77 lines
2.6 KiB
JavaScript
77 lines
2.6 KiB
JavaScript
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const { promises: fsPromises } = require('fs');
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const path = require('path');
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const commonPathPrefix = require('common-path-prefix');
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const findUp = require('find-up');
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/** @type {Map<string, string | undefined>} */
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let packageJsonTypeMap = new Map();
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/**
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* Infers the current active module system from loader context and options.
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* @this {import('webpack').loader.LoaderContext}
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* @param {import('webpack').ModuleFilenameHelpers} ModuleFilenameHelpers Webpack's module filename helpers.
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* @param {import('../types').NormalizedLoaderOptions} options The normalized loader options.
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* @return {Promise<'esm' | 'cjs'>} The inferred module system.
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*/
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async function getModuleSystem(ModuleFilenameHelpers, options) {
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// Check loader options -
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// if `esModule` is set we don't have to do extra guess work.
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switch (typeof options.esModule) {
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case 'boolean': {
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return options.esModule ? 'esm' : 'cjs';
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}
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case 'object': {
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if (
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options.esModule.include &&
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ModuleFilenameHelpers.matchPart(this.resourcePath, options.esModule.include)
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) {
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return 'esm';
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}
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if (
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options.esModule.exclude &&
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ModuleFilenameHelpers.matchPart(this.resourcePath, options.esModule.exclude)
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) {
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return 'cjs';
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}
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break;
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}
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default: // Do nothing
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}
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// Check current resource's extension
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if (/\.mjs$/.test(this.resourcePath)) return 'esm';
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if (/\.cjs$/.test(this.resourcePath)) return 'cjs';
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// Load users' `package.json` -
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// We will cache the results in a global variable so it will only be parsed once.
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let packageJsonType = packageJsonTypeMap.get(this.rootContext);
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if (!packageJsonType) {
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try {
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const commonPath = commonPathPrefix([this.rootContext, this.resourcePath], '/');
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const stopPath = path.resolve(commonPath, '..');
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const packageJsonPath = await findUp(
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(dir) => {
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if (dir === stopPath) return findUp.stop;
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return 'package.json';
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},
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{ cwd: path.dirname(this.resourcePath) }
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);
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const buffer = await fsPromises.readFile(packageJsonPath, { encoding: 'utf-8' });
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const rawPackageJson = buffer.toString('utf-8');
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({ type: packageJsonType } = JSON.parse(rawPackageJson));
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packageJsonTypeMap.set(this.rootContext, packageJsonType);
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} catch (e) {
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// Failed to parse `package.json`, do nothing.
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}
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}
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// Check `package.json` for the `type` field -
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// fallback to use `cjs` for anything ambiguous.
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return packageJsonType === 'module' ? 'esm' : 'cjs';
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}
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module.exports = getModuleSystem;
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