pre-order traversal

traversal
in-order traversal
post-order traversal
pre-order traversal
traverse

   <data> Processing {nodes} in a {graph} one at a time, usually
   in some specified order.  Traversal of a tree is {recursive}ly
   defined to mean visiting the {root node} and traversing its
   children.  Visiting a node usually involves transforming it in
   some way or collecting data from it.

   In "pre-order traversal", a node is visited __before__ its
   children.  In "post-order" traversal, a node is visited
   __after__ its children.  The more rarely used "in-order"
   traversal is generally applicable only to binary trees, and is
   where you visit first a node's left child, then the node
   itself, and then its right child.

   For the binary tree:

        T
       / \
      I   S
     / \
    D   E

   A pre-order traversal visits the nodes in the order T I D E S.
   A post-order traversal visits them in the order D E I S T.  An
   in-order traversal visits them in the order D I E T S.

   (2001-10-01)