| // 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/visitor.dart'; |
| import 'package:analyzer/dart/element/type.dart'; |
| |
| import '../analyzer.dart'; |
| import '../util/dart_type_utilities.dart'; |
| |
| const _desc = r'Use collection literals when possible.'; |
| |
| const _details = r''' |
| |
| **DO** use collection literals when possible. |
| |
| **BAD:** |
| ```dart |
| var points = List(); |
| var addresses = Map(); |
| var uniqueNames = Set(); |
| var ids = LinkedHashSet(); |
| var coordinates = LinkedHashMap(); |
| ``` |
| |
| **GOOD:** |
| ```dart |
| var points = []; |
| var addresses = <String,String>{}; |
| var uniqueNames = <String>{}; |
| var ids = <int>{}; |
| var coordinates = <int,int>{}; |
| ``` |
| |
| **EXCEPTIONS:** |
| |
| There are cases with `LinkedHashSet` or `LinkedHashMap` where a literal constructor |
| will trigger a type error so those will be excluded from the lint. |
| |
| ```dart |
| void main() { |
| LinkedHashSet<int> linkedHashSet = LinkedHashSet.from([1, 2, 3]); // OK |
| LinkedHashMap linkedHashMap = LinkedHashMap(); // OK |
| |
| printSet(LinkedHashSet<int>()); // LINT |
| printHashSet(LinkedHashSet<int>()); // OK |
| |
| printMap(LinkedHashMap<int, int>()); // LINT |
| printHashMap(LinkedHashMap<int, int>()); // OK |
| } |
| |
| void printSet(Set<int> ids) => print('$ids!'); |
| void printHashSet(LinkedHashSet<int> ids) => printSet(ids); |
| void printMap(Map map) => print('$map!'); |
| void printHashMap(LinkedHashMap map) => printMap(map); |
| ``` |
| '''; |
| |
| class PreferCollectionLiterals extends LintRule implements NodeLintRule { |
| PreferCollectionLiterals() |
| : super( |
| name: 'prefer_collection_literals', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| var visitor = _Visitor(this); |
| registry.addInstanceCreationExpression(this, visitor); |
| registry.addMethodInvocation(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| _Visitor(this.rule); |
| |
| @override |
| void visitMethodInvocation(MethodInvocation node) { |
| // ['foo', 'bar', 'baz'].toSet(); |
| if (node.methodName.name != 'toSet') { |
| return; |
| } |
| if (node.target is ListLiteral) { |
| rule.reportLint(node); |
| } |
| } |
| |
| @override |
| void visitInstanceCreationExpression(InstanceCreationExpression node) { |
| var constructorName = node.constructorName.name?.name; |
| |
| // Lists, Maps. |
| if (_isList(node) || _isMap(node) || _isHashMap(node)) { |
| if (_shouldSkipLinkedHashLint(node, _isTypeHashMap)) { |
| return; |
| } |
| if (constructorName == null && node.argumentList.arguments.isEmpty) { |
| rule.reportLint(node); |
| } |
| return; |
| } |
| |
| // Sets. |
| if (_isSet(node) || _isHashSet(node)) { |
| if (_shouldSkipLinkedHashLint(node, _isTypeHashSet)) { |
| return; |
| } |
| |
| var args = node.argumentList.arguments; |
| if (constructorName == null) { |
| // Skip: LinkedHashSet(equals: (a, b) => false, hashCode: (o) => 13) |
| if (args.isEmpty) { |
| rule.reportLint(node); |
| } |
| } else if (constructorName == 'from' || constructorName == 'of') { |
| if (args.length != 1) { |
| return; |
| } |
| if (args.first is ListLiteral) { |
| rule.reportLint(node); |
| } |
| } |
| } |
| } |
| |
| bool _isSet(Expression expression) => _isTypeSet(expression.staticType); |
| bool _isHashSet(Expression expression) => |
| _isTypeHashSet(expression.staticType); |
| bool _isList(Expression expression) => |
| DartTypeUtilities.isClass(expression.staticType, 'List', 'dart.core'); |
| bool _isMap(Expression expression) => _isTypeMap(expression.staticType); |
| bool _isHashMap(Expression expression) => |
| _isTypeHashMap(expression.staticType); |
| bool _isTypeSet(DartType? type) => |
| DartTypeUtilities.isClass(type, 'Set', 'dart.core'); |
| bool _isTypeHashSet(DartType? type) => |
| DartTypeUtilities.isClass(type, 'LinkedHashSet', 'dart.collection'); |
| bool _isTypeMap(DartType? type) => |
| DartTypeUtilities.isClass(type, 'Map', 'dart.core'); |
| bool _isTypeHashMap(DartType? type) => |
| DartTypeUtilities.isClass(type, 'LinkedHashMap', 'dart.collection'); |
| |
| bool _shouldSkipLinkedHashLint( |
| InstanceCreationExpression node, bool Function(DartType node) typeCheck) { |
| if (_isHashMap(node) || _isHashSet(node)) { |
| // Skip: LinkedHashSet<int> s = ...; or LinkedHashMap<int> s = ...; |
| var parent = node.parent; |
| if (parent is VariableDeclaration) { |
| var parent2 = parent.parent; |
| if (parent2 is VariableDeclarationList) { |
| var assignmentType = parent2.type?.type; |
| if (assignmentType != null && typeCheck(assignmentType)) { |
| return true; |
| } |
| } |
| } |
| // Skip: function(LinkedHashSet()); when function(LinkedHashSet mySet) or |
| // function(LinkedHashMap()); when function(LinkedHashMap myMap) |
| if (parent is ArgumentList) { |
| var paramType = node.staticParameterElement?.type; |
| if (paramType == null || typeCheck(paramType)) { |
| return true; |
| } |
| } |
| // Skip: <int, LinkedHashSet>{}.putIfAbsent(3, () => LinkedHashSet()); |
| // or <int, LinkedHashMap>{}.putIfAbsent(3, () => LinkedHashMap()); |
| if (parent is ExpressionFunctionBody) { |
| var expressionType = parent.expression.staticType; |
| if (expressionType != null && typeCheck(expressionType)) { |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| } |