Start modeling the TranslatedType -> ForeignValueLayout mapping

Author: DougGregor

Sources/JExtractSwift/ImportedDecls.swift

@@ -189,7 +189,7 @@ public struct ImportedFunc: ImportedDecl, CustomStringConvertible {
               cCompatibleConvention: .indirect,
               originalSwiftType: "\(raw: parentName.swiftTypeName)",
               cCompatibleSwiftType: "UnsafeRawPointer",
-              cCompatibleJavaMemoryLayout: .memorySegment,
+              cCompatibleJavaMemoryLayout: .heapObject,
               javaType: .javaForeignMemorySegment
             ).importedTypeName
           )
@@ -204,7 +204,7 @@ public struct ImportedFunc: ImportedDecl, CustomStringConvertible {
               cCompatibleConvention: .indirect,
               originalSwiftType: "\(raw: parentName.swiftTypeName)",
               cCompatibleSwiftType: "UnsafeRawPointer",
-              cCompatibleJavaMemoryLayout: .memorySegment,
+              cCompatibleJavaMemoryLayout: .heapObject,
               javaType: .javaForeignMemorySegment
             ).importedTypeName
           )

Sources/JExtractSwift/JavaConstants/ForeignValueLayouts.swift

@@ -54,7 +54,6 @@ public struct ForeignValueLayout: CustomStringConvertible {
 }
 
 extension ForeignValueLayout {
-  public static let SwiftSelf = Self(inlineComment: "Self", javaConstant: "SWIFT_SELF")
   public static let SwiftPointer = Self(javaConstant: "SWIFT_POINTER")
 
   public static let SwiftBool = Self(javaConstant: "SWIFT_BOOL")
@@ -63,6 +62,7 @@ extension ForeignValueLayout {
   public static let SwiftInt64 = Self(javaConstant: "SWIFT_INT64")
   public static let SwiftInt32 = Self(javaConstant: "SWIFT_INT32")
   public static let SwiftInt16 = Self(javaConstant: "SWIFT_INT16")
+  public static let SwiftUInt16 = Self(javaConstant: "SWIFT_UINT16")
   public static let SwiftInt8 = Self(javaConstant: "SWIFT_INT8")
 
   public static let SwiftFloat = Self(javaConstant: "SWIFT_FLOAT")

Sources/JExtractSwift/TranslatedType.swift

@@ -33,7 +33,7 @@ extension Swift2JavaVisitor {
           cCompatibleConvention: .direct,
           originalSwiftType: type,
           cCompatibleSwiftType: "@convention(c) () -> Void",
-          cCompatibleJavaMemoryLayout: .memorySegment,
+          cCompatibleJavaMemoryLayout: .cFunction,
           javaType: .javaLangRunnable
         )
       }
@@ -134,7 +134,7 @@ extension Swift2JavaVisitor {
         cCompatibleConvention: .direct,
         originalSwiftType: type,
         cCompatibleSwiftType: "UnsafeMutableRawPointer",
-        cCompatibleJavaMemoryLayout: .memorySegment,
+        cCompatibleJavaMemoryLayout: .heapObject,
         javaType: .javaForeignMemorySegment
       )
     }
@@ -155,7 +155,7 @@ extension Swift2JavaVisitor {
       cCompatibleConvention: .indirect,
       originalSwiftType: type,
       cCompatibleSwiftType: "UnsafeMutablePointer<\(type)>",
-      cCompatibleJavaMemoryLayout: .memorySegment,
+      cCompatibleJavaMemoryLayout: .heapObject,
       javaType: .class(package: nil, name: name)
     )
   }
@@ -235,15 +235,49 @@ extension TranslatedType {
   }
 }
 
+/// Describes the C-compatible layout as it should be referenced from Java.
 enum CCompatibleJavaMemoryLayout {
-  /// A primitive Java type.
+  /// A primitive Java type that has a direct counterpart in C.
   case primitive(JavaType)
 
   /// The Swift "Int" type, which may be either a Java int (32-bit platforms) or
   /// Java long (64-bit platforms).
   case int
 
-  case memorySegment
+  /// A Swift heap object, which is treated as a pointer for interoperability
+  /// purposes but must be retained/released to keep it alive.
+  case heapObject
+
+  /// A C function pointer. In Swift, this will be a @convention(c) function.
+  /// In Java, a downcall handle to a function.
+  case cFunction
+}
+
+extension TranslatedType {
+  /// Determine the foreign value layout to use for the translated type with
+  /// the Java Foreign Function and Memory API.
+  var foreignValueLayout: ForeignValueLayout {
+    switch cCompatibleJavaMemoryLayout {
+    case .primitive(let javaType):
+      switch javaType {
+      case .boolean: return .SwiftBool
+      case .byte: return .SwiftInt8
+      case .char: return .SwiftUInt16
+      case .short: return .SwiftInt16
+      case .int: return .SwiftInt32
+      case .long: return .SwiftInt64
+      case .float: return .SwiftFloat
+      case .double: return .SwiftDouble
+      case .array, .class, .void: fatalError("Not a primitive type")
+      }
+
+    case .int:
+      return .SwiftInt
+
+    case .heapObject, .cFunction:
+      return .SwiftPointer
+    }
+  }
 }
 
 enum TypeTranslationError: Error {