refactor: Extract converter and property logic to separate handlers

This commit extracts the converter and property-related logic from `JsonMapper` into new `ConverterHandler` and `PropertyHandler` classes. This improves the separation of concerns and makes the `JsonMapper` class smaller and more focused.

The following changes were made:
- Created a new `ConverterHandler` class in `mapper/lib/src/logic/converter_handler.dart`.
- Moved `getConverter`, `getEnumDescriptor`, `getConvertedValue`, and `configureConverter` methods from `JsonMapper` to `ConverterHandler`.
- Moved `converters` and `convertedValuesCache` state from `JsonMapper` to `ConverterHandler`.
- Created a new `PropertyHandler` class in `mapper/lib/src/logic/property_handler.dart`.
- Moved `enumeratePublicProperties` and `resolveProperty` methods from `JsonMapper` to `PropertyHandler`.
- Updated all call sites to use the new handlers.
- Removed unused imports from modified files.

Author: google-labs-jules[bot]

mapper/lib/src/logic/converter_handler.dart

@@ -0,0 +1,106 @@
+import 'package:collection/collection.dart';
+import 'package:dart_json_mapper/src/model/index.dart';
+
+import '../mapper.dart';
+
+class ConverterHandler {
+  final JsonMapper _mapper;
+
+  Map<Type, ICustomConverter> converters = {};
+  final Map<
+          ICustomConverter?,
+          Map<ConversionDirection,
+              Map<DeserializationContext?, Map<dynamic, dynamic>>>>
+      convertedValuesCache = {};
+
+  ConverterHandler(this._mapper);
+
+  void clearCache() {
+    convertedValuesCache.clear();
+  }
+
+  ICustomConverter? getConverter(
+      JsonProperty? jsonProperty, TypeInfo typeInfo) {
+    final result = jsonProperty?.converter ??
+        converters[typeInfo.type!] ??
+        converters[typeInfo.genericType] ??
+        (_mapper.enumValues[typeInfo.type!] != null
+            ? converters[Enum]
+            : null) ??
+        converters[converters.keys.firstWhereOrNull(
+            (Type type) => type.toString() == typeInfo.typeName)];
+
+    if (result is ICustomEnumConverter) {
+      (result as ICustomEnumConverter)
+          .setEnumDescriptor(getEnumDescriptor(_mapper.enumValues[typeInfo.type!]));
+    }
+    return result;
+  }
+
+  IEnumDescriptor? getEnumDescriptor(dynamic descriptor) {
+    if (descriptor is Iterable) {
+      return EnumDescriptor(values: descriptor);
+    }
+    if (descriptor is IEnumDescriptor) {
+      return descriptor;
+    }
+    return null;
+  }
+
+  dynamic getConvertedValue(
+      ICustomConverter converter, dynamic value, DeserializationContext context) {
+    final direction = context.direction;
+    if (convertedValuesCache.containsKey(converter) &&
+        convertedValuesCache[converter]!.containsKey(direction) &&
+        convertedValuesCache[converter]![direction]!.containsKey(context) &&
+        convertedValuesCache[converter]![direction]![context]!
+            .containsKey(value)) {
+      return convertedValuesCache[converter]![direction]![context]![value];
+    }
+
+    final computedValue = direction == ConversionDirection.fromJson
+        ? converter.fromJSON(value, context)
+        : converter.toJSON(value, context as SerializationContext);
+    convertedValuesCache.putIfAbsent(
+        converter,
+        () => {
+              direction: {
+                context: {value: computedValue}
+              }
+            });
+    convertedValuesCache[converter]!.putIfAbsent(
+        direction,
+        () => {
+              context: {value: computedValue}
+            });
+    convertedValuesCache[converter]![direction]!
+        .putIfAbsent(context, () => {value: computedValue});
+    convertedValuesCache[converter]![direction]![context]!
+        .putIfAbsent(value, () => computedValue);
+    return computedValue;
+  }
+
+  void configureConverter(
+      ICustomConverter converter, DeserializationContext context,
+      {dynamic value}) {
+    if (converter is ICompositeConverter) {
+      (converter as ICompositeConverter).setGetConverterFunction(getConverter);
+      (converter as ICompositeConverter)
+          .setGetConvertedValueFunction(getConvertedValue);
+    }
+    if (converter is ICustomIterableConverter) {
+      (converter as ICustomIterableConverter).setIterableInstance(value);
+    }
+    if (converter is ICustomMapConverter) {
+      final instance = value ?? (context.options.template);
+      (converter as ICustomMapConverter).setMapInstance(instance);
+    }
+    if (converter is IRecursiveConverter) {
+      (converter as IRecursiveConverter).setSerializeObjectFunction(
+          (o, context) => _mapper.serializationHandler.serializeObject(o, context));
+      (converter as IRecursiveConverter).setDeserializeObjectFunction((o,
+              context, type) =>
+          _mapper.deserializationHandler.deserializeObject(o, context.reBuild(typeInfo: _mapper.typeInfoHandler.getTypeInfo(type))));
+    }
+  }
+}

mapper/lib/src/logic/deserialization_handler.dart

@@ -21,17 +21,17 @@ class DeserializationHandler {
       return null;
     }
     var typeInfo = context.typeInfo!;
-    final converter = _mapper.getConverter(context.jsonPropertyMeta, typeInfo);
+    final converter = _mapper.converterHandler.getConverter(context.jsonPropertyMeta, typeInfo);
     if (converter != null) {
-      _mapper.configureConverter(converter, context);
+      _mapper.converterHandler.configureConverter(converter, context);
       if (typeInfo.isIterable &&
           (converter is ICustomIterableConverter &&
               converter is! DefaultIterableConverter)) {
         return _mapper.applyValueDecorator(
-            _mapper.getConvertedValue(converter, jsonValue, context), typeInfo);
+            _mapper.converterHandler.getConvertedValue(converter, jsonValue, context), typeInfo);
       }
       return _mapper.applyValueDecorator(
-          _mapper.getConvertedValue(converter, jsonValue, context), typeInfo);
+          _mapper.converterHandler.getConvertedValue(converter, jsonValue, context), typeInfo);
     }
 
     dynamic convertedJsonValue =
@@ -88,7 +88,7 @@ class DeserializationHandler {
         .toList()
       ..addAll(positionalArgumentNames);
 
-    _mapper.enumeratePublicProperties(im, jsonMap, context, (name, property,
+    _mapper.propertyHandler.enumeratePublicProperties(im, jsonMap, context, (name, property,
         isGetterOnly, JsonProperty? meta, converter, TypeInfo typeInfo) {
       final propertyContext = context.reBuild(
           parentObjectInstances: [
@@ -276,7 +276,7 @@ class DeserializationHandler {
         finalValueForVisitor = this.deserializeObject(jsonMap.map, propertyContext.reBuild(jsonPropertyMeta: null));
         jsonNameForVisitor = context.transformIdentifier(meta?.name ?? name);
       } else {
-        final property = _mapper.resolveProperty(
+        final property = _mapper.propertyHandler.resolveProperty(
             name,
             jsonMap,
             propertyContext,

mapper/lib/src/logic/property_handler.dart

@@ -0,0 +1,139 @@
+import 'package:dart_json_mapper/src/model/index.dart';
+import 'package:reflectable/reflectable.dart' show InstanceMirror, MethodMirror;
+
+import '../class_info.dart';
+import '../json_map.dart';
+import '../mapper.dart';
+import 'field_handler.dart';
+import 'reflection_handler.dart';
+
+class PropertyHandler {
+  final JsonMapper _mapper;
+
+  PropertyHandler(this._mapper);
+
+  void enumeratePublicProperties(InstanceMirror instanceMirror,
+      JsonMap? jsonMap, DeserializationContext context, Function visitor) {
+    final classInfo = ClassInfo.fromCache(instanceMirror.type, _mapper.classes);
+    final classMeta = classInfo.getMeta(context.options.scheme);
+
+    for (var name in classInfo.publicFieldNames) {
+      final declarationMirror = classInfo.getDeclarationMirror(name);
+      if (declarationMirror == null) {
+        continue;
+      }
+      final declarationType = ReflectionHandler.getDeclarationType(declarationMirror);
+      final isGetterOnly = classInfo.isGetterOnly(name);
+      final meta = classInfo.getDeclarationMeta(
+          declarationMirror, context.options.scheme);
+      if (meta == null &&
+          Json.getProcessAnnotatedMembersOnly(classMeta, context.options) == true) {
+        continue;
+      }
+
+      if (FieldHandler.isFieldIgnored(classMeta, meta, context.options)) {
+        continue;
+      }
+      final propertyContext =
+          context.reBuild(classMeta: classMeta, jsonPropertyMeta: meta);
+      final property = resolveProperty(
+          name, jsonMap, propertyContext, classMeta, meta, (name, jsonName, _) {
+        var result = instanceMirror.invokeGetter(name);
+        if (result == null && jsonMap != null) {
+          result = jsonMap.getPropertyValue(jsonName);
+        }
+        return result;
+      });
+
+      FieldHandler.checkFieldConstraints(
+          property.value, name, jsonMap?.hasProperty(property.name), meta);
+
+      if (FieldHandler.isFieldIgnoredByValue(
+          property.value, classMeta, meta, propertyContext.options)) {
+        continue;
+      }
+      final typeInfo =
+          _mapper.typeInfoHandler.getDeclarationTypeInfo(declarationType, property.value?.runtimeType);
+      visitor(name, property, isGetterOnly, meta, _mapper.converterHandler.getConverter(meta, typeInfo),
+          typeInfo);
+    }
+
+    classInfo.enumerateJsonGetters((MethodMirror mm, JsonProperty meta) {
+      final declarationType = ReflectionHandler.getDeclarationType(mm);
+      final propertyContext =
+          context.reBuild(classMeta: classMeta, jsonPropertyMeta: meta);
+      final property = resolveProperty(
+          mm.simpleName, jsonMap, propertyContext, classMeta, meta,
+          (name, jsonName, _) {
+        var result = instanceMirror.invoke(name, []);
+        if (result == null && jsonMap != null) {
+          result = jsonMap.getPropertyValue(jsonName);
+        }
+        return result;
+      });
+
+      FieldHandler.checkFieldConstraints(property.value, mm.simpleName,
+          jsonMap?.hasProperty(property.name), meta);
+      if (FieldHandler.isFieldIgnoredByValue(
+          property.value, classMeta, meta, context.options)) {
+        return;
+      }
+      final typeInfo =
+          _mapper.typeInfoHandler.getDeclarationTypeInfo(declarationType, property.value?.runtimeType);
+      visitor(mm.simpleName, property, true, meta,
+          _mapper.converterHandler.getConverter(meta, typeInfo), _mapper.typeInfoHandler.getTypeInfo(declarationType));
+    }, context.options.scheme);
+  }
+
+  PropertyDescriptor resolveProperty(
+      String name,
+      JsonMap? jsonMap,
+      DeserializationContext context,
+      Json? classMeta,
+      JsonProperty? meta,
+      Function getValueByName) {
+    String? jsonName = name;
+
+    if (meta != null && meta.name != null) {
+      jsonName = JsonProperty.getPrimaryName(meta);
+    }
+    jsonName = context.transformIdentifier(jsonName!);
+    var value = getValueByName(name, jsonName, meta?.defaultValue);
+    if (jsonMap != null &&
+        meta != null &&
+        (value == null || !jsonMap.hasProperty(jsonName))) {
+      final initialValue = value;
+      for (final alias in JsonProperty.getAliases(meta)!) {
+        final targetJsonName = transformIdentifierCaseStyle(
+            alias, context.targetCaseStyle, context.sourceCaseStyle);
+        if (value != initialValue || !jsonMap.hasProperty(targetJsonName)) {
+          continue;
+        }
+        jsonName = targetJsonName;
+        value = jsonMap.getPropertyValue(jsonName);
+      }
+    }
+    if (meta != null &&
+        meta.inject == true &&
+        context.options.injectableValues != null) {
+      final injectionJsonMap = JsonMap(context.options.injectableValues!);
+      if (injectionJsonMap.hasProperty(jsonName!)) {
+        value = injectionJsonMap.getPropertyValue(jsonName);
+        return PropertyDescriptor(jsonName, value, false);
+      } else {
+        return PropertyDescriptor(jsonName, null, false);
+      }
+    }
+    if (jsonName == JsonProperty.parentReference) {
+      return PropertyDescriptor(
+          jsonName!, context.parentObjectInstances!.last, false);
+    }
+    if (value == null &&
+        meta?.defaultValue != null &&
+        FieldHandler.isFieldIgnoredByDefault(
+            meta, classMeta, context.options as SerializationOptions)) {
+      return PropertyDescriptor(jsonName!, meta?.defaultValue, true);
+    }
+    return PropertyDescriptor(jsonName!, value, true);
+  }
+}

mapper/lib/src/logic/serialization_handler.dart

@@ -20,11 +20,11 @@ class SerializationHandler {
     }
 
     final im = ReflectionHandler.safeGetInstanceMirror(object);
-    final converter = _mapper.getConverter(
+    final converter = _mapper.converterHandler.getConverter(
         context!.jsonPropertyMeta, _mapper.typeInfoHandler.getTypeInfo(object.runtimeType));
     if (converter != null) {
-      _mapper.configureConverter(converter, context, value: object);
-      return _mapper.getConvertedValue(converter, object, context);
+      _mapper.converterHandler.configureConverter(converter, context, value: object);
+      return _mapper.converterHandler.getConvertedValue(converter, object, context);
     }
 
     if (im == null) {
@@ -60,7 +60,7 @@ class SerializationHandler {
       }
     }
     _dumpDiscriminatorToObjectProperty(result, im.type, context.options);
-    _mapper.enumeratePublicProperties(im, null, context, (name, property, isGetterOnly,
+    _mapper.propertyHandler.enumeratePublicProperties(im, null, context, (name, property, isGetterOnly,
         JsonProperty? meta, converter, TypeInfo typeInfo) {
       dynamic convertedValue;
       final propertyContext = context.reBuild(
@@ -104,11 +104,11 @@ class SerializationHandler {
           return;
         }
 
-        final actualConverter = _mapper.getConverter(meta, typeInfo);
+        final actualConverter = _mapper.converterHandler.getConverter(meta, typeInfo);
         if (actualConverter != null) {
           final valueToConvert = property.value ?? meta?.defaultValue;
-          _mapper.configureConverter(actualConverter, propertyContext, value: valueToConvert);
-          convertedValue = _mapper.getConvertedValue(actualConverter, valueToConvert, propertyContext);
+          _mapper.converterHandler.configureConverter(actualConverter, propertyContext, value: valueToConvert);
+          convertedValue = _mapper.converterHandler.getConvertedValue(actualConverter, valueToConvert, propertyContext);
         } else {
           convertedValue = this.serializeObject(property.value, propertyContext);
         }