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<?php
/**
* A tool for running hook functions.
*
* Copyright 2004, 2005 Evan Prodromou <evan@wikitravel.org>.
*
* 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
*
* @author Evan Prodromou <evan@wikitravel.org>
* @see hooks.txt
* @file
*/
/**
* @since 1.18
*/
class MWHookException extends MWException {}
/**
* Hooks class.
*
* Used to supersede $wgHooks, because globals are EVIL.
*
* @since 1.18
*/
class Hooks {
protected static $handlers = array();
/**
* Clears hooks registered via Hooks::register(). Does not touch $wgHooks.
* This is intended for use while testing and will fail if MW_PHPUNIT_TEST is not defined.
*
* @since 1.21
*
* @param string $name the name of the hook to clear.
*
* @throws MWException if not in testing mode.
*/
public static function clear( $name ) {
if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
throw new MWException( 'can not reset hooks in operation.' );
}
unset( self::$handlers[$name] );
}
/**
* Attach an event handler to a given hook
*
* @since 1.18
*
* @param string $name name of hook
* @param $callback Mixed: callback function to attach
*/
public static function register( $name, $callback ) {
if( !isset( self::$handlers[$name] ) ) {
self::$handlers[$name] = array();
}
self::$handlers[$name][] = $callback;
}
/**
* Returns true if a hook has a function registered to it.
* The function may have been registered either via Hooks::register or in $wgHooks.
*
* @since 1.18
*
* @param string $name name of hook
* @return Boolean: true if the hook has a function registered to it
*/
public static function isRegistered( $name ) {
global $wgHooks;
return !empty( $wgHooks[$name] ) || !empty( self::$handlers[$name] );
}
/**
* Returns an array of all the event functions attached to a hook
* This combines functions registered via Hooks::register and with $wgHooks.
* @since 1.18
*
* @throws MWException
* @throws FatalError
* @param string $name name of the hook
*
* @return array
*/
public static function getHandlers( $name ) {
global $wgHooks;
// Return quickly in the most common case
if ( empty( self::$handlers[$name] ) && empty( $wgHooks[$name] ) ) {
return array();
}
if ( !is_array( self::$handlers ) ) {
throw new MWException( "Local hooks array is not an array!\n" );
}
if ( !is_array( $wgHooks ) ) {
throw new MWException( "Global hooks array is not an array!\n" );
}
if ( empty( Hooks::$handlers[$name] ) ) {
$hooks = $wgHooks[$name];
} elseif ( empty( $wgHooks[$name] ) ) {
$hooks = Hooks::$handlers[$name];
} else {
// so they are both not empty...
$hooks = array_merge( Hooks::$handlers[$name], $wgHooks[$name] );
}
if ( !is_array( $hooks ) ) {
throw new MWException( "Hooks array for event '$name' is not an array!\n" );
}
return $hooks;
}
/**
* Call hook functions defined in Hooks::register
*
* @param string $event event name
* @param $args Array: parameters passed to hook functions
*
* @throws MWException
* @throws FatalError
* @return Boolean True if no handler aborted the hook
*/
public static function run( $event, $args = array() ) {
global $wgHooks;
// Return quickly in the most common case
if ( empty( self::$handlers[$event] ) && empty( $wgHooks[$event] ) ) {
return true;
}
wfProfileIn( 'hook: ' . $event );
$hooks = self::getHandlers( $event );
foreach ( $hooks as $hook ) {
$object = null;
$method = null;
$func = null;
$data = null;
$have_data = false;
$closure = false;
$badhookmsg = false;
/**
* $hook can be: a function, an object, an array of $function and
* $data, an array of just a function, an array of object and
* method, or an array of object, method, and data.
*/
if ( is_array( $hook ) ) {
if ( count( $hook ) < 1 ) {
throw new MWException( 'Empty array in hooks for ' . $event . "\n" );
} elseif ( is_object( $hook[0] ) ) {
$object = $hook[0];
if ( $object instanceof Closure ) {
$closure = true;
if ( count( $hook ) > 1 ) {
$data = $hook[1];
$have_data = true;
}
} else {
if ( count( $hook ) < 2 ) {
$method = 'on' . $event;
} else {
$method = $hook[1];
if ( count( $hook ) > 2 ) {
$data = $hook[2];
$have_data = true;
}
}
}
} elseif ( is_string( $hook[0] ) ) {
$func = $hook[0];
if ( count( $hook ) > 1) {
$data = $hook[1];
$have_data = true;
}
} else {
throw new MWException( 'Unknown datatype in hooks for ' . $event . "\n" );
}
} elseif ( is_string( $hook ) ) { # functions look like strings, too
$func = $hook;
} elseif ( is_object( $hook ) ) {
$object = $hook;
if ( $object instanceof Closure ) {
$closure = true;
} else {
$method = "on" . $event;
}
} else {
throw new MWException( 'Unknown datatype in hooks for ' . $event . "\n" );
}
/* We put the first data element on, if needed. */
if ( $have_data ) {
$hook_args = array_merge( array( $data ), $args );
} else {
$hook_args = $args;
}
if ( $closure ) {
$callback = $object;
$func = "hook-$event-closure";
} elseif ( isset( $object ) ) {
$func = get_class( $object ) . '::' . $method;
$callback = array( $object, $method );
} else {
$callback = $func;
}
// Run autoloader (workaround for call_user_func_array bug)
is_callable( $callback );
/**
* Call the hook. The documentation of call_user_func_array clearly
* states that FALSE is returned on failure. However this is not
* case always. In some version of PHP if the function signature
* does not match the call signature, PHP will issue an warning:
* Param y in x expected to be a reference, value given.
*
* In that case the call will also return null. The following code
* catches that warning and provides better error message. The
* function documentation also says that:
* In other words, it does not depend on the function signature
* whether the parameter is passed by a value or by a reference.
* There is also PHP bug http://bugs.php.net/bug.php?id=47554 which
* is unsurprisingly marked as bogus. In short handling of failures
* with call_user_func_array is a failure, the documentation for that
* function is wrong and misleading and PHP developers don't see any
* problem here.
*/
$retval = null;
set_error_handler( 'Hooks::hookErrorHandler' );
wfProfileIn( $func );
try {
$retval = call_user_func_array( $callback, $hook_args );
} catch ( MWHookException $e ) {
$badhookmsg = $e->getMessage();
}
wfProfileOut( $func );
restore_error_handler();
/* String return is an error; false return means stop processing. */
if ( is_string( $retval ) ) {
throw new FatalError( $retval );
} elseif( $retval === null ) {
if ( $closure ) {
$prettyFunc = "$event closure";
} elseif( is_array( $callback ) ) {
if( is_object( $callback[0] ) ) {
$prettyClass = get_class( $callback[0] );
} else {
$prettyClass = strval( $callback[0] );
}
$prettyFunc = $prettyClass . '::' . strval( $callback[1] );
} else {
$prettyFunc = strval( $callback );
}
if ( $badhookmsg ) {
throw new MWException(
'Detected bug in an extension! ' .
"Hook $prettyFunc has invalid call signature; " . $badhookmsg
);
} else {
throw new MWException(
'Detected bug in an extension! ' .
"Hook $prettyFunc failed to return a value; " .
'should return true to continue hook processing or false to abort.'
);
}
} elseif ( !$retval ) {
wfProfileOut( 'hook: ' . $event );
return false;
}
}
wfProfileOut( 'hook: ' . $event );
return true;
}
/**
* This REALLY should be protected... but it's public for compatibility
*
* @since 1.18
*
* @param int $errno Unused
* @param string $errstr error message
* @throws MWHookException
* @return Boolean: false
*/
public static function hookErrorHandler( $errno, $errstr ) {
if ( strpos( $errstr, 'expected to be a reference, value given' ) !== false ) {
throw new MWHookException( $errstr );
}
return false;
}
}