Support for RecordState in DArtObject.getField()

Change-Id: I095ee40e69617b0a45c1bcb493ef4891dbef4138
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/260002
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/dart/constant/value.dart

@@ -11,6 +11,7 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/dart/element/type_provider.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/dart/constant/has_type_parameter_reference.dart';
+import 'package:analyzer/src/dart/element/extensions.dart';
 import 'package:analyzer/src/dart/element/type_system.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:meta/meta.dart';
@@ -447,6 +448,8 @@ class DartObjectImpl implements DartObject {
     InstanceState state = _state;
     if (state is GenericState) {
       return state.fields[name];
+    } else if (state is RecordState) {
+      return state.getField(name);
     }
     return null;
   }
@@ -2578,6 +2581,16 @@ class RecordState extends InstanceState {
     return BoolState.TRUE_STATE;
   }
 
+  /// Returns the value of the field with the given [name].
+  DartObject? getField(String name) {
+    final index = RecordTypeExtension.positionalFieldIndex(name);
+    if (index != null && index < positionalFields.length) {
+      return positionalFields[index];
+    } else {
+      return namedFields[name];
+    }
+  }
+
   @override
   BoolState isIdentical(TypeSystemImpl typeSystem, InstanceState rightOperand) {
     var equal = equalEqual(typeSystem, rightOperand);

pkg/analyzer/lib/src/dart/element/extensions.dart

@@ -156,12 +156,18 @@ extension RecordTypeExtension on RecordType {
   }
 
   RecordTypePositionalField? positionalField(String name) {
+    final index = positionalFieldIndex(name);
+    if (index != null && index < positionalFields.length) {
+      return positionalFields[index];
+    }
+    return null;
+  }
+
+  /// Attempt to parse `$0`, `$1`, etc.
+  static int? positionalFieldIndex(String name) {
     final match = _positionalName.firstMatch(name);
     if (match != null) {
-      final index = int.tryParse(match.group(1)!);
-      if (index != null && index < positionalFields.length) {
-        return positionalFields[index];
-      }
+      return int.tryParse(match.group(1)!);
     }
     return null;
   }

pkg/analyzer/test/src/dart/constant/value_test.dart

@@ -473,6 +473,25 @@ class DartObjectImplTest {
     expect(_symbolValue("a"), _symbolValue("a"));
   }
 
+  void test_getField_record() {
+    final record = _recordValue([
+      _intValue(0),
+      _intValue(1),
+    ], {
+      'a': _intValue(2),
+      'b': _intValue(3),
+    });
+
+    expect(record.getField(r'$0'), _intValue(0));
+    expect(record.getField(r'$1'), _intValue(1));
+    expect(record.getField(r'$2'), isNull);
+    expect(record.getField(r'$-2'), isNull);
+
+    expect(record.getField(r'a'), _intValue(2));
+    expect(record.getField(r'b'), _intValue(3));
+    expect(record.getField(r'c'), isNull);
+  }
+
   void test_getValue_bool_false() {
     expect(_boolValue(false).toBoolValue(), false);
   }