pkg/analysis_server/lib/src/services/correction/dart/convert_to_if_null.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:analysis_server/src/services/correction/dart/abstract_producer.dart';
import 'package:analysis_server/src/services/correction/fix.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/token.dart';
import 'package:analyzer_plugin/utilities/change_builder/change_builder_dart.dart';
import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
import 'package:analyzer_plugin/utilities/range_factory.dart';

class ConvertToIfNull extends CorrectionProducer {
  @override
  FixKind get fixKind => DartFixKind.CONVERT_TO_IF_NULL;

  @override
  Future<void> compute(DartChangeBuilder builder) async {
    var conditional = node.thisOrAncestorOfType<ConditionalExpression>();
    if (conditional == null) {
      return;
    }
    var condition = conditional.condition as BinaryExpression;
    Expression nullableExpression;
    Expression defaultExpression;
    if (condition.operator.type == TokenType.EQ_EQ) {
      nullableExpression = conditional.elseExpression;
      defaultExpression = conditional.thenExpression;
    } else {
      nullableExpression = conditional.thenExpression;
      defaultExpression = conditional.elseExpression;
    }
    await builder.addFileEdit(file, (DartFileEditBuilder builder) {
      builder.addReplacement(range.node(conditional), (builder) {
        builder.write(utils.getNodeText(nullableExpression));
        builder.write(' ?? ');
        builder.write(utils.getNodeText(defaultExpression));
      });
    });
  }

  /// Return an instance of this class. Used as a tear-off in `FixProcessor`.
  static ConvertToIfNull newInstance() => ConvertToIfNull();
}