Regex for replacing unterscored class names with namespaces

gistfile1.txt

# Moves Tx_Mynamespace_Subname_Classname classes to the Tx\Mynamespace\Subname namespace.
<\?php([\s\S]*class) Tx_Mynamespace_(.+?)_
<?php\nnamespace Tx\\\\Mynamespace\\\\$2;$1 

# Moves Tx_Mynamespace_Classname classes to the Tx\Mynamespace namespace.
<\?php([\s\S]*class) Tx_Mynamespace_(.+?)
<?php\nnamespace Tx\\\\Mynamespace;$1 $2