Source

File: wp-includes/class-wp-hook.php

public function do_all_hook( &$args ) {
		$nesting_level                      = $this->nesting_level++;
		$this->iterations[ $nesting_level ] = array_keys( $this->callbacks );

		do {
			$priority = current( $this->iterations[ $nesting_level ] );
			foreach ( $this->callbacks[ $priority ] as $the_ ) {
				call_user_func_array( $the_['function'], $args );
			}
		} while ( false !== next( $this->iterations[ $nesting_level ] ) );

		unset( $this->iterations[ $nesting_level ] );
		$this->nesting_level--;
	}