lib/src/rules/avoid_escaping_inner_quotes.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:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/visitor.dart';

import '../analyzer.dart';

const _desc = r'Avoid escaping inner quotes by converting surrounding quotes.';

const _details = r'''
Avoid escaping inner quotes by converting surrounding quotes.

**BAD:**
```dart
var s = 'It\'s not fun';
```

**GOOD:**
```dart
var s = "It's not fun";
```

''';

class AvoidEscapingInnerQuotes extends LintRule {
  static const LintCode code = LintCode(
      'avoid_escaping_inner_quotes', "Unnecessary escape of '{0}'.",
      correctionMessage: "Try changing the outer quotes to '{1}'.");

  AvoidEscapingInnerQuotes()
      : super(
            name: 'avoid_escaping_inner_quotes',
            description: _desc,
            details: _details,
            group: Group.style);

  @override
  LintCode get lintCode => code;

  @override
  void registerNodeProcessors(
      NodeLintRegistry registry, LinterContext context) {
    var visitor = _Visitor(this);
    registry.addSimpleStringLiteral(this, visitor);
    registry.addStringInterpolation(this, visitor);
  }
}

class _Visitor extends SimpleAstVisitor<void> {
  final LintRule rule;

  _Visitor(this.rule);

  @override
  void visitSimpleStringLiteral(SimpleStringLiteral node) {
    if (node.isRaw || node.isMultiline) return;
    _check(node, node.value, node.isSingleQuoted);
  }

  @override
  void visitStringInterpolation(StringInterpolation node) {
    if (node.isRaw || node.isMultiline) return;

    var text = StringBuffer();
    for (var element in node.elements) {
      if (element is InterpolationString) {
        text.write(element.value);
      }
    }
    _check(node, text.toString(), node.isSingleQuoted);
  }

  void _check(AstNode node, String text, bool isSingleQuoted) {
    if (_isChangeable(text, isSingleQuoted: isSingleQuoted)) {
      rule.reportLint(node,
          arguments: [isSingleQuoted ? "'" : '"', isSingleQuoted ? '"' : "'"]);
    }
  }

  bool _isChangeable(String text, {required bool isSingleQuoted}) =>
      text.contains(isSingleQuoted ? "'" : '"') &&
      !text.contains(isSingleQuoted ? '"' : "'");
}