pkg/linter/lib/src/rules/prefer_adjacent_string_concatenation.dart

// Copyright (c) 2017, 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/analysis_rule/rule_context.dart';
import 'package:analyzer/analysis_rule/rule_visitor_registry.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/error/error.dart';

import '../analyzer.dart';

const _desc = r'Use adjacent strings to concatenate string literals.';

class PreferAdjacentStringConcatenation extends LintRule {
  PreferAdjacentStringConcatenation()
    : super(
        name: LintNames.prefer_adjacent_string_concatenation,
        description: _desc,
      );

  @override
  DiagnosticCode get diagnosticCode =>
      LinterLintCode.preferAdjacentStringConcatenation;

  @override
  void registerNodeProcessors(
    RuleVisitorRegistry registry,
    RuleContext context,
  ) {
    var visitor = _Visitor(this);
    registry.addBinaryExpression(this, visitor);
  }
}

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

  _Visitor(this.rule);

  @override
  void visitBinaryExpression(BinaryExpression node) {
    if (node.operator.type.lexeme == '+' &&
        node.leftOperand is StringLiteral &&
        node.rightOperand is StringLiteral) {
      rule.reportAtToken(node.operator);
    }
  }
}