Introducing lazy structs.

* share/txr/stdlib/struct.tl (lnew): New macro.

* struct.c (struct_type): Turn id into a bitfield one bit
smaller than cnum. New Boolean bitfield lazy.
(struct_init): Register make-lazy-struct intrinsic.
(make_struct): Initialize lazy bitfield to zero.
(lazy_struct_init, check_init_lazy_struct): New static
functions.
(make_lazy_struct): New function.
(copy_struct, clear_struct, replace_struct, reset_struct,
lookup_slot, struct_inst_equal, struct_inst_hash):
Call check_init_lazy_struct on all structures involved.
(lookup_slot): Call check_init_lazy_struct.
(struct_inst_mark): If the struct is lazy, it has one
instance slot which must be marked, holding the argfun
function passed into make_lazy_struct.

* struct.h (make_lazy_struct): Declared.

* txr.1: Documented lnew and make-lazy-struct.

1 files changed, 1 insertions, 0 deletions

diff --git a/struct.h b/struct.h
index d5545bf4..3d5b1942 100644
--- a/struct.h
+++ b/struct.h
@@ -31,6 +31,7 @@ val make_struct_type(val name, val super,
 val struct_type_p(val obj);
 val super(val type);
 val make_struct(val type, val plist, struct args *);
+val make_lazy_struct(val type, val argfun);
 val copy_struct(val strct);
 val clear_struct(val strct, val value);
 val replace_struct(val target, val source);