Find location of node in tree using Clojure zippers

Question

I have a tree of an unknown structure. First, I want to find a node containing a string of text, "Something". Then, after identifying the string's location in the tree, I want to update a different node relative to the string's location. The data is a deeply nested map with several branches of lists.

Is that possible with zippers?

I've studied this approach to editing trees: http://www.exampler.com/blog/2010/09/01/editing-trees-in-clojure-with-clojurezip/. Problem is, I don't beforehand know the location of the string.

Liles

Answer 1

Yes! This is exactly the kind of task zippers where designed for.

• Repeatedly call zip/next until you find the node you are looking for.
• Then call zip/path to find out where you are relative to the root.
• Then call zip/up, zip/down, zip/left etc to get to the node to modify.
• update the node
• call zip/root to get your new map containing these changes.

Chatty

Excellent! That's all I needed. – Liles