Add BC for PHP 7.2, see https://bugs.php.net/bug.php?id=73947

ChangeLog.md

@@ -3,6 +3,12 @@ Pattern matching changelog
 
 ## ?.?.? / ????-??-??
 
+## 7.1.1 / 2017-01-16
+
+* Added BC for PHP 7.2: Empty optional patterns should not be NULLed
+  See https://bugs.php.net/bug.php?id=73947
+  (@thekid) 
+
 ## 7.1.0 / 2016-08-29
 
 * Added version compatibility with XP 8 - @thekid

src/main/php/text/regex/MatchResult.class.php

@@ -25,7 +25,15 @@ static function __static() {
    */
   public function __construct($length, $matches) {
     $this->length= $length;
-    $this->matches= $matches;
+
+    // Ensure empty patterns are not NULLed to ensure BC.
+    // See https://bugs.php.net/bug.php?id=73947
+    foreach ($matches as $group => $match) {
+      $this->matches[$group]= [];
+      foreach ($match as $i => $segment) {
+        $this->matches[$group][$i]= (string)$segment;
+      }
+    }
   }
 
   /**

src/test/php/text/regex/unittest/PatternTest.class.php

@@ -202,4 +202,12 @@ public function stringCastWithFlag() {
   public function stringCastWithFlags() {
     $this->assertEquals('/end$/iU', (string)new Pattern('end$', Pattern::CASE_INSENSITIVE | Pattern::UNGREEDY));
   }
+
+  #[@test]
+  public function php_bug_73947() {
+    $this->assertEquals(
+      ['http://domain', 'http', '', 'domain'],
+      Pattern::compile('([a-z]+)://([^@]+@)?([a-z]+)')->match('http://domain')->group(0)
+    );
+  }
 }