index.js

/* eslint-disable no-param-reassign, no-shadow, no-undefined */
import { dirname, normalize, resolve, sep } from 'path';

import builtinList from 'builtin-modules';
import deepMerge from 'deepmerge';
import isModule from 'is-module';

import { isDirCached, isFileCached, readCachedFile } from './cache';
import { exists, readFile, realpath } from './fs';
import { resolveImportSpecifiers } from './resolveImportSpecifiers';
import { getMainFields, getPackageName, normalizeInput } from './util';
import handleDeprecatedOptions from './deprecated-options';

const builtins = new Set(builtinList);
const ES6_BROWSER_EMPTY = '\0node-resolve:empty.js';
const deepFreeze = (object) => {
  Object.freeze(object);

  for (const value of Object.values(object)) {
    if (typeof value === 'object' && !Object.isFrozen(value)) {
      deepFreeze(value);
    }
  }

  return object;
};

const baseConditions = ['default', 'module'];
const baseConditionsEsm = [...baseConditions, 'import'];
const baseConditionsCjs = [...baseConditions, 'require'];
const defaults = {
  dedupe: [],
  // It's important that .mjs is listed before .js so that Rollup will interpret npm modules
  // which deploy both ESM .mjs and CommonJS .js files as ESM.
  extensions: ['.mjs', '.js', '.json', '.node'],
  resolveOnly: [],
  moduleDirectories: ['node_modules']
};
export const DEFAULTS = deepFreeze(deepMerge({}, defaults));

export function nodeResolve(opts = {}) {
  const { warnings } = handleDeprecatedOptions(opts);

  const options = { ...defaults, ...opts };
  const { extensions, jail, moduleDirectories } = options;
  const conditionsEsm = [...baseConditionsEsm, ...(options.exportConditions || [])];
  const conditionsCjs = [...baseConditionsCjs, ...(options.exportConditions || [])];
  const packageInfoCache = new Map();
  const idToPackageInfo = new Map();
  const mainFields = getMainFields(options);
  const useBrowserOverrides = mainFields.indexOf('browser') !== -1;
  const isPreferBuiltinsSet = options.preferBuiltins === true || options.preferBuiltins === false;
  const preferBuiltins = isPreferBuiltinsSet ? options.preferBuiltins : true;
  const rootDir = options.rootDir || process.cwd();
  let { dedupe } = options;
  let rollupOptions;

  if (typeof dedupe !== 'function') {
    dedupe = (importee) =>
      options.dedupe.includes(importee) || options.dedupe.includes(getPackageName(importee));
  }

  const resolveOnly = options.resolveOnly.map((pattern) => {
    if (pattern instanceof RegExp) {
      return pattern;
    }
    const normalized = pattern.replace(/[\\^$*+?.()|[\]{}]/g, '\\$&');
    return new RegExp(`^${normalized}$`);
  });

  const browserMapCache = new Map();
  let preserveSymlinks;

  return {
    name: 'node-resolve',

    buildStart(options) {
      rollupOptions = options;

      for (const warning of warnings) {
        this.warn(warning);
      }

      ({ preserveSymlinks } = options);
    },

    generateBundle() {
      readCachedFile.clear();
      isFileCached.clear();
      isDirCached.clear();
    },

    async resolveId(importee, importer, opts) {
      if (importee === ES6_BROWSER_EMPTY) {
        return importee;
      }
      // ignore IDs with null character, these belong to other plugins
      if (/\0/.test(importee)) return null;

      if (/\0/.test(importer)) {
        importer = undefined;
      }

      // strip query params from import
      const [importPath, params] = importee.split('?');
      const importSuffix = `${params ? `?${params}` : ''}`;
      importee = importPath;

      const baseDir = !importer || dedupe(importee) ? rootDir : dirname(importer);

      // https://github.com/defunctzombie/package-browser-field-spec
      const browser = browserMapCache.get(importer);
      if (useBrowserOverrides && browser) {
        const resolvedImportee = resolve(baseDir, importee);
        if (browser[importee] === false || browser[resolvedImportee] === false) {
          return ES6_BROWSER_EMPTY;
        }
        const browserImportee =
          browser[importee] ||
          browser[resolvedImportee] ||
          browser[`${resolvedImportee}.js`] ||
          browser[`${resolvedImportee}.json`];
        if (browserImportee) {
          importee = browserImportee;
        }
      }

      const parts = importee.split(/[/\\]/);
      let id = parts.shift();
      let isRelativeImport = false;

      if (id[0] === '@' && parts.length > 0) {
        // scoped packages
        id += `/${parts.shift()}`;
      } else if (id[0] === '.') {
        // an import relative to the parent dir of the importer
        id = resolve(baseDir, importee);
        isRelativeImport = true;
      }

      if (
        !isRelativeImport &&
        resolveOnly.length &&
        !resolveOnly.some((pattern) => pattern.test(id))
      ) {
        if (normalizeInput(rollupOptions.input).includes(importee)) {
          return null;
        }
        return false;
      }

      const importSpecifierList = [];

      if (importer === undefined && !importee[0].match(/^\.?\.?\//)) {
        // For module graph roots (i.e. when importer is undefined), we
        // need to handle 'path fragments` like `foo/bar` that are commonly
        // found in rollup config files. If importee doesn't look like a
        // relative or absolute path, we make it relative and attempt to
        // resolve it. If we don't find anything, we try resolving it as we
        // got it.
        importSpecifierList.push(`./${importee}`);
      }

      const importeeIsBuiltin = builtins.has(importee);

      if (importeeIsBuiltin) {
        // The `resolve` library will not resolve packages with the same
        // name as a node built-in module. If we're resolving something
        // that's a builtin, and we don't prefer to find built-ins, we
        // first try to look up a local module with that name. If we don't
        // find anything, we resolve the builtin which just returns back
        // the built-in's name.
        importSpecifierList.push(`${importee}/`);
      }

      // TypeScript files may import '.js' to refer to either '.ts' or '.tsx'
      if (importer && importee.endsWith('.js')) {
        for (const ext of ['.ts', '.tsx']) {
          if (importer.endsWith(ext) && extensions.includes(ext)) {
            importSpecifierList.push(importee.replace(/.js$/, ext));
          }
        }
      }

      importSpecifierList.push(importee);

      const warn = (...args) => this.warn(...args);
      const isRequire =
        opts && opts.custom && opts.custom['node-resolve'] && opts.custom['node-resolve'].isRequire;
      const exportConditions = isRequire ? conditionsCjs : conditionsEsm;

      const resolvedWithoutBuiltins = await resolveImportSpecifiers({
        importSpecifierList,
        exportConditions,
        warn,
        packageInfoCache,
        extensions,
        mainFields,
        preserveSymlinks,
        useBrowserOverrides,
        baseDir,
        moduleDirectories
      });

      const resolved =
        importeeIsBuiltin && preferBuiltins
          ? {
              packageInfo: undefined,
              hasModuleSideEffects: () => null,
              hasPackageEntry: true,
              packageBrowserField: false
            }
          : resolvedWithoutBuiltins;
      if (!resolved) {
        return null;
      }

      const { packageInfo, hasModuleSideEffects, hasPackageEntry, packageBrowserField } = resolved;
      let { location } = resolved;
      if (packageBrowserField) {
        if (Object.prototype.hasOwnProperty.call(packageBrowserField, location)) {
          if (!packageBrowserField[location]) {
            browserMapCache.set(location, packageBrowserField);
            return ES6_BROWSER_EMPTY;
          }
          location = packageBrowserField[location];
        }
        browserMapCache.set(location, packageBrowserField);
      }

      if (hasPackageEntry && !preserveSymlinks) {
        const fileExists = await exists(location);
        if (fileExists) {
          location = await realpath(location);
        }
      }

      idToPackageInfo.set(location, packageInfo);

      if (hasPackageEntry) {
        if (importeeIsBuiltin && preferBuiltins) {
          if (!isPreferBuiltinsSet && resolvedWithoutBuiltins && resolved !== importee) {
            this.warn(
              `preferring built-in module '${importee}' over local alternative at '${resolvedWithoutBuiltins.location}', pass 'preferBuiltins: false' to disable this behavior or 'preferBuiltins: true' to disable this warning`
            );
          }
          return false;
        } else if (jail && location.indexOf(normalize(jail.trim(sep))) !== 0) {
          return null;
        }
      }

      if (options.modulesOnly && (await exists(location))) {
        const code = await readFile(location, 'utf-8');
        if (isModule(code)) {
          return {
            id: `${location}${importSuffix}`,
            moduleSideEffects: hasModuleSideEffects(location)
          };
        }
        return null;
      }
      const result = {
        id: `${location}${importSuffix}`,
        moduleSideEffects: hasModuleSideEffects(location)
      };
      return result;
    },

    load(importee) {
      if (importee === ES6_BROWSER_EMPTY) {
        return 'export default {};';
      }
      return null;
    },

    getPackageInfoForId(id) {
      return idToPackageInfo.get(id);
    }
  };
}

export default nodeResolve;