For example, in the syntax tree often used by compilers, one sometimes uses a complete traversal, illustrated below for the simple search tree made up of days of the week. Here we start at the root and go all the way around the tree, visiting each node three times. The three kinds of traversals are included: preorder in blue, inorder in green, and postorder in orange.

Complete Tree Traversal (click picture or days.pdf).

CompleteTraversal(root); CompleteTraversal(node x) {      if (x != null) {           blue visit (preorder);           CompleteTraversal(x.left);           green visit (inorder);           CompleteTraversal(x.right);           orange visit (postorder);      } }

Monday Friday Friday Friday Monday Tuesday Thursday Saturday Saturday Sunday Sunday Sunday Saturday Thursday Thursday Tuesday Wednesday Wednesday Wednesday Tuesday Monday

Compilers use this kind of traversal during semantic analysis, where information can be passed down the tree (inherited) and passed up the tree (synthesized). It is also possible to leave important information at a node during the first or second visit, and pick it up or use it during a later visit.