[swift2objc] Support properties that throw (#1939)

Author: AmrAhmed119

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

@@ -72,11 +72,6 @@ bool _parseVariableIsConstant(Json variableSymbolJson) {
 bool _parseVariableThrows(Json json) {
   final throws = json['declarationFragments']
       .any((frag) => matchFragment(frag, 'keyword', 'throws'));
-  if (throws) {
-    // TODO(https://github.com/dart-lang/native/issues/1765): Support throwing
-    // getters.
-    throw Exception("Throwing getters aren't supported yet, at ${json.path}");
-  }
   return throws;
 }
 

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

@@ -9,6 +9,7 @@ import '../../ast/_core/shared/parameter.dart';
 import '../../ast/declarations/built_in/built_in_declaration.dart';
 import '../../ast/declarations/compounds/class_declaration.dart';
 import '../../ast/declarations/compounds/members/initializer_declaration.dart';
+import '../../ast/declarations/compounds/members/method_declaration.dart';
 import '../../ast/declarations/compounds/members/property_declaration.dart';
 import '../../parser/_core/utils.dart';
 import '../_core/unique_namer.dart';
@@ -51,16 +52,15 @@ ClassDeclaration transformCompound(
   transformedCompound.nestedDeclarations
       .fillNestingParents(transformedCompound);
 
-  transformedCompound.properties = originalCompound.properties
+  final transformedProperties = originalCompound.properties
       .map((property) => transformProperty(
             property,
             wrappedCompoundInstance,
             parentNamer,
             transformationMap,
           ))
       .nonNulls
-      .toList()
-    ..sort((Declaration a, Declaration b) => a.id.compareTo(b.id));
+      .toList();
 
   transformedCompound.initializers = originalCompound.initializers
       .map((initializer) => transformInitializer(
@@ -72,17 +72,25 @@ ClassDeclaration transformCompound(
       .toList()
     ..sort((Declaration a, Declaration b) => a.id.compareTo(b.id));
 
-  transformedCompound.methods = originalCompound.methods
+  final transformedMethods = originalCompound.methods
       .map((method) => transformMethod(
             method,
             wrappedCompoundInstance,
             parentNamer,
             transformationMap,
           ))
       .nonNulls
+      .toList();
+
+  transformedCompound.properties = transformedProperties
+      .whereType<PropertyDeclaration>()
       .toList()
     ..sort((Declaration a, Declaration b) => a.id.compareTo(b.id));
 
+  transformedCompound.methods = (transformedMethods +
+      transformedProperties.whereType<MethodDeclaration>().toList())
+    ..sort((Declaration a, Declaration b) => a.id.compareTo(b.id));
+
   return transformedCompound;
 }
 

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

@@ -1,6 +1,8 @@
 import '../../ast/_core/interfaces/declaration.dart';
 import '../../ast/declarations/built_in/built_in_declaration.dart';
 import '../../ast/declarations/compounds/class_declaration.dart';
+import '../../ast/declarations/compounds/members/method_declaration.dart';
+import '../../ast/declarations/compounds/members/property_declaration.dart';
 import '../../ast/declarations/globals/globals.dart';
 import '../../parser/_core/utils.dart';
 import '../_core/unique_namer.dart';
@@ -21,23 +23,30 @@ ClassDeclaration transformGlobals(
     isWrapper: true,
   );
 
-  transformedGlobals.properties = globals.variables
+  final transformedProperties = globals.variables
       .map((variable) => transformGlobalVariable(
             variable,
             globalNamer,
             transformationMap,
           ))
-      .toList()
-    ..sort((Declaration a, Declaration b) => a.id.compareTo(b.id));
+      .toList();
 
-  transformedGlobals.methods = globals.functions
+  final transformedMethods = globals.functions
       .map((function) => transformGlobalFunction(
             function,
             globalNamer,
             transformationMap,
           ))
+      .toList();
+
+  transformedGlobals.properties = transformedProperties
+      .whereType<PropertyDeclaration>()
       .toList()
     ..sort((Declaration a, Declaration b) => a.id.compareTo(b.id));
 
+  transformedGlobals.methods = (transformedMethods +
+      transformedProperties.whereType<MethodDeclaration>().toList())
+    ..sort((Declaration a, Declaration b) => a.id.compareTo(b.id));
+
   return transformedGlobals;
 }

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

@@ -1,4 +1,6 @@
+import '../../ast/_core/interfaces/declaration.dart';
 import '../../ast/_core/interfaces/variable_declaration.dart';
+import '../../ast/declarations/compounds/members/method_declaration.dart';
 import '../../ast/declarations/compounds/members/property_declaration.dart';
 import '../../ast/declarations/globals/globals.dart';
 import '../_core/unique_namer.dart';
@@ -13,7 +15,7 @@ import 'transform_referred_type.dart';
 // through the wrapped class instance in the wrapper class. In global variable
 // case, it can be  referenced directly since it's not a member of any entity.
 
-PropertyDeclaration? transformProperty(
+Declaration? transformProperty(
   PropertyDeclaration originalProperty,
   PropertyDeclaration wrappedClassInstance,
   UniqueNamer globalNamer,
@@ -36,7 +38,7 @@ PropertyDeclaration? transformProperty(
   );
 }
 
-PropertyDeclaration transformGlobalVariable(
+Declaration transformGlobalVariable(
   GlobalVariableDeclaration globalVariable,
   UniqueNamer globalNamer,
   TransformationMap transformationMap,
@@ -54,7 +56,7 @@ PropertyDeclaration transformGlobalVariable(
 
 // -------------------------- Core Implementation --------------------------
 
-PropertyDeclaration _transformVariable(
+Declaration _transformVariable(
   VariableDeclaration originalVariable,
   UniqueNamer globalNamer,
   TransformationMap transformationMap, {
@@ -71,6 +73,25 @@ PropertyDeclaration _transformVariable(
       ? originalVariable.hasSetter
       : !originalVariable.isConstant;
 
+  if (originalVariable.throws) {
+    return MethodDeclaration(
+      id: originalVariable.id,
+      name: wrapperPropertyName,
+      returnType: transformedType,
+      params: [],
+      hasObjCAnnotation: true,
+      isStatic: originalVariable is PropertyDeclaration
+          ? originalVariable.isStatic
+          : true,
+      statements: [
+        'let result = try $variableReferenceExpression',
+        'return $transformedType(result)',
+      ],
+      throws: true,
+      async: originalVariable.async,
+    );
+  }
+
   final transformedProperty = PropertyDeclaration(
     id: originalVariable.id,
     name: wrapperPropertyName,

pkgs/swift2objc/test/integration/throwing_getters_input.swift

@@ -0,0 +1,29 @@
+import Foundation
+
+public class MyClass {
+  public init(y: Int) throws {}
+
+  public var classGetter: MyClass {
+    get throws {
+        try MyClass(y: 3)
+    }
+  }
+  public var otherClassGetter: OtherClass {
+    get throws {
+        OtherClass()
+    }
+  }
+}
+
+public class OtherClass {}
+
+public var globalClassGetter: MyClass {
+    get throws {
+        try MyClass(y: 4)
+    }
+}
+public var globalOtherClassGetter: OtherClass {
+    get throws {
+        OtherClass()
+    }
+}

pkgs/swift2objc/test/integration/throwing_getters_output.swift

@@ -0,0 +1,49 @@
+// Test preamble text
+
+import Foundation
+
+@objc public class GlobalsWrapper: NSObject {
+  @objc static public func globalClassGetterWrapper() throws -> MyClassWrapper {
+    let result = try globalClassGetter
+    return MyClassWrapper(result)
+  }
+
+  @objc static public func globalOtherClassGetterWrapper() throws -> OtherClassWrapper {
+    let result = try globalOtherClassGetter
+    return OtherClassWrapper(result)
+  }
+
+}
+
+@objc public class OtherClassWrapper: NSObject {
+  var wrappedInstance: OtherClass
+
+  init(_ wrappedInstance: OtherClass) {
+    self.wrappedInstance = wrappedInstance
+  }
+
+}
+
+@objc public class MyClassWrapper: NSObject {
+  var wrappedInstance: MyClass
+
+  init(_ wrappedInstance: MyClass) {
+    self.wrappedInstance = wrappedInstance
+  }
+
+  @objc init(y: Int) throws {
+    wrappedInstance = try MyClass(y: y)
+  }
+
+  @objc public func otherClassGetter() throws -> OtherClassWrapper {
+    let result = try wrappedInstance.otherClassGetter
+    return OtherClassWrapper(result)
+  }
+
+  @objc public func classGetter() throws -> MyClassWrapper {
+    let result = try wrappedInstance.classGetter
+    return MyClassWrapper(result)
+  }
+
+}
+