Merge pull request #33 from retronym/topic/boxing

Use Scala's null-aware boxing, rather than Java's.

Author: retronym

project/CodeGen.scala

@@ -4,6 +4,12 @@
 
 sealed abstract class Type(val code: Char, val prim: String, val ref: String) {
   def boxed: String = ref
+  def unbox(expr: String) = {
+    s"scala.runtime.BoxesRunTime.unboxTo${prim.head.toUpper + prim.tail}($expr)"
+  }
+  def box(expr: String) = {
+    s"scala.runtime.BoxesRunTime.boxTo${ref.head.toUpper + ref.tail}($expr)"
+  }
 }
 object Type {
   case object Boolean extends Type('Z', "boolean", "Boolean")
@@ -218,15 +224,15 @@ object CodeGen {
     val suffix = specializedSuffix(tparamNames, tps)
     val List(r) = tps
     val applyMethodBody = if (r == Type.Void) s"apply$suffix(); return scala.runtime.BoxedUnit.UNIT;"
-      else s"return (${r.ref}) apply$suffix();"
+      else s"return ${r.box(s"apply$suffix()")};"
     val code = s"""
      |$copyright
      |
      |$packaging
      |
      |@FunctionalInterface
      |public interface JFunction0$suffix extends JFunction0 {
-     |    abstract ${r.prim} apply$suffix();
+     |    ${r.prim} apply$suffix();
      |
      |    default Object apply() { $applyMethodBody }
      |}
@@ -239,16 +245,16 @@ object CodeGen {
     val tparamNames = function1Spec.map(_._1)
     val suffix = specializedSuffix(tparamNames, tps)
     val List(t, r) = tps
-    val applyMethodBody = if (r == Type.Void) s"apply$suffix((${t.ref}) t); return scala.runtime.BoxedUnit.UNIT;"
-      else s"return (${r.ref}) apply$suffix((${t.ref}) t);"
+    val applyMethodBody = if (r == Type.Void) s"apply$suffix(${t.unbox("t")}); return scala.runtime.BoxedUnit.UNIT;"
+      else s"return ${r.box(s"apply$suffix(${t.unbox("t")})")};"
     val code = s"""
      |$copyright
      |
      |$packaging
      |
      |@FunctionalInterface
      |public interface JFunction1$suffix extends JFunction1 {
-     |    abstract ${r.prim} apply$suffix(${t.prim} v1);
+     |    ${r.prim} apply$suffix(${t.prim} v1);
      |
      |    default Object apply(Object t) { $applyMethodBody }
      |}
@@ -260,16 +266,16 @@ object CodeGen {
     val tparamNames = function2Spec.map(_._1)
     val suffix = specializedSuffix(tparamNames, tps)
     val List(t1, t2, r) = tps
-    val applyMethodBody = if (r == Type.Void) s"apply$suffix((${t1.ref}) v1, (${t2.ref}) v2); return scala.runtime.BoxedUnit.UNIT;"
-      else s"return (${r.ref}) apply$suffix((${t1.ref}) v1, (${t2.ref}) v2);"
+    val applyMethodBody = if (r == Type.Void) s"apply$suffix(${t1.unbox("v1")}, ${t2.unbox("v2")}); return scala.runtime.BoxedUnit.UNIT;"
+      else s"return ${r.box(s"apply$suffix(${t1.unbox("v1")}, ${t2.unbox("v2")}")});"
     val code = s"""
      |$copyright
      |
      |$packaging
      |
      |@FunctionalInterface
      |public interface JFunction2$suffix extends JFunction2 {
-     |    abstract ${r.prim} apply$suffix(${t1.prim} v1, ${t2.prim} v2);
+     |    ${r.prim} apply$suffix(${t1.prim} v1, ${t2.prim} v2);
      |
      |    default Object apply(Object v1, Object v2) { $applyMethodBody }
      |}
@@ -288,11 +294,11 @@ object CodeGen {
   private def function0SpecMethods = {
     val apply = specialized("apply", function0Spec) {
       case (name, List(r)) =>
-        val applyCall = s"apply();"
-        def body = if (r == Type.Void) applyCall else s"return (${r.ref}) $applyCall"
+        val applyCall = s"apply()"
+        def body = if (r == Type.Void) applyCall else s"return ${r.unbox(applyCall)}"
         s"""
         |default ${r.prim} $name() {
-        |    $body
+        |    $body;
         |}
         |""".stripMargin.trim
     }
@@ -317,11 +323,11 @@ object CodeGen {
   private def function1SpecMethods = {
     val apply = specialized("apply", function1Spec) {
       case (name, List(t1, r)) =>
-        val applyCall = s"apply((T1) ((${t1.ref}) v1));"
-        def body = if (r == Type.Void) applyCall else s"return (${r.ref}) $applyCall"
+        val applyCall = s"apply((T1) ${t1.box("v1")})"
+        def body = if (r == Type.Void) applyCall else s"return ${r.unbox(applyCall)}"
         s"""
         |default ${r.prim} $name(${t1.prim} v1) {
-        |    $body
+        |    $body;
         |}
         |""".stripMargin.trim
     }
@@ -348,12 +354,12 @@ object CodeGen {
   private def function2SpecMethods = {
     val apply = specialized("apply", function2Spec) {
       case (name, List(t1, t2, r)) =>
-        val applyCall = s"apply((T1) ((${t1.ref}) v1), (T2) ((${t2.ref}) v2));"
-        def body = if (r == Type.Void) applyCall else s"return (${r.ref}) $applyCall"
+        val applyCall = s"apply((T1) ${t1.box("v1")}, (T2) ${t2.box("v2")})"
+        def body = if (r == Type.Void) applyCall else s"return ${r.unbox(applyCall)}"
 
         s"""
         |default ${r.prim} $name(${t1.prim} v1, ${t2.prim} v2) {
-        |    $body
+        |    $body;
         |}
         |""".stripMargin.trim
     }

src/test/java/scala/compat/java8/BoxingTest.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2012-2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+package scala.compat.java8;
+
+import org.junit.Test;
+
+public class BoxingTest {
+    @Test
+    public void nullBoxesInterpretedAsZeroF1() {
+        JFunction1 jFunction1 = new JFunction1$mcII$sp() {
+            @Override
+            public int apply$mcII$sp(int v1) {
+                return v1 + 1;
+            }
+        };
+        Integer result = (Integer) jFunction1.apply(null);
+        assert (result.intValue() == 1);
+    }
+
+    @Test
+    public void nullBoxesInterpretedAsZeroF2() {
+        JFunction2 jFunction2 = new JFunction2$mcIII$sp() {
+            @Override
+            public int apply$mcIII$sp(int v1, int v2) {
+                return v1 + v2 + 1;
+            }
+        };
+        Integer result = (Integer) jFunction2.apply(null, null);
+        assert (result.intValue() == 1);
+    }
+}