From b3930804c6e89f31cad41376beecd30940932e5f Mon Sep 17 00:00:00 2001
From: "Erik C. Thauvin" <erik@thauvin.net>
Date: Wed, 15 Mar 2023 22:57:27 -0700
Subject: [PATCH] Switched to using codePoints in toHtmlEntities

---
 .../main/java/rife/render/EncodeHtmlEntities.java | 15 ++++++++++-----
 lib/src/main/java/rife/render/RenderUtils.java    |  2 +-
 lib/src/main/java/rife/render/Rot13.java          |  4 ++--
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/lib/src/main/java/rife/render/EncodeHtmlEntities.java b/lib/src/main/java/rife/render/EncodeHtmlEntities.java
index 5e33b49..4d3b35e 100644
--- a/lib/src/main/java/rife/render/EncodeHtmlEntities.java
+++ b/lib/src/main/java/rife/render/EncodeHtmlEntities.java
@@ -44,14 +44,19 @@ public class EncodeHtmlEntities implements ValueRenderer {
      * @param text the String to convert.
      * @return the converted string.
      */
+    @SuppressWarnings("PMD.AvoidReassigningLoopVariables")
     public static String toHtmlEntities(String text) {
-        var buff = new StringBuilder(text.length() * 6);
-
+        // https://stackoverflow.com/a/6766497/8356718
+        var sb = new StringBuilder(text.length() * 6);
         for (var i = 0; i < text.length(); i++) {
-            buff.append("&#").append((int) text.charAt(i)).append(';');
+            var codePoint = text.codePointAt(i);
+            // Skip over the second char in a surrogate pair
+            if (codePoint > 0xffff) {
+                i++;
+            }
+            sb.append(String.format("&#%s;", codePoint));
         }
-
-        return buff.toString();
+        return sb.toString();
     }
 
     /**
diff --git a/lib/src/main/java/rife/render/RenderUtils.java b/lib/src/main/java/rife/render/RenderUtils.java
index 609f65b..85ea7f1 100644
--- a/lib/src/main/java/rife/render/RenderUtils.java
+++ b/lib/src/main/java/rife/render/RenderUtils.java
@@ -33,7 +33,7 @@ public final class RenderUtils {
      *
      * @param template the template
      * @param valueId  the ID of the value to fetch
-     * @return The fetched value.
+     * @return the fetched value.
      */
     public static String fetchValue(Template template, String valueId) {
         Object value = null;
diff --git a/lib/src/main/java/rife/render/Rot13.java b/lib/src/main/java/rife/render/Rot13.java
index a18ae41..ea51982 100644
--- a/lib/src/main/java/rife/render/Rot13.java
+++ b/lib/src/main/java/rife/render/Rot13.java
@@ -37,8 +37,8 @@ public class Rot13 implements ValueRenderer {
     /**
      * Translates a String to/from ROT13.
      *
-     * @param src The source String.
-     * @return The translated String.
+     * @param src the source String.
+     * @return the translated String.
      */
     public static String rot13(String src) {
         if (src == null || src.isEmpty()) {