From 051f20a8b7b76ecd9f773ac83aac138867aa0976 Mon Sep 17 00:00:00 2001
From: Claude Brisson <claude@renegat.net>
Date: Mon, 25 Jul 2022 08:14:15 +0200
Subject: Make templates cloneable - fixes VELOCITY-958

---
 .../main/java/org/apache/velocity/Template.java    |  7 +++-
 .../velocity/runtime/parser/node/SimpleNode.java   | 41 +++++++++++++++++++++-
 .../apache/velocity/runtime/resource/Resource.java | 28 ++++++++++++++-
 3 files changed, 73 insertions(+), 3 deletions(-)

(limited to 'velocity-engine-core')

diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/Template.java b/velocity-engine-core/src/main/java/org/apache/velocity/Template.java
index c5c0e1e4..31cca192 100644
--- a/velocity-engine-core/src/main/java/org/apache/velocity/Template.java
+++ b/velocity-engine-core/src/main/java/org/apache/velocity/Template.java
@@ -65,7 +65,7 @@ import java.util.concurrent.ConcurrentHashMap;
  * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
  * @version $Id$
  */
-public class Template extends Resource
+public class Template extends Resource implements Cloneable
 {
     /*
      * The name of the variable to use when placing
@@ -433,4 +433,9 @@ public class Template extends Resource
             throw ve;
         }
     }
+
+    @Override
+    protected void deepCloneData() throws CloneNotSupportedException {
+        setData(((SimpleNode)data).clone(this));
+    }
 }
diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/SimpleNode.java b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/SimpleNode.java
index ac9f7da8..f85d6926 100644
--- a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/SimpleNode.java
+++ b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/parser/node/SimpleNode.java
@@ -44,7 +44,7 @@ import org.slf4j.Logger;
 /**
  *
  */
-public class SimpleNode implements Node
+public class SimpleNode implements Node, Cloneable
 {
     /** */
     protected RuntimeServices rsvc = null;
@@ -608,4 +608,43 @@ public class SimpleNode implements Node
     {
         return parser;
     }
+
+    /**
+     * Root node deep cloning
+     * @param template owner template
+     * @return cloned node
+     * @throws CloneNotSupportedException
+     * @since 2.4
+     */
+    public Node clone(Template template) throws CloneNotSupportedException
+    {
+        if (parent != null) {
+            throw new IllegalStateException("cannot clone a child node without knowing its parent");
+        }
+        return clone(template, null);
+    }
+
+    /**
+     * Child node deep cloning
+     * @param template owner template
+     * @param parent parent node
+     * @return cloned node
+     * @throws CloneNotSupportedException
+     * @since 2.4
+     */
+    protected Node clone(Template template, Node parent) throws CloneNotSupportedException
+    {
+        SimpleNode clone = (SimpleNode)super.clone();
+        clone.template = template;
+        clone.parent = parent;
+        if (children != null)
+        {
+            clone.children = new SimpleNode[children.length];
+            for (int i = 0; i < children.length; ++i)
+            {
+                clone.children[i] = ((SimpleNode)children[i]).clone(template, clone);
+            }
+        }
+        return clone;
+    }
 }
diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/Resource.java b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/Resource.java
index faf93a62..5922604d 100644
--- a/velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/Resource.java
+++ b/velocity-engine-core/src/main/java/org/apache/velocity/runtime/resource/Resource.java
@@ -35,7 +35,7 @@ import org.slf4j.Logger;
  * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
  * @version $Id$
  */
-public abstract class Resource
+public abstract class Resource implements Cloneable
 {
     protected RuntimeServices rsvc = null;
     protected Logger log = null;
@@ -291,4 +291,30 @@ public abstract class Resource
     {
         return type;
     }
+
+    /**
+     * @return cloned resource
+     * @since 2.4
+     */
+    @Override
+    public Object clone() {
+        try
+        {
+            Resource clone = (Resource) super.clone();
+            clone.deepCloneData();
+            return clone;
+        }
+        catch (CloneNotSupportedException e) {
+            throw new RuntimeException("cloning not supported");
+        }
+    }
+
+    /**
+     * Deep cloning of resource data
+     * @return cloned data
+     */
+    protected void deepCloneData() throws CloneNotSupportedException
+    {
+        // default implementation does nothing
+    }
 }
-- 
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