From 4cf5d248c947c47bc6647286121b4b2012eaca24 Mon Sep 17 00:00:00 2001
From: 1okey <antonskochko@gmail.com>
Date: Fri, 3 Jul 2026 15:13:10 +0300
Subject: [PATCH] feat: adds a null-safe operator to the
 BinaryOperatorEvaluator

---
 .../Expression/BinaryOperatorEvaluator.php    | 10 ++++-
 tests/EndToEndTest.php                        | 38 ++++++++++++++++++-
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/src/Processor/Expression/BinaryOperatorEvaluator.php b/src/Processor/Expression/BinaryOperatorEvaluator.php
index bced418c..c7fa1020 100644
--- a/src/Processor/Expression/BinaryOperatorEvaluator.php
+++ b/src/Processor/Expression/BinaryOperatorEvaluator.php
@@ -113,6 +113,7 @@ public static function evaluate(
             case '>=':
             case '<':
             case '<=':
+            case '<=>':
                 $l_value = Evaluator::evaluate($conn, $scope, $left, $row, $result);
                 $r_value = Evaluator::evaluate($conn, $scope, $right, $row, $result);
 
@@ -138,11 +139,18 @@ public static function evaluate(
                 }
 
                 if ($l_value === null || $r_value === null) {
+                    // The null-safe equal operator never returns NULL: it yields 1 when both
+                    // operands are NULL and 0 when exactly one of them is NULL.
+                    if ($expr->operator === '<=>') {
+                        return (($l_value === null && $r_value === null) ? 1 : 0) ^ $expr->negatedInt;
+                    }
+
                     return null;
                 }
 
                 switch ($expr->operator) {
                     case '=':
+                    case '<=>':
                         if ($as_string) {
                             return (\strtolower((string) $l_value) === \strtolower((string) $r_value) ? 1 : 0)
                                 ^ $expr->negatedInt;
@@ -327,7 +335,6 @@ public static function evaluate(
             case 'BINARY':
             case 'COLLATE':
             case '^':
-            case '<=>':
             case '||':
             case 'XOR':
             case 'SOUNDS':
@@ -385,6 +392,7 @@ public static function getColumnSchema(
             case '>=':
             case '<':
             case '<=':
+            case '<=>':
             case 'LIKE':
             case 'IS':
             case 'RLIKE':
diff --git a/tests/EndToEndTest.php b/tests/EndToEndTest.php
index 1d5352dc..5fce3fdb 100644
--- a/tests/EndToEndTest.php
+++ b/tests/EndToEndTest.php
@@ -1542,7 +1542,7 @@ public function testNestedFunctions()
         $pdo = self::getConnectionToFullDB();
 
         $query = $pdo->prepare("
-            SELECT 
+            SELECT
                 SUM(
                     TIMESTAMPDIFF(
                         SECOND,
@@ -1576,4 +1576,40 @@ public function testNestedFunctionsFromDB()
 
         $this->assertSame((int)$count, (int)$query->fetchColumn());
     }
+
+    public function testNullSafeEqualOperator(): void
+    {
+        $pdo = self::getPdo('mysql:host=localhost;dbname=testdb');
+        $pdo->setAttribute(\PDO::ATTR_EMULATE_PREPARES, false);
+
+        $query = $pdo->prepare(
+            'SELECT
+                1 <=> 1 AS `equal_ints`,
+                1 <=> 2 AS `unequal_ints`,
+                NULL <=> NULL AS `both_null`,
+                1 <=> NULL AS `left_not_null`,
+                NULL <=> 1 AS `right_not_null`,
+                \'a\' <=> \'a\' AS `equal_strings`,
+                \'a\' <=> \'b\' AS `unequal_strings`'
+        );
+
+        $query->execute();
+
+        $results = array_map(function ($row) {
+            return array_map('intval', $row);
+        }, $query->fetchAll(\PDO::FETCH_ASSOC));
+
+        $this->assertSame(
+            [[
+                'equal_ints' => 1,
+                'unequal_ints' => 0,
+                'both_null' => 1,
+                'left_not_null' => 0,
+                'right_not_null' => 0,
+                'equal_strings' => 1,
+                'unequal_strings' => 0,
+            ]],
+            $results
+        );
+    }
 }