ffi: provide support for unions.

* ffi.c (union_s): New symbol variable.
(ffi_find_memb, ffi_memb_not_found): New static functions.
(ffi_union_in, ffi_union_put, ffi_union_get): New static
functions.
(make_ffi_type_union): New static function.
(ffi_struct_compile): Handle union syntax using
ffi_struct_compile to compile the member definitions to types,
and make_ffi_type_union to produce the type node.
(struct uni): New struct type.
(uni_struct, uni_struct_checked): New static functions.
(union_destroy_op, union_mark_op): New static functions.
(union_ops): New static struct.
(make_union_common, make_union_tft): New static functions.
(union_get_ptr, make_union, union_members, union_get,
union_put, union_in, union_out): New functions.
(ffi_init): Initialize union_s. Register intrinsics
make-union, union-members, union-get, union-put, union-in,
union-out.

* ffi.h (union_s, union_get_ptr, make_union, union_members,
union_get, union_put, union_in, union_out): Declared.

* txr.1: Documented unions.

1 files changed, 8 insertions, 1 deletions

diff --git a/ffi.h b/ffi.h
index ee09ebf5..34aca3c6 100644
--- a/ffi.h
+++ b/ffi.h
@@ -51,7 +51,7 @@ extern val le_float_s, le_double_s;
 
 extern val array_s, zarray_s, carray_s;
 
-extern val struct_s;
+extern val struct_s, union_s;
 
 extern val str_d_s, wstr_s, wstr_d_s, bstr_s, bstr_d_s;
 
@@ -121,4 +121,11 @@ val unum_carray(val carray);
 val num_carray(val carray);
 val put_carray(val carray, val offs, val stream);
 val fill_carray(val carray, val offs, val stream);
+mem_t *union_get_ptr(val uni);
+val make_union(val type);
+val union_members(val uni);
+val union_get(val uni, val memb);
+val union_put(val uni, val memb, val newval);
+val union_in(val uni, val memb, val memb_obj);
+val union_out(val uni, val memb, val memb_obj);
 void ffi_init(void);