Zsh completion inside quotes

Zsh completion inside quotes

Here is my completion function:
f()
{
reply=('ok')
}
compctl -K f c
Then I do
c
tab
c ok
Something works. Then I do tab after b
c ok "a b"
and nothing happens. I expect a b to be replaced with ok (as it does in
bash).
How could I achieve it?
I really need to do completions inside quotes. Typical launch of my
program looks like this: c 'a, &b, c[d]' 'a < 1 and b == "2013"'