JS: a better fix for wrapping/unwrapping JS objects implemented in Java

jso/impl/src/main/java/org/teavm/jso/impl/JSAliasRenderer.java

@@ -35,11 +35,13 @@ class JSAliasRenderer implements RendererListener, VirtualMethodContributor {
     private static String variableChars = "abcdefghijklmnopqrstuvwxyz";
     private SourceWriter writer;
     private ListableClassReaderSource classSource;
+    private JSTypeHelper typeHelper;
 
     @Override
     public void begin(RenderingManager context, BuildTarget buildTarget) {
         writer = context.getWriter();
         classSource = context.getClassSource();
+        typeHelper = new JSTypeHelper(context.getClassSource());
     }
 
     @Override
@@ -48,6 +50,8 @@ class JSAliasRenderer implements RendererListener, VirtualMethodContributor {
             return;
         }
 
+        writer.append("let ").appendFunction("$rt_jso_marker").ws().append("=").ws()
+                .appendGlobal("Symbol").append("('jsoClass');").newLine();
         writer.append("(function()").ws().append("{").softNewLine().indent();
         writer.append("var c;").softNewLine();
         for (String className : classSource.getClassNames()) {
@@ -74,20 +78,23 @@ class JSAliasRenderer implements RendererListener, VirtualMethodContributor {
                     }
                 }
             }
-            if (methods.isEmpty() && properties.isEmpty()) {
+
+            var isJsClassImpl = typeHelper.isJavaScriptImplementation(className);
+            if (methods.isEmpty() && properties.isEmpty() && !isJsClassImpl) {
                 continue;
             }
 
-            boolean first = true;
+            writer.append("c").ws().append("=").ws().appendClass(className).append(".prototype;")
+                    .softNewLine();
+            if (isJsClassImpl) {
+                writer.append("c[").appendFunction("$rt_jso_marker").append("]").ws().append("=").ws().append("true;")
+                        .softNewLine();
+            }
+
             for (var aliasEntry : methods.entrySet()) {
                 if (classReader.getMethod(aliasEntry.getValue()) == null) {
                     continue;
                 }
-                if (first) {
-                    writer.append("c").ws().append("=").ws().appendClass(className).append(".prototype;")
-                            .softNewLine();
-                    first = false;
-                }
                 if (isKeyword(aliasEntry.getKey())) {
                     writer.append("c[\"").append(aliasEntry.getKey()).append("\"]");
                 } else {
@@ -101,11 +108,6 @@ class JSAliasRenderer implements RendererListener, VirtualMethodContributor {
                 if (propInfo.getter == null || classReader.getMethod(propInfo.getter) == null) {
                     continue;
                 }
-                if (first) {
-                    writer.append("c").ws().append("=").ws().appendClass(className).append(".prototype;")
-                            .softNewLine();
-                    first = false;
-                }
                 writer.append("Object.defineProperty(c,")
                         .ws().append("\"").append(aliasEntry.getKey()).append("\",")
                         .ws().append("{").indent().softNewLine();
@@ -128,7 +130,8 @@ class JSAliasRenderer implements RendererListener, VirtualMethodContributor {
     private boolean hasClassesToExpose() {
         for (String className : classSource.getClassNames()) {
             ClassReader cls = classSource.get(className);
-            if (cls.getMethods().stream().anyMatch(method -> getPublicAlias(method) != null)) {
+            if (cls.getMethods().stream().anyMatch(method -> getPublicAlias(method) != null)
+                    || typeHelper.isJavaScriptImplementation(className)) {
                 return true;
             }
         }

jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java

@@ -72,6 +72,8 @@ public class JSOPlugin implements TeaVMPlugin {
                 wrapperGenerator);
         jsHost.add(new MethodReference(JSWrapper.class, "jsToWrapper", JSObject.class, JSWrapper.class),
                 wrapperGenerator);
+        jsHost.add(new MethodReference(JSWrapper.class, "isJSImplementation", Object.class, boolean.class),
+                wrapperGenerator);
 
         host.add(new MethodReference(JSWrapper.class, "jsToWrapper", JSObject.class, JSWrapper.class),
                 wrapperGenerator);

jso/impl/src/main/java/org/teavm/jso/impl/JSWrapper.java

@@ -59,6 +59,9 @@ public final class JSWrapper {
             return null;
         }
         var js = directJavaToJs(o);
+        if (isJSImplementation(o)) {
+            return o;
+        }
         if (wrappers != null) {
             var type = JSObjects.typeOf(js);
             if (type.equals("object") || type.equals("function")) {
@@ -161,18 +164,21 @@ public final class JSWrapper {
     @NoSideEffects
     public static native boolean isJava(JSObject obj);
 
+    @NoSideEffects
+    private static native boolean isJSImplementation(Object obj);
+
     public static JSObject unwrap(Object o) {
         if (o == null) {
             return null;
         }
-        return o instanceof JSWrapper ? ((JSWrapper) o).js : directJavaToJs(o);
+        return isJSImplementation(o) ? directJavaToJs(o) : ((JSWrapper) o).js;
     }
 
     public static JSObject maybeUnwrap(Object o) {
         if (o == null) {
             return null;
         }
-        return o instanceof JSWrapper ? unwrap(o) : directJavaToJs(o);
+        return isJava(o) ? unwrap(o) : directJavaToJs(o);
     }
 
     public static JSObject javaToJs(Object o) {

jso/impl/src/main/java/org/teavm/jso/impl/JSWrapperGenerator.java

@@ -48,6 +48,17 @@ public class JSWrapperGenerator implements Injector, DependencyPlugin {
                     context.getWriter().append(")");
                 }
                 break;
+            case "isJSImplementation":
+                if (context.getPrecedence().ordinal() >= Precedence.EQUALITY.ordinal()) {
+                    context.getWriter().append("(");
+                }
+                context.writeExpr(context.getArgument(0), Precedence.MEMBER_ACCESS);
+                context.getWriter().append("[").appendFunction("$rt_jso_marker").append("]")
+                        .ws().append("===").ws().append("true");
+                if (context.getPrecedence().ordinal() >= Precedence.EQUALITY.ordinal()) {
+                    context.getWriter().append(")");
+                }
+                break;
         }
     }