5 files changed, 52 insertions, 0 deletions
diff --git a/phpBB/phpbb/db/migration/helper.php b/phpBB/phpbb/db/migration/helper.php
index e40deeb37b..bce2efff51 100644
--- a/phpBB/phpbb/db/migration/helper.php
+++ b/phpBB/phpbb/db/migration/helper.php
@@ -81,4 +81,36 @@ class helper
 
 		return $steps;
 	}
+
+	/**
+	 * Reverse the update steps from an array of data changes
+	 *
+	 * 'If' statements and custom methods will be skipped, for all
+	 * other calls the reverse method of the tool class will be called
+	 *
+	 * @param array $steps Update changes from migration
+	 *
+	 * @return array
+	 */
+	public function reverse_update_data($steps)
+	{
+		$reversed_array = array();
+
+		foreach ($steps as $step)
+		{
+			$parts = explode('.', $step[0]);
+			$parameters = $step[1];
+
+			$class = $parts[0];
+			$method = isset($parts[1]) ? $parts[1] : false;
+
+			if ($class !== 'if' && $class !== 'custom')
+			{
+				array_unshift($parameters, $method);
+				$reversed_array[] = array($class . '.reverse', $parameters);
+			}
+		}
+
+		return array_reverse($reversed_array);
+	}
 }
diff --git a/phpBB/phpbb/db/migration/tool/config.php b/phpBB/phpbb/db/migration/tool/config.php
index f93e7118c4..2a76409db5 100644
--- a/phpBB/phpbb/db/migration/tool/config.php
+++ b/phpBB/phpbb/db/migration/tool/config.php
@@ -150,6 +150,11 @@ class config implements \phpbb\db\migration\tool\tool_interface
 					$arguments[0],
 				);
 			break;
+
+			case 'reverse':
+				// It's like double negative
+				$call = array_shift($arguments);
+			break;
 		}
 
 		if ($call)
diff --git a/phpBB/phpbb/db/migration/tool/config_text.php b/phpBB/phpbb/db/migration/tool/config_text.php
index bf8ac55023..21b8a8b3a0 100644
--- a/phpBB/phpbb/db/migration/tool/config_text.php
+++ b/phpBB/phpbb/db/migration/tool/config_text.php
@@ -115,6 +115,11 @@ class config_text implements \phpbb\db\migration\tool\tool_interface
 					$arguments[] = '';
 				}
 			break;
+
+			case 'reverse':
+				// It's like double negative
+				$call = array_shift($arguments);
+			break;
 		}
 
 		if ($call)
diff --git a/phpBB/phpbb/db/migration/tool/module.php b/phpBB/phpbb/db/migration/tool/module.php
index 035625b095..a6baf40dc1 100644
--- a/phpBB/phpbb/db/migration/tool/module.php
+++ b/phpBB/phpbb/db/migration/tool/module.php
@@ -454,6 +454,11 @@ class module implements \phpbb\db\migration\tool\tool_interface
 			case 'remove':
 				$call = 'add';
 			break;
+
+			case 'reverse':
+				// It's like double negative
+				$call = array_shift($arguments);
+			break;
 		}
 
 		if ($call)
diff --git a/phpBB/phpbb/db/migration/tool/permission.php b/phpBB/phpbb/db/migration/tool/permission.php
index ceff6d7d5a..3a1e2e344b 100644
--- a/phpBB/phpbb/db/migration/tool/permission.php
+++ b/phpBB/phpbb/db/migration/tool/permission.php
@@ -637,6 +637,11 @@ class permission implements \phpbb\db\migration\tool\tool_interface
 					$arguments[0],
 				);
 			break;
+
+			case 'reverse':
+				// It's like double negative
+				$call = array_shift($arguments);
+			break;
 		}
 
 		if ($call)