alternative to lua_call

["Juris Kalnins" <juris@...>]

I wonder if there is an easy way to implement the following
without doing excessive stack moves.

There are many cases where calling Lua functions from C involves a lot
of stack shuffling. For example, when using C API to iterate over
sequence using Lua iterator protocol, or when lua_CFunction is forwarding
call to another Lua function. It would help to have a more generic way to  
call
Lua function from C. Something like:

lua_calli(L, int fi, int argi, int reti, int nret)
fi - index of function
argi - index of first functoin argument
reti - index where first return value should be located
nret - if not LUA_MULTRET, number of returned values

so lua_call(L, a, b) would be the same as lua_calli(L, -a-1, -a, -a-1, b),
and lua_calli(L, idx, idx + 1, idx + 2, 2) where idx is the index
of iterator function, would update stack with values from the next  
iteration.

It is easy to implement this by duplicating function + arguments on a  
stack.
But I don't know how to do any better, since stack position of called  
function
value is tightly coupled with the call frame in Lua internals.
Any ideas.