add Vec_unit to util

src/util/Sidekick_util.ml

@@ -6,7 +6,9 @@ module Util = Util
 module Vec = Vec
 module VecI32 = VecI32
 module Vec_float = Vec_float
+module Vec_unit = Vec_unit
 module Vec_sig = Vec_sig
+
 module Bitvec = Bitvec
 module Int_id = Int_id
 

src/util/Vec_unit.ml

@@ -0,0 +1,28 @@
+
+type elt = unit
+
+(* no need to store anything so we don't even provide an actual vector
+   since unit is a "zero sized type" as rustaceans would say. *)
+type t = {
+  mutable size: int;
+}
+
+let create ?cap:_ () : t = { size=0 }
+let clear self = self.size <- 0
+let copy {size} = {size}
+let get (_self:t) _ = ()
+let size self = self.size
+let iter ~f:_ (_self:t) = ()
+let iteri ~f:_ (_self:t) = ()
+let is_empty self = self.size = 0
+let push (self:t) _ = self.size <- 1 + self.size
+let fast_remove (self:t) _ = self.size <- self.size - 1
+let ensure_size (self:t) i = self.size <- max self.size i
+let set _ _ _ = ()
+let pop self = self.size <- self.size - 1; ()
+let filter_in_place _ _ = ()
+let shrink (self:t) i = self.size <- i
+let to_iter self k = for _i=0 to self.size - 1 do k () done
+let to_array self = Iter.to_array (to_iter self)
+let fold_left f acc self = Iter.fold f acc (to_iter self)
+let pp ppx out self = Iter.pp_seq ppx out (to_iter self)

src/util/Vec_unit.mli

@@ -0,0 +1,2 @@
+
+include Vec_sig.S with type elt= unit