ocaml-containers/multiMap.ml

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

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*)

(** {6 Multimap} *)

module type S = sig
  type key
  type value
  type t

  val empty : t
    (** Empty multimap *)

  val is_empty : t -> bool
    (** Empty multimap? *)

  val add : t -> key -> value -> t
    (** Add a key/value binding *)

  val remove : t -> key -> value -> t
    (** Remove the binding *)

  val remove_all : t -> key -> t
    (** Remove the key from the map *)

  val mem : t -> key -> bool
    (** Is there a binding for this key? *)

  val find : t -> key -> value list
    (** List of values for this key *)

  val find_iter : t -> key -> (value -> unit) -> unit
    (** Iterate on bindings for this key *)

  val count : t -> key -> int
    (** Number of bindings for this key *)

  val iter : t -> (key -> value -> unit) -> unit
    (** Iterate on all key/value *)

  val fold : t -> 'a -> ('a -> key -> value -> 'a) -> 'a
    (** Fold on all key/value *)

  val size : t -> int
    (** Number of keys *)

  val union : t -> t -> t
    (** Union of multimaps *)

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

  val diff : t -> t -> t
    (** Difference of maps, ie bindings of the first that are not
        in the second *)

  val equal : t -> t -> bool
    (** Same multimap *)

  val compare : t -> t -> int
    (** Total order on multimaps *)

  val submap : t -> t -> bool
    (** [submap m1 m2] is true iff all bindings of [m1] are also in [m2] *)

  val to_seq : t -> (key * value) Sequence.t

  val of_seq : ?init:t -> (key * value) Sequence.t -> t

  val keys : t -> key Sequence.t

  val values : t -> value Sequence.t
    (** Some values may occur several times *)
end

module type OrderedType = sig
  type t
  val compare : t -> t -> int
end

module Make(K : OrderedType)(V : OrderedType) = struct
  type key = K.t
  type value = V.t

  module M = Map.Make(K)
  module S = Set.Make(V)

  type t = S.t M.t
    (** Map of sets *)

  let empty = M.empty

  let is_empty = M.is_empty

  let add m k v =
    let set = try M.find k m with Not_found -> S.empty in
    M.add k (S.add v set) m

  let remove m k v =
    try
      let set = M.find k m in
      let set' = S.remove v set in
      if S.is_empty set'
        then M.remove k m
        else M.add k set' m
    with Not_found ->
      m

  let remove_all m k =
    M.remove k m

  let mem m k = M.mem k m

  let find m k =
    try
      let set = M.find k m in
      S.elements set
    with Not_found ->
      []

  let find_iter m k f =
    try
      let set = M.find k m in
      S.iter f set
    with Not_found ->
      ()

  let count m k =
    try
      let set = M.find k m in
      S.cardinal set
    with Not_found ->
      0

  let iter m f =
    M.iter (fun k set -> S.iter (fun v -> f k v) set) m

  let fold m acc f =
    M.fold (fun k set acc -> S.fold (fun v acc -> f acc k v) set acc) m acc

  let size m = M.cardinal m

  let union m1 m2 =
    M.merge
      (fun k v1 v2 -> match v1, v2 with
        | None, None -> None
        | Some set1, Some set2 -> Some (S.union set1 set2)
        | Some set, None
        | None, Some set -> Some set)
      m1 m2

  let inter m1 m2 =
    M.merge
      (fun k v1 v2 -> match v1, v2 with
        | None, _
        | _, None -> None
        | Some set1, Some set2 ->
          let set = S.inter set1 set2 in
          if S.is_empty set
            then None
            else Some set)
      m1 m2

  let diff m1 m2 =
    M.merge
      (fun k v1 v2 -> match v1, v2 with
        | None, _ -> None
        | Some set, None -> Some set
        | Some set1, Some set2 ->
          let set' = S.diff set1 set2 in
          if S.is_empty set'
            then None
            else Some set')
      m1 m2

  let equal m1 m2 =
    M.equal S.equal m1 m2

  let compare m1 m2 =
    M.compare S.compare m1 m2

  let submap m1 m2 =
    M.for_all
      (fun k set1 ->
        try
          let set2 = M.find k m2 in
          S.subset set1 set2
        with Not_found ->
          false)
      m1

  let to_seq m =
    Sequence.from_iter (fun k -> iter m (fun x y -> k (x,y)))

  let of_seq ?(init=empty) seq =
    Sequence.fold (fun m (k,v) -> add m k v) init seq

  let keys m =
    Sequence.from_iter (fun k -> M.iter (fun x _ -> k x) m)

  let values m =
    Sequence.from_iter (fun k -> iter m (fun _ v -> k v))
end