feat(gen): add impl of proxy component generator

packages/wyatt_component_copy_with_gen/lib/src/generators/component_multi_proxy_generator.dart

@@ -0,0 +1,101 @@
+// Copyright (C) 2023 WYATT GROUP
+// Please see the AUTHORS file for details.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+import 'dart:async';
+
+import 'package:analyzer/dart/element/element.dart';
+import 'package:build/build.dart';
+import 'package:source_gen/source_gen.dart';
+import 'package:wyatt_component_copy_with_extension/wyatt_component_copy_with_extension.dart';
+
+class ComponentMultiProxyGenerator
+    extends GeneratorForAnnotation<ComponentProxyExtension> {
+  @override
+  FutureOr<String> generateForAnnotatedElement(
+    Element element,
+    ConstantReader annotation,
+    BuildStep buildStep,
+  ) {
+    /// Check element type
+    if (element is! ClassElement) {
+      throw InvalidGenerationSourceError(
+        'Only classes can be annotated with "CopyWith". "$element" is '
+        'not a ClassElement.',
+        element: element,
+      );
+    }
+
+    final classAnnotation = ComponentProxyExtension(
+      skipFields: annotation.peek('skipFields')?.boolValue ?? true,
+    );
+
+    final multiProxyClassName =
+        element.displayName.replaceAll('Component', 'MultiProxy');
+    final generatedCode = StringBuffer()
+      ..write(
+        '@ComponentCopyWithExtension() class '
+        '\$$multiProxyClassName extends ${element.displayName} with '
+        '\$\$${multiProxyClassName}CWMixin {',
+      )
+      ..write('final bool? freezed; '
+          'final ${element.displayName} Function(BuildContext context) select;')
+      ..write('\$$multiProxyClassName(');
+
+    if (classAnnotation.skipFields ?? true) {
+      generatedCode.write('this.select,');
+      for (final field in element.constructors.first.parameters
+          .where((element) => element.isNamed == false)) {
+        generatedCode.write('super.${field.displayName},');
+      }
+
+      generatedCode
+        ..write('{')
+        ..write('this.freezed,');
+      for (final field in element.constructors.first.parameters
+          .where((element) => element.isNamed)) {
+        if (field.isRequiredNamed) {
+          generatedCode.write('required ');
+        }
+        generatedCode.write('super.${field.displayName},');
+      }
+      generatedCode
+        ..write('});')
+        ..write('  factory \$$multiProxyClassName.multi( '
+            ' ${element.displayName} Function(BuildContext context) test, '
+            '{bool freezed = true}) => '
+            '\$$multiProxyClassName( '
+            'test, '
+            'freezed: freezed,); ')
+        ..write(
+          '  ${element.displayName}? compo; '
+          '@override '
+          'Widget build(BuildContext context) {  final component = '
+          '(compo ??= select(context)).copyWith.call(',
+        );
+      for (final field in element.constructors.first.parameters) {
+        generatedCode.write('${field.displayName}:${field.displayName},');
+      }
+      generatedCode
+        ..write(');')
+        ..write('if (!(freezed ?? true)) { '
+            'compo = null; } '
+            'return component; '
+            '}} ');
+    }
+
+    return generatedCode.toString();
+  }
+}