[swift2objc] Support Swift ARC features (#2055)

Author: nikeokoronkwo

pkgs/swift2objc/lib/src/ast/declarations/compounds/members/property_declaration.dart

@@ -40,6 +40,12 @@ class PropertyDeclaration extends AstNode
   PropertyStatements? getter;
   PropertyStatements? setter;
 
+  bool unowned;
+
+  bool weak;
+
+  bool lazy;
+
   bool isStatic;
 
   PropertyDeclaration(
@@ -54,6 +60,9 @@ class PropertyDeclaration extends AstNode
       this.isStatic = false,
       this.throws = false,
       this.async = false,
+      this.unowned = false,
+      this.weak = false,
+      this.lazy = false,
       this.mutating = false})
       : assert(!(isConstant && hasSetter)),
         assert(!(hasSetter && throws));

pkgs/swift2objc/lib/src/generator/generators/class_generator.dart

@@ -144,8 +144,15 @@ List<String> _generateClassProperty(PropertyDeclaration property) {
   if (property.isStatic) {
     header.write('static ');
   }
+  final prefixes = [
+    if (property.unowned) 'unowned',
+    if (property.weak) 'weak',
+  ];
+
+  var prefix = prefixes.isEmpty ? '' : '${prefixes.join(' ')} ';
+  var propSwiftType = property.type.swiftType;
 
-  header.write('public var ${property.name}: ${property.type.swiftType} {');
+  header.write('public ${prefix}var ${property.name}: $propSwiftType {');
 
   final getterLines = [
     'get ${generateAnnotations(property)}{',

pkgs/swift2objc/lib/src/parser/parsers/declaration_parsers/parse_variable_declaration.dart

@@ -22,10 +22,13 @@ PropertyDeclaration parsePropertyDeclaration(
     type: _parseVariableType(propertySymbolJson, symbolgraph),
     hasObjCAnnotation: parseSymbolHasObjcAnnotation(propertySymbolJson),
     isConstant: info.constant,
-    hasSetter: info.constant ? false : info.setter,
     isStatic: isStatic,
     throws: info.throws,
     async: info.async,
+    unowned: info.unowned,
+    weak: info.weak,
+    lazy: info.lazy,
+    hasSetter: info.constant ? false : info.setter,
   );
 }
 
@@ -72,6 +75,9 @@ bool _findKeywordInFragments(Json json, String keyword) {
 typedef ParsedPropertyInfo = ({
   bool async,
   bool throws,
+  bool unowned,
+  bool weak,
+  bool lazy,
   bool constant,
   bool getter,
   bool setter,
@@ -84,6 +90,9 @@ ParsedPropertyInfo parsePropertyInfo(Json json) {
     constant: _parseVariableIsConstant(json),
     async: _findKeywordInFragments(json, 'async'),
     throws: _findKeywordInFragments(json, 'throws'),
+    unowned: _findKeywordInFragments(json, 'unowned'),
+    weak: _findKeywordInFragments(json, 'weak'),
+    lazy: _findKeywordInFragments(json, 'lazy'),
     getter: getter,
     setter: setter,
     mutating: _findKeywordInFragments(json, 'mutating')

pkgs/swift2objc/lib/src/transformer/transformers/transform_variable.dart

@@ -119,6 +119,13 @@ Declaration _transformVariable(
     isConstant: originalVariable.isConstant,
     throws: originalVariable.throws,
     async: originalVariable.async,
+    unowned: originalVariable is PropertyDeclaration
+        ? originalVariable.unowned
+        : false,
+    lazy:
+        originalVariable is PropertyDeclaration ? originalVariable.lazy : false,
+    weak:
+        originalVariable is PropertyDeclaration ? originalVariable.weak : false,
   );
 
   final getterStatements = _generateGetterStatements(

pkgs/swift2objc/test/integration/classes_and_properties_input.swift

@@ -29,17 +29,23 @@ public class MyClass {
 
     public let representableConstantProperty: Int
 
+    public weak var weakProperty: MyOtherClass?
+    public unowned var unownedProperty: MyOtherClass
+    public lazy var lazyProperty: Int = { 1 }();
+
 
     init(
         customVariableProperty: MyOtherClass, 
         customConstantProperty: MyOtherClass,
         representableVariableProperty: Int,
-        representableConstantProperty: Int
+        representableConstantProperty: Int,
+        unownedProperty: MyOtherClass
     ) {
         self.customVariableProperty = customVariableProperty
         self.customConstantProperty = customConstantProperty
         self.representableVariableProperty = representableVariableProperty
         self.representableConstantProperty = representableConstantProperty
+        self.unownedProperty = unownedProperty
     }
 }
 

pkgs/swift2objc/test/integration/classes_and_properties_output.swift

@@ -14,6 +14,33 @@ import Foundation
 @objc public class MyClassWrapper: NSObject {
   var wrappedInstance: MyClass
 
+  @objc public var lazyProperty: Int {
+    get {
+      wrappedInstance.lazyProperty
+    }
+    set {
+      wrappedInstance.lazyProperty = newValue
+    }
+  }
+
+  @objc public weak var weakProperty: MyOtherClassWrapper? {
+    get {
+      wrappedInstance.weakProperty == nil ? nil : MyOtherClassWrapper(wrappedInstance.weakProperty!)
+    }
+    set {
+      wrappedInstance.weakProperty = newValue?.wrappedInstance
+    }
+  }
+
+  @objc public unowned var unownedProperty: MyOtherClassWrapper {
+    get {
+      MyOtherClassWrapper(wrappedInstance.unownedProperty)
+    }
+    set {
+      wrappedInstance.unownedProperty = newValue.wrappedInstance
+    }
+  }
+
   @objc public var customGetterProperty: MyOtherClassWrapper {
     get {
       MyOtherClassWrapper(wrappedInstance.customGetterProperty)

pkgs/swift2objc/test/unit/parse_function_info_test.dart

@@ -18,7 +18,7 @@ void main() {
       decl.id: ParsedSymbol(json: Json(null), declaration: decl)
   };
   final emptySymbolgraph = ParsedSymbolgraph(parsedSymbols, {});
-  group('Valid json', () {
+  group('Function Valid json', () {
     void expectEqualParams(
       List<Parameter> actualParams,
       List<Parameter> expectedParams,

pkgs/swift2objc/test/unit/parse_variable_info_test.dart

@@ -1,8 +1,6 @@
 import 'dart:convert';
 
-// import 'package:swift2objc/src/ast/declarations/built_in/built_in_declaration.dart';
 import 'package:swift2objc/src/parser/_core/json.dart';
-// import 'package:swift2objc/src/parser/_core/parsed_symbolgraph.dart';
 import 'package:swift2objc/src/parser/parsers/declaration_parsers/parse_variable_declaration.dart';
 import 'package:test/test.dart';
 
@@ -303,7 +301,6 @@ void main() {
             ]'''));
 
       final info = parsePropertyInfo(json);
-
       expect(info.getter, isTrue);
       expect(info.async, isTrue);
       expect(info.throws, isTrue);