Zebra_MPTT is a PHP class that provides an implementation of the modified preorder tree traversal algorithm. It provides methods for adding nodes anywhere in the tree, deleting nodes, moving and copying nodes around the tree, and for retrieving information about the nodes. It uses table locks to ensure that database integrity is always preserved and that concurrent MySQL sessions don’t compromise data integrity. A caching mechanism ensures that regardless of the type or the number of retrieval operations, the database is read only once per script execution.
