[JExtract/JNI] Add support for variables (#306)

* add support for variables

* prefix boolean variables with `is` to match Java conventions

* add confined arena constructor with current thread

* add variable tests

* PR feedback

* add test for isWarm

Author: madsodgaard

Samples/JExtractJNISampleApp/Sources/MySwiftLibrary/MySwiftClass.swift

@@ -16,6 +16,31 @@ public class MySwiftClass {
   let x: Int64
   let y: Int64
 
+  public let constant: Int64 = 100
+  public var mutable: Int64 = 0
+  public var product: Int64 {
+    return x * y
+  }
+  public var throwingVariable: Int64 {
+    get throws {
+      throw MySwiftClassError.swiftError
+    }
+  }
+  public var mutableDividedByTwo: Int64 {
+    get {
+      return mutable / 2
+    }
+    set {
+      mutable = newValue * 2
+    }
+  }
+  public let warm: Bool = false
+  public var getAsync: Int64 {
+    get async {
+      return 42
+    }
+  }
+
   public static func method() {
     p("Hello from static method in a class!")
   }

Samples/JExtractJNISampleApp/Sources/MySwiftLibrary/MySwiftLibrary.swift

@@ -23,6 +23,8 @@
   import Darwin.C
 #endif
 
+public var globalVariable: Int64 = 0
+
 public func helloWorld() {
   p("\(#function)")
 }

Samples/JExtractJNISampleApp/Sources/MySwiftLibrary/swift-java.config

@@ -1,4 +1,4 @@
 {
   "javaPackage": "com.example.swift",
-  "mode": "jni"
+  "mode": "jni",
 }

Samples/JExtractJNISampleApp/src/main/java/com/example/swift/HelloJava2SwiftJNI.java

@@ -41,10 +41,12 @@ static void examples() {
 
         MySwiftClass.method();
 
-        try (var arena = new ConfinedSwiftMemorySession(Thread.currentThread())) {
+        try (var arena = new ConfinedSwiftMemorySession()) {
             MySwiftClass myClass = MySwiftClass.init(10, 5, arena);
             MySwiftClass myClass2 = MySwiftClass.init(arena);
 
+            System.out.println("myClass.isWarm: " + myClass.isWarm());
+
             try {
                 myClass.throwingFunction();
             } catch (Exception e) {

Samples/JExtractJNISampleApp/src/test/java/com/example/swift/MySwiftClassTest.java

@@ -22,43 +22,100 @@
 public class MySwiftClassTest {
     @Test
     void init_noParameters() {
-        try (var arena = new ConfinedSwiftMemorySession(Thread.currentThread())) {
+        try (var arena = new ConfinedSwiftMemorySession()) {
             MySwiftClass c = MySwiftClass.init(arena);
             assertNotNull(c);
         }
     }
 
     @Test
     void init_withParameters() {
-        try (var arena = new ConfinedSwiftMemorySession(Thread.currentThread())) {
+        try (var arena = new ConfinedSwiftMemorySession()) {
             MySwiftClass c = MySwiftClass.init(1337, 42, arena);
             assertNotNull(c);
         }
     }
 
     @Test
     void sum() {
-        try (var arena = new ConfinedSwiftMemorySession(Thread.currentThread())) {
+        try (var arena = new ConfinedSwiftMemorySession()) {
             MySwiftClass c = MySwiftClass.init(20, 10, arena);
             assertEquals(30, c.sum());
         }
     }
 
     @Test
     void xMultiplied() {
-        try (var arena = new ConfinedSwiftMemorySession(Thread.currentThread())) {
+        try (var arena = new ConfinedSwiftMemorySession()) {
             MySwiftClass c = MySwiftClass.init(20, 10, arena);
             assertEquals(200, c.xMultiplied(10));
         }
     }
 
     @Test
     void throwingFunction() {
-        try (var arena = new ConfinedSwiftMemorySession(Thread.currentThread())) {
+        try (var arena = new ConfinedSwiftMemorySession()) {
             MySwiftClass c = MySwiftClass.init(20, 10, arena);
             Exception exception = assertThrows(Exception.class, () -> c.throwingFunction());
 
             assertEquals("swiftError", exception.getMessage());
         }
     }
+
+    @Test
+    void constant() {
+        try (var arena = new ConfinedSwiftMemorySession()) {
+            MySwiftClass c = MySwiftClass.init(20, 10, arena);
+            assertEquals(100, c.getConstant());
+        }
+    }
+
+    @Test
+    void mutable() {
+        try (var arena = new ConfinedSwiftMemorySession()) {
+            MySwiftClass c = MySwiftClass.init(20, 10, arena);
+            assertEquals(0, c.getMutable());
+            c.setMutable(42);
+            assertEquals(42, c.getMutable());
+        }
+    }
+
+    @Test
+    void product() {
+        try (var arena = new ConfinedSwiftMemorySession()) {
+            MySwiftClass c = MySwiftClass.init(20, 10, arena);
+            assertEquals(200, c.getProduct());
+        }
+    }
+
+    @Test
+    void throwingVariable() {
+        try (var arena = new ConfinedSwiftMemorySession()) {
+            MySwiftClass c = MySwiftClass.init(20, 10, arena);
+
+            Exception exception = assertThrows(Exception.class, () -> c.getThrowingVariable());
+
+            assertEquals("swiftError", exception.getMessage());
+        }
+    }
+
+    @Test
+    void mutableDividedByTwo() {
+        try (var arena = new ConfinedSwiftMemorySession()) {
+            MySwiftClass c = MySwiftClass.init(20, 10, arena);
+            assertEquals(0, c.getMutableDividedByTwo());
+            c.setMutable(20);
+            assertEquals(10, c.getMutableDividedByTwo());
+            c.setMutableDividedByTwo(5);
+            assertEquals(10, c.getMutable());
+        }
+    }
+
+    @Test
+    void isWarm() {
+        try (var arena = new ConfinedSwiftMemorySession()) {
+            MySwiftClass c = MySwiftClass.init(20, 10, arena);
+            assertFalse(c.isWarm());
+        }
+    }
 }

Samples/JExtractJNISampleApp/src/test/java/com/example/swift/MySwiftLibraryTest.java

@@ -54,4 +54,11 @@ void call_writeString_jextract() {
 
         assertEquals(string.length(), reply);
     }
+
+    @Test
+    void globalVariable() {
+        assertEquals(0, MySwiftLibrary.getGlobalVariable());
+        MySwiftLibrary.setGlobalVariable(100);
+        assertEquals(100, MySwiftLibrary.getGlobalVariable());
+    }
 }

Sources/JExtractSwiftLib/Convenience/String+Extensions.swift

@@ -22,4 +22,14 @@ extension String {
 
     return "\(f.uppercased())\(String(dropFirst()))"
   }
-}
+
+  /// Returns whether the string is of the format `isX`
+  var hasJavaBooleanNamingConvention: Bool {
+    guard self.hasPrefix("is"), self.count > 2 else {
+      return false
+    }
+
+    let thirdCharacterIndex = self.index(self.startIndex, offsetBy: 2)
+    return self[thirdCharacterIndex].isUppercase
+  }
+}

Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaTranslation.swift

@@ -127,8 +127,8 @@ extension FFMSwift2JavaGenerator {
 
       // Name.
       let javaName = switch decl.apiKind {
-      case .getter: "get\(decl.name.toCamelCase)"
-      case .setter: "set\(decl.name.toCamelCase)"
+      case .getter: decl.javaGetterName
+      case .setter: decl.javaSetterName
       case .function, .initializer: decl.name
       }
 

Sources/JExtractSwiftLib/ImportedDecls.swift

@@ -154,3 +154,21 @@ extension ImportedFunc: Hashable {
     return lhs === rhs
   }
 }
+
+extension ImportedFunc {
+  var javaGetterName: String {
+    let returnsBoolean = self.functionSignature.result.type.asNominalTypeDeclaration?.knownTypeKind == .bool
+
+    if !returnsBoolean {
+      return "get\(self.name.toCamelCase)"
+    } else if !self.name.hasJavaBooleanNamingConvention {
+      return "is\(self.name.toCamelCase)"
+    } else {
+      return self.name.toCamelCase
+    }
+  }
+
+  var javaSetterName: String {
+    "set\(self.name.toCamelCase)"
+  }
+}

Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift

@@ -79,6 +79,11 @@ extension JNISwift2JavaGenerator {
         printFunctionBinding(&printer, decl)
         printer.println()
       }
+
+      for decl in analysis.importedGlobalVariables {
+        printFunctionBinding(&printer, decl)
+        printer.println()
+      }
     }
   }
 
@@ -113,10 +118,17 @@ extension JNISwift2JavaGenerator {
 
       for initializer in decl.initializers {
         printInitializerBindings(&printer, initializer, type: decl)
+        printer.println()
       }
 
       for method in decl.methods {
         printFunctionBinding(&printer, method)
+        printer.println()
+      }
+
+      for variable in decl.variables {
+        printFunctionBinding(&printer, variable)
+        printer.println()
       }
 
       printDestroyFunction(&printer, decl)