Consider how to extend the URI according to the scheme-specific/protocol-specific parts of the comparison ladder

[glynos]

1. string comparison
2. case normalization
3. percent encoding
4. path segment normalization
5. *scheme-specific
6. *protocol specific

This can be done rather cleanly by passing functions to the transformer functions instead of enum values, and by using the decorator pattern. I'll experiment without and see how it works out...