pkg/analysis_server/lib/src/services/correction/dart/convert_into_is_not_empty.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:_fe_analyzer_shared/src/scanner/token.dart';
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/search/hierarchy.dart';
import 'package:analyzer/dart/ast/ast.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 ConvertIntoIsNotEmpty extends CorrectionProducer {
  @override
  AssistKind get assistKind => DartAssistKind.CONVERT_INTO_IS_NOT_EMPTY;

  @override
  Future<void> compute(ChangeBuilder builder) async {
    // prepare "expr.isEmpty"
    AstNode isEmptyAccess;
    SimpleIdentifier isEmptyIdentifier;
    if (node is SimpleIdentifier) {
      var identifier = node as SimpleIdentifier;
      var parent = identifier.parent;
      // normal case (but rare)
      if (parent is PropertyAccess) {
        isEmptyIdentifier = parent.propertyName;
        isEmptyAccess = parent;
      }
      // usual case
      if (parent is PrefixedIdentifier) {
        isEmptyIdentifier = parent.identifier;
        isEmptyAccess = parent;
      }
    }
    if (isEmptyIdentifier == null) {
      return;
    }
    // should be "isEmpty"
    var propertyElement = isEmptyIdentifier.staticElement;
    if (propertyElement == null || 'isEmpty' != propertyElement.name) {
      return;
    }
    // should have "isNotEmpty"
    var propertyTarget = propertyElement.enclosingElement;
    if (propertyTarget == null ||
        getChildren(propertyTarget, 'isNotEmpty').isEmpty) {
      return;
    }
    // should be in PrefixExpression
    if (isEmptyAccess.parent is! PrefixExpression) {
      return;
    }
    var prefixExpression = isEmptyAccess.parent as PrefixExpression;
    // should be !
    if (prefixExpression.operator.type != TokenType.BANG) {
      return;
    }

    await builder.addDartFileEdit(file, (builder) {
      builder.addDeletion(
          range.startStart(prefixExpression, prefixExpression.operand));
      builder.addSimpleReplacement(range.node(isEmptyIdentifier), 'isNotEmpty');
    });
  }

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