Reorg: Move StubObject classes in includes to its own directory

Bug: T166010
Change-Id: Idcf0e9dc6e0841e4f132207bce0f96774dad898c

4 files changed, 505 insertions, 0 deletions

diff --git a/includes/StubObject/DeprecatedGlobal.php b/includes/StubObject/DeprecatedGlobal.php
new file mode 100644
index 000000000000..1ec79a91ee72
--- /dev/null
+++ b/includes/StubObject/DeprecatedGlobal.php
@@ -0,0 +1,65 @@
+<?php
+/**
+ * Delayed loading of deprecated global objects.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\StubObject;
+
+/**
+ * Class to allow throwing wfDeprecated warnings
+ * when people use globals that we do not want them to.
+ */
+class DeprecatedGlobal extends StubObject {
+	protected $version;
+
+	/**
+	 * @param string $name Global name
+	 * @param callable|string $callback Factory function or class name to construct
+	 * @param string|false $version Version global was deprecated in
+	 */
+	public function __construct( $name, $callback, $version = false ) {
+		parent::__construct( $name, $callback );
+		$this->version = $version;
+	}
+
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _newObject() {
+		/*
+		 * Put the caller offset for wfDeprecated as 6, as
+		 * that gives the function that uses this object, since:
+		 *
+		 * 1 = this function ( _newObject )
+		 * 2 = MediaWiki\StubObject\StubObject::_unstub
+		 * 3 = MediaWiki\StubObject\StubObject::_call
+		 * 4 = MediaWiki\StubObject\StubObject::__call
+		 * 5 = MediaWiki\StubObject\DeprecatedGlobal::<method of global called>
+		 * 6 = Actual function using the global.
+		 * (the same applies to _get/__get or _set/__set instead of _call/__call)
+		 *
+		 * Of course its theoretically possible to have other call
+		 * sequences for this method, but that seems to be
+		 * rather unlikely.
+		 */
+		wfDeprecated( '$' . $this->global, $this->version, false, 6 );
+		return parent::_newObject();
+	}
+}
+
+class_alias( DeprecatedGlobal::class, 'DeprecatedGlobal' );
diff --git a/includes/StubObject/StubGlobalUser.php b/includes/StubObject/StubGlobalUser.php
new file mode 100644
index 000000000000..66b91f983c94
--- /dev/null
+++ b/includes/StubObject/StubGlobalUser.php
@@ -0,0 +1,157 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\StubObject;
+
+use InvalidArgumentException;
+use User;
+
+/**
+ * Stub object for the global user ($wgUser) that makes it possible to change the
+ * relevant underlying object while still ensuring that deprecation warnings will
+ * be emitted upon method calls.
+ *
+ * @internal Will be removed in 1.38
+ *
+ * @since 1.37
+ * @author Danny712
+ */
+class StubGlobalUser extends StubObject {
+
+	/** @var bool */
+	public static $destructorDeprecationDisarmed = false;
+
+	/** @var User */
+	public $realUser;
+
+	/**
+	 * @param User $realUser
+	 */
+	public function __construct( User $realUser ) {
+		parent::__construct( 'wgUser' );
+		$this->realUser = $realUser;
+	}
+
+	/**
+	 * @return User
+	 */
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _newObject() {
+		// Based on MediaWiki\StubObject\DeprecatedGlobal::_newObject
+		/*
+		 * Put the caller offset for wfDeprecated as 6, as
+		 * that gives the function that uses this object, since:
+		 *
+		 * 1 = this function ( _newObject )
+		 * 2 = MediaWiki\StubObject\StubGlobalUser::_unstub
+		 * 3 = MediaWiki\StubObject\StubObject::_call
+		 * 4 = MediaWiki\StubObject\StubObject::__call
+		 * 5 = MediaWiki\StubObject\StubGlobalUser::<method of global called>
+		 * 6 = Actual function using the global.
+		 * (the same applies to _get/__get or _set/__set instead of _call/__call)
+		 *
+		 * Of course its theoretically possible to have other call
+		 * sequences for this method, but that seems to be
+		 * rather unlikely.
+		 */
+		// Officially deprecated since 1.35
+		wfDeprecated( '$wgUser', '1.35', false, 6 );
+		return $this->realUser;
+	}
+
+	/**
+	 * Reset the stub global user to a different "real" user object, while ensuring that
+	 * any method calls on that object will still trigger deprecation notices.
+	 *
+	 * @param StubGlobalUser|User $user
+	 */
+	public static function setUser( $user ) {
+		// This is intended to be interacting with the deprecated global
+		// phpcs:ignore MediaWiki.Usage.DeprecatedGlobalVariables.Deprecated$wgUser
+		global $wgUser;
+
+		self::$destructorDeprecationDisarmed = true;
+		// Supports MediaWiki\StubObject\StubGlobalUser parameter in case something fetched the existing value of
+		// $wgUser, set it to something else, and now is trying to restore it
+		$realUser = self::getRealUser( $user );
+		$wgUser = new self( $realUser );
+		self::$destructorDeprecationDisarmed = false;
+	}
+
+	/**
+	 * Get the relevant "real" user object based on either a User object or a MediaWiki\StubObject\StubGlobalUser
+	 * wrapper. Bypasses deprecation notices from converting a MediaWiki\StubObject\StubGlobalUser to an actual
+	 * user, and does not change $wgUser.
+	 *
+	 * @param StubGlobalUser|User $globalUser
+	 * @return User
+	 */
+	public static function getRealUser( $globalUser ): User {
+		if ( $globalUser instanceof StubGlobalUser ) {
+			return $globalUser->realUser;
+		} elseif ( $globalUser instanceof User ) {
+			return $globalUser;
+		} else {
+			throw new InvalidArgumentException(
+				'$globalUser must be a User (or MediaWiki\StubObject\StubGlobalUser), got ' .
+				( is_object( $globalUser ) ? get_class( $globalUser ) : gettype( $globalUser ) )
+			);
+		}
+	}
+
+	/**
+	 * This function creates a new object of the real class and replace it in
+	 * the global variable.
+	 * This is public, for the convenience of external callers wishing to access
+	 * properties, e.g. eval.php
+	 *
+	 * Overriding MediaWiki\StubObject\StubObject::_unstub because for some reason that thinks there is
+	 * an unstub loop when trying to use the magic __set() logic, but there isn't
+	 * any loop because _newObject() returns a specific instance of User rather
+	 * than calling any methods that could then try to use $wgUser. The main difference
+	 * between this and the parent method is that we don't try to check for
+	 * recursion loops.
+	 *
+	 * @param string $name Name of the method called in this object.
+	 * @param int $level Level to go in the stack trace to get the function
+	 *   who called this function.
+	 * @return User The unstubbed version
+	 */
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _unstub( $name = '_unstub', $level = 2 ) {
+		if ( !$GLOBALS[$this->global] instanceof self ) {
+			return $GLOBALS[$this->global]; // already unstubbed.
+		}
+
+		$caller = wfGetCaller( $level );
+		wfDebug( "Unstubbing \${$this->global} on call of "
+			. "\${$this->global}::$name from $caller" );
+		$GLOBALS[$this->global] = $this->_newObject();
+		return $GLOBALS[$this->global];
+	}
+
+	public function __destruct() {
+		if ( !self::$destructorDeprecationDisarmed ) {
+			wfDeprecatedMsg( '$wgUser reassignment detected', '1.37', false, 3 );
+		}
+	}
+}
+
+class_alias( StubGlobalUser::class, 'StubGlobalUser' );
diff --git a/includes/StubObject/StubObject.php b/includes/StubObject/StubObject.php
new file mode 100644
index 000000000000..0fd027abec89
--- /dev/null
+++ b/includes/StubObject/StubObject.php
@@ -0,0 +1,239 @@
+<?php
+
+// phpcs:disable MediaWiki.Commenting.FunctionComment.ObjectTypeHintReturn
+// phpcs:disable MediaWiki.Commenting.FunctionComment.ObjectTypeHintParam
+
+/**
+ * Delayed loading of global objects.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\StubObject;
+
+use MWException;
+use Wikimedia\ObjectFactory\ObjectFactory;
+
+/**
+ * Class to implement stub globals, which are globals that delay loading the
+ * their associated module code by deferring initialisation until the first
+ * method call.
+ *
+ * Note on reference parameters:
+ *
+ * If the called method takes any parameters by reference, the __call magic
+ * here won't work correctly. The solution is to unstub the object before
+ * calling the method.
+ *
+ * Note on unstub loops:
+ *
+ * Unstub loops (infinite recursion) sometimes occur when a constructor calls
+ * another function, and the other function calls some method of the stub. The
+ * best way to avoid this is to make constructors as lightweight as possible,
+ * deferring any initialisation which depends on other modules. As a last
+ * resort, you can use MediaWiki\StubObject\StubObject::isRealObject() to break the loop, but as a
+ * general rule, the stub object mechanism should be transparent, and code
+ * which refers to it should be kept to a minimum.
+ *
+ * @newable
+ */
+class StubObject {
+	/** @var null|string */
+	protected $global;
+
+	/** @var null|string */
+	protected $class;
+
+	/** @var null|callable */
+	protected $factory;
+
+	/** @var array */
+	protected $params;
+
+	/**
+	 * @stable to call
+	 *
+	 * @param string|null $global Name of the global variable.
+	 * @param string|callable|null $class Name of the class of the real object
+	 *                               or a factory function to call
+	 * @param array $params Parameters to pass to constructor of the real object.
+	 */
+	public function __construct( $global = null, $class = null, $params = [] ) {
+		$this->global = $global;
+		if ( is_callable( $class ) ) {
+			$this->factory = $class;
+		} else {
+			$this->class = $class;
+		}
+		$this->params = $params;
+	}
+
+	/**
+	 * Returns a bool value whenever $obj is a stub object. Can be used to break
+	 * a infinite loop when unstubbing an object.
+	 *
+	 * @param object $obj Object to check.
+	 * @return bool True if $obj is not an instance of MediaWiki\StubObject\StubObject class.
+	 */
+	public static function isRealObject( $obj ) {
+		return is_object( $obj ) && !$obj instanceof self;
+	}
+
+	/**
+	 * Unstubs an object, if it is a stub object. Can be used to break a
+	 * infinite loop when unstubbing an object or to avoid reference parameter
+	 * breakage.
+	 *
+	 * @param object &$obj Object to check.
+	 * @return void
+	 */
+	public static function unstub( &$obj ) {
+		if ( $obj instanceof self ) {
+			$obj = $obj->_unstub( 'unstub', 3 );
+		}
+	}
+
+	/**
+	 * Function called if any function exists with that name in this object.
+	 * It is used to unstub the object. Only used internally, PHP will call
+	 * self::__call() function and that function will call this function.
+	 * This function will also call the function with the same name in the real
+	 * object.
+	 *
+	 * @param string $name Name of the function called
+	 * @param array $args Arguments
+	 * @return mixed
+	 */
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _call( $name, $args ) {
+		$this->_unstub( $name, 5 );
+		return call_user_func_array( [ $GLOBALS[$this->global], $name ], $args );
+	}
+
+	/**
+	 * Create a new object to replace this stub object.
+	 * @return object
+	 */
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _newObject() {
+		$params = $this->factory
+			? [ 'factory' => $this->factory ]
+			: [ 'class' => $this->class ];
+
+		// ObjectFactory::getObjectFromSpec accepts an array, not just a callable (phan bug)
+		// @phan-suppress-next-line PhanTypeInvalidCallableArraySize
+		return ObjectFactory::getObjectFromSpec( $params + [
+				'args' => $this->params,
+				'closure_expansion' => false,
+			] );
+	}
+
+	/**
+	 * Function called by PHP if no function with that name exists in this
+	 * object.
+	 *
+	 * @param string $name Name of the function called
+	 * @param array $args Arguments
+	 * @return mixed
+	 */
+	public function __call( $name, $args ) {
+		return $this->_call( $name, $args );
+	}
+
+	/**
+	 * Wrapper for __get(), similar to _call() above
+	 *
+	 * @param string $name Name of the property to get
+	 * @return mixed
+	 */
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _get( $name ) {
+		$this->_unstub( "__get($name)", 5 );
+		return $GLOBALS[$this->global]->$name;
+	}
+
+	/**
+	 * Function called by PHP if no property with that name exists in this
+	 * object.
+	 *
+	 * @param string $name Name of the property to get
+	 * @return mixed
+	 */
+	public function __get( $name ) {
+		return $this->_get( $name );
+	}
+
+	/**
+	 * Wrapper for __set(), similar to _call() above
+	 *
+	 * @param string $name Name of the property to set
+	 * @param mixed $value New property value
+	 */
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _set( $name, $value ) {
+		$this->_unstub( "__set($name)", 5 );
+		$GLOBALS[$this->global]->$name = $value;
+	}
+
+	/**
+	 * Function called by PHP if no property with that name exists in this
+	 * object.
+	 *
+	 * @param string $name Name of the property to set
+	 * @param mixed $value New property value
+	 */
+	public function __set( $name, $value ) {
+		$this->_set( $name, $value );
+	}
+
+	/**
+	 * This function creates a new object of the real class and replace it in
+	 * the global variable.
+	 * This is public, for the convenience of external callers wishing to access
+	 * properties, e.g. eval.php
+	 *
+	 * @param string $name Name of the method called in this object.
+	 * @param int $level Level to go in the stack trace to get the function
+	 *   who called this function.
+	 * @return object The unstubbed version of itself
+	 * @throws MWException
+	 */
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _unstub( $name = '_unstub', $level = 2 ) {
+		static $recursionLevel = 0;
+
+		if ( !$GLOBALS[$this->global] instanceof self ) {
+			return $GLOBALS[$this->global]; // already unstubbed.
+		}
+
+		if ( get_class( $GLOBALS[$this->global] ) != $this->class ) {
+			$caller = wfGetCaller( $level );
+			if ( ++$recursionLevel > 2 ) {
+				throw new MWException( "Unstub loop detected on call of "
+					. "\${$this->global}->$name from $caller\n" );
+			}
+			wfDebug( "Unstubbing \${$this->global} on call of "
+				. "\${$this->global}::$name from $caller" );
+			$GLOBALS[$this->global] = $this->_newObject();
+			--$recursionLevel;
+			return $GLOBALS[$this->global];
+		}
+	}
+}
+
+class_alias( StubObject::class, 'StubObject' );
diff --git a/includes/StubObject/StubUserLang.php b/includes/StubObject/StubUserLang.php
new file mode 100644
index 000000000000..7db0dde0ec63
--- /dev/null
+++ b/includes/StubObject/StubUserLang.php
@@ -0,0 +1,44 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\StubObject;
+
+use Language;
+use RequestContext;
+
+/**
+ * Stub object for the user language. Assigned to the $wgLang global.
+ */
+class StubUserLang extends StubObject {
+
+	public function __construct() {
+		parent::__construct( 'wgLang' );
+	}
+
+	/**
+	 * @return Language
+	 */
+	// phpcs:ignore PSR2.Methods.MethodDeclaration.Underscore
+	public function _newObject() {
+		return RequestContext::getMain()->getLanguage();
+	}
+}
+
+class_alias( StubUserLang::class, 'StubUserLang' );