| // Copyright (c) 2019, 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/src/dart/ast/ast.dart'; // ignore: implementation_imports |
| |
| import '../analyzer.dart'; |
| |
| const _desc = r'Use spread collections when possible.'; |
| |
| const _details = r''' |
| |
| Use spread collections when possible. |
| |
| Collection literals are excellent when you want to create a new collection out |
| of individual items. But, when existing items are already stored in another |
| collection, spread collection syntax leads to simpler code. |
| |
| **BAD:** |
| |
| ```dart |
| Widget build(BuildContext context) { |
| return CupertinoPageScaffold( |
| child: ListView( |
| children: [ |
| Tab2Header(), |
| ]..addAll(buildTab2Conversation()), |
| ), |
| ); |
| } |
| ``` |
| |
| ```dart |
| var ints = [1, 2, 3]; |
| print(['a']..addAll(ints.map((i) => i.toString()))..addAll(['c'])); |
| ``` |
| |
| ```dart |
| var things; |
| var l = ['a']..addAll(things ?? const []); |
| ``` |
| |
| |
| **GOOD:** |
| |
| ```dart |
| Widget build(BuildContext context) { |
| return CupertinoPageScaffold( |
| child: ListView( |
| children: [ |
| Tab2Header(), |
| ...buildTab2Conversation(), |
| ], |
| ), |
| ); |
| } |
| ``` |
| |
| ```dart |
| var ints = [1, 2, 3]; |
| print(['a', ...ints.map((i) => i.toString()), 'c'); |
| ``` |
| |
| ```dart |
| var things; |
| var l = ['a', ...?things]; |
| ``` |
| '''; |
| |
| class PreferSpreadCollections extends LintRule implements NodeLintRule { |
| PreferSpreadCollections() |
| : super( |
| name: 'prefer_spread_collections', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addMethodInvocation(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitMethodInvocation(MethodInvocation invocation) { |
| if (invocation.methodName.name != 'addAll' || |
| !invocation.isCascaded || |
| invocation.argumentList.arguments.length != 1) { |
| return; |
| } |
| |
| final cascade = invocation.thisOrAncestorOfType<CascadeExpression>(); |
| final sections = cascade?.cascadeSections; |
| final target = cascade?.target; |
| // todo (pq): add support for Set literals. |
| if (target is! ListLiteral || |
| (target is ListLiteralImpl && target.inConstantContext) || |
| (sections != null && sections[0] != invocation)) { |
| return; |
| } |
| |
| final argument = invocation.argumentList.arguments[0]; |
| if (argument is ListLiteral) { |
| // Handled by: prefer_inlined_adds |
| return; |
| } |
| |
| rule.reportLint(invocation.methodName); |
| } |
| } |