json_serializable: refactor enum logic (#1204)

Refactor a function into to functions
Simplify the return value

Author: kevmoo

json_serializable/lib/src/enum_utils.dart

@@ -27,73 +27,78 @@ String? enumValueMapFromType(
     return null;
   }
 
-  MapEntry<FieldElement, dynamic> generateEntry(FieldElement fe) {
-    final annotation =
-        const TypeChecker.fromRuntime(JsonValue).firstAnnotationOfExact(fe);
-
-    dynamic fieldValue;
-    if (annotation == null) {
-      if (jsonEnum.valueField != null) {
-        // TODO: fieldRename is pointless here!!! At least log a warning!
-
-        final fieldElementType = fe.type.element2 as EnumElement;
-
-        final e = fieldElementType.getField(jsonEnum.valueField!);
-
-        if (e == null || e.isStatic) {
-          throw InvalidGenerationSourceError(
-            '`JsonEnum.valueField` was set to "${jsonEnum.valueField}", but '
-            'that is not a valid, instance field on '
-            '`${typeToCode(targetType)}`.',
-            element: targetType.element2,
-          );
-        }
-
-        final reader = ConstantReader(fe.computeConstantValue());
-        final valueReader = reader.read(jsonEnum.valueField!);
-        if (valueReader.validValueType) {
-          fieldValue = valueReader.literalValue;
-        } else {
-          throw InvalidGenerationSourceError(
-            '`JsonEnum.valueField` was set to "${jsonEnum.valueField}", but '
-            'that field does not have a type of String, int, or null.',
-            element: targetType.element2,
-          );
-        }
-      } else {
-        fieldValue = encodedFieldName(jsonEnum.fieldRename, fe.name);
-      }
-    } else {
-      final reader = ConstantReader(annotation);
+  final enumMap = {
+    for (var field in enumFields)
+      field: generateEntry(
+        field: field,
+        jsonEnum: jsonEnum,
+        targetType: targetType,
+      ),
+  };
+
+  final items = enumMap.entries
+      .map((e) => '  ${targetType.element2!.name}.${e.key.name}: '
+          '${jsonLiteralAsDart(e.value)},')
+      .join();
+
+  return 'const ${constMapName(targetType)} = {\n$items\n};';
+}
+
+Object? generateEntry({
+  required FieldElement field,
+  required JsonEnum jsonEnum,
+  required DartType targetType,
+}) {
+  final annotation =
+      const TypeChecker.fromRuntime(JsonValue).firstAnnotationOfExact(field);
+
+  if (annotation == null) {
+    if (jsonEnum.valueField != null) {
+      // TODO: fieldRename is pointless here!!! At least log a warning!
+
+      final fieldElementType = field.type.element2 as EnumElement;
 
-      final valueReader = reader.read('value');
+      final e = fieldElementType.getField(jsonEnum.valueField!);
 
+      if (e == null || e.isStatic) {
+        throw InvalidGenerationSourceError(
+          '`JsonEnum.valueField` was set to "${jsonEnum.valueField}", but '
+          'that is not a valid, instance field on '
+          '`${typeToCode(targetType)}`.',
+          element: targetType.element2,
+        );
+      }
+
+      final reader = ConstantReader(field.computeConstantValue());
+      final valueReader = reader.read(jsonEnum.valueField!);
       if (valueReader.validValueType) {
-        fieldValue = valueReader.literalValue;
+        return valueReader.literalValue;
       } else {
-        final targetTypeCode = typeToCode(targetType);
         throw InvalidGenerationSourceError(
-          'The `JsonValue` annotation on `$targetTypeCode.${fe.name}` does '
-          'not have a value of type String, int, or null.',
-          element: fe,
+          '`JsonEnum.valueField` was set to "${jsonEnum.valueField}", but '
+          'that field does not have a type of String, int, or null.',
+          element: targetType.element2,
         );
       }
+    } else {
+      return encodedFieldName(jsonEnum.fieldRename, field.name);
     }
+  } else {
+    final reader = ConstantReader(annotation);
 
-    final entry = MapEntry(fe, fieldValue);
+    final valueReader = reader.read('value');
 
-    return entry;
+    if (valueReader.validValueType) {
+      return valueReader.literalValue;
+    } else {
+      final targetTypeCode = typeToCode(targetType);
+      throw InvalidGenerationSourceError(
+        'The `JsonValue` annotation on `$targetTypeCode.${field.name}` does '
+        'not have a value of type String, int, or null.',
+        element: field,
+      );
+    }
   }
-
-  final enumMap =
-      Map<FieldElement, dynamic>.fromEntries(enumFields.map(generateEntry));
-
-  final items = enumMap.entries
-      .map((e) => '  ${targetType.element2!.name}.${e.key.name}: '
-          '${jsonLiteralAsDart(e.value)},')
-      .join();
-
-  return 'const ${constMapName(targetType)} = {\n$items\n};';
 }
 
 const _jsonEnumChecker = TypeChecker.fromRuntime(JsonEnum);