| // Copyright (c) 2018, 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 'package:analyzer/dart/element/element.dart'; |
| |
| import '../analyzer.dart'; |
| |
| const _desc = r'Avoid double and int checks.'; |
| |
| const _details = r''' |
| |
| **AVOID** to check if type is double or int. |
| |
| When compiled to JS, integer values are represented as floats. That can lead to |
| some unexpected behavior when using either `is` or `is!` where the type is |
| either `int` or `double`. |
| |
| **BAD:** |
| ```dart |
| f(num x) { |
| if (x is double) { |
| ... |
| } else if (x is int) { |
| ... |
| } |
| } |
| ``` |
| |
| **GOOD:** |
| ```dart |
| f(dynamic x) { |
| if (x is num) { |
| ... |
| } else { |
| ... |
| } |
| } |
| ``` |
| |
| '''; |
| |
| class AvoidDoubleAndIntChecks extends LintRule implements NodeLintRule { |
| AvoidDoubleAndIntChecks() |
| : super( |
| name: 'avoid_double_and_int_checks', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| var visitor = _Visitor(this, context); |
| registry.addIfStatement(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| final LinterContext context; |
| |
| _Visitor(this.rule, this.context); |
| |
| @override |
| void visitIfStatement(IfStatement node) { |
| var elseStatement = node.elseStatement; |
| if (elseStatement is IfStatement) { |
| var ifCondition = node.condition; |
| var elseCondition = elseStatement.condition; |
| if (ifCondition is IsExpression && elseCondition is IsExpression) { |
| var typeProvider = context.typeProvider; |
| var ifExpression = ifCondition.expression; |
| var elseIsExpression = elseCondition.expression; |
| if (ifExpression is SimpleIdentifier && |
| elseIsExpression is SimpleIdentifier && |
| ifExpression.name == elseIsExpression.name && |
| ifCondition.type.type == typeProvider.doubleType && |
| elseCondition.type.type == typeProvider.intType && |
| (ifExpression.staticElement is ParameterElement || |
| ifExpression.staticElement is LocalVariableElement)) { |
| rule.reportLint(elseCondition); |
| } |
| } |
| } |
| } |
| } |