[GitHub] [kafka] chia7712 commented on a change in pull request #8556: MINOR: Add a duplicate() method to Message classes

[GitBox <gi...@apache.org>]

chia7712 commented on a change in pull request #8556:
URL: https://github.com/apache/kafka/pull/8556#discussion_r415539913



##########
File path: generator/src/main/java/org/apache/kafka/message/MessageDataGenerator.java
##########
@@ -2112,6 +2131,83 @@ private void generateFieldHashCode(FieldSpec field) {
         }
     }
 
+    private void generateClassDuplicate(String className, StructSpec struct) {
+        buffer.printf("@Override%n");
+        buffer.printf("public %s duplicate() {%n", className);
+        buffer.incrementIndent();
+        buffer.printf("%s _duplicate = new %s();%n", className, className);
+        for (FieldSpec field : struct.fields()) {
+            generateFieldDuplicate(new Target(field,
+                field.camelCaseName(),
+                field.camelCaseName(),
+                input -> String.format("_duplicate.%s = %s", field.camelCaseName(), input)));
+        }
+        buffer.printf("return _duplicate;%n");
+        buffer.decrementIndent();
+        buffer.printf("}%n");
+    }
+
+    private void generateFieldDuplicate(Target target) {
+        FieldSpec field = target.field();
+        if ((field.type() instanceof FieldType.BoolFieldType) ||
+                (field.type() instanceof FieldType.Int8FieldType) ||
+                (field.type() instanceof FieldType.Int16FieldType) ||
+                (field.type() instanceof FieldType.Int32FieldType) ||
+                (field.type() instanceof FieldType.Int64FieldType) ||
+                (field.type() instanceof FieldType.Float64FieldType) ||
+                (field.type() instanceof FieldType.UUIDFieldType)) {
+            buffer.printf("%s;%n", target.assignmentStatement(target.sourceVariable()));
+        } else {
+            IsNullConditional cond = IsNullConditional.forName(target.sourceVariable()).
+                nullableVersions(target.field().nullableVersions()).
+                ifNull(() -> buffer.printf("%s;%n", target.assignmentStatement("null")));
+            if (field.type().isBytes()) {
+                if (field.zeroCopy()) {
+                    cond.ifShouldNotBeNull(() ->
+                        buffer.printf("%s;%n", target.assignmentStatement(
+                            String.format("%s.duplicate()", target.sourceVariable()))));
+                } else {
+                    cond.ifShouldNotBeNull(() -> {
+                        headerGenerator.addImport(MessageGenerator.MESSAGE_UTIL_CLASS);
+                        buffer.printf("%s;%n", target.assignmentStatement(
+                            String.format("MessageUtil.duplicate(%s)",
+                                target.sourceVariable())));
+                    });
+                }
+            } else if (field.type().isStruct()) {
+                cond.ifShouldNotBeNull(() ->
+                    buffer.printf("%s;%n", target.assignmentStatement(
+                        String.format("%s.duplicate()", target.sourceVariable()))));
+            } else if (field.type().isString()) {
+                // Strings are immutable, so we don't need to duplicate them.
+                cond.ifShouldNotBeNull(() ->
+                    buffer.printf("%s;%n", target.assignmentStatement(
+                        target.sourceVariable())));
+            } else if (field.type().isArray()) {
+                cond.ifShouldNotBeNull(() -> {
+                    String newArrayName =
+                        String.format("new%s", field.capitalizedCamelCaseName());
+                    buffer.printf("%s %s = new %s();%n",

Review comment:
       What about adding the expected number of elements?




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