This is a vim omnicompletion which captures completions from zsh's completion engine. This is an application of this zsh completion capturing method.
The script works reasonably well for most cases I tested. There is a corner case where descriptions aren't displayed for some prefix types which may or may not be fixed later on.
While it does work reasonably well, this entire script is a HUGE HACK. Don't expect more than proof of concept code quality. Also note the completion capturing script requires (at the time of this writing) a nightly version of zsh which includes the patch from here:
http://www.zsh.org/mla/workers/2013/msg00728.html https://github.com/zsh-users/zsh/commit/b0a0441902f848da4284e107c29e43e222252959
Install using vundle:
Bundle 'Valodim/vim-zsh-completion'
BundleInstall
Use as omnicompletion ftplugin for zsh files as usual (^X^O). Or bind to user completion (^X^U) with:
:set completefunc=zsh_completion#Complete