How to make an eclipse plugin listen to a newly compiled project?

Whenever you hit CRTL+S on eclipse it automatically compiles the project. I was wondering if you guys have any idea on how I can make a plugin listen to any compilation change. How exactly the compiler or the IDE could trigger the parsing of an 开发者_开发百科AST tree for new compilation unit? Any idea is greatly appreciated.

the building process in Eclipse is handled by Builders.

In this article there are some notes explaining how ti interact with background auto-build