(*
copyright (c) 2013, simon cruanes
all rights reserved.

redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

redistributions of source code must retain the above copyright notice, this
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form must reproduce the above copyright notice, this list of conditions and the
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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*)

(** {2 Imperative Bitvectors} *)

type t

val empty : unit -> t
  (** Empty bitvector *)

val create : size:int -> bool -> t
  (** Create a bitvector of given size, with given default value *)

val copy : t -> t
  (** Copy of bitvector *)

val cardinal : t -> int
  (** Number of bits set *)

val length : t -> int
  (** Length of underlying array *)

val resize : t -> int -> unit
  (** Resize the BV so that it has at least the given physical length *)

val is_empty : t -> bool
  (** Any bit set? *)

val set : t -> int -> unit
  (** Set i-th bit. *)

val get : t -> int -> bool
  (** Is the i-th bit true? Returns false if the index is too high*)

val reset : t -> int -> unit
  (** Set i-th bit to 0 *)

val flip : t -> int -> unit
  (** Flip i-th bit *)

val clear : t -> unit
  (** Set every bit to 0 *)

val iter : t -> (int -> bool -> unit) -> unit
  (** Iterate on all bits *)

val iter_true : t -> (int -> unit) -> unit
  (** Iterate on bits set to 1 *)

val to_list : t -> int list
  (** List of indexes that are true *)

val of_list : int list -> t
  (** From a list of true bits *)

val first : t -> int
  (** First set bit, or
      @raise Not_found if all bits are 0 *)

val filter : t -> (int -> bool) -> unit
  (** [filter bv p] only keeps the true bits of [bv] whose [index]
      satisfies [p index] *)

val union_into : into:t -> t -> unit
  (** [union ~into bv] sets [into] to the union of itself and [bv]. *)

val inter_into : into:t -> t -> unit
  (** [union ~into bv] sets [into] to the intersection of itself and [bv] *)

val union : t -> t -> t
  (** [union bv1 bv2] returns the union of the two sets *)

val inter : t -> t -> t
  (** Intersection of bitvectors *)

val select : t -> 'a array -> 'a list
  (** [select arr bv] selects the elements of [arr] whose index
      correspond to a true bit in [bv]. If [bv] is too short, elements of [arr]
      with too high an index cannot be selected and are therefore not
      selected. *)

val selecti : t -> 'a array -> ('a * int) list
  (** Same as {!select}, but selected elements are paired with their index *)