Module Core_kernel.Map

Test if invariants of internal AVL search tree hold.

The empty map.

Map with one (key, data) pair.

Creates map from an association list with unique keys.

Creates map from an association list with unique keys. Returns an error if duplicate 'a keys are found.

Creates map from an association list with unique keys. Raises an exception if duplicate 'a keys are found.

of_hashtbl_exn creates a map from bindings present in a hash table. of_hashtbl_exn raises if there are distinct keys a1 and a2 in the table with comparator.compare a1 a2 = 0, which is only possible if the hash-table comparison function is different than comparator.compare. In the common case, the comparison is the same, in which case of_hashtbl_exn does not raise, regardless of the keys present in the table.

Creates map from an association list with possibly repeated keys.

Combines an association list into a map, folding together bound values with common keys.

Combines an association list into a map, reducing together bound values with common keys.

of_iteri ~iteri behaves like of_alist, except that instead of taking a concrete datastruture, it takes an iteration function. For instance, to convert a string table into a map: of_iteri (module String) ~f:(Hashtbl.iteri table). It is faster than adding the elements one by one.

Creates a t from a Tree.t and a Comparator.t. This is an O(n) operation as it must discover the length of the Tree.t.

Creates map from a sorted array of key-data pairs. The input array must be sorted, as given by the relevant comparator (either in ascending or descending order), and must not contain any duplicate keys. If either of these conditions does not hold, an error is returned.

Like of_sorted_array except it returns a map with broken invariants when an Error would have been returned.

of_increasing_iterator_unchecked c ~len ~f behaves like of_sorted_array_unchecked c (Array.init len ~f), with the additional restriction that a decreasing order is not supported. The advantage is not requiring you to allocate an intermediate array. f will be called with 0, 1, ... len - 1, in order.

of_increasing_sequence c seq behaves like of_sorted_array c (Sequence.to_array seq), but does not allocate the intermediate array.

The sequence will be folded over once, and the additional time complexity is O(n).

Tests whether a map is empty or not.

length map returns number of elements in map. O(1), but Tree.length is O(n).

add_exn t ~key ~data returns t extended with key mapped to data, raising if mem key t.

Returns a new map with the specified new binding; if the key was already bound, its previous binding disappears.

If key is not present then add a singleton list, otherwise, cons data onto the head of the existing list.

If k is present then remove its head element; if result is empty, remove the key.

find_multi t key returns t's values for key if key is present in the table, and returns the empty list otherwise.

change t key ~f returns a new map m that is the same as t on all keys except for key, and whose value for key is defined by f, i.e., find m key = f (find t key).

update t key ~f is change t key ~f:(fun o -> Some (f o)).

Returns the value bound to the given key if it exists, and None otherwise.

Returns the value bound to the given key, raising Not_found if none such exists.

Returns a new map with any binding for the key in question removed.

mem map key tests whether map contains a binding for key.

Iterates two maps side by side. The complexity of this function is O(M+N). If two inputs are [(0, a); (1, a)] and [(1, b); (2, b)], f will be called with [(0, `Left a); (1, `Both (a, b)); (2, `Right b)]

Returns new map with bound values replaced by the result of f applied to them.

Like map, but f takes both key and data as arguments.

Folds over keys and data in map in increasing order of key.

Folds over keys and data in map in decreasing order of key.

Folds over two maps side by side, like iter2.

Returns new map with bound values filtered by the result of f applied to them.

Like filter_map, but function takes both key and data as arguments.

partition_mapi t ~f returns two new ts, with each key in t appearing in exactly one of the result maps depending on its mapping in f.

partition_map t ~f = partition_mapi t ~f:(fun ~key:_ ~data -> f data)

     partitioni_tf t ~f
     =
     partition_mapi t ~f:(fun ~key ~data ->
       if f ~key ~data
       then `Fst data
       else `Snd data)

partition_tf t ~f = partitioni_tf t ~f:(fun ~key:_ ~data -> f data)

Total ordering between maps. The first argument is a total ordering used to compare data associated with equal keys in the two maps.

Hash function: a building block to use when hashing data structures containing maps in them. hash_fold_direct hash_fold_key is compatible with compare_direct iff hash_fold_key is compatible with (comparator m).compare of the map m being hashed.

equal cmp m1 m2 tests whether the maps m1 and m2 are equal, that is, contain equal keys and associate them with equal data. cmp is the equality predicate used to compare the data associated with the keys.

Returns list of keys in map.

Returns list of data in map.

Creates association list from map.

• Parameter key_order: default is `Increasing

Merges two maps. The runtime is O(length(t1) + length(t2)). In particular, you shouldn't use this function to merge a list of maps. Consider using merge_skewed instead.

A special case of merge, merge_skewed t1 t2 is a map containing all the bindings of t1 and t2. Bindings that appear in both t1 and t2 are merged using the combine function. In a call combine ~key v1 v2 the value v1 comes from t1 and v2 from t2.

The runtime of merge_skewed is O(l1 * log(l2)), where l1 is the length of the smaller map and l2 the length of the larger map. This is likely to be faster than merge when one of the maps is a lot smaller, or when you merge a list of maps.

symmetric_diff t1 t2 ~data_equal returns a list of changes between t1 and t2. It is intended to be efficient in the case where t1 and t2 share a large amount of structure. The keys in the output sequence will be in sorted order.

min_elt map returns Some (key, data) pair corresponding to the minimum key in map, None if map is empty.

max_elt map returns Some (key, data) pair corresponding to the maximum key in map, and None if map is empty.

split t key returns a map of keys strictly less than key, the mapping of key if any, and a map of keys strictly greater than key.

Runtime is O(m + log n) where n is the size of the input map, and m is the size of the smaller of the two output maps. The O(m) term is due to the need to calculate the length of the output maps. *

append ~lower_part ~upper_part returns `Ok map where map contains all the (key, value) pairs from the two input maps if all the keys from lower_part are less than all the keys from upper_part. Otherwise it returns `Overlapping_key_ranges.

Runtime is O(log n) where n is the size of the larger input map. This can be significantly faster than Map.merge or repeated Map.add.

      assert (match Map.append ~lower_part ~upper_part with
        | `Ok whole_map ->
          whole_map
          = Map.(of_alist_exn (List.append (to_alist lower_part) (to_alist upper_part)))
        | `Overlapping_key_ranges -> true);

subrange t ~lower_bound ~upper_bound returns a map containing all the entries from t whose keys lie inside the interval indicated by ~lower_bound and ~upper_bound. If this interval is empty, an empty map is returned.

Runtime is O(m + log n) where n is the size of the input map, and m is the size of the output map. The O(m) term is due to the need to calculate the length of the output map.

fold_range_inclusive t ~min ~max ~init ~f folds f (with initial value ~init) over all keys (and their associated values) that are in the range [min, max] (inclusive).

range_to_alist t ~min ~max returns an associative list of the elements whose keys lie in [min, max] (inclusive), with the smallest key being at the head of the list.

closest_key t dir k returns the (key, value) pair in t with key closest to k, which satisfies the given inequality bound.

For example, closest_key t `Less_than k would be the pair with the closest key to k where key < k.

to_sequence can be used to get the same results as closest_key. It is less efficient for individual lookups but more efficient for finding many elements starting at some value.

nth t n finds the (key, value) pair of rank n (i.e., such that there are exactly n keys strictly less than the found key), if one exists. O(log(length t) + n) time.

rank t k if k is in t, returns the number of keys strictly less than k in t, otherwise None.

to_sequence ?order ?keys_greater_or_equal_to ?keys_less_or_equal_to t gives a sequence of key-value pairs between keys_less_or_equal_to and keys_greater_or_equal_to inclusive, presented in order. If keys_greater_or_equal_to > keys_less_or_equal_to, the sequence is empty. Cost is O(log n) up front and amortized O(1) to produce each element.

• Parameter order: `Increasing_key is the default

This shrinker and the other shrinkers for maps and trees produce a shrunk value by dropping a key-value pair, shrinking a key or shrinking a value. A shrunk key will override an existing key's value.