ivy-extract-loader.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
import { MessageExtractor } from '@angular/localize/src/tools/src/extract/extraction';
import { getOptions } from 'loader-utils';
import * as nodePath from 'path';

interface LocalizeExtractLoaderOptions {
  messageHandler: (messages: import('@angular/localize').ɵParsedMessage[]) => void;
}

export default function localizeExtractLoader(
  this: import('webpack').loader.LoaderContext,
  content: string,
  // Source map types are broken in the webpack type definitions
  // tslint:disable-next-line: no-any
  map: any,
) {
  const loaderContext = this;

  // Casts are needed to workaround the loader-utils typings limited support for option values
  const options = (getOptions(this) as unknown) as LocalizeExtractLoaderOptions | undefined;

  // Setup a Webpack-based logger instance
  const logger = {
    // level 2 is warnings
    level: 2,
    debug(...args: string[]): void {
      // tslint:disable-next-line: no-console
      console.debug(...args);
    },
    info(...args: string[]): void {
      loaderContext.emitWarning(args.join(''));
    },
    warn(...args: string[]): void {
      loaderContext.emitWarning(args.join(''));
    },
    error(...args: string[]): void {
      loaderContext.emitError(args.join(''));
    },
  };

  let filename = loaderContext.resourcePath;
  if (map?.file) {
    // The extractor's internal sourcemap handling expects the filenames to match
    filename = nodePath.join(loaderContext.context, map.file);
  }

  // Setup a virtual file system instance for the extractor
  // * MessageExtractor itself uses readFile, relative and resolve
  // * Internal SourceFileLoader (sourcemap support) uses dirname, exists, readFile, and resolve
  const filesystem = {
    readFile(path: string): string {
      if (path === filename) {
        return content;
      } else if (path === filename + '.map') {
        return typeof map === 'string' ? map : JSON.stringify(map);
      } else {
        throw new Error('Unknown file requested: ' + path);
      }
    },
    relative(from: string, to: string): string {
      return nodePath.relative(from, to);
    },
    resolve(...paths: string[]): string {
      return nodePath.resolve(...paths);
    },
    exists(path: string): boolean {
      return path === filename || path === filename + '.map';
    },
    dirname(path: string): string {
      return nodePath.dirname(path);
    },
  };

  // tslint:disable-next-line: no-any
  const extractor = new MessageExtractor(filesystem as any, logger, {
    // tslint:disable-next-line: no-any
    basePath: this.rootContext as any,
    useSourceMaps: !!map,
  });

  const messages = extractor.extractMessages(filename);
  if (messages.length > 0) {
    options?.messageHandler(messages);
  }

  // Pass through the original content now that messages have been extracted
  this.callback(undefined, content, map);
}