Hive_generator built value support

hive_generator/lib/src/builder.dart

@@ -1,12 +1,58 @@
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/nullability_suffix.dart';
 import 'package:analyzer/dart/element/type.dart';
 
 class AdapterField {
   final int index;
-  final String name;
-  final DartType type;
+  final PropertyAccessorElement element;
 
-  AdapterField(this.index, this.name, this.type);
+  String get name => element.variable.name;
+  DartType get type => element.variable.type;
+
+  bool get isNullable {
+    switch (element.variable.type?.nullabilitySuffix) {
+      case NullabilitySuffix.none:
+        return false;
+      default:
+        return true;
+    }
+  }
+
+  AdapterField(this.index, this.element);
+  BuiltAdapterField toBuilt(bool nestedBuilders) => BuiltAdapterField(
+        index,
+        element,
+        nestedBuilders,
+      );
+}
+
+class BuiltAdapterField extends AdapterField {
+  DartType _type;
+
+  @override
+  DartType get type => _type ?? super.type;
+  set type(DartType type) => _type = type;
+
+  bool nestedBuilders;
+
+  BuiltAdapterField(
+    int index,
+    PropertyAccessorElement element,
+    this.nestedBuilders,
+  ) : super(index, element);
+
+  bool get hasNullableAnnotation => element.metadata.any((metadata) =>
+      metadata.computeConstantValue()?.toStringValue() == 'nullable');
+
+  bool get hasNullableType =>
+      element?.returnType?.nullabilitySuffix == NullabilitySuffix.question;
+
+  @override
+  bool get isNullable => hasNullableAnnotation || hasNullableType;
+
+  @override
+  BuiltAdapterField toBuilt(bool nestedBuilders) =>
+      throw StateError('Already is an BuiltAdapterField');
 }
 
 abstract class Builder {