| // Copyright (c) 2016, 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'Prefer final for variable declarations if they are not reassigned.'; |
| |
| const _details = r''' |
| |
| **DO** prefer declaring variables as final if they are not reassigned later in |
| the code. |
| |
| Declaring variables as final when possible is a good practice because it helps |
| avoid accidental reassignments and allows the compiler to do optimizations. |
| |
| **BAD:** |
| ``` |
| void badMethod() { |
| var label = 'hola mundo! badMethod'; // LINT |
| print(label); |
| } |
| ``` |
| |
| **GOOD:** |
| ``` |
| void goodMethod() { |
| final label = 'hola mundo! goodMethod'; |
| print(label); |
| } |
| ``` |
| |
| **GOOD:** |
| ``` |
| void mutableCase() { |
| var label = 'hola mundo! mutableCase'; |
| print(label); |
| label = 'hello world'; |
| print(label); |
| } |
| ``` |
| |
| '''; |
| |
| class PreferFinalLocals extends LintRule implements NodeLintRule { |
| PreferFinalLocals() |
| : super( |
| name: 'prefer_final_locals', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| List<String> get incompatibleRules => const ['unnecessary_final']; |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addVariableDeclaration(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitVariableDeclaration(VariableDeclaration node) { |
| if (node.isConst || |
| node.isFinal || |
| node.equals == null || |
| node.initializer == null) { |
| return; |
| } |
| |
| final function = node.thisOrAncestorOfType<FunctionBody>(); |
| if (function != null && |
| !function.isPotentiallyMutatedInScope(node.declaredElement)) { |
| rule.reportLint(node.name); |
| } |
| } |
| } |