pkg/vm/lib/modular/specializer/set_factory_specializer.dart

// Copyright (c) 2020, 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 'package:kernel/ast.dart';
import 'package:kernel/core_types.dart' show CoreTypes;
import 'package:kernel/core_types.dart';

import 'factory_specializer.dart';

/// Replaces invocation of Set factory constructors with
/// factories of VM-specific classes.
/// new LinkedHashSet<E>() => new _Set<E>()
class SetFactorySpecializer extends BaseSpecializer {
  final Procedure _linkedHashSetDefaultFactory;
  final Constructor _internalLinkedHashSetConstructor;

  SetFactorySpecializer(CoreTypes coreTypes)
      : _linkedHashSetDefaultFactory = assertNotNull(
          coreTypes.index.getProcedure(
            'dart:collection',
            'LinkedHashSet',
            '',
          ),
        ),
        _internalLinkedHashSetConstructor = assertNotNull(
          coreTypes.index.getConstructor(
            'dart:_compact_hash',
            '_Set',
            '',
          ),
        ) {
    transformers.addAll({
      _linkedHashSetDefaultFactory: transformLinkedHashSet,
    });
  }

  static T assertNotNull<T>(T t) {
    assert(t != null);
    return t;
  }

  TreeNode transformLinkedHashSet(StaticInvocation node) {
    final args = node.arguments;
    assert(args.positional.isEmpty);
    if (args.named.isEmpty) {
      return ConstructorInvocation(
        _internalLinkedHashSetConstructor,
        Arguments([], types: args.types),
      );
    }
    return node;
  }
}