feat(normalize-class): add NormalizeClassPlugin for class deduplication during code generation

Author: rawvoid

plugins/src/main/java/io/github/rawvoid/jaxb/plugin/NormalizeClassPlugin.java

@@ -0,0 +1,327 @@
+/*
+ * Copyright 2026 Rawvoid(https://github.com/rawvoid)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.github.rawvoid.jaxb.plugin;
+
+import com.sun.codemodel.*;
+import com.sun.tools.xjc.Options;
+import com.sun.tools.xjc.outline.ClassOutline;
+import com.sun.tools.xjc.outline.Outline;
+import com.sun.tools.xjc.outline.PackageOutline;
+import org.xml.sax.ErrorHandler;
+import org.xml.sax.SAXException;
+
+import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+/**
+ * @author Rawvoid
+ */
+@Option(name = "Xnormalize-class", description = "Normalize generated classes")
+public class NormalizeClassPlugin extends AbstractPlugin {
+
+    @Override
+    public boolean run(Outline outline, Options opt, ErrorHandler errorHandler) throws SAXException {
+        outline.getAllPackageContexts().forEach(packageOutline -> {
+            removeDuplicateClasses(packageOutline);
+        });
+        return true;
+    }
+
+    private void removeDuplicateClasses(PackageOutline packageOutline) {
+        var classOutlines = packageOutline.getClasses();
+
+        var groupedClasses = groupingEqualClasses(classOutlines);
+        for (var groupedClass : groupedClasses) {
+            if (groupedClass.size() <= 1) {
+                continue;
+            }
+            groupedClass.sort(Comparator.comparing(this::innerDepth));
+            var savingClass = groupedClass.getFirst();
+
+            var removeClasses = groupedClass.subList(1, groupedClass.size());
+            removeAndReplaceClass(removeClasses, savingClass);
+        }
+    }
+
+    private int innerDepth(ClassOutline classOutline) {
+        return innerDepth(classOutline.implClass);
+    }
+
+    private int innerDepth(JDefinedClass definedClass) {
+        var depth = 0;
+        var currentContainer = definedClass.parentContainer();
+        while (currentContainer instanceof JDefinedClass) {
+            depth++;
+            currentContainer = currentContainer.parentContainer();
+        }
+        return depth;
+    }
+
+    private List<List<ClassOutline>> groupingEqualClasses(Set<? extends ClassOutline> classes) {
+        List<List<ClassOutline>> groupedClasses = new ArrayList<>();
+        for (var classOutline : classes) {
+            groupedClasses.stream()
+                .filter(group -> isEqual(group.getFirst().implClass, classOutline.implClass))
+                .findFirst()
+                .ifPresentOrElse(group -> group.add(classOutline),
+                    () -> groupedClasses.add(new ArrayList<>(List.of(classOutline))));
+        }
+        return groupedClasses;
+    }
+
+    private void removeAndReplaceClass(List<ClassOutline> removeClasses, ClassOutline replaceClassOutline) {
+        var replaceClass = replaceClassOutline.implClass;
+        var packageOutline = replaceClassOutline._package();
+        var outline = replaceClassOutline.parent();
+
+        removeClasses.forEach(classOutline -> {
+            var removeClass = classOutline.implClass;
+            removeFromParentContainer(removeClass);
+            var jPackage = removeClass.getPackage();
+
+            outline.getClasses().forEach(c -> {
+                var definedClass = c.implClass;
+
+                definedClass.fields().forEach((fieldName, fieldVar) -> {
+                    replaceType(fieldVar.type(), removeClass, replaceClass, () -> fieldVar.type(replaceClass));
+                });
+
+                definedClass.methods().forEach(method -> {
+                    replaceType(method.type(), removeClass, replaceClass, () -> method.type(replaceClass));
+
+                    method.params().forEach(param -> {
+                        replaceType(param.type(), removeClass, replaceClass, () -> param.type(replaceClass));
+                    });
+                });
+            });
+        });
+    }
+
+    private void removeFromParentContainer(JDefinedClass definedClass) {
+        var parentContainer = definedClass.parentContainer();
+
+        var classes = parentContainer.classes();
+        while (classes.hasNext()) {
+            var nextClass = classes.next();
+            if (nextClass == definedClass) {
+                classes.remove();
+                break;
+            }
+        }
+    }
+
+    private void replaceType(JType currentType, JDefinedClass targetType, JDefinedClass newTargetType, Runnable typeSetter) {
+        try {
+            var clazz = currentType.getClass();
+            if (currentType instanceof JDefinedClass) {
+                if (currentType == targetType) {
+                    typeSetter.run();
+                }
+            } else if (clazz.getSimpleName().equals("JNarrowedClass")) {
+                var argsField = clazz.getField("args");
+                argsField.setAccessible(true);
+                var args = (List<JClass>) argsField.get(currentType);
+
+                args.replaceAll(arg -> arg == targetType ? newTargetType : arg);
+            } else if (clazz.getSimpleName().equals("JArrayClass")) {
+                var componentTypeField = clazz.getField("componentType");
+                componentTypeField.setAccessible(true);
+                var componentType = (JType) componentTypeField.get(currentType);
+
+                if (componentType == targetType) {
+                    componentTypeField.set(currentType, newTargetType);
+                }
+            }
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            throw new IllegalStateException("Failed to replace type for " + currentType.fullName(), e);
+        }
+    }
+
+    private boolean isEqual(JDefinedClass class1, JDefinedClass class2) {
+        if (!class1.name().equals(class2.name())) {
+            return false;
+        }
+
+        if (class1.classes().hasNext() || class2.classes().hasNext()) {
+
+            return false;
+        }
+
+        if (class1.superClass() != class2.superClass()) {
+            return false;
+        }
+
+        var implements1 = StreamSupport.stream(Spliterators
+                .spliteratorUnknownSize(class1._implements(), Spliterator.ORDERED), false)
+            .collect(Collectors.toSet());
+        var implements2 = StreamSupport.stream(Spliterators
+                .spliteratorUnknownSize(class2._implements(), Spliterator.ORDERED), false)
+            .collect(Collectors.toSet());
+
+        if (!implements1.equals(implements2)) {
+            return false;
+        }
+
+        if (!isEqual(class1.annotations(), class2.annotations())) {
+            return false;
+        }
+
+        var fields1 = class1.fields();
+        var fields2 = class2.fields();
+
+        if (fields1.size() != fields2.size()) {
+            return false;
+        }
+
+        for (var entry : fields1.entrySet()) {
+            var fieldName = entry.getKey();
+            var field1 = entry.getValue();
+            var field2 = fields2.get(fieldName);
+
+            if (field2 == null) {
+                return false;
+            }
+
+            if (!field1.type().fullName().equals(field2.type().fullName())) {
+                return false;
+            }
+
+            if (!isEqual(field1.annotations(), field2.annotations())) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private boolean isEqual(Collection<JAnnotationUse> annos1, Collection<JAnnotationUse> annos2) {
+        if (annos1.size() != annos2.size()) {
+            return false;
+        }
+
+        var map1 = annos1.stream()
+            .collect(Collectors.groupingBy(a -> a.getAnnotationClass().fullName()));
+        var map2 = annos2.stream()
+            .collect(Collectors.groupingBy(a -> a.getAnnotationClass().fullName()));
+
+        if (!map1.keySet().equals(map2.keySet())) {
+            return false;
+        }
+
+        for (var fullName : map1.keySet()) {
+            var list1 = map1.get(fullName);
+            var list2 = map2.get(fullName);
+
+            if (list1.size() != list2.size()) {
+                return false;
+            }
+
+            for (var i = 0; i < list1.size(); i++) {
+                var anno1 = list1.get(i);
+                var anno2 = list2.get(i);
+
+                if (!isEqual(anno1, anno2)) {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+
+    private boolean isEqual(JAnnotationUse anno1, JAnnotationUse anno2) {
+        var members1 = anno1.getAnnotationMembers();
+        var members2 = anno2.getAnnotationMembers();
+
+        if (members1.size() != members2.size()) {
+            return false;
+        }
+
+        for (var entry : members1.entrySet()) {
+            var memberName = entry.getKey();
+            var member1 = entry.getValue();
+            var member2 = members2.get(memberName);
+
+            if (member2 == null) {
+                return false;
+            }
+
+            if (member1.getClass() != member2.getClass()) {
+                return false;
+            }
+
+            if (!isEqual(member1, member2)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private boolean isEqual(JAnnotationValue value1, JAnnotationValue value2) {
+        if (value1.getClass() != value2.getClass()) {
+            return false;
+        }
+
+        if (value1 instanceof JAnnotationStringValue) {
+            var stringValue1 = value1.toString();
+            var stringValue2 = value2.toString();
+            if (!stringValue1.equals(stringValue2)) {
+                return false;
+            }
+        } else if (value1 instanceof JAnnotationClassValue) {
+            var type1 = ((JAnnotationClassValue) value1).type();
+            var type2 = ((JAnnotationClassValue) value2).type();
+            if (!type1.fullName().equals(type2.fullName())) {
+                return false;
+            }
+
+            var value1Value = ((JAnnotationClassValue) value1).value();
+            var value2Value = ((JAnnotationClassValue) value2).value();
+            if (!value1Value.equals(value2Value)) {
+                return false;
+            }
+        } else if (value1 instanceof JAnnotationArrayMember) {
+            var values1 = ((JAnnotationArrayMember) value1).annotations2()
+                .stream().toList();
+            var values2 = ((JAnnotationArrayMember) value2).annotations2()
+                .stream().toList();
+
+            if (values1.size() != values2.size()) {
+                return false;
+            }
+
+            for (var i = 0; i < values1.size(); i++) {
+                var value1Item = values1.get(i);
+                var value2Item = values2.get(i);
+                if (!isEqual(value1Item, value2Item)) {
+                    return false;
+                }
+            }
+        } else if (value1 instanceof JAnnotationUse anno1) {
+            var anno2 = (JAnnotationUse) value2;
+            if (!isEqual(anno1, anno2)) {
+                return false;
+            }
+        } else {
+            throw new IllegalArgumentException("Unknown annotation value type: " + value1.getClass());
+        }
+
+        return true;
+    }
+}

plugins/src/main/resources/META-INF/services/com.sun.tools.xjc.Plugin

@@ -7,3 +7,4 @@ io.github.rawvoid.jaxb.plugin.ConvertNamePlugin
 io.github.rawvoid.jaxb.plugin.ElementWrapperPlugin
 io.github.rawvoid.jaxb.plugin.NsPrefixPlugin
 io.github.rawvoid.jaxb.plugin.FlattenInnerClassPlugin
+io.github.rawvoid.jaxb.plugin.NormalizeClassPlugin