In computing, an unparser is a system that constructs a set of characters or image components from a given parse tree.
[1][2] An unparser is in effect the reverse of a traditional parser that takes a set of string of characters and produces a parse tree.
Unparsing generally involves the application of a specific set of rules to the parse tree as a "tree walk" takes place.
[1] Given that the tree may involve both textual and graphic elements, the unparser may have two separate modules, each of which handles the relevant components.
[2] In such cases the "master unparser" looks up the "master unparse table" to determine if a given nested structure should be handled by one module, or the other.