Refactoring post #150

Author: cowtowncoder

src/main/java/tools/jackson/dataformat/xml/ser/DTD.java

@@ -1,5 +1,9 @@
 package tools.jackson.dataformat.xml.ser;
 
+import javax.xml.stream.XMLStreamException;
+
+import org.codehaus.stax2.XMLStreamWriter2;
+
 /**
  * Value container to represent XML Document Type Declaration,
  * to be written using {@link XmlGeneratorInitializer}.
@@ -8,7 +12,9 @@
  */
 public record DTD(String rootName,
         String systemId, String publicId,
-        String internalSubset) {
+        String internalSubset)
+    implements XmlPrologDirective
+{
     public DTD {
         rootName = _nonEmptyNonNull("rootName", rootName);
         systemId = _emptyToNull(systemId);
@@ -27,4 +33,11 @@ static String _nonEmptyNonNull(String prop, String str) {
         }
         return str;
     }
+
+    @Override
+    public void write(ToXmlGenerator xmlGen, XMLStreamWriter2 xmlWriter)
+        throws XMLStreamException
+    {
+        xmlWriter.writeDTD(rootName(), systemId(), publicId(), internalSubset());
+    }
 }

src/main/java/tools/jackson/dataformat/xml/ser/ToXmlGenerator.java

@@ -261,8 +261,7 @@ public void initGenerator() throws JacksonException
 
             // 19-Apr-2026, tatu: [dataformat-xml#150] Allow outputting DTD
             if (_dtd != null) {
-                _xmlWriter.writeDTD(_dtd.rootName(), _dtd.systemId(), _dtd.publicId(),
-                        _dtd.internalSubset());
+                _dtd.write(this, _xmlWriter);
             }
 
         } catch (XMLStreamException e) {

src/main/java/tools/jackson/dataformat/xml/ser/XmlPrologDirective.java

@@ -0,0 +1,20 @@
+package tools.jackson.dataformat.xml.ser;
+
+import javax.xml.stream.XMLStreamException;
+
+import org.codehaus.stax2.XMLStreamWriter2;
+
+/**
+ * Common API for XML nodes -- Comments, DTDs, Processing Instructions -- to
+ * be written <b>before</b> actual XML Document (root node).
+ *
+ * @since 3.2
+ */
+public interface XmlPrologDirective
+{
+    /**
+     * Method to call to actually write out the directive.
+     */
+    public void write(ToXmlGenerator xmlGen, XMLStreamWriter2 sw)
+        throws XMLStreamException;
+}