User defined REVERSE() function Unicode support 🎉

packages/mysql-on-sqlite/src/sqlite/class-wp-sqlite-pdo-user-defined-functions.php

@@ -934,15 +934,20 @@ public function version() {
 	 * Method to emulate MySQL REVERSE() function.
 	 *
 	 * Takes a string and returns the reverse of it.
+	 * Compatible with MySQL behaviour for utf8mb4 strings.
 	 *
-	* @param string|null $str The string to reverse.
-	*
-	* @return string|null reversed string, or NULL.
-	*/
+	 * @param string|null $str The string to reverse.
+	 *
+	 * @return string|null reversed string, or NULL.
+	 */
 	public function reverse( $str ) {
 		if ( null === $str ) {
 			return null;
 		}
+		if ( preg_match( '/[^\x00-\x7F]/', $str ) ) {
+			preg_match_all( '/./u', $str, $matches );
+			return implode( '', array_reverse( $matches[0] ) );
+		}
 		return strrev( $str );
 	}
 

packages/mysql-on-sqlite/tests/WP_MySQL_On_SQLite_Tests.php

@@ -12585,6 +12585,14 @@ public function testReverseFunction(): void {
 		$result = $this->assertQuery( "SELECT REVERSE('aoeuidhtns') AS reversed" );
 		$this->assertSame( 'snthdiueoa', $result[0]->reversed );
 
+		// Unicode reverse.
+		$result = $this->assertQuery( "SELECT REVERSE('Héllö Wörld!') AS reversed" );
+		$this->assertSame( '!dlröW ölléH', $result[0]->reversed );
+
+		// Emoji reverse.
+		$result = $this->assertQuery( "SELECT REVERSE('Text with 😁😂🤣 emoji 🚀') AS reversed" );
+		$this->assertSame( '🚀 ijome 🤣😂😁 htiw txeT', $result[0]->reversed );
+
 		// Empty string.
 		$result = $this->assertQuery( "SELECT REVERSE('') AS reversed" );
 		$this->assertSame( '', $result[0]->reversed );