pkg/linter/lib/src/rules/avoid_unnecessary_containers.dart

// 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/analysis_rule/analysis_rule.dart';
import 'package:analyzer/analysis_rule/rule_context.dart';
import 'package:analyzer/analysis_rule/rule_visitor_registry.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/error/error.dart';

import '../analyzer.dart';
import '../diagnostic.dart' as diag;
import '../util/flutter_utils.dart';

const _desc = r'Avoid unnecessary containers.';

class AvoidUnnecessaryContainers extends AnalysisRule {
  new()
    : super(name: LintNames.avoid_unnecessary_containers, description: _desc);

  @override
  DiagnosticCode get diagnosticCode => diag.avoidUnnecessaryContainers;

  @override
  void registerNodeProcessors(
    RuleVisitorRegistry registry,
    RuleContext context,
  ) {
    var visitor = _Visitor(this);

    registry.addInstanceCreationExpression(this, visitor);
  }
}

class _Visitor(final AnalysisRule rule) extends SimpleAstVisitor<void> {
  @override
  void visitInstanceCreationExpression(InstanceCreationExpression node) {
    if (!node.staticType.isWidgetType) return;

    var parent = node.parent;
    if (parent is NamedArgument && parent.name.lexeme == 'child') {
      var args = parent.thisOrAncestorOfType<ArgumentList>();
      if (args?.arguments.length == 1) {
        var parentCreation = parent
            .thisOrAncestorOfType<InstanceCreationExpression>();
        if (parentCreation != null) {
          if (parentCreation.isWidgetTypeContainer) {
            rule.reportAtNode(parentCreation.constructorName);
          }
        }
      }
    }
  }
}