.
path.traverse({
// eslint-disable-next-line complexity -- I don't know how to do it better
MemberExpression(memberExpPath) {
const { node } = memberExpPath;
if (node.object.type === 'MetaProperty' &&
node.object.meta.name === 'import' &&
node.object.property.name === 'meta' &&
node.property.type === 'Identifier' &&
node.property.name === 'url') {
urlMetas.push(memberExpPath);
for (const name of Object.keys(memberExpPath.scope.getAllBindings())) {
urlScopeIdentifiers.add(name);
}
}
if (node.object.type === 'MetaProperty' &&
node.object.meta.name === 'import' &&
node.object.property.name === 'meta' &&
node.property.type === 'Identifier' &&
node.property.name === 'filename') {
filenameMetas.push(memberExpPath);
}
if (node.object.type === 'MetaProperty' &&
node.object.meta.name === 'import' &&
node.object.property.name === 'meta' &&
node.property.type === 'Identifier' &&
node.property.name === 'dirname') {
dirnameMetas.push(memberExpPath);
}
},
CallExpression(callExpPath) {
const { node } = callExpPath;
if (node.callee.type === 'MemberExpression' &&
node.callee.object.type === 'MetaProperty' &&
node.callee.object.meta.name === 'import' &&
node.callee.object.property.name === 'meta' &&
node.callee.property.type === 'Identifier' &&
node.callee.property.name === 'resolve') {
resolveMetas.push(callExpPath);
for (const name of Object.keys(callExpPath.scope.getAllBindings())) {
resolveScopeIdentifiers.add(name);
}
}
},
OptionalCallExpression(callExpPath) {
const { node } = callExpPath;
if (node.callee.type === 'MemberExpression' &&
node.callee.object.type === 'MetaProperty' &&
node.callee.object.meta.name === 'import' &&
node.callee.object.property.name === 'meta' &&
node.callee.property.type === 'Identifier' &&
node.callee.property.name === 'resolve') {
resolveMetas.push(callExpPath);
for (const name of Object.keys(callExpPath.scope.getAllBindings())) {
resolveScopeIdentifiers.add(name);
}
}
}
});
// For url and resolve, we'll potentially need to add imports, depending on the target.
if ((urlMetas.length !== 0) || (resolveMetas.length !== 0)) {
// eslint-disable-next-line @typescript-eslint/init-declarations -- no obvious default
let metaUrlReplacement;
// eslint-disable-next-line @typescript-eslint/init-declarations -- no obvious default
let metaResolveReplacement;
switch (target) {
case 'CommonJS': {
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion -- deterministic casting
metaUrlReplacement = template.smart.ast `require('url').pathToFileURL(__filename).toString()`;
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion -- deterministic casting
metaResolveReplacement = (args) => template.smart.ast `require('url').pathToFileURL(require.resolve(${args})).toString()`;
break;
}
case 'ES6': {
let urlId = 'url';
let createRequireId = 'createRequire';
while (urlScopeIdentifiers.has(urlId) || resolveScopeIdentifiers.has(urlId)) {
urlId = path.scope.generateUidIdentifier('url').name;
}
while (resolveScopeIdentifiers.has(createRequireId)) {
createRequireId = path.scope.generateUidIdentifier('createRequire').name;
}
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion -- deterministic casting
path.node.body.unshift(template.smart.ast `import ${urlId} from 'url';`);
if (resolveMetas.length !== 0) {
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion -- deterministic casting
path.node.body.unshift(template.smart.ast `import { createRequire as ${createRequireId} } from 'module';`);
}
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion -- deterministic casting
metaUrlReplacement = template.smart.ast `${urlId}.pathToFileURL(__filename).toString()`;
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion -- deterministic casting
metaResolveReplacement = (args) => template.smart.ast `${urlId}.pathToFileURL(${createRequireId}(${urlId}.pathToFileURL(__filename).toString()).resolve(${args})).toString()`;
break;
}
}
for (const meta of urlMetas) {
meta.replaceWith(metaUrlReplacement);
}
for (const meta of resolveMetas) {
meta.replaceWith(metaResolveReplacement(meta.node.arguments));
}
}
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion -- deterministic casting
const metaFilenameReplacement = template.smart.ast `__filename`;
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion -- deterministic casting
const metaDirnameReplacement = template.smart.ast `__dirname`;
for (const meta of filenameMetas) {
meta.replaceWith(metaFilenameReplacement);
}
for (const meta of dirnameMetas) {
meta.replaceWith(metaDirnameReplacement);
}
}
}
};
}
exports.default = index;