Module BatMap

module BatMap: sig .. end

Association tables over ordered types.

This module implements applicative association tables, also known as finite maps or dictionaries, given a total ordering function over the keys. All operations over maps are purely applicative (no side-effects). The implementation uses balanced binary trees, and therefore searching and insertion take time logarithmic in the size of the map.

Note OCaml, Batteries Included, provides two implementations of maps: polymorphic maps and functorized maps. Functorized maps (see BatMap.S and BatMap.Make) are slightly more complex to use but offer stronger type-safety. Polymorphic maps make it easier to shoot yourself in the foot. In case of doubt, you should use functorized maps.

Functorized maps

The important part is the BatMap.Make module which builds association maps from a user-provided datatype and comparison function. In the BatMap.Make module (or its output signature BatMap.S) are documentated all functions available on maps.

Here is a typical example of use:

      module MyKeyType = struct
        type t = my_type
        let compare = my_compare_function
      end
      module MyMap = Map.Make(MyKeyType)

      let some_map = MyMap.add something MyMap.empty
            ...

To define maps with integer/string keys:

      module IntMap = Map.Make(Int)
      module StringMap = Map.Make(String)

Author(s): Xavier Leroy (Base library), Nicolas Cannasse, Markus Mottl, David Rajchenbach-Teller, Gabriel Scherer

module type S = sig .. end

module Make: functor (Ord : BatInterfaces.OrderedType) -> S  with type key = Ord.t

Functor building an implementation of the map structure given a totally ordered type.

Common instantiations

module Int: S  with type key = int

module Int32: S  with type key = int32

module Int64: S  with type key = int64

module Nativeint: S  with type key = nativeint

module Float: S  with type key = float

module Char: S  with type key = char

module String: S  with type key = string

Polymorphic maps

The functions below present the manipulation of polymorphic maps, as were provided by the Extlib PMap module.

They are similar in functionality to the functorized BatMap.Make module, but only uses the Pervasives.compare function to compare elements. If you need to compare using a custom comparison function, it is recommended to use the functorized maps provided by BatMap.Make.

type ('a, 'b) t

val empty : ('a, 'b) t

The empty map, using compare as key comparison function.

val is_empty : ('a, 'b) t -> bool

Returns true if the map is empty.

val singleton : 'a -> 'b -> ('a, 'b) t

Creates a new map with a single binding.

val cardinal : ('a, 'b) t -> int

Return the number of bindings of a map.

val add : 'a -> 'b -> ('a, 'b) t -> ('a, 'b) t

add x y m returns a map containing the same bindings as m, plus a binding of x to y. If x was already bound in m, its previous binding disappears. If x was already bound to some z that is physically equal to y, then the returned map is physically equal to m.

Before 3.3.0 physical equality was not ensured.

val update : 'a -> 'a -> 'b -> ('a, 'b) t -> ('a, 'b) t

update k1 k2 v2 m replace the previous binding of k1 in m by k2 associated to v2. This is equivalent to add k2 v2 (remove k1) m, but more efficient in the case where k1 and k2 have the same key ordering. If k1 and k2 have the same key ordering and v2 is physically equal to the value k1 is bound to in m then the returned map will be physically equal to m

Before 3.3.0 physical equality was not ensured.
Since 2.4.0
Raises Not_found if k1 is not bound in m.

val update_stdlib : 'a -> ('b option -> 'b option) -> ('a, 'b) t -> ('a, 'b) t

update_stdlib k f m returns a map containing the same bindings as m, except k has a new binding as determined by f: First, calculate y as f (find_opt k m). If y = Some v then k will be bound to v in the resulting map. Else k will not be bound in the resulting map.

If v is physically equal to the value of the previous binding of k in m, then the returned map will be physically equal to m.

This function does the same thing as update in the stdlib, but has a different name for backwards compatibility reasons.

Since 3.3.0

val find : 'a -> ('a, 'b) t -> 'b

find x m returns the current binding of x in m, or raises Not_found if no such binding exists.

val find_opt : 'a -> ('a, 'b) t -> 'b option

find_opt x m returns Some b where b is the current binding * of x in m, or None if no such binding exists.

val find_default : 'b -> 'a -> ('a, 'b) t -> 'b

find_default d x m returns the current binding of x in m, or the default value d if no such binding exists.

val find_first : ('a -> bool) -> ('a, 'b) t -> 'a * 'b

find_first f m returns the first binding (k, v) for which f k is true or raises Not_found if there is no such binding. f must be monotonically increasing, i.e. if k1 < k2 && f k1 is true then f k2 must also be true.

Since 3.3.0

val find_first_opt : ('a -> bool) -> ('a, 'b) t -> ('a * 'b) option

find_first_opt f m returns Some (k, v) for the first binding (k, v) for which f k is true or returns None if there is no such binding. f must be monotonically increasing, i.e. if k1 < k2 && f k1 is true then f k2 must also be true.

Since 3.3.0

val find_last : ('a -> bool) -> ('a, 'b) t -> 'a * 'b

find_last f m returns the last binding (k, v) for which f k is true or raises Not_found if there is no such binding. f must be monotonically decreasing, i.e. if k1 < k2 && f k2 is true then f k1 must also be true.

Since 3.3.0

val find_last_opt : ('a -> bool) -> ('a, 'b) t -> ('a * 'b) option

find_last_opt f m returns Some (k, v) for the last binding (k, v) for which f k is true or returns None if there is no such binding. f must be monotonically decreasing, i.e. if k1 < k2 && f k2 is true then f k1 must also be true.

Since 3.3.0

val remove : 'a -> ('a, 'b) t -> ('a, 'b) t

remove x m returns a map containing the same bindings as m, except for x which is unbound in the returned map. The returned map is physically equal to the passed one if x was already unbound.

Before 3.3.0 physical equality was not ensured

val remove_exn : 'a -> ('a, 'b) t -> ('a, 'b) t

remove_exn x m behaves like remove x m except that it raises an exception if x is unbound in m.

Since 3.2.0
Raises Not_found if x is unbound in m

val mem : 'a -> ('a, 'b) t -> bool

mem x m returns true if m contains a binding for x, and false otherwise.

val iter : ('a -> 'b -> unit) -> ('a, 'b) t -> unit

iter f m applies f to all bindings in map m. f receives the key as first argument, and the associated value as second argument. The order in which the bindings are passed to f is unspecified. Only current bindings are presented to f: bindings hidden by more recent bindings are not passed to f.

val map : ('b -> 'c) -> ('a, 'b) t -> ('a, 'c) t

map f m returns a map with same domain as m, where the associated value a of all bindings of m has been replaced by the result of the application of f to a. The order in which the associated values are passed to f is unspecified.

val mapi : ('a -> 'b -> 'c) -> ('a, 'b) t -> ('a, 'c) t

Same as map, but the function receives as arguments both the key and the associated value for each binding of the map.

val fold : ('b -> 'c -> 'c) -> ('a, 'b) t -> 'c -> 'c

fold f m a computes (f kN dN ... (f k1 d1 (f k0 d0 a))...), where k0,k1..kN are the keys of all bindings in m, and d0,d1..dN are the associated data. The order in which the bindings are presented to f is unspecified.

val foldi : ('a -> 'b -> 'c -> 'c) -> ('a, 'b) t -> 'c -> 'c

Same as fold, but the function receives as arguments both the key and the associated value for each binding of the map.

val at_rank_exn : int -> ('key, 'a) t -> 'key * 'a

at_rank_exn i m returns the (key,value) pair whose key is at rank i in m, that is the i-th element in increasing order of the keys (the 0-th element being the smallest key in m with its associated value).

Since 2.4
Raises
- Not_found if m = empty.
- Invalid_argument error_message if i < 0 || i >= cardinal m

val filterv : ('a -> bool) -> ('key, 'a) t -> ('key, 'a) t

filterv f m returns a map where only the values a of m such that f a = true remain. The bindings are passed to f in increasing order with respect to the ordering over the type of the keys.

val filter : ('key -> 'a -> bool) -> ('key, 'a) t -> ('key, 'a) t

filter f m returns a map where only the (key, value) pairs of m such that f key value = true remain. The bindings are passed to f in increasing order with respect to the ordering over the type of the keys. If f returns true for all bindings of m the returned map is physically equal to m.

Before 3.3.0 physical equality was not ensured.

val filter_map : ('key -> 'a -> 'b option) -> ('key, 'a) t -> ('key, 'b) t

filter_map f m combines the features of filter and map. It calls calls f key0 a0, f key1 a1, f keyn an where a0..an are the elements of m and key0..keyn the respective corresponding keys. It returns the map of (keyi, bi) pairs such as f keyi ai = Some bi (when f returns None, the corresponding element of m is discarded).

val choose : ('key, 'a) t -> 'key * 'a

Return one binding of the given map. Which binding is chosen is unspecified, but equal bindings will be chosen for equal maps.

Raises Not_found if the map is empty

val choose_opt : ('key, 'a) t -> ('key * 'a) option

Return Some (k, v) for one binding (k, v) of the given map, if the map is not empty. Else, return None. Which binding is chosen is unspecified, but equal bindings will be chosen for equal maps.

Since 3.3.0

val any : ('key, 'a) t -> 'key * 'a

Return one binding of the given map. The difference with choose is that there is no guarantee that equals elements will be picked for equal sets. This merely returns the quickest binding to get (O(1)).

Raises Not_found if the map is empty.

val split : 'key ->
       ('key, 'a) t -> ('key, 'a) t * 'a option * ('key, 'a) t

split x m returns a triple (l, data, r), where l is the map with all the bindings of m whose key is strictly less than x; r is the map with all the bindings of m whose key is strictly greater than x; data is None if m contains no binding for x, or Some v if m binds v to x.

val min_binding : ('key, 'a) t -> 'key * 'a

Returns the binding with the smallest key. Raises Not_found if the map is empty.

val min_binding_opt : ('key, 'a) t -> ('key * 'a) option

Return Some (key, value) for the key, value pair with the smallest key, or None if the map is empty.

Since 3.3.0

val pop_min_binding : ('key, 'a) t -> ('key * 'a) * ('key, 'a) t

Returns the binding with the smallest key along with the rest of the map.

val max_binding : ('key, 'a) t -> 'key * 'a

Return the (key, value) pair with the largest key. Raises Not_found if the map is empty.

val max_binding_opt : ('key, 'a) t -> ('key * 'a) option

Return Some (key, value) for the key, value pair with the largest key, or None if the map is empty.

Since 3.3.0

val pop_max_binding : ('key, 'a) t -> ('key * 'a) * ('key, 'a) t

Returns the binding with the largest key along with the rest of the map.

val enum : ('a, 'b) t -> ('a * 'b) BatEnum.t

Creates an enumeration for this map, enumerating (key, value) pairs with the keys in increasing order.

val backwards : ('a, 'b) t -> ('a * 'b) BatEnum.t

Creates an enumeration for this map, enumerating (key, value) pairs with the keys in decreasing order.

val keys : ('a, 'b) t -> 'a BatEnum.t

Return an enumeration of all the keys of a map.

val values : ('a, 'b) t -> 'b BatEnum.t

Return an enumeration of all the values of a map.

val of_enum : ('a * 'b) BatEnum.t -> ('a, 'b) t

Creates a map from an enumeration.

val for_all : ('a -> 'b -> bool) -> ('a, 'b) t -> bool

Tests whether all (key, value) pairs satisfy a predicate function.

val exists : ('a -> 'b -> bool) -> ('a, 'b) t -> bool

Tests whether some (key, value) pair satisfies a predicate function.

val partition : ('a -> 'b -> bool) ->
       ('a, 'b) t -> ('a, 'b) t * ('a, 'b) t

partition p m returns a pair of maps (m1, m2), where m1 contains all the bindings of s that satisfy the predicate p, and m2 is the map with all the bindings of s that do not satisfy p.

val add_carry : 'a -> 'b -> ('a, 'b) t -> ('a, 'b) t * 'b option

add_carry k v m adds the binding (k, v) to m, returning the new map and optionally the previous value bound to k.

val modify : 'a -> ('b -> 'b) -> ('a, 'b) t -> ('a, 'b) t

modify k f m replaces the previous binding for k with f applied to that value. If k is unbound in m or Not_found is raised during the search, Not_found is raised.

Since 1.2.0
Raises Not_found if k is unbound in m (or f raises Not_found)

val modify_def : 'b -> 'a -> ('b -> 'b) -> ('a, 'b) t -> ('a, 'b) t

modify_def v0 k f m replaces the previous binding for k with f applied to that value. If k is unbound in m or Not_found is raised during the search, f v0 is inserted (as if the value found were v0).

Since 1.3.0

val modify_opt : 'a -> ('b option -> 'b option) -> ('a, 'b) t -> ('a, 'b) t

modify_opt k f m allow to modify the binding for k in m or absence thereof.

Since 2.1

val extract : 'a -> ('a, 'b) t -> 'b * ('a, 'b) t

extract k m removes the current binding of k from m, returning the value k was bound to and the updated m.

val pop : ('a, 'b) t -> ('a * 'b) * ('a, 'b) t

pop m returns a binding from m and m without that binding.

val union : ('a, 'b) t -> ('a, 'b) t -> ('a, 'b) t

union m1 m2 merges two maps, using the comparison function of m1. In case of conflicted bindings, m2's bindings override m1's. Equivalent to foldi add m2 m1. The resulting map uses the comparison function of m1.

val union_stdlib : ('key -> 'a -> 'a -> 'a option) ->
       ('key, 'a) t -> ('key, 'a) t -> ('key, 'a) t

union_stdlib f m1 m2 computes a map whose keys are a subset of the keys of m1 and of m2. When the same binding is defined in both arguments, the function f is used to combine them. This function is similar to merge, except f is only called if a key is present in both m1 and m2. If a key is present in either m1 or m2 but not in both, it (and the corresponding value) will be present in the resulting map.

This is the union method from the stdlib map, renamed for backwards compatibility.

Since 3.3.0

val to_seq : ('key, 'a) t -> ('key * 'a) BatSeq.t

Iterate on the whole map, in ascending order of keys.

Since 3.3.0

val to_rev_seq : ('key, 'a) t -> ('key * 'a) BatSeq.t

Iterate on the whole map, in descending order of keys.

Since 3.3.0

val to_seq_from : 'key -> ('key, 'a) t -> ('key * 'a) BatSeq.t

to_seq_from k m iterates on a subset of the bindings in m, namely those bindings greater or equal to k, in ascending order.

Since 3.3.0

val add_seq : ('key * 'a) BatSeq.t -> ('key, 'a) t -> ('key, 'a) t

add the given bindings to the map, in order.

Since 3.3.0

val of_seq : ('key * 'a) BatSeq.t -> ('key, 'a) t

build a map from the given bindings

Since 3.3.0

val diff : ('a, 'b) t -> ('a, 'b) t -> ('a, 'b) t

diff m1 m2 removes all bindings of keys found in m2 from m1, using the comparison function of m1. Equivalent to foldi (fun k _v m -> remove k m) m2 m1. The resulting map uses the comparison function of m1.

val intersect : ('b -> 'c -> 'd) ->
       ('a, 'b) t -> ('a, 'c) t -> ('a, 'd) t

intersect merge_f m1 m2 returns a map with bindings only for keys bound in both m1 and m2, and with k bound to merge_f v1 v2, where v1 and v2 are k's bindings in m1 and m2. The resulting map uses the comparison function of m1.

val merge : ('key -> 'a option -> 'b option -> 'c option) ->
       ('key, 'a) t -> ('key, 'b) t -> ('key, 'c) t

merge f m1 m2 computes a map whose keys is a subset of keys of m1 and of m2. The presence of each such binding, and the corresponding value, is determined with the function f. The resulting map uses the comparison function of m1.

val compare : ('b -> 'b -> int) -> ('a, 'b) t -> ('a, 'b) t -> int

val equal : ('b -> 'b -> bool) -> ('a, 'b) t -> ('a, 'b) t -> bool

Construct a comparison or equality function for maps based on a value comparison or equality function. Uses the key comparison function to compare keys

module Exceptionless: sig .. end

Exceptionless versions of functions

module Infix: sig .. end

Infix operators over a BatPMap

val (-->) : ('a, 'b) t -> 'a -> 'b

Map find and insert from Infix

val (<--) : ('a, 'b) t -> 'a * 'b -> ('a, 'b) t

val bindings : ('key, 'a) t -> ('key * 'a) list

Return the list of all bindings of the given map. The returned list is sorted in increasing key order.

Added for compatibility with stdlib 3.12

Boilerplate code

Printing

val print : ?first:string ->
       ?last:string ->
       ?sep:string ->
       ?kvsep:string ->
       ('a BatInnerIO.output -> 'b -> unit) ->
       ('a BatInnerIO.output -> 'c -> unit) ->
       'a BatInnerIO.output -> ('b, 'c) t -> unit

module PMap: sig .. end