pkg/analysis_server/lib/src/services/correction/dart/convert_into_is_not.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/assist.dart';
import 'package:analysis_server/src/services/correction/dart/abstract_producer.dart';
import 'package:analysis_server/src/services/correction/util.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/precedence.dart';
import 'package:analyzer/dart/ast/token.dart';
import 'package:analyzer_plugin/utilities/assist/assist.dart';
import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
import 'package:analyzer_plugin/utilities/range_factory.dart';

class ConvertIntoIsNot extends CorrectionProducer {
  @override
  AssistKind get assistKind => DartAssistKind.CONVERT_INTO_IS_NOT;

  @override
  Future<void> compute(ChangeBuilder builder) async {
    // Find the is expression
    var isExpression = node.thisOrAncestorOfType<IsExpression>();
    if (isExpression == null) {
      var node = this.node;
      if (node is PrefixExpression) {
        var operand = node.operand;
        if (operand is ParenthesizedExpression &&
            operand.expression is IsExpression) {
          isExpression = operand.expression as IsExpression;
        }
      } else if (node is ParenthesizedExpression &&
          node.expression is IsExpression) {
        isExpression = node.expression as IsExpression;
      }
    }
    if (isExpression == null) {
      return;
    }
    if (isExpression.notOperator != null) {
      return;
    }
    // prepare enclosing ()
    var parent = isExpression.parent;
    if (parent is! ParenthesizedExpression) {
      return;
    }
    var parExpression = parent as ParenthesizedExpression;
    // prepare enclosing !()
    var parent2 = parent.parent;
    if (parent2 is! PrefixExpression) {
      return;
    }
    var prefExpression = parent2 as PrefixExpression;
    if (prefExpression.operator.type != TokenType.BANG) {
      return;
    }

    await builder.addDartFileEdit(file, (builder) {
      if (getExpressionParentPrecedence(prefExpression) >=
          Precedence.relational) {
        builder.addDeletion(range.token(prefExpression.operator));
      } else {
        builder.addDeletion(
            range.startEnd(prefExpression, parExpression.leftParenthesis));
        builder.addDeletion(
            range.startEnd(parExpression.rightParenthesis, prefExpression));
      }
      builder.addSimpleInsertion(isExpression.isOperator.end, '!');
    });
  }

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