pkg/linter/lib/src/rules/prefer_inlined_adds.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';

const _desc = r'Inline list item declarations where possible.';

class PreferInlinedAdds extends MultiAnalysisRule {
  PreferInlinedAdds()
    : super(name: LintNames.prefer_inlined_adds, description: _desc);

  @override
  List<DiagnosticCode> get diagnosticCodes => [
    LinterLintCode.preferInlinedAddsMultiple,
    LinterLintCode.preferInlinedAddsSingle,
  ];

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

class _Visitor extends SimpleAstVisitor<void> {
  final MultiAnalysisRule rule;

  _Visitor(this.rule);

  @override
  void visitMethodInvocation(MethodInvocation invocation) {
    var addAll = invocation.methodName.name == 'addAll';
    if ((invocation.methodName.name != 'add' && !addAll) ||
        !invocation.isCascaded ||
        invocation.argumentList.arguments.length != 1) {
      return;
    }

    var cascade = invocation.thisOrAncestorOfType<CascadeExpression>();
    var sections = cascade?.cascadeSections;
    var target = cascade?.target;
    if (target is! ListLiteral ||
        (sections != null && sections.first != invocation)) {
      // TODO(pq): consider extending to handle set literals.
      return;
    }

    if (addAll && invocation.argumentList.arguments.first is! ListLiteral) {
      // Handled by: prefer_spread_collections
      return;
    }

    rule.reportAtNode(
      invocation.methodName,
      diagnosticCode: addAll
          ? LinterLintCode.preferInlinedAddsMultiple
          : LinterLintCode.preferInlinedAddsSingle,
    );
  }
}