Function loadModule

packages/haul-core/src/utils/importModule.ts:38–202

(
  filename: string,
  provided: {
    resolve: Options['resolve'];
    parentModule: NonNullable<Options['parentModule']>;
    ignore: NonNullable<Options['ignore']>;
    cache: NonNullable<Options['cache']>;
    runtime: Runtime;
  }
)

const builtinModules = ['debug'].concat(Module.builtinModules);

function loadModule(
  filename: string,
  provided: {
    resolve: Options['resolve'];
    parentModule: NonNullable<Options['parentModule']>;
    ignore: NonNullable<Options['ignore']>;
    cache: NonNullable<Options['cache']>;
    runtime: Runtime;
  }
) {
  // Resolve absolute module location using parent's resolver.
  const moduleFilename = provided.resolve(filename);

  // Use native require if requested module is a build-in one.
  // Built-in modules are not kept in isolated cache, but in the native cache.
  if (builtinModules.includes(moduleFilename)) {
    return nativeRequire(moduleFilename);
  }

  // Use exports from cache is available.
  if (provided.cache[moduleFilename]) {
    return provided.cache[moduleFilename].exports;
  }

  let moduleBody: string;
  try {
    moduleBody = fs.readFileSync(moduleFilename, 'utf8');
  } catch (error) {
    throw new Error(
      `Module '${filename}' resolved to '${moduleFilename}' not found: ${error.code}`
    );
  }

  // Instantiating a new Module will setup some some properties, but won't
  // load the module code by itself, so we can do it ourselves later.
  const module = new Module(moduleFilename, provided.parentModule);
  module.filename = moduleFilename;
  // Resolve lookup paths (for example paths to node_modules for each parent directory).
  module.paths = ((Module as unknown) as {
    _resolveLookupPaths: (request: string, parent?: Module) => string[][];
  })
    ._resolveLookupPaths(module.filename, provided.parentModule)
    .reduce(
      (acc, item) =>
        Array.isArray(item) ? acc.concat(...item) : acc.concat(item),
      []
    )
    .concat(path.dirname(module.filename));
  provided.cache[module.id] = module;

  // Create resolver for this module.
  const currentResolve = ((Module.createRequireFromPath(
    module.filename
  ) as unknown) as {
    resolve: RequireResolve;
  }).resolve;

  // Create require function for this module.