| // 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/dart/ast/ast.dart'; |
| import 'package:analyzer/dart/ast/token.dart'; |
| import 'package:analyzer/dart/ast/visitor.dart'; |
| |
| import '../analyzer.dart'; |
| import '../util/dart_type_utilities.dart'; |
| |
| const _desc = r'Use interpolation to compose strings and values.'; |
| |
| const _details = r''' |
| |
| **PREFER** using interpolation to compose strings and values. |
| |
| Using interpolation when composing strings and values is usually easier to write |
| and read than concatenation. |
| |
| **BAD:** |
| ``` |
| 'Hello, ' + name + '! You are ' + (year - birth) + ' years old.'; |
| ``` |
| |
| **GOOD:** |
| ``` |
| 'Hello, $name! You are ${year - birth} years old.'; |
| ``` |
| |
| '''; |
| |
| class PreferInterpolationToComposeStrings extends LintRule |
| implements NodeLintRule { |
| PreferInterpolationToComposeStrings() |
| : super( |
| name: 'prefer_interpolation_to_compose_strings', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addBinaryExpression(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| final skippedNodes = <AstNode>{}; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitBinaryExpression(BinaryExpression node) { |
| if (skippedNodes.contains(node)) { |
| return; |
| } |
| if (node.operator.type == TokenType.PLUS) { |
| //OK(#735): str1 + str2 |
| if (node.leftOperand is! StringLiteral && |
| node.rightOperand is! StringLiteral) { |
| return; |
| } |
| //OK: 'foo' + 'bar' |
| if (node.leftOperand is StringLiteral && |
| node.rightOperand is StringLiteral) { |
| return; |
| } |
| if (DartTypeUtilities.isClass( |
| node.leftOperand.staticType, 'String', 'dart.core') || |
| DartTypeUtilities.isClass( |
| node.rightOperand.staticType, 'String', 'dart.core')) { |
| DartTypeUtilities.traverseNodesInDFS(node).forEach(skippedNodes.add); |
| rule.reportLint(node); |
| } |
| } |
| } |
| } |