pkg/nnbd_migration/lib/src/utilities/resolution_utils.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 'package:analyzer/dart/ast/token.dart';
import 'package:analyzer/src/generated/resolver.dart';

/// This mixin provides utilities that are useful to visitors implementing
/// resolution-like behaviors.
mixin ResolutionUtils {
  List<String> _objectGetNames;

  TypeProvider get typeProvider;

  /// Determines whether the given getter or method name is declared on
  /// `Object` (and is hence valid to call on a nullable type).
  bool isDeclaredOnObject(String name) =>
      (_objectGetNames ??= _computeObjectGetNames()).contains(name);

  /// Determines whether the given property/method access token is null-aware.
  bool isNullAwareToken(TokenType tokenType) {
    switch (tokenType) {
      case TokenType.PERIOD:
      case TokenType.PERIOD_PERIOD:
        return false;
      case TokenType.QUESTION_PERIOD:
        return true;
      default:
        throw new UnimplementedError(
            'Unexpected token passed to isNullAwareToken: $tokenType');
    }
  }

  List<String> _computeObjectGetNames() {
    var result = <String>[];
    var objectClass = typeProvider.objectType.element;
    for (var accessor in objectClass.accessors) {
      assert(accessor.isGetter);
      assert(!accessor.name.startsWith('_'));
      result.add(accessor.name);
    }
    for (var method in objectClass.methods) {
      assert(!method.name.startsWith('_'));
      result.add(method.name);
    }
    return result;
  }
}