According to CaGEL* (e.g. p.636 ff), prepositions can take predicative complements, as in
 She worked as a waitress
 He passed for dead
 I took you for granted
 They left him for dead
 I love you as a friend
Now, I get how these are predicatives, but I'm uncertain as to how to analyse the PPs as wholes. I'm thinking they are complements in - and adjunct in  – is this correct? And, if so, what kinds of complement are we dealing with in -?
*Huddleston, R., and Pullum, G. K., 2002. The Cambridge Grammar of the English Language. Cambridge: Cambridge University Press.