From 072d6df374f92fc7545d4e0ebe2a04f30a79a868 Mon Sep 17 00:00:00 2001
From: PHJ2000 <105151063+PHJ2000@users.noreply.github.com>
Date: Mon, 5 Oct 2026 22:43:13 +0900
Subject: [PATCH] Preserve precision when comparing numbers of the same type

---
 .../handlebars/helper/ConditionalHelpers.java |  6 ++
 .../helper/ConditionalHelpersTest.java        | 58 +++++++++++++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 handlebars/src/test/java/com/github/jknack/handlebars/helper/ConditionalHelpersTest.java

diff --git a/handlebars/src/main/java/com/github/jknack/handlebars/helper/ConditionalHelpers.java b/handlebars/src/main/java/com/github/jknack/handlebars/helper/ConditionalHelpers.java
index 0633b9dc..5e8e3d21 100644
--- a/handlebars/src/main/java/com/github/jknack/handlebars/helper/ConditionalHelpers.java
+++ b/handlebars/src/main/java/com/github/jknack/handlebars/helper/ConditionalHelpers.java
@@ -423,6 +423,12 @@ protected boolean eq(final Object a, final Object b) {
     boolean value = Objects.equals(a, b);
     if (!value) {
       if (a instanceof Number && b instanceof Number) {
+        if (a.getClass() == b.getClass()
+            && a instanceof Comparable
+            && !(a instanceof Double)
+            && !(a instanceof Float)) {
+          return cmp(a, b) == 0;
+        }
         // int vs double: 2 vs 2.0
         return ((Number) a).doubleValue() == ((Number) b).doubleValue();
       }
diff --git a/handlebars/src/test/java/com/github/jknack/handlebars/helper/ConditionalHelpersTest.java b/handlebars/src/test/java/com/github/jknack/handlebars/helper/ConditionalHelpersTest.java
new file mode 100644
index 00000000..38bacc48
--- /dev/null
+++ b/handlebars/src/test/java/com/github/jknack/handlebars/helper/ConditionalHelpersTest.java
@@ -0,0 +1,58 @@
+/*
+ * Handlebars.java: https://github.com/jknack/handlebars.java
+ * Apache License Version 2.0 http://www.apache.org/licenses/LICENSE-2.0
+ * Copyright (c) 2012 Edgar Espina
+ */
+package com.github.jknack.handlebars.helper;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.junit.jupiter.api.Test;
+
+import com.github.jknack.handlebars.Handlebars;
+
+public class ConditionalHelpersTest {
+  @Test
+  public void compareLargeLongsWithoutRounding() throws IOException {
+    Handlebars handlebars = new Handlebars().registerHelpers(ConditionalHelpers.class);
+    assertEquals(
+        "false/true",
+        handlebars
+            .compileInline("{{eq a b}}/{{neq a b}}")
+            .apply(Map.of("a", 9007199254740992L, "b", 9007199254740993L)));
+    assertFalse(ConditionalHelpers.eq.eq(Long.MAX_VALUE, Long.MAX_VALUE - 1));
+    assertTrue(ConditionalHelpers.eq.eq(Long.MAX_VALUE, Long.MAX_VALUE));
+  }
+
+  @Test
+  public void compareBigNumbersWithoutRounding() {
+    assertFalse(
+        ConditionalHelpers.eq.eq(
+            new BigInteger("9007199254740992"), new BigInteger("9007199254740993")));
+    assertFalse(
+        ConditionalHelpers.eq.eq(
+            new BigDecimal("1.00000000000000001"), new BigDecimal("1.00000000000000002")));
+    assertFalse(ConditionalHelpers.eq.eq(new BigDecimal("1e-400"), new BigDecimal("2e-400")));
+    assertTrue(ConditionalHelpers.eq.eq(new BigDecimal("2.0"), new BigDecimal("2.00")));
+  }
+
+  @Test
+  public void preserveOtherNumericComparisons() {
+    assertTrue(ConditionalHelpers.eq.eq(2, 2.0));
+    assertTrue(ConditionalHelpers.eq.eq(0.0, -0.0));
+    assertTrue(ConditionalHelpers.eq.eq(0.0f, -0.0f));
+    assertTrue(ConditionalHelpers.eq.eq(Double.NaN, Double.NaN));
+    assertTrue(ConditionalHelpers.eq.eq(Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY));
+    assertTrue(ConditionalHelpers.eq.eq(new AtomicLong(2), new AtomicLong(2)));
+    assertFalse(ConditionalHelpers.eq.eq(null, 2));
+    assertFalse(ConditionalHelpers.eq.eq("2", 2));
+  }
+}