Module Bounded_int_table

A Bounded_int_table is a table whose keys can be mapped to integers in a fixed range, 0 ... num_keys - 1, where num_keys is specified at table-creation time. The purpose of Bounded_int_table is to be faster than Hashtbl in situations where one is willing to pay a space cost for the speed.

Bounded_int_table presents a subset of the Hashtbl interface. The key type can be any type, but table creation requires a key_to_int function, which will be used to extract the integer of all keys. If multiple keys map to the same integer, then only one of them can be in the table at a time. Any operation that supplies a key whose corresponding integer is outside the allowed range for the table will cause an exception.

A Bounded_int_table is implemented using two fixed-size arrays of size num_keys, which are supplied at table-creation time. The space used does not depend on the length of the table but rather only on num_keys. Operations that deal with a single element (find, mem, add, remove, set) take constant time, and perform one or two array operations. Operations that deal with all of the keys defined in the table (data, fold, iter, keys, to_alist) take time proportional to the length of the table, not num_keys.

type ('key, 'data) t
val sexp_of_t : ('key -> Ppx_sexp_conv_lib.Sexp.t) -> ('data -> Ppx_sexp_conv_lib.Sexp.t) -> ('key, 'data) t -> Ppx_sexp_conv_lib.Sexp.t
type ('a, 'b) table = ('a, 'b) t
include Core_kernel.Invariant.S2 with type ('a, 'b) t := ('a, 'b) t
val invariant : ('a -> unit) -> ('b -> unit) -> ('a, 'b) t -> unit

Equality only requires the keys and values to be the same, not the bin or sexp formatting or the integers the keys correspond to (see key_to_int).

include Core_kernel.Equal.S2 with type ('a, 'b) t := ('a, 'b) t
val create : ?⁠sexp_of_key:('key -> Core_kernel.Sexp.t) -> num_keys:int -> key_to_int:('key -> int) -> unit -> ('key, 'data) t

create ~num_keys ~key_to_int returns a table where the keys can map to 0 ... num_keys - 1, according to key_to_int. It is an error if num_keys < 0.

sexp_of_key, if supplied, will be used to display keys in error messages.

val num_keys : (_, _) t -> int
val is_empty : (_, _) t -> bool

Standard hashtbl functions

val keys : ('key, _) t -> 'key list
val data : (_, 'data) t -> 'data list
val find : ('key, 'data) t -> 'key -> 'data option
val find_exn : ('key, 'data) t -> 'key -> 'data
val find_or_add : ('key, 'data) t -> 'key -> default:(unit -> 'data) -> 'data
val fold : ('key, 'data) t -> init:'accum -> f:(key:'key -> data:'data -> 'accum -> 'accum) -> 'accum
val iter_keys : ('key, _) t -> f:('key -> unit) -> unit
val iter : (_, 'data) t -> f:('data -> unit) -> unit
val iteri : ('key, 'data) t -> f:(key:'key -> data:'data -> unit) -> unit
val filter_mapi : ('key, 'data1) t -> f:(key:'key -> data:'data1 -> 'data2 option) -> ('key, 'data2) t
val filter_map : ('key, 'data1) t -> f:('data1 -> 'data2 option) -> ('key, 'data2) t
val filter_keys : ('key, 'data1) t -> f:('key -> bool) -> ('key, 'data1) t
val filter : ('key, 'data1) t -> f:('data1 -> bool) -> ('key, 'data1) t
val filteri : ('key, 'data1) t -> f:(key:'key -> data:'data1 -> bool) -> ('key, 'data1) t
val mapi : ('key, 'data1) t -> f:(key:'key -> data:'data1 -> 'data2) -> ('key, 'data2) t
val map : ('key, 'data1) t -> f:('data1 -> 'data2) -> ('key, 'data2) t
val for_alli : ('key, 'data) t -> f:(key:'key -> data:'data -> bool) -> bool
val existsi : ('key, 'data) t -> f:(key:'key -> data:'data -> bool) -> bool
val for_all : (_, 'data) t -> f:('data -> bool) -> bool
val exists : (_, 'data) t -> f:('data -> bool) -> bool
val length : (_, _) t -> int
val mem : ('key, _) t -> 'key -> bool
val remove : ('key, _) t -> 'key -> unit
val set : ('a, 'b) t -> key:'a -> data:'b -> unit
val add : ('a, 'b) t -> key:'a -> data:'b -> [ `Ok | `Duplicate of 'b ]
val add_exn : ('a, 'b) t -> key:'a -> data:'b -> unit
val to_alist : ('key, 'data) t -> ('key * 'data) list
val clear : (_, _) t -> unit
module With_key : functor (Key : sig ... end) -> sig ... end
val debug : bool Core_kernel.ref

set debug := true to turn on debugging, including potentially slow invariant checking.