[optimize] Make combining two NodeListImpl more efficient

Author: adamretter

exist-core/pom.xml

@@ -775,6 +775,7 @@
                                 <include>src/main/java/org/exist/config/Configuration.java</include>
                                 <include>src/main/java/org/exist/config/ConfigurationImpl.java</include>
                                 <include>src/main/java/org/exist/config/Configurator.java</include>
+                                <include>src/main/java/org/exist/dom/NodeListImpl.java</include>
                                 <include>src/main/java/org/exist/dom/memtree/AttrImpl.java</include>
                                 <include>src/main/java/org/exist/dom/memtree/DocumentImpl.java</include>
                                 <include>src/main/java/org/exist/dom/memtree/DOMIndexer.java</include>
@@ -1035,6 +1036,7 @@
                                 <exclude>src/main/java/org/exist/config/Configuration.java</exclude>
                                 <exclude>src/main/java/org/exist/config/ConfigurationImpl.java</exclude>
                                 <exclude>src/main/java/org/exist/config/Configurator.java</exclude>
+                                <exclude>src/main/java/org/exist/dom/NodeListImpl.java</exclude>
                                 <exclude>src/main/java/org/exist/dom/memtree/AttrImpl.java</exclude>
                                 <exclude>src/main/java/org/exist/dom/memtree/DocumentImpl.java</exclude>
                                 <exclude>src/main/java/org/exist/dom/memtree/DocumentTypeImpl.java</exclude>

exist-core/src/main/java/org/exist/dom/NodeListImpl.java

@@ -1,4 +1,28 @@
 /*
+ * Elemental
+ * Copyright (C) 2024, Evolved Binary Ltd
+ *
+ * [email protected]
+ * https://www.evolvedbinary.com | https://www.elemental.xyz
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; version 2.1.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * NOTE: Parts of this file contain code from 'The eXist-db Authors'.
+ *       The original license header is included below.
+ *
+ * =====================================================================
+ *
  * eXist-db Open Source Native XML Database
  * Copyright (C) 2001 The eXist-db Authors
  *
@@ -46,6 +70,26 @@ public boolean add(final Node node) {
         return super.add(node);
     }
 
+    /**
+     * Add all elements of the other NodeListImpl to
+     * this NodeListImpl.
+     *
+     * @param other NodeListImpl to add.
+     *
+     * @return true if the list was modified, false otherwise.
+     */
+    public boolean addAll(final NodeListImpl other) {
+        if (other == null) {
+            return false;
+        }
+
+        if (other.isEmpty()) {
+            return false;
+        }
+
+        return addAll((ArrayList<Node>) other);
+    }
+
     /**
      * Add all elements of the other NodeList to
      * this NodeList
@@ -54,18 +98,26 @@ public boolean add(final Node node) {
      *   if none or only some were added.
      */
     public boolean addAll(final NodeList other) {
+        if (other == null) {
+            return false;
+        }
+
+        if (other instanceof NodeListImpl) {
+            return addAll((NodeListImpl) other);
+        }
+
         if (other.getLength() == 0) {
             return false;
-        } else {
-            boolean result = true;
-            for(int i = 0; i < other.getLength(); i++) {
-                if(!add(other.item(i))) {
-                    result = false;
-                    break;
-                }
+        }
+
+        boolean result = true;
+        for (int i = 0; i < other.getLength(); i++) {
+            if (!add(other.item(i))) {
+                result = false;
+                break;
             }
-            return result;
         }
+        return result;
     }
 
     @Override