Correctly get Collection generic parameter type

Elytrium · Aug 30, 2023 · 6a7ece2 · 6a7ece2
1 parent 8e0c2a5
commit 6a7ece2
Showing 1 changed file with 67 additions and 2 deletions.
diff --git a/src/main/java/net/elytrium/serializer/language/reader/YamlReader.java b/src/main/java/net/elytrium/serializer/language/reader/YamlReader.java
@@ -22,7 +22,9 @@
 import java.io.BufferedReader;
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
+import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
+import java.lang.reflect.TypeVariable;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -180,6 +182,65 @@ public void readSerializableObject(@Nullable Field owner, Object holder, Class<?
     }
   }
 
+  private int getParameterIndex(TypeVariable<?>[] variables, TypeVariable<?> expected) {
+    for (int i = 0; i < variables.length; ++i) {
+      if (variables[i].getName().equals(expected.getName())) {
+        return i;
+      }
+    }
+
+    return -1;
+  }
+
+  private Type getCollectionTypeFromSuperclass(Type type, Type superclass) {
+    Type superclassType = this.getCollectionType(superclass);
+    if (superclassType instanceof TypeVariable<?> typeVariable && type instanceof ParameterizedType parameterizedType) {
+      Class<?> rawSuperclass = (Class<?>) parameterizedType.getRawType();
+      int index = this.getParameterIndex(rawSuperclass.getTypeParameters(), typeVariable);
+      if (index != -1) {
+        return parameterizedType.getActualTypeArguments()[index];
+      }
+    }
+
+    return superclassType;
+  }
+
+  private Type getCollectionType(Type type) {
+    if (type == null) {
+      return null;
+    }
+
+    Class<?> clazz = null;
+
+    if (type instanceof ParameterizedType parameterizedType) {
+      clazz = (Class<?>) parameterizedType.getRawType();
+      if (clazz.equals(Collection.class)) {
+        return parameterizedType.getActualTypeArguments()[0];
+      }
+    }
+
+    if (type instanceof Class<?> typeClazz) {
+      clazz = typeClazz;
+    }
+
+    if (clazz != null) {
+      Type genericSuperclass = clazz.getGenericSuperclass();
+      Type superclassType = this.getCollectionTypeFromSuperclass(type, genericSuperclass);
+      if (superclassType != null) {
+        return superclassType;
+      }
+
+      for (Type genericInterface : clazz.getGenericInterfaces()) {
+        Type genericInterfaceType = this.getCollectionTypeFromSuperclass(type, genericInterface);
+        if (genericInterfaceType != null) {
+          return genericInterfaceType;
+        }
+      }
+    }
+
+    return null;
+  }
+
   private void updatePlaceholders(Object holder, Field node) throws ReflectiveOperationException {
     RegisterPlaceholders placeholders = node.getAnnotation(RegisterPlaceholders.class);
     if (placeholders == null) {
@@ -188,15 +249,19 @@ private void updatePlaceholders(Object holder, Field node) throws ReflectiveOper
 
     if (placeholders != null) {
       PlaceholderReplacer<?, ?> replacer = null;
+      Object value = node.get(holder);
       if (placeholders.replacer() == DefaultPlaceholderReplacer.class) {
-        replacer = this.config.getRegisteredReplacer(node.getType());
+        if (value instanceof Collection<?>) {
+          replacer = this.config.getRegisteredReplacer((Class<?>) this.getCollectionType(node.getGenericType()));
+        } else {
+          replacer = this.config.getRegisteredReplacer(node.getType());
+        }
       }
 
       if (replacer == null) {
         replacer = this.config.getAndCacheReplacer(placeholders.replacer());
       }
 
-      Object value = node.get(holder);
       if (this.config.isRegisterPlaceholdersForCollectionEntries() && value instanceof Collection<?> collection) {
         for (Object entry : collection) {
           Placeholders.addPlaceholders(entry, replacer, placeholders.wrapWithBraces(), placeholders.value());