CIL to Ctypes interface

[avsm]

Just keeping this issue to remind myself that I started working on a simple CIL -> Ctypes transformer that got this far in 10 minutes:

$ opam install cil
$ gcc -E /usr/include/ncurses.h > tmp.h
# utop
# require "cil";;
let f = Frontc.parse "tmp.h" () in
let print_typ typ = Pretty.sprint ~width:50 (Cil.d_type () typ) in
Cil.(iterGlobals f (function |GVarDecl(
    {vname; vtype=TFun(rty,Some attr,_,_)},_) -> 
        Printf.printf "%s (%s) -> %s\n" vname 
            (String.concat ", " (List.map (fun (_,ty,_) ->
                print_typ ty) attr)) (print_typ rty) |_ -> () ));;

which outputs from the C header file:

use_screen (SCREEN *, int (*)(SCREEN * , void * ), void *) -> int 
use_window (WINDOW *, int (*)(WINDOW * , void * ), void *) -> int 
wresize (WINDOW *, int , int ) -> int 
nofilter () -> void 
wgetparent (WINDOW const   *) -> WINDOW *
is_cleared (WINDOW const   *) -> _Bool 
is_idcok (WINDOW const   *) -> _Bool 
is_idlok (WINDOW const   *) -> _Bool 
is_immedok (WINDOW const   *) -> _Bool 

A bit more work and that could turn into a Ctypes call, and we could have a camlp4 extension that lets you write "#include <ncurses.h>" and automatically import in type-safe OCaml calls. A ppx equivalent should also be straightforward with an extension_point.

[aziem]

I'd just like to make a note here regarding using CIL for this purpose: I have found that using CIL to parse a pre-processed header file on OSX fails due to the OSX standard library containing functions using block pointers.

I have been trying to auto-generate the Ctypes binding code for enums but ran into the above issue. As far as I know (at least the version of CIL I have installed) can't parse function prototypes which use block pointers.

I could generate a header file which has been preprocessed using:

gcc -E -nostdinc <headerfile>

this then does not include the function prototypes using block pointers but the resulting file will not contain types (e.g. bool or size_t) from the standard library and CIL will again complain that it can't parse the processed file: I can't see an option to get CIL to ignore this and just give me the parse tree.

I have hacked around this by adding typedefs containing bool, size_t, unint64_t to the processed header file by hand, which CIL can then parse, but this is a not a nice way of solving the problem.

[yallop]

It may be that using clang (via clang-ocaml?) is a better option than CIL.

[yallop]

There's a start on a CIL-based bindings generator here.