Collecting completion candidates from multiple files

[Daniele Nicolodi]

Hello,

is there a standard facility and/or user interface to collect completion 
candidates from multiple files composing a project?

I'm developing a mode for a language that has an "include" facility and 
I would like to support collecting completion candidates from the 
definitions contained in all the files that compose a project, 
independently of whether the current buffer has an explicit "include" 
directive or not.

Thank you.

Cheers,
Dan