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.

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the building process in Eclipse is handled by Builders.

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