[native_assets_cli] Split up syntax generator

pkgs/json_syntax_generator/lib/src/generator/code_generation_helpers.dart

@@ -0,0 +1,10 @@
+// Copyright (c) 2025, 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.
+
+/// Wraps the [input] in curly braces if it's not empty.
+String wrapBracesIfNotEmpty(String input) => input.isEmpty ? input : '{$input}';
+
+/// Wraps the [input] in curly braces or adds a semicolon if it's empty.
+String wrapInBracesOrSemicolon(String input) =>
+    input.isEmpty ? ';' : '{ $input }';

pkgs/json_syntax_generator/lib/src/generator/enum_class_generator.dart

@@ -0,0 +1,60 @@
+// Copyright (c) 2025, 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 '../model/class_info.dart';
+
+class EnumGenerator {
+  final EnumClassInfo classInfo;
+
+  EnumGenerator(this.classInfo);
+
+  String generate() {
+    final buffer = StringBuffer();
+    final className = classInfo.name;
+    final enumValues = classInfo.enumValues;
+
+    final staticFinals = <String>[];
+    for (final value in enumValues) {
+      final valueName = value.name;
+      final jsonValue = value.jsonValue;
+      staticFinals.add(
+        'static const $valueName = $className._(\'$jsonValue\');',
+      );
+    }
+
+    buffer.writeln('''
+class $className {
+  final String name;
+
+  const $className._(this.name);
+
+  ${staticFinals.join('\n\n')}
+
+  static const List<$className> values = [
+    ${enumValues.map((e) => e.name).join(',')}
+  ];
+
+  static final Map<String, $className> _byName = {
+    for (final value in values) value.name: value,
+  };
+
+  $className.unknown(this.name) : assert(!_byName.keys.contains(name));
+
+  factory $className.fromJson(String name) {
+    final knownValue = _byName[name];
+    if(knownValue != null) {
+      return knownValue;
+    }
+    return $className.unknown(name);
+  }
+
+  bool get isKnown => _byName[name] != null;
+
+  @override
+  String toString() => name;
+}
+''');
+    return buffer.toString();
+  }
+}

pkgs/json_syntax_generator/lib/src/generator/helper_library.dart

@@ -41,6 +41,15 @@ extension on Map<String, Object?> {
     return list.cast();
   }
 
+  List<T>? optionalListParsed<T extends Object?>(
+    String key,
+    T Function(Object?) elementParser,
+  ) {
+    final jsonValue = optionalList(key);
+    if (jsonValue == null) return null;
+    return [for (final element in jsonValue) elementParser(element)];
+  }
+
   Map<String, T> map$<T extends Object?>(String key) =>
       _castMap<T>(get<Map<String, Object?>>(key), key);
 
@@ -92,6 +101,14 @@ extension on Map<String, Object?> {
     }
     return Uri.file(path);
   }
+
+  void setOrRemove(String key, Object? value) {
+    if (value == null) {
+      remove(key);
+    } else {
+      this[key] = value;
+    }
+  }
 }
 
 extension on List<Uri> {

pkgs/json_syntax_generator/lib/src/generator/normal_class_generator.dart

@@ -0,0 +1,131 @@
+// Copyright (c) 2025, 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 '../model/class_info.dart';
+import 'code_generation_helpers.dart';
+import 'property_generator.dart';
+
+class ClassGenerator {
+  final NormalClassInfo classInfo;
+
+  ClassGenerator(this.classInfo);
+
+  String generate() {
+    final buffer = StringBuffer();
+    final className = classInfo.name;
+    final superclass = classInfo.superclass;
+    final superclassName = superclass?.name;
+    final properties = classInfo.properties;
+    final identifyingSubtype = classInfo.taggedUnionKey;
+
+    final constructorParams = <String>[];
+    final setupParams = <String>[];
+    final constructorSetterCalls = <String>[];
+    final accessors = <String>[];
+    final superParams = <String>[];
+
+    final propertyNames =
+        {
+            for (final property in properties) property.name,
+            if (superclass != null)
+              for (final property in superclass.properties) property.name,
+          }.toList()
+          ..sort();
+    for (final propertyName in propertyNames) {
+      final superClassProperty = superclass?.getProperty(propertyName);
+      final thisClassProperty = classInfo.getProperty(propertyName);
+      final property = superClassProperty ?? thisClassProperty!;
+      if (superClassProperty != null) {
+        if (identifyingSubtype == null) {
+          constructorParams.add(
+            '${property.isRequired ? 'required ' : ''}super.${property.name}',
+          );
+        } else {
+          superParams.add("type: '$identifyingSubtype'");
+        }
+      } else {
+        final dartType = property.type;
+        constructorParams.add(
+          '${property.isRequired ? 'required ' : ''}$dartType ${property.name}',
+        );
+        setupParams.add(
+          '${property.isRequired ? 'required' : ''} $dartType ${property.name}',
+        );
+        if (property.setterPrivate) {
+          constructorSetterCalls.add('_${property.name} = ${property.name};');
+        } else {
+          constructorSetterCalls.add(
+            'this.${property.name} = ${property.name};',
+          );
+        }
+      }
+      if (thisClassProperty != null) {
+        accessors.add(PropertyGenerator(thisClassProperty).generate());
+      }
+    }
+
+    if (constructorSetterCalls.isNotEmpty) {
+      constructorSetterCalls.add('json.sortOnKey();');
+    }
+
+    if (superclass != null) {
+      buffer.writeln('''
+class $className extends $superclassName {
+  $className.fromJson(super.json) : super.fromJson();
+
+  $className(${wrapBracesIfNotEmpty(constructorParams.join(', '))})
+    : super(${superParams.join(',')}) 
+    ${wrapInBracesOrSemicolon(constructorSetterCalls.join('\n    '))}
+''');
+      if (setupParams.isNotEmpty) {
+        buffer.writeln('''
+  /// Setup all fields for [$className] that are not in
+  /// [$superclassName].
+  void setup (
+    ${wrapBracesIfNotEmpty(setupParams.join(','))}
+  ) {
+    ${constructorSetterCalls.join('\n')}
+  }
+''');
+      }
+
+      buffer.writeln('''
+  ${accessors.join('\n')}
+
+  @override
+  String toString() => '$className(\$json)';
+}
+''');
+    } else {
+      buffer.writeln('''
+class $className {
+  final Map<String, Object?> json;
+
+  $className.fromJson(this.json);
+
+  $className(${wrapBracesIfNotEmpty(constructorParams.join(', '))}) : json = {} {
+    ${constructorSetterCalls.join('\n    ')}
+  }
+
+  ${accessors.join('\n')}
+
+  @override
+  String toString() => '$className(\$json)';
+}
+''');
+    }
+
+    if (identifyingSubtype != null) {
+      buffer.writeln('''
+extension ${className}Extension on $superclassName {
+  bool get is$className => type == '$identifyingSubtype';
+
+  $className get as$className => $className.fromJson(json);
+}
+''');
+    }
+
+    return buffer.toString();
+  }
+}