Merge pull request #124 from DougGregor/javakit-implicitly-unwrapped-optionals

Java2Swift: Use implicitly-unwrapped optionals for field types and method results

Author: DougGregor

Sources/Java2SwiftLib/JavaClassTranslator.swift

@@ -131,7 +131,7 @@ struct JavaClassTranslator {
       }
 
       do {
-        let typeName = try translator.getSwiftTypeNameAsString(javaType, outerOptional: false)
+        let typeName = try translator.getSwiftTypeNameAsString(javaType, outerOptional: .nonoptional)
         return "\(typeName)"
       } catch {
         translator.logUntranslated("Unable to translate '\(fullName)' interface '\(javaType.getTypeName())': \(error)")
@@ -459,7 +459,7 @@ extension JavaClassTranslator {
 
     // Map the result type.
     let resultTypeStr: String
-    let resultType = try translator.getSwiftTypeNameAsString(javaMethod.getGenericReturnType()!, outerOptional: true)
+    let resultType = try translator.getSwiftTypeNameAsString(javaMethod.getGenericReturnType()!, outerOptional: .implicitlyUnwrappedOptional)
     if resultType != "Void" {
       resultTypeStr = " -> \(resultType)"
     } else {
@@ -480,7 +480,7 @@ extension JavaClassTranslator {
   /// Render a single Java field into the corresponding Swift property, or
   /// throw an error if that is not possible for any reason.
   package func renderField(_ javaField: Field) throws -> DeclSyntax {
-    let typeName = try translator.getSwiftTypeNameAsString(javaField.getGenericType()!, outerOptional: true)
+    let typeName = try translator.getSwiftTypeNameAsString(javaField.getGenericType()!, outerOptional: .implicitlyUnwrappedOptional)
     let fieldAttribute: AttributeSyntax = javaField.isStatic ? "@JavaStaticField" : "@JavaField";
     let swiftFieldName = javaField.getName().escapedSwiftName
     return """
@@ -501,7 +501,7 @@ extension JavaClassTranslator {
     """
 
     let mappingSyntax: DeclSyntax = """
-      public var enumValue: \(raw: name)? {
+      public var enumValue: \(raw: name)! {
         let classObj = self.javaClass
         \(raw: enumConstants.map {
           // The equals method takes a java object, so we need to cast it here
@@ -547,7 +547,7 @@ extension JavaClassTranslator {
     return try parameters.compactMap { javaParameter in
       guard let javaParameter else { return nil }
 
-      let typeName = try translator.getSwiftTypeNameAsString(javaParameter.getParameterizedType()!, outerOptional: true)
+      let typeName = try translator.getSwiftTypeNameAsString(javaParameter.getParameterizedType()!, outerOptional: .optional)
       let paramName = javaParameter.getName()
       return "_ \(raw: paramName): \(raw: typeName)"
     }

Sources/Java2SwiftLib/JavaTranslator.swift

@@ -104,7 +104,7 @@ extension JavaTranslator {
 // MARK: Type translation
 extension JavaTranslator {
   /// Turn a Java type into a string.
-  func getSwiftTypeNameAsString(_ javaType: Type, outerOptional: Bool) throws -> String {
+  func getSwiftTypeNameAsString(_ javaType: Type, outerOptional: OptionalKind) throws -> String {
     // Replace type variables with their bounds.
     if let typeVariable = javaType.as(TypeVariable<GenericDeclaration>.self),
       typeVariable.getBounds().count == 1,
@@ -124,7 +124,7 @@ extension JavaTranslator {
 
     // Handle array types by recursing into the component type.
     if let arrayType = javaType.as(GenericArrayType.self) {
-      let elementType = try getSwiftTypeNameAsString(arrayType.getGenericComponentType()!, outerOptional: true)
+      let elementType = try getSwiftTypeNameAsString(arrayType.getGenericComponentType()!, outerOptional: .optional)
       return "[\(elementType)]"
     }
 
@@ -135,21 +135,21 @@ extension JavaTranslator {
     {
       var rawSwiftType = try getSwiftTypeNameAsString(rawJavaType, outerOptional: outerOptional)
 
-      let makeOptional: Bool
-      if rawSwiftType.last == "?" {
-        makeOptional = true
+      let optionalSuffix: String
+      if let lastChar = rawSwiftType.last, lastChar == "?" || lastChar == "!" {
+        optionalSuffix = "\(lastChar)"
         rawSwiftType.removeLast()
       } else {
-        makeOptional = false
+        optionalSuffix = ""
       }
 
       let typeArguments = try parameterizedType.getActualTypeArguments().compactMap { typeArg in
         try typeArg.map { typeArg in
-          try getSwiftTypeNameAsString(typeArg, outerOptional: false)
+          try getSwiftTypeNameAsString(typeArg, outerOptional: .nonoptional)
         }
       }
 
-      return "\(rawSwiftType)<\(typeArguments.joined(separator: ", "))>\(makeOptional ? "?" : "")"
+      return "\(rawSwiftType)<\(typeArguments.joined(separator: ", "))>\(optionalSuffix)"
     }
 
     // Handle direct references to Java classes.
@@ -159,8 +159,15 @@ extension JavaTranslator {
 
     let (swiftName, isOptional) = try getSwiftTypeName(javaClass)
     var resultString = swiftName
-    if isOptional && outerOptional {
-      resultString += "?"
+    if isOptional {
+      switch outerOptional {
+      case .implicitlyUnwrappedOptional:
+        resultString += "!"
+      case .optional:
+        resultString += "?"
+      case .nonoptional:
+        break
+      }
     }
     return resultString
   }

Sources/Java2SwiftLib/OptionalKind.swift

@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+/// Describes the kind of optional type to use.
+enum OptionalKind {
+  /// The value is nonoptional.
+  case nonoptional
+
+  /// The value is optional.
+  case optional
+
+  /// The value uses an implicitly-unwrapped optional.
+  case implicitlyUnwrappedOptional
+}

Sources/JavaKitMacros/JavaFieldMacro.swift

@@ -27,7 +27,7 @@ extension JavaFieldMacro: AccessorMacro {
     guard let varDecl = declaration.as(VariableDeclSyntax.self),
       let binding = varDecl.bindings.first,
       let fieldNameAsWritten = binding.pattern.as(IdentifierPatternSyntax.self)?.identifier.trimmed.text,
-      let fieldType = binding.typeAnnotation?.type.trimmed,
+      let fieldType = binding.typeAnnotation?.type.typeReference,
       binding.accessorBlock == nil
     else {
       return []

Sources/JavaKitMacros/JavaMethodMacro.swift

@@ -55,7 +55,7 @@ extension JavaMethodMacro: BodyMacro {
     let params = funcDecl.signature.parameterClause.parameters
     let resultType: String =
       funcDecl.signature.returnClause.map { result in
-        ", resultType: \(result.type.trimmedDescription).self"
+        ", resultType: \(result.type.typeReferenceString).self"
       } ?? ""
     let paramNames = params.map { param in param.parameterName?.text ?? "" }.joined(separator: ", ")
 
@@ -126,3 +126,25 @@ extension FunctionParameterListSyntax {
     return firstIndex { $0.parameterName?.text == name }
   }
 }
+
+extension TypeSyntaxProtocol {
+  /// Produce a reference to the given type syntax node with any adjustments
+  /// needed to pretty-print it back into source.
+  var typeReference: TypeSyntax {
+    if let iuoType = self.as(ImplicitlyUnwrappedOptionalTypeSyntax.self) {
+      return TypeSyntax(
+        OptionalTypeSyntax(
+          wrappedType: iuoType.wrappedType.trimmed
+        )
+      )
+    }
+
+    return TypeSyntax(trimmed)
+  }
+
+  /// Produce a reference to the given type syntax node with any adjustments
+  /// needed to pretty-print it back into source, as a string.
+  var typeReferenceString: String {
+    typeReference.description
+  }
+}

Tests/Java2SwiftTests/Java2SwiftTests.swift

@@ -74,7 +74,7 @@ class Java2SwiftTests: XCTestCase {
         """,
         """
           @JavaStaticMethod
-          public func forName<T: AnyJavaObject>(_ arg0: JavaString) throws -> MyJavaClass<JavaObject>? where ObjectType == MyJavaClass<T>
+          public func forName<T: AnyJavaObject>(_ arg0: JavaString) throws -> MyJavaClass<JavaObject>! where ObjectType == MyJavaClass<T>
         """,
       ]
     )
@@ -88,7 +88,7 @@ class Java2SwiftTests: XCTestCase {
         "import JavaKit",
         "enum MonthCases: Equatable",
         "case APRIL",
-        "public var enumValue: MonthCases?",
+        "public var enumValue: MonthCases!",
         """
             } else if self.equals(classObj.APRIL?.as(JavaObject.self)) {
               return MonthCases.APRIL
@@ -105,7 +105,7 @@ class Java2SwiftTests: XCTestCase {
         """,
         """
           @JavaStaticField(isFinal: true)
-          public var APRIL: Month?
+          public var APRIL: Month!
         """
       ])
   }
@@ -121,7 +121,7 @@ class Java2SwiftTests: XCTestCase {
       expectedChunks: [
         """
           @JavaMethod
-          public func subList(_ arg0: Int32, _ arg1: Int32) -> JavaList<JavaObject>?
+          public func subList(_ arg0: Int32, _ arg1: Int32) -> JavaList<JavaObject>!
         """
       ]
     )
@@ -138,7 +138,7 @@ class Java2SwiftTests: XCTestCase {
       expectedChunks: [
         """
           @JavaMethod
-          public func subList(_ arg0: Int32, _ arg1: Int32) -> JavaList<JavaObject>?
+          public func subList(_ arg0: Int32, _ arg1: Int32) -> JavaList<JavaObject>!
         """
       ]
     )
@@ -161,15 +161,15 @@ class Java2SwiftTests: XCTestCase {
         "import JavaKit",
         """
           @JavaMethod
-          public func redirectInput() -> ProcessBuilder.Redirect?
+          public func redirectInput() -> ProcessBuilder.Redirect!
         """,
         """
         extension ProcessBuilder {
           @JavaClass("java.lang.ProcessBuilder$Redirect")
           public struct Redirect {
         """,
         """
-        public func redirectError() -> ProcessBuilder.Redirect?
+        public func redirectError() -> ProcessBuilder.Redirect!
         """,
         """
         extension ProcessBuilder.Redirect {
@@ -178,7 +178,7 @@ class Java2SwiftTests: XCTestCase {
         """,
         """
           @JavaMethod
-          public func type() -> ProcessBuilder.Redirect.`Type`?
+          public func type() -> ProcessBuilder.Redirect.`Type`!
         """,
       ]
     )
@@ -201,15 +201,15 @@ class Java2SwiftTests: XCTestCase {
         "import JavaKit",
         """
           @JavaMethod
-          public func redirectInput() -> ProcessBuilder.PBRedirect?
+          public func redirectInput() -> ProcessBuilder.PBRedirect!
         """,
         """
         extension ProcessBuilder {
           @JavaClass("java.lang.ProcessBuilder$Redirect")
           public struct PBRedirect {
         """,
         """
-        public func redirectError() -> ProcessBuilder.PBRedirect?
+        public func redirectError() -> ProcessBuilder.PBRedirect!
         """,
         """
         extension ProcessBuilder.PBRedirect {
@@ -218,7 +218,7 @@ class Java2SwiftTests: XCTestCase {
         """,
         """
           @JavaMethod
-          public func type() -> ProcessBuilder.PBRedirect.JavaType?
+          public func type() -> ProcessBuilder.PBRedirect.JavaType!
         """
       ]
     )

Tests/JavaKitMacroTests/JavaClassMacroTests.swift

@@ -42,6 +42,9 @@ class JavaKitMacroTests: XCTestCase {
           @JavaField
           public var myField: Int64
       
+          @JavaField
+          public var objectField: JavaObject!
+
           @JavaField(isFinal: true)
           public var myFinalField: Int64
         }
@@ -76,6 +79,14 @@ class JavaKitMacroTests: XCTestCase {
                   self[javaFieldName: "myField", fieldType: Int64.self] = newValue
               }
           }
+          public var objectField: JavaObject! {
+              get {
+                  self[javaFieldName: "objectField", fieldType: JavaObject?.self]
+              }
+              nonmutating set {
+                  self[javaFieldName: "objectField", fieldType: JavaObject?.self] = newValue
+              }
+          }
           public var myFinalField: Int64 {
               get {
                   self[javaFieldName: "myFinalField", fieldType: Int64.self]