build_web_compilers/lib/src/sdk_js_copy_builder.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:async';
import 'dart:io';

import 'package:build/build.dart';
import 'package:path/path.dart' as p;

import 'common.dart';

/// Copies the dart_sdk.js and require.js files from the sdk itself, into the
/// build_web_compilers package at `lib/dart_sdk.js` and `lib/require.js`.
class SdkJsCopyBuilder implements Builder {
  @override
  final buildExtensions = {
    r'$lib$': ['src/dev_compiler/dart_sdk.js', 'src/dev_compiler/require.js']
  };

  /// Path to the dart_sdk.js file that should be used for all ddc web apps.
  final _sdkJsLocation =
      p.join(sdkDir, 'lib', 'dev_compiler', 'kernel', 'amd', 'dart_sdk.js');

  /// Path to the require.js file that should be used for all ddc web apps.
  final _sdkRequireJsLocation =
      p.join(sdkDir, 'lib', 'dev_compiler', 'kernel', 'amd', 'require.js');

  @override
  FutureOr<void> build(BuildStep buildStep) async {
    if (buildStep.inputId.package != 'build_web_compilers') {
      throw StateError('This builder should only be applied to the '
          'build_web_compilers package');
    }
    await buildStep.writeAsBytes(
        AssetId('build_web_compilers', 'lib/src/dev_compiler/dart_sdk.js'),
        await File(_sdkJsLocation).readAsBytes());
    await buildStep.writeAsBytes(
        AssetId('build_web_compilers', 'lib/src/dev_compiler/require.js'),
        await File(_sdkRequireJsLocation).readAsBytes());
  }
}