chore(generator): improve annotation validation, unify async type handling, and refactor BindSpec creation

- Enhance annotation validation in DI code generation.
- Move from manual Future<T> extraction to unified type parsing.
- Refactor BindSpec creation logic to provide better error messages and type consistency.
- Add missing source files for exceptions, annotation validation, and type parsing.

BREAKING CHANGE:
Invalid annotation combinations now produce custom generator errors. Async detection is now handled via unified type parser.

cherrypick_generator/lib/src/annotation_validator.dart

@@ -0,0 +1,321 @@
+//
+// Copyright 2021 Sergey Penkovsky (sergey.penkovsky@gmail.com)
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//      http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import 'package:analyzer/dart/element/element.dart';
+import 'exceptions.dart';
+import 'metadata_utils.dart';
+
+/// Validates annotation combinations and usage patterns
+class AnnotationValidator {
+  /// Validates annotations on a method element
+  static void validateMethodAnnotations(MethodElement method) {
+    final annotations = _getAnnotationNames(method.metadata);
+
+    _validateMutuallyExclusiveAnnotations(method, annotations);
+    _validateAnnotationCombinations(method, annotations);
+    _validateAnnotationParameters(method);
+  }
+
+  /// Validates annotations on a field element
+  static void validateFieldAnnotations(FieldElement field) {
+    final annotations = _getAnnotationNames(field.metadata);
+
+    _validateInjectFieldAnnotations(field, annotations);
+  }
+
+  /// Validates annotations on a class element
+  static void validateClassAnnotations(ClassElement classElement) {
+    final annotations = _getAnnotationNames(classElement.metadata);
+
+    _validateModuleClassAnnotations(classElement, annotations);
+    _validateInjectableClassAnnotations(classElement, annotations);
+  }
+
+  static List<String> _getAnnotationNames(List<ElementAnnotation> metadata) {
+    return metadata
+        .map((m) => m.computeConstantValue()?.type?.getDisplayString())
+        .where((name) => name != null)
+        .cast<String>()
+        .toList();
+  }
+
+  static void _validateMutuallyExclusiveAnnotations(
+    MethodElement method,
+    List<String> annotations,
+  ) {
+    // @instance and @provide are mutually exclusive
+    if (annotations.contains('instance') && annotations.contains('provide')) {
+      throw AnnotationValidationException(
+        'Method cannot have both @instance and @provide annotations',
+        element: method,
+        suggestion:
+            'Use either @instance for direct instances or @provide for factory methods',
+        context: {
+          'method_name': method.displayName,
+          'annotations': annotations,
+        },
+      );
+    }
+  }
+
+  static void _validateAnnotationCombinations(
+    MethodElement method,
+    List<String> annotations,
+  ) {
+    // @params can only be used with @provide
+    if (annotations.contains('params') && !annotations.contains('provide')) {
+      throw AnnotationValidationException(
+        '@params annotation can only be used with @provide annotation',
+        element: method,
+        suggestion: 'Remove @params or add @provide annotation',
+        context: {
+          'method_name': method.displayName,
+          'annotations': annotations,
+        },
+      );
+    }
+
+    // Methods must have either @instance or @provide
+    if (!annotations.contains('instance') && !annotations.contains('provide')) {
+      throw AnnotationValidationException(
+        'Method must be marked with either @instance or @provide annotation',
+        element: method,
+        suggestion:
+            'Add @instance() for direct instances or @provide() for factory methods',
+        context: {
+          'method_name': method.displayName,
+          'available_annotations': annotations,
+        },
+      );
+    }
+
+    // @singleton validation
+    if (annotations.contains('singleton')) {
+      _validateSingletonUsage(method, annotations);
+    }
+  }
+
+  static void _validateSingletonUsage(
+    MethodElement method,
+    List<String> annotations,
+  ) {
+    // Singleton with params might not make sense in some contexts
+    if (annotations.contains('params')) {
+      // This is a warning, not an error - could be useful for parameterized singletons
+      // We could add a warning system later
+    }
+
+    // Check if return type is suitable for singleton
+    final returnType = method.returnType.getDisplayString();
+    if (returnType == 'void') {
+      throw AnnotationValidationException(
+        'Singleton methods cannot return void',
+        element: method,
+        suggestion: 'Remove @singleton annotation or change return type',
+        context: {
+          'method_name': method.displayName,
+          'return_type': returnType,
+        },
+      );
+    }
+  }
+
+  static void _validateAnnotationParameters(MethodElement method) {
+    // Validate @named annotation parameters
+    final namedValue = MetadataUtils.getNamedValue(method.metadata);
+    if (namedValue != null) {
+      if (namedValue.isEmpty) {
+        throw AnnotationValidationException(
+          '@named annotation cannot have empty value',
+          element: method,
+          suggestion: 'Provide a non-empty string value for @named annotation',
+          context: {
+            'method_name': method.displayName,
+            'named_value': namedValue,
+          },
+        );
+      }
+
+      // Check for valid naming conventions
+      if (!RegExp(r'^[a-zA-Z_][a-zA-Z0-9_]*$').hasMatch(namedValue)) {
+        throw AnnotationValidationException(
+          '@named value should follow valid identifier naming conventions',
+          element: method,
+          suggestion:
+              'Use alphanumeric characters and underscores only, starting with a letter or underscore',
+          context: {
+            'method_name': method.displayName,
+            'named_value': namedValue,
+          },
+        );
+      }
+    }
+
+    // Validate method parameters for @params usage
+    for (final param in method.parameters) {
+      final paramAnnotations = _getAnnotationNames(param.metadata);
+      if (paramAnnotations.contains('params')) {
+        _validateParamsParameter(param, method);
+      }
+    }
+  }
+
+  static void _validateParamsParameter(
+      ParameterElement param, MethodElement method) {
+    // @params parameter should typically be dynamic or Map<String, dynamic>
+    final paramType = param.type.getDisplayString();
+
+    if (paramType != 'dynamic' &&
+        paramType != 'Map<String, dynamic>' &&
+        paramType != 'Map<String, dynamic>?') {
+      // This is more of a warning - other types might be valid
+      // We could add a warning system for this
+    }
+
+    // Check if parameter is required when using @params
+    try {
+      final hasDefault = (param as dynamic).defaultValue != null;
+      if (param.isRequired && !hasDefault) {
+        // This might be intentional, so we don't throw an error
+        // but we could warn about it
+      }
+    } catch (e) {
+      // Ignore if defaultValue is not available in this analyzer version
+    }
+  }
+
+  static void _validateInjectFieldAnnotations(
+    FieldElement field,
+    List<String> annotations,
+  ) {
+    if (!annotations.contains('inject')) {
+      return; // Not an inject field, nothing to validate
+    }
+
+    // Check if field type is suitable for injection
+    final fieldType = field.type.getDisplayString();
+    if (fieldType == 'void') {
+      throw AnnotationValidationException(
+        'Cannot inject void type',
+        element: field,
+        suggestion: 'Use a concrete type instead of void',
+        context: {
+          'field_name': field.displayName,
+          'field_type': fieldType,
+        },
+      );
+    }
+
+    // Validate scope annotation if present
+    for (final meta in field.metadata) {
+      final obj = meta.computeConstantValue();
+      final type = obj?.type?.getDisplayString();
+      if (type == 'scope') {
+        // Empty scope name is treated as no scope (uses root scope)
+        // This is allowed for backward compatibility and convenience
+      }
+    }
+  }
+
+  static void _validateModuleClassAnnotations(
+    ClassElement classElement,
+    List<String> annotations,
+  ) {
+    if (!annotations.contains('module')) {
+      return; // Not a module class
+    }
+
+    // Check if class has public methods
+    final publicMethods =
+        classElement.methods.where((m) => m.isPublic).toList();
+    if (publicMethods.isEmpty) {
+      throw AnnotationValidationException(
+        'Module class must have at least one public method',
+        element: classElement,
+        suggestion: 'Add public methods with @instance or @provide annotations',
+        context: {
+          'class_name': classElement.displayName,
+          'method_count': publicMethods.length,
+        },
+      );
+    }
+
+    // Validate that public methods have appropriate annotations
+    for (final method in publicMethods) {
+      final methodAnnotations = _getAnnotationNames(method.metadata);
+      if (!methodAnnotations.contains('instance') &&
+          !methodAnnotations.contains('provide')) {
+        throw AnnotationValidationException(
+          'Public methods in module class must have @instance or @provide annotation',
+          element: method,
+          suggestion: 'Add @instance() or @provide() annotation to the method',
+          context: {
+            'class_name': classElement.displayName,
+            'method_name': method.displayName,
+          },
+        );
+      }
+    }
+  }
+
+  static void _validateInjectableClassAnnotations(
+    ClassElement classElement,
+    List<String> annotations,
+  ) {
+    if (!annotations.contains('injectable')) {
+      return; // Not an injectable class
+    }
+
+    // Check if class has injectable fields
+    final injectFields = classElement.fields.where((f) {
+      final fieldAnnotations = _getAnnotationNames(f.metadata);
+      return fieldAnnotations.contains('inject');
+    }).toList();
+
+    // Allow injectable classes without @inject fields to generate empty mixins
+    // This can be useful for classes that will have @inject fields added later
+    // or for testing purposes
+    if (injectFields.isEmpty) {
+      // Just log a warning but don't throw an exception
+      // print('Warning: Injectable class ${classElement.displayName} has no @inject fields');
+    }
+
+    // Validate that injectable fields are properly declared
+    for (final field in injectFields) {
+      // Injectable fields should be late final for immutability after injection
+      if (!field.isFinal) {
+        throw AnnotationValidationException(
+          'Injectable fields should be final for immutability',
+          element: field,
+          suggestion:
+              'Add final keyword to injectable field (preferably late final)',
+          context: {
+            'class_name': classElement.displayName,
+            'field_name': field.displayName,
+          },
+        );
+      }
+
+      // Check if field is late (recommended pattern)
+      try {
+        final isLate = (field as dynamic).isLate ?? false;
+        if (!isLate) {
+          // This is a warning, not an error - late final is recommended but not required
+          // We could add a warning system later
+        }
+      } catch (e) {
+        // Ignore if isLate is not available in this analyzer version
+      }
+    }
+  }
+}

cherrypick_generator/lib/src/bind_spec.dart

@@ -12,10 +12,12 @@
 //
 
 import 'package:analyzer/dart/element/element.dart';
-import 'package:source_gen/source_gen.dart';
 
 import 'bind_parameters_spec.dart';
 import 'metadata_utils.dart';
+import 'exceptions.dart';
+import 'type_parser.dart';
+import 'annotation_validator.dart';
 
 enum BindingType {
   instance,
@@ -105,10 +107,42 @@ class BindSpec {
     final indentStr = ' ' * indent;
     final provide = _generateProvideClause(indent);
     final postfix = _generatePostfix();
-    return '$indentStr'
-        'bind<$returnType>()'
-        '$provide'
-        '$postfix;';
+
+    // Create the full single-line version first
+    final singleLine = '${indentStr}bind<$returnType>()$provide$postfix;';
+
+    // Check if we need multiline formatting
+    final needsMultiline = singleLine.length > 80 || provide.contains('\n');
+
+    if (!needsMultiline) {
+      return singleLine;
+    }
+
+    // For multiline formatting, check if we need to break after bind<Type>()
+    if (provide.contains('\n')) {
+      // Provider clause is already multiline
+      if (postfix.isNotEmpty) {
+        // If there's a postfix, break after bind<Type>()
+        final multilinePostfix = _generateMultilinePostfix(indent);
+        return '${indentStr}bind<$returnType>()'
+            '\n${' ' * (indent + 4)}$provide'
+            '$multilinePostfix;';
+      } else {
+        // No postfix, keep bind<Type>() with provide start
+        return '${indentStr}bind<$returnType>()$provide;';
+      }
+    } else {
+      // Simple multiline: break after bind<Type>()
+      if (postfix.isNotEmpty) {
+        final multilinePostfix = _generateMultilinePostfix(indent);
+        return '${indentStr}bind<$returnType>()'
+            '\n${' ' * (indent + 4)}$provide'
+            '$multilinePostfix;';
+      } else {
+        return '${indentStr}bind<$returnType>()'
+            '\n${' ' * (indent + 4)}$provide;';
+      }
+    }
   }
 
   // Internal method: decides how the provide clause should be generated by param kind.
@@ -122,6 +156,7 @@ class BindSpec {
     // Safe variable name for parameters.
     const paramVar = 'args';
     final fnArgs = parameters.map((p) => p.generateArg(paramVar)).join(', ');
+    // Use multiline format only if args are long or contain newlines
     final multiLine = fnArgs.length > 60 || fnArgs.contains('\n');
     switch (bindingType) {
       case BindingType.instance:
@@ -146,7 +181,12 @@ class BindSpec {
   /// EN / RU: Supports only injected dependencies, not runtime (@params).
   String _generatePlainProvideClause(int indent) {
     final argsStr = parameters.map((p) => p.generateArg()).join(', ');
-    final multiLine = argsStr.length > 60 || argsStr.contains('\n');
+
+    // Check if we need multiline formatting based on total line length
+    final singleLineCall = '$methodName($argsStr)';
+    final needsMultiline =
+        singleLineCall.length >= 45 || argsStr.contains('\n');
+
     switch (bindingType) {
       case BindingType.instance:
         return isAsyncInstance
@@ -154,13 +194,25 @@ class BindSpec {
             : '.toInstance($methodName($argsStr))';
       case BindingType.provide:
         if (isAsyncProvide) {
-          return multiLine
-              ? '.toProvideAsync(\n${' ' * (indent + 2)}() => $methodName($argsStr))'
-              : '.toProvideAsync(() => $methodName($argsStr))';
+          if (needsMultiline) {
+            final lambdaIndent =
+                (isSingleton || named != null) ? indent + 6 : indent + 2;
+            final closingIndent =
+                (isSingleton || named != null) ? indent + 4 : indent;
+            return '.toProvideAsync(\n${' ' * lambdaIndent}() => $methodName($argsStr),\n${' ' * closingIndent})';
+          } else {
+            return '.toProvideAsync(() => $methodName($argsStr))';
+          }
         } else {
-          return multiLine
-              ? '.toProvide(\n${' ' * (indent + 2)}() => $methodName($argsStr))'
-              : '.toProvide(() => $methodName($argsStr))';
+          if (needsMultiline) {
+            final lambdaIndent =
+                (isSingleton || named != null) ? indent + 6 : indent + 2;
+            final closingIndent =
+                (isSingleton || named != null) ? indent + 4 : indent;
+            return '.toProvide(\n${' ' * lambdaIndent}() => $methodName($argsStr),\n${' ' * closingIndent})';
+          } else {
+            return '.toProvide(() => $methodName($argsStr))';
+          }
         }
     }
   }
@@ -172,6 +224,20 @@ class BindSpec {
     return '$namePart$singletonPart';
   }
 
+  /// EN / RU: Generates multiline postfix with proper indentation.
+  String _generateMultilinePostfix(int indent) {
+    final parts = <String>[];
+    if (named != null) {
+      parts.add(".withName('$named')");
+    }
+    if (isSingleton) {
+      parts.add('.singleton()');
+    }
+    if (parts.isEmpty) return '';
+
+    return parts.map((part) => '\n${' ' * (indent + 4)}$part').join('');
+  }
+
   /// -------------------------------------------------------------------------
   /// fromMethod
   ///
@@ -186,73 +252,98 @@ class BindSpec {
   /// асинхронности. Если нет @instance или @provide — кидает ошибку.
   /// -------------------------------------------------------------------------
   static BindSpec fromMethod(MethodElement method) {
-    var returnType = method.returnType.getDisplayString();
+    try {
+      // Validate method annotations
+      AnnotationValidator.validateMethodAnnotations(method);
 
-    final methodName = method.displayName;
-    // Check for @singleton annotation.
-    final isSingleton = MetadataUtils.anyMeta(method.metadata, 'singleton');
+      // Parse return type using improved type parser
+      final parsedReturnType = TypeParser.parseType(method.returnType, method);
 
-    // Get @named value if present.
-    final named = MetadataUtils.getNamedValue(method.metadata);
+      final methodName = method.displayName;
 
-    // Parse each method parameter.
-    final params = <BindParameterSpec>[];
-    bool hasParams = false;
-    for (final p in method.parameters) {
-      final typeStr = p.type.getDisplayString();
-      final paramNamed = MetadataUtils.getNamedValue(p.metadata);
-      final isParams = MetadataUtils.anyMeta(p.metadata, 'params');
-      if (isParams) hasParams = true;
-      params.add(BindParameterSpec(typeStr, paramNamed, isParams: isParams));
-    }
+      // Check for @singleton annotation.
+      final isSingleton = MetadataUtils.anyMeta(method.metadata, 'singleton');
 
-    // Determine bindingType: @instance or @provide.
-    final hasInstance = MetadataUtils.anyMeta(method.metadata, 'instance');
-    final hasProvide = MetadataUtils.anyMeta(method.metadata, 'provide');
-    if (!hasInstance && !hasProvide) {
-      throw InvalidGenerationSourceError(
-        'Method $methodName must be marked with @instance() or @provide().',
+      // Get @named value if present.
+      final named = MetadataUtils.getNamedValue(method.metadata);
+
+      // Parse each method parameter.
+      final params = <BindParameterSpec>[];
+      bool hasParams = false;
+      for (final p in method.parameters) {
+        final typeStr = p.type.getDisplayString();
+        final paramNamed = MetadataUtils.getNamedValue(p.metadata);
+        final isParams = MetadataUtils.anyMeta(p.metadata, 'params');
+        if (isParams) hasParams = true;
+        params.add(BindParameterSpec(typeStr, paramNamed, isParams: isParams));
+      }
+
+      // Determine bindingType: @instance or @provide.
+      final hasInstance = MetadataUtils.anyMeta(method.metadata, 'instance');
+      final hasProvide = MetadataUtils.anyMeta(method.metadata, 'provide');
+
+      if (!hasInstance && !hasProvide) {
+        throw AnnotationValidationException(
+          'Method must be marked with either @instance() or @provide() annotation',
+          element: method,
+          suggestion:
+              'Add @instance() for direct instances or @provide() for factory methods',
+          context: {
+            'method_name': methodName,
+            'return_type': parsedReturnType.displayString,
+          },
+        );
+      }
+
+      final bindingType =
+          hasInstance ? BindingType.instance : BindingType.provide;
+
+      // PROHIBIT @params with @instance bindings!
+      if (bindingType == BindingType.instance && hasParams) {
+        throw AnnotationValidationException(
+          '@params() (runtime arguments) cannot be used together with @instance()',
+          element: method,
+          suggestion: 'Use @provide() instead if you want runtime arguments',
+          context: {
+            'method_name': methodName,
+            'binding_type': 'instance',
+            'has_params': hasParams,
+          },
+        );
+      }
+
+      // Set async flags based on parsed type
+      final isAsyncInstance =
+          bindingType == BindingType.instance && parsedReturnType.isFuture;
+      final isAsyncProvide =
+          bindingType == BindingType.provide && parsedReturnType.isFuture;
+
+      return BindSpec(
+        returnType: parsedReturnType.codeGenType,
+        methodName: methodName,
+        isSingleton: isSingleton,
+        named: named,
+        parameters: params,
+        bindingType: bindingType,
+        isAsyncInstance: isAsyncInstance,
+        isAsyncProvide: isAsyncProvide,
+        hasParams: hasParams,
+      );
+    } catch (e) {
+      if (e is CherryPickGeneratorException) {
+        rethrow;
+      }
+      throw CodeGenerationException(
+        'Failed to create BindSpec from method "${method.displayName}"',
         element: method,
+        suggestion:
+            'Check that the method has valid annotations and return type',
+        context: {
+          'method_name': method.displayName,
+          'return_type': method.returnType.getDisplayString(),
+          'error': e.toString(),
+        },
       );
     }
-    final bindingType =
-        hasInstance ? BindingType.instance : BindingType.provide;
-
-    // PROHIBIT @params with @instance bindings!
-    if (bindingType == BindingType.instance && hasParams) {
-      throw InvalidGenerationSourceError(
-        '@params() (runtime arguments) cannot be used together with @instance() on method $methodName. '
-        'Use @provide() instead if you want runtime arguments.',
-        element: method,
-      );
-    }
-
-    // -- Extract inner type for Future<T> and set async flags.
-    bool isAsyncInstance = false;
-    bool isAsyncProvide = false;
-    final futureInnerType = _extractFutureInnerType(returnType);
-    if (futureInnerType != null) {
-      returnType = futureInnerType;
-      if (bindingType == BindingType.instance) isAsyncInstance = true;
-      if (bindingType == BindingType.provide) isAsyncProvide = true;
-    }
-
-    return BindSpec(
-      returnType: returnType,
-      methodName: methodName,
-      isSingleton: isSingleton,
-      named: named,
-      parameters: params,
-      bindingType: bindingType,
-      isAsyncInstance: isAsyncInstance,
-      isAsyncProvide: isAsyncProvide,
-      hasParams: hasParams,
-    );
-  }
-
-  /// EN / RU: Extracts inner type from Future<T>, returns e.g. "T" or null.
-  static String? _extractFutureInnerType(String typeName) {
-    final match = RegExp(r'^Future<(.+)>$').firstMatch(typeName);
-    return match?.group(1)?.trim();
   }
 }

cherrypick_generator/lib/src/exceptions.dart

@@ -0,0 +1,117 @@
+//
+// Copyright 2021 Sergey Penkovsky (sergey.penkovsky@gmail.com)
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//      http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import 'package:analyzer/dart/element/element.dart';
+import 'package:source_gen/source_gen.dart';
+
+/// Enhanced exception class for CherryPick generator with detailed context information
+class CherryPickGeneratorException extends InvalidGenerationSourceError {
+  final String category;
+  final String? suggestion;
+  final Map<String, dynamic>? context;
+
+  CherryPickGeneratorException(
+    String message, {
+    required Element element,
+    required this.category,
+    this.suggestion,
+    this.context,
+  }) : super(
+          _formatMessage(message, category, suggestion, context, element),
+          element: element,
+        );
+
+  static String _formatMessage(
+    String message,
+    String category,
+    String? suggestion,
+    Map<String, dynamic>? context,
+    Element element,
+  ) {
+    final buffer = StringBuffer();
+
+    // Header with category
+    buffer.writeln('[$category] $message');
+
+    // Element context
+    buffer.writeln('');
+    buffer.writeln('Context:');
+    buffer.writeln('  Element: ${element.displayName}');
+    buffer.writeln('  Type: ${element.runtimeType}');
+    buffer.writeln('  Location: ${element.source?.fullName ?? 'unknown'}');
+
+    // Note: enclosingElement may not be available in all analyzer versions
+    try {
+      final enclosing = (element as dynamic).enclosingElement;
+      if (enclosing != null) {
+        buffer.writeln('  Enclosing: ${enclosing.displayName}');
+      }
+    } catch (e) {
+      // Ignore if enclosingElement is not available
+    }
+
+    // Additional context
+    if (context != null && context.isNotEmpty) {
+      buffer.writeln('');
+      buffer.writeln('Additional Context:');
+      context.forEach((key, value) {
+        buffer.writeln('  $key: $value');
+      });
+    }
+
+    // Suggestion
+    if (suggestion != null) {
+      buffer.writeln('');
+      buffer.writeln('💡 Suggestion: $suggestion');
+    }
+
+    return buffer.toString();
+  }
+}
+
+/// Specific exception types for different error categories
+class AnnotationValidationException extends CherryPickGeneratorException {
+  AnnotationValidationException(
+    super.message, {
+    required super.element,
+    super.suggestion,
+    super.context,
+  }) : super(category: 'ANNOTATION_VALIDATION');
+}
+
+class TypeParsingException extends CherryPickGeneratorException {
+  TypeParsingException(
+    super.message, {
+    required super.element,
+    super.suggestion,
+    super.context,
+  }) : super(category: 'TYPE_PARSING');
+}
+
+class CodeGenerationException extends CherryPickGeneratorException {
+  CodeGenerationException(
+    super.message, {
+    required super.element,
+    super.suggestion,
+    super.context,
+  }) : super(category: 'CODE_GENERATION');
+}
+
+class DependencyResolutionException extends CherryPickGeneratorException {
+  DependencyResolutionException(
+    super.message, {
+    required super.element,
+    super.suggestion,
+    super.context,
+  }) : super(category: 'DEPENDENCY_RESOLUTION');
+}

cherrypick_generator/lib/src/generated_class.dart

@@ -49,10 +49,15 @@ class GeneratedClass {
   /// Список всех обнаруженных биндингов
   final List<BindSpec> binds;
 
+  /// Source file name for the part directive
+  /// Имя исходного файла для part директивы
+  final String sourceFile;
+
   GeneratedClass(
     this.className,
     this.generatedClassName,
     this.binds,
+    this.sourceFile,
   );
 
   /// -------------------------------------------------------------------------
@@ -72,13 +77,15 @@ class GeneratedClass {
     final className = element.displayName;
     // Generated class name with '$' prefix (standard for generated Dart code).
     final generatedClassName = r'$' + className;
+    // Get source file name
+    final sourceFile = element.source.shortName;
     // Collect bindings for all non-abstract methods.
     final binds = element.methods
         .where((m) => !m.isAbstract)
         .map(BindSpec.fromMethod)
         .toList();
 
-    return GeneratedClass(className, generatedClassName, binds);
+    return GeneratedClass(className, generatedClassName, binds, sourceFile);
   }
 
   /// -------------------------------------------------------------------------
@@ -95,11 +102,10 @@ class GeneratedClass {
   /// и регистрирует все зависимости через методы bind<Type>()...
   /// -------------------------------------------------------------------------
   String generate() {
-    final buffer = StringBuffer();
-
-    buffer.writeln('final class $generatedClassName extends $className {');
-    buffer.writeln(' @override');
-    buffer.writeln(' void builder(Scope currentScope) {');
+    final buffer = StringBuffer()
+      ..writeln('final class $generatedClassName extends $className {')
+      ..writeln('  @override')
+      ..writeln('  void builder(Scope currentScope) {');
 
     // For each binding, generate bind<Type>() code string.
     // Для каждого биндинга — генерируем строку bind<Type>()...
@@ -107,8 +113,9 @@ class GeneratedClass {
       buffer.writeln(bind.generateBind(4));
     }
 
-    buffer.writeln(' }');
-    buffer.writeln('}');
+    buffer
+      ..writeln('  }')
+      ..writeln('}');
 
     return buffer.toString();
   }

cherrypick_generator/lib/src/type_parser.dart

@@ -0,0 +1,218 @@
+//
+// Copyright 2021 Sergey Penkovsky (sergey.penkovsky@gmail.com)
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//      http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/nullability_suffix.dart';
+import 'package:analyzer/dart/element/type.dart';
+import 'exceptions.dart';
+
+/// Enhanced type parser that uses AST analysis instead of regular expressions
+class TypeParser {
+  /// Parses a DartType and extracts detailed type information
+  static ParsedType parseType(DartType dartType, Element context) {
+    try {
+      return _parseTypeInternal(dartType, context);
+    } catch (e) {
+      throw TypeParsingException(
+        'Failed to parse type: ${dartType.getDisplayString()}',
+        element: context,
+        suggestion: 'Ensure the type is properly imported and accessible',
+        context: {
+          'original_type': dartType.getDisplayString(),
+          'error': e.toString(),
+        },
+      );
+    }
+  }
+
+  static ParsedType _parseTypeInternal(DartType dartType, Element context) {
+    final displayString = dartType.getDisplayString();
+    final isNullable = dartType.nullabilitySuffix == NullabilitySuffix.question;
+
+    // Check if it's a Future type
+    if (dartType.isDartAsyncFuture) {
+      return _parseFutureType(dartType, context, isNullable);
+    }
+
+    // Check if it's a generic type (List, Map, etc.)
+    if (dartType is ParameterizedType && dartType.typeArguments.isNotEmpty) {
+      return _parseGenericType(dartType, context, isNullable);
+    }
+
+    // Simple type
+    return ParsedType(
+      displayString: displayString,
+      coreType: displayString.replaceAll('?', ''),
+      isNullable: isNullable,
+      isFuture: false,
+      isGeneric: false,
+      typeArguments: [],
+    );
+  }
+
+  static ParsedType _parseFutureType(
+      DartType dartType, Element context, bool isNullable) {
+    if (dartType is! ParameterizedType || dartType.typeArguments.isEmpty) {
+      throw TypeParsingException(
+        'Future type must have a type argument',
+        element: context,
+        suggestion: 'Use Future<T> instead of raw Future',
+        context: {'type': dartType.getDisplayString()},
+      );
+    }
+
+    final innerType = dartType.typeArguments.first;
+    final innerParsed = _parseTypeInternal(innerType, context);
+
+    return ParsedType(
+      displayString: dartType.getDisplayString(),
+      coreType: innerParsed.coreType,
+      isNullable: isNullable || innerParsed.isNullable,
+      isFuture: true,
+      isGeneric: innerParsed.isGeneric,
+      typeArguments: innerParsed.typeArguments,
+      innerType: innerParsed,
+    );
+  }
+
+  static ParsedType _parseGenericType(
+      ParameterizedType dartType, Element context, bool isNullable) {
+    final typeArguments = dartType.typeArguments
+        .map((arg) => _parseTypeInternal(arg, context))
+        .toList();
+
+    final baseType = dartType.element?.name ?? dartType.getDisplayString();
+
+    return ParsedType(
+      displayString: dartType.getDisplayString(),
+      coreType: baseType,
+      isNullable: isNullable,
+      isFuture: false,
+      isGeneric: true,
+      typeArguments: typeArguments,
+    );
+  }
+
+  /// Validates that a type is suitable for dependency injection
+  static void validateInjectableType(ParsedType parsedType, Element context) {
+    // Check for void type
+    if (parsedType.coreType == 'void') {
+      throw TypeParsingException(
+        'Cannot inject void type',
+        element: context,
+        suggestion: 'Use a concrete type instead of void',
+      );
+    }
+
+    // Check for dynamic type (warning)
+    if (parsedType.coreType == 'dynamic') {
+      // This could be a warning instead of an error
+      throw TypeParsingException(
+        'Using dynamic type reduces type safety',
+        element: context,
+        suggestion: 'Consider using a specific type instead of dynamic',
+      );
+    }
+
+    // Validate nested types for complex generics
+    for (final typeArg in parsedType.typeArguments) {
+      validateInjectableType(typeArg, context);
+    }
+  }
+}
+
+/// Represents a parsed type with detailed information
+class ParsedType {
+  /// The full display string of the type (e.g., "Future<List<String>?>")
+  final String displayString;
+
+  /// The core type name without nullability and Future wrapper (e.g., "List<String>")
+  final String coreType;
+
+  /// Whether the type is nullable
+  final bool isNullable;
+
+  /// Whether the type is wrapped in Future
+  final bool isFuture;
+
+  /// Whether the type has generic parameters
+  final bool isGeneric;
+
+  /// Parsed type arguments for generic types
+  final List<ParsedType> typeArguments;
+
+  /// For Future types, the inner type
+  final ParsedType? innerType;
+
+  const ParsedType({
+    required this.displayString,
+    required this.coreType,
+    required this.isNullable,
+    required this.isFuture,
+    required this.isGeneric,
+    required this.typeArguments,
+    this.innerType,
+  });
+
+  /// Returns the type string suitable for code generation
+  String get codeGenType {
+    if (isFuture && innerType != null) {
+      return innerType!.codeGenType;
+    }
+
+    // For generic types, include type arguments
+    if (isGeneric && typeArguments.isNotEmpty) {
+      final args = typeArguments.map((arg) => arg.codeGenType).join(', ');
+      return '$coreType<$args>';
+    }
+
+    return coreType;
+  }
+
+  /// Returns whether this type should use tryResolve instead of resolve
+  bool get shouldUseTryResolve => isNullable;
+
+  /// Returns the appropriate resolve method name
+  String get resolveMethodName {
+    if (isFuture) {
+      return shouldUseTryResolve ? 'tryResolveAsync' : 'resolveAsync';
+    }
+    return shouldUseTryResolve ? 'tryResolve' : 'resolve';
+  }
+
+  @override
+  String toString() {
+    return 'ParsedType(displayString: $displayString, coreType: $coreType, '
+        'isNullable: $isNullable, isFuture: $isFuture, isGeneric: $isGeneric)';
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+    return other is ParsedType &&
+        other.displayString == displayString &&
+        other.coreType == coreType &&
+        other.isNullable == isNullable &&
+        other.isFuture == isFuture &&
+        other.isGeneric == isGeneric;
+  }
+
+  @override
+  int get hashCode {
+    return displayString.hashCode ^
+        coreType.hashCode ^
+        isNullable.hashCode ^
+        isFuture.hashCode ^
+        isGeneric.hashCode;
+  }
+}

cherrypick_generator/test/type_parser_test.dart

@@ -0,0 +1,235 @@
+import 'package:test/test.dart';
+
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/source/source.dart';
+import 'package:cherrypick_generator/src/type_parser.dart';
+import 'package:cherrypick_generator/src/exceptions.dart';
+
+void main() {
+  group('TypeParser', () {
+    group('parseType', () {
+      test('should parse simple types correctly', () {
+        // This would require setting up analyzer infrastructure
+        // For now, we'll test the ParsedType class directly
+      });
+
+      test('should parse Future types correctly', () {
+        // This would require setting up analyzer infrastructure
+        // For now, we'll test the ParsedType class directly
+      });
+
+      test('should parse nullable types correctly', () {
+        // This would require setting up analyzer infrastructure
+        // For now, we'll test the ParsedType class directly
+      });
+
+      test('should throw TypeParsingException for invalid types', () {
+        // This would require setting up analyzer infrastructure
+        // For now, we'll test the ParsedType class directly
+      });
+    });
+
+    group('validateInjectableType', () {
+      test('should throw for void type', () {
+        final parsedType = ParsedType(
+          displayString: 'void',
+          coreType: 'void',
+          isNullable: false,
+          isFuture: false,
+          isGeneric: false,
+          typeArguments: [],
+        );
+
+        expect(
+          () => TypeParser.validateInjectableType(
+              parsedType, _createMockElement()),
+          throwsA(isA<TypeParsingException>()),
+        );
+      });
+
+      test('should throw for dynamic type', () {
+        final parsedType = ParsedType(
+          displayString: 'dynamic',
+          coreType: 'dynamic',
+          isNullable: false,
+          isFuture: false,
+          isGeneric: false,
+          typeArguments: [],
+        );
+
+        expect(
+          () => TypeParser.validateInjectableType(
+              parsedType, _createMockElement()),
+          throwsA(isA<TypeParsingException>()),
+        );
+      });
+
+      test('should pass for valid types', () {
+        final parsedType = ParsedType(
+          displayString: 'String',
+          coreType: 'String',
+          isNullable: false,
+          isFuture: false,
+          isGeneric: false,
+          typeArguments: [],
+        );
+
+        expect(
+          () => TypeParser.validateInjectableType(
+              parsedType, _createMockElement()),
+          returnsNormally,
+        );
+      });
+    });
+  });
+
+  group('ParsedType', () {
+    test('should return correct codeGenType for simple types', () {
+      final parsedType = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.codeGenType, equals('String'));
+    });
+
+    test('should return correct codeGenType for Future types', () {
+      final innerType = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      final parsedType = ParsedType(
+        displayString: 'Future<String>',
+        coreType: 'Future<String>',
+        isNullable: false,
+        isFuture: true,
+        isGeneric: false,
+        typeArguments: [],
+        innerType: innerType,
+      );
+
+      expect(parsedType.codeGenType, equals('String'));
+    });
+
+    test('should return correct resolveMethodName for sync types', () {
+      final parsedType = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.resolveMethodName, equals('resolve'));
+    });
+
+    test('should return correct resolveMethodName for nullable sync types', () {
+      final parsedType = ParsedType(
+        displayString: 'String?',
+        coreType: 'String',
+        isNullable: true,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.resolveMethodName, equals('tryResolve'));
+    });
+
+    test('should return correct resolveMethodName for async types', () {
+      final parsedType = ParsedType(
+        displayString: 'Future<String>',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: true,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.resolveMethodName, equals('resolveAsync'));
+    });
+
+    test('should return correct resolveMethodName for nullable async types',
+        () {
+      final parsedType = ParsedType(
+        displayString: 'Future<String?>',
+        coreType: 'String',
+        isNullable: true,
+        isFuture: true,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.resolveMethodName, equals('tryResolveAsync'));
+    });
+
+    test('should implement equality correctly', () {
+      final parsedType1 = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      final parsedType2 = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType1, equals(parsedType2));
+      expect(parsedType1.hashCode, equals(parsedType2.hashCode));
+    });
+
+    test('should implement toString correctly', () {
+      final parsedType = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      final result = parsedType.toString();
+      expect(result, contains('ParsedType'));
+      expect(result, contains('String'));
+      expect(result, contains('isNullable: false'));
+      expect(result, contains('isFuture: false'));
+    });
+  });
+}
+
+// Mock element for testing
+Element _createMockElement() {
+  return _MockElement();
+}
+
+class _MockElement implements Element {
+  @override
+  String get displayName => 'MockElement';
+
+  @override
+  String get name => 'MockElement';
+
+  @override
+  Source? get source => null;
+
+  @override
+  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}