I've written a minor mode to work with semantic-ia-fast-jump, let's say `xxx-mode'.
As a result, I want `xxx-mode' to be automatically turned on every time I entered
into a semantic enabled buffer.

I've noticed that lots of semantic's minor modes are turned on in this way, such as
semantic-highlight-mode. But now the internal code is too hard for me to find the
right function/hook. Can someone tell me how to do this?