JS: reduce size of declaration of classes without fields

core/src/main/java/org/teavm/backend/javascript/rendering/NameFrequencyEstimator.java

@@ -129,6 +129,17 @@ class NameFrequencyEstimator extends RecursiveVisitor implements MethodNodeVisit
         for (String iface : cls.getClassHolder().getInterfaces()) {
             consumer.consume(iface);
         }
+
+        boolean hasFields = false;
+        for (FieldHolder field : cls.getClassHolder().getFields()) {
+            if (!field.hasModifier(ElementModifier.STATIC)) {
+                hasFields = true;
+                break;
+            }
+        }
+        if (!hasFields) {
+            consumer.consumeFunction("$rt_classWithoutFields");
+        }
     }
 
     @Override

core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java

@@ -252,7 +252,8 @@ public class Renderer implements RenderingManager {
                 "$rt_isInstance", "$rt_nativeThread", "$rt_suspending", "$rt_resuming", "$rt_invalidPointer",
                 "$rt_s", "$rt_eraseClinit", "$rt_imul", "$rt_wrapException", "$rt_checkBounds",
                 "$rt_checkUpperBound", "$rt_checkLowerBound", "$rt_wrapFunction0", "$rt_wrapFunction1",
-                "$rt_wrapFunction2", "$rt_wrapFunction3", "$rt_wrapFunction4" };
+                "$rt_wrapFunction2", "$rt_wrapFunction3", "$rt_wrapFunction4",
+                "$rt_classWithoutFields" };
         boolean first = true;
         for (String name : names) {
             if (!first) {
@@ -303,10 +304,6 @@ public class Renderer implements RenderingManager {
         ScopedName jsName = naming.getNameFor(cls.getName());
         debugEmitter.addClass(jsName.value, cls.getName(), cls.getParentName());
         try {
-            renderFunctionDeclaration(jsName);
-            writer.append("()").ws().append("{")
-                    .indent().softNewLine();
-            boolean thisAliased = false;
             List<FieldHolder> nonStaticFields = new ArrayList<>();
             List<FieldHolder> staticFields = new ArrayList<>();
             for (FieldHolder field : cls.getClassHolder().getFields()) {
@@ -316,6 +313,45 @@ public class Renderer implements RenderingManager {
                     nonStaticFields.add(field);
                 }
             }
+
+            if (nonStaticFields.isEmpty() && !cls.getClassHolder().getName().equals("java.lang.Object")) {
+                renderShortClassFunctionDeclaration(cls, jsName);
+            } else {
+                renderFullClassFunctionDeclaration(cls, jsName, nonStaticFields);
+            }
+
+            for (FieldHolder field : staticFields) {
+                Object value = field.getInitialValue();
+                if (value == null) {
+                    value = getDefaultValue(field.getType());
+                }
+                FieldReference fieldRef = new FieldReference(cls.getName(), field.getName());
+                if (value instanceof String) {
+                    context.lookupString((String) value);
+                    postponedFieldInitializers.add(new PostponedFieldInitializer(fieldRef, (String) value));
+                    value = null;
+                }
+
+                ScopedName fieldName = naming.getFullNameFor(fieldRef);
+                if (fieldName.scoped) {
+                    writer.append(naming.getScopeName()).append(".");
+                } else {
+                    writer.append("var ");
+                }
+                writer.append(fieldName.value).ws().append("=").ws();
+                context.constantToString(writer, value);
+                writer.append(";").softNewLine();
+            }
+        } catch (IOException e) {
+            throw new RenderingException("IO error occurred", e);
+        }
+    }
+
+    private void renderFullClassFunctionDeclaration(PreparedClass cls, ScopedName jsName,
+            List<FieldHolder> nonStaticFields) throws IOException {
+        boolean thisAliased = false;
+        renderFunctionDeclaration(jsName);
+        writer.append("()").ws().append("{").indent().softNewLine();
         if (nonStaticFields.size() > 1) {
             thisAliased = true;
             writer.append("var a").ws().append("=").ws().append("this;").ws();
@@ -347,32 +383,21 @@ public class Renderer implements RenderingManager {
             writer.append(";");
         }
         writer.newLine();
-
-            for (FieldHolder field : staticFields) {
-                Object value = field.getInitialValue();
-                if (value == null) {
-                    value = getDefaultValue(field.getType());
-                }
-                FieldReference fieldRef = new FieldReference(cls.getName(), field.getName());
-                if (value instanceof String) {
-                    context.lookupString((String) value);
-                    postponedFieldInitializers.add(new PostponedFieldInitializer(fieldRef, (String) value));
-                    value = null;
     }
 
-                ScopedName fieldName = naming.getFullNameFor(fieldRef);
+    private void renderShortClassFunctionDeclaration(PreparedClass cls, ScopedName jsName) throws IOException {
-                if (fieldName.scoped) {
+        if (jsName.scoped) {
             writer.append(naming.getScopeName()).append(".");
         } else {
             writer.append("var ");
         }
-                writer.append(fieldName.value).ws().append("=").ws();
+        writer.append(jsName.value).ws().append("=").ws().appendFunction("$rt_classWithoutFields").append("(");
-                context.constantToString(writer, value);
+        if (cls.getClassHolder().hasModifier(ElementModifier.INTERFACE)) {
-                writer.append(";").softNewLine();
+            writer.append("0");
-            }
+        } else if (!cls.getParentName().equals("java.lang.Object")) {
-        } catch (IOException e) {
+            writer.appendClass(cls.getParentName());
-            throw new RenderingException("IO error occurred", e);
         }
+        writer.append(");").newLine();
     }
 
     private void renderMethodBodies(PreparedClass cls) throws RenderingException {

core/src/main/resources/org/teavm/backend/javascript/runtime.js

@@ -700,3 +700,14 @@ function $rt_checkLowerBound(index) {
     }
     return index;
 }
+function $rt_classWithoutFields(superclass) {
+    if (superclass === 0) {
+        return function() {};
+    }
+    if (superclass === void 0) {
+        superclass = $rt_objcls();
+    }
+    return function() {
+        superclass.call(this);
+    };
+}