%--------------------------------------------------%
% vim: ts=4 sw=4 et ft=mercury
%--------------------------------------------------%
% Copyright (C) 2005-2006, 2010-2012 The University of Melbourne.
% Copyright (C) 2014-2019, 2021-2022 The Mercury team.
% This file is distributed under the terms specified in COPYING.LIB.
%--------------------------------------------------%
%
% File: set_ctree234.m.
% Author: zs.
% Stability: high.
%
% This module implements sets using 2-3-4 trees extended with element counts.
% This representation has higher constant factors for most operations than
% ordered lists, but it has much better worst-case complexity, and is likely
% to be faster for large sets. Specifically,
%
% - the cost of lookups is only logarithmic in the size of the set, not linear;
%
% - for operations that are intrinsically linear in the size of one input
%   operand or the other, the counts allow us to choose to be linear in the
%   size of the smaller set.
%
%--------------------------------------------------%
%--------------------------------------------------%

:- module set_ctree234.
:- interface.

:- import_module bool.
:- import_module list.

%--------------------------------------------------%

:- type set_ctree234(_T).

%--------------------------------------------------%
%
% Initial creation of sets.
%

    % init = Set is true iff Set is an empty set.
    %
:- func init = set_ctree234(T).

    % singleton_set(Elem, Set) is true iff Set is the set containing just
    % the single element Elem.
    %
:- pred singleton_set(T, set_ctree234(T)).
:- mode singleton_set(in, out) is det.
:- mode singleton_set(out, in) is semidet.

:- func make_singleton_set(T) = set_ctree234(T).

%--------------------------------------------------%
%
% Emptiness and singleton-ness tests.
%

    % is_empty(Set) is true iff Set is an empty set.
    %
:- pred is_empty(set_ctree234(_T)::in) is semidet.

    % is_non_empty(Set) is true iff Set is not an empty set.
    %
:- pred is_non_empty(set_ctree234(T)::in) is semidet.

:- pred is_singleton(set_ctree234(T)::in, T::out) is semidet.

%--------------------------------------------------%
%
% Membership tests.
%

    % member(X, Set) is true iff X is a member of Set.
    %
:- pred member(T, set_ctree234(T)).
:- mode member(in, in) is semidet.
:- mode member(out, in) is nondet.

    % one_member(Set, X) is true iff X is a member of Set.
    %
:- pred one_member(set_ctree234(T)::in, T::out) is nondet.

    % is_member(Set, X, Result) returns `Result = yes' iff
    % X is a member of Set.
    %
:- func is_member(set_ctree234(T), T) = bool.
:- pred is_member(set_ctree234(T)::in, T::in, bool::out) is det.

    % contains(Set, X) is true iff X is a member of Set.
    %
:- pred contains(set_ctree234(T)::in, T::in) is semidet.

%--------------------------------------------------%
%
% Insertions and deletions.
%

    % insert(X, Set0, Set) is true iff Set is the union of Set0
    % and the set containing only X.
    %
:- func insert(T, set_ctree234(T)) = set_ctree234(T).
:- pred insert(T::in, set_ctree234(T)::in, set_ctree234(T)::out) is det.

    % insert_new(X, Set0, Set) is true iff Set0 does not contain X,
    % and Set is the union of Set0 and the set containing only X.
    %
:- pred insert_new(T::in, set_ctree234(T)::in, set_ctree234(T)::out)
    is semidet.

    % insert_list(Xs, Set0, Set) is true iff Set is the union of Set0
    % and the set containing only the members of Xs.
    %
:- func insert_list(list(T), set_ctree234(T)) = set_ctree234(T).
:- pred insert_list(list(T)::in, set_ctree234(T)::in, set_ctree234(T)::out)
    is det.

    % delete(X, Set0, Set) is true iff Set is the
    % relative complement of Set0 and the set containing only X, i.e.
    % if Set is the set which contains all the elements of Set0
    % except X.
    %
:- func delete(T, set_ctree234(T)) = set_ctree234(T).
:- pred delete(T::in, set_ctree234(T)::in, set_ctree234(T)::out) is det.

    % delete_list(Xs, Set0, Set) is true iff Set is the relative complement
    % of Set0 and the set containing only the members of Xs.
    %
:- func delete_list(list(T), set_ctree234(T)) = set_ctree234(T).
:- pred delete_list(list(T)::in, set_ctree234(T)::in, set_ctree234(T)::out)
    is det.

    % remove(X, Set0, Set) is true iff Set0 contains X,
    % and Set is the relative complement of Set0 and the set containing
    % only X, i.e. if Set is the set which contains all the elements
    % of Set0 except X.
    %
    % The det_remove version throws an exception instead of failing.
    %
:- pred remove(T::in, set_ctree234(T)::in, set_ctree234(T)::out) is semidet.
:- pred det_remove(T::in, set_ctree234(T)::in, set_ctree234(T)::out) is det.

    % remove_list(Xs, Set0, Set) is true iff Xs does not contain any
    % duplicates, Set0 contains every member of Xs, and Set is the
    % relative complement of Set0 and the set containing only the members of
    % Xs.
    %
    % The det_remove_list version throws an exception instead of failing.
    %
:- pred remove_list(list(T)::in, set_ctree234(T)::in, set_ctree234(T)::out)
    is semidet.
:- pred det_remove_list(list(T)::in, set_ctree234(T)::in, set_ctree234(T)::out)
    is det.

    % remove_least(X, Set0, Set) is true iff X is the least element in
    % Set0, and Set is the set which contains all the elements of Set0
    % except X.
    %
:- pred remove_least(T::out, set_ctree234(T)::in, set_ctree234(T)::out)
    is semidet.

%--------------------------------------------------%
%
% Comparisons between sets.
%

    % equal(SetA, SetB) is true iff SetA and SetB contain
    % the same elements.
    %
:- pred equal(set_ctree234(T)::in, set_ctree234(T)::in) is semidet.

    % subset(SetA, SetB) is true iff SetA is a subset of SetB.
    %
:- pred subset(set_ctree234(T)::in, set_ctree234(T)::in) is semidet.

    % superset(SetA, SetB) is true iff SetA is a superset of SetB.
    %
:- pred superset(set_ctree234(T)::in, set_ctree234(T)::in) is semidet.

%--------------------------------------------------%
%
% Operations on two or more sets.
%

    % union(SetA, SetB) = Set is true iff Set is the union of SetA and
    % SetB.
    %
:- func union(set_ctree234(T), set_ctree234(T)) = set_ctree234(T).
:- pred union(set_ctree234(T)::in, set_ctree234(T)::in, set_ctree234(T)::out)
    is det.

    % union_list(A, B) is true iff B is the union of all the sets in A.
    %
:- func union_list(list(set_ctree234(T))) = set_ctree234(T).
:- pred union_list(list(set_ctree234(T))::in, set_ctree234(T)::out) is det.

    % power_union(A) = B is true iff B is the union of all the sets in A.
    %
:- func power_union(set_ctree234(set_ctree234(T))) = set_ctree234(T).
:- pred power_union(set_ctree234(set_ctree234(T))::in, set_ctree234(T)::out)
    is det.

    % intersect(SetA, SetB) = Set is true iff Set is the intersection of
    % SetA and SetB.
    %
:- func intersect(set_ctree234(T), set_ctree234(T)) = set_ctree234(T).
:- pred intersect(set_ctree234(T)::in, set_ctree234(T)::in,
    set_ctree234(T)::out) is det.

    % intersect_list(A) = B is true iff B is the intersection
    % of all the sets in A.
    %
:- func intersect_list(list(set_ctree234(T))) = set_ctree234(T).

    % power_intersect(A, B) is true iff B is the intersection
    % of all the sets in A.
    %
:- func power_intersect(set_ctree234(set_ctree234(T))) = set_ctree234(T).

    % difference(SetA, SetB, Set) is true iff Set is the set containing
    % all the elements of SetA except those that occur in SetB.
    %
:- func difference(set_ctree234(T), set_ctree234(T)) = set_ctree234(T).
:- pred difference(set_ctree234(T)::in, set_ctree234(T)::in,
    set_ctree234(T)::out) is det.

    % intersection_and_differences(SetA, SetB, InAandB, OnlyInA, OnlyInB):
    % Given SetA and SetB, return the elements that occur in both sets,
    % and those that occur only in one or the other.
    %
:- pred intersection_and_differences(set_ctree234(T)::in, set_ctree234(T)::in,
    set_ctree234(T)::out, set_ctree234(T)::out, set_ctree234(T)::out) is det.

%--------------------------------------------------%
%
% Operations that divide a set into two parts.
%

    % divide(Pred, Set, TruePart, FalsePart):
    % TruePart consists of those elements of Set for which Pred succeeds;
    % FalsePart consists of those elements of Set for which Pred fails.
    % NOTE: This is the same as filter/4.
    %
:- pred divide(pred(T)::in(pred(in) is semidet),
    set_ctree234(T)::in, set_ctree234(T)::out, set_ctree234(T)::out) is det.

    % divide_by_set(DivideBySet, Set, InPart, OutPart):
    % InPart consists of those elements of Set which are also in
    % DivideBySet; OutPart consists of those elements of which are
    % not in DivideBySet.
    %
:- pred divide_by_set(set_ctree234(T)::in, set_ctree234(T)::in,
    set_ctree234(T)::out, set_ctree234(T)::out) is det.

%--------------------------------------------------%
%
% Converting lists to sets.
%

    % list_to_set(List) = Set is true iff Set is the set
    % containing only the members of List.
    %
    % `from_list' is a synonym for `list_to_set'.
    %
:- func list_to_set(list(T)) = set_ctree234(T).
:- func from_list(list(T)) = set_ctree234(T).

    % sorted_list_to_set(List) = Set is true iff Set is the set
    % containing only the members of List. List must be sorted
    % in ascending order and must not contain any duplicates.
    %
:- func sorted_list_to_set(list(T)) = set_ctree234(T).

    % rev_sorted_list_to_set(List) = Set is true iff Set is the set
    % containing only the members of List. List must be sorted
    % in descending order and must not contain any duplicates.
    %
:- func rev_sorted_list_to_set(list(T)) = set_ctree234(T).

%--------------------------------------------------%
%
% Converting sets to lists.
%

    % to_sorted_list(Set) = List is true iff List is the list
    % of all the members of Set, in sorted order.
    %
:- func to_sorted_list(set_ctree234(T)) = list(T).

%--------------------------------------------------%
%
% Counting.
%

    % count(Set, Count) is true iff Set has Count elements.
    %
:- func count(set_ctree234(T)) = int.

:- pred verify_depths(set_ctree234(T)::in, list(int)::out) is det.

%--------------------------------------------------%
%
% Standard higher order functions on collections.
%

    % all_true(Pred, Set) succeeds iff Pred(Element) succeeds for all the
    % elements of Set.
    %
:- pred all_true(pred(T)::in(pred(in) is semidet),
    set_ctree234(T)::in) is semidet.

    % Return the set of items for which the predicate succeeds.
    %
:- pred filter(pred(T)::in(pred(in) is semidet),
    set_ctree234(T)::in, set_ctree234(T)::out) is det.

    % Return the set of items for which the predicate succeeds,
    % and the set for which it fails.
    %
:- pred filter(pred(T)::in(pred(in) is semidet),
    set_ctree234(T)::in, set_ctree234(T)::out, set_ctree234(T)::out) is det.

:- func filter_map(func(T1) = T2, set_ctree234(T1)) = set_ctree234(T2).
:- mode filter_map(in(func(in) = out is semidet), in) = out is det.

:- pred filter_map(pred(T1, T2)::in(pred(in, out) is semidet),
    set_ctree234(T1)::in, set_ctree234(T2)::out) is det.

:- func map(func(T1) = T2, set_ctree234(T1)) = set_ctree234(T2).
:- pred map(pred(T1, T2)::in(pred(in, out) is det),
    set_ctree234(T1)::in, set_ctree234(T2)::out) is det.

:- func fold(func(T1, T2) = T2, set_ctree234(T1), T2) = T2.
:- pred fold(pred(T1, T2, T2), set_ctree234(T1), T2, T2).
:- mode fold(in(pred(in, in, out) is det), in, in, out) is det.
:- mode fold(in(pred(in, mdi, muo) is det), in, mdi, muo) is det.
:- mode fold(in(pred(in, di, uo) is det), in, di, uo) is det.
:- mode fold(in(pred(in, in, out) is semidet), in, in, out) is semidet.
:- mode fold(in(pred(in, mdi, muo) is semidet), in, mdi, muo) is semidet.
:- mode fold(in(pred(in, di, uo) is semidet), in, di, uo) is semidet.

:- pred fold2(pred(T1, T2, T2, T3, T3), set_ctree234(T1),
    T2, T2, T3, T3).
:- mode fold2(in(pred(in, in, out, in, out) is det),
    in, in, out, in, out) is det.
:- mode fold2(in(pred(in, in, out, mdi, muo) is det),
    in, in, out, mdi, muo) is det.
:- mode fold2(in(pred(in, in, out, di, uo) is det),
    in, in, out, di, uo) is det.
:- mode fold2(in(pred(in, in, out, in, out) is semidet),
    in, in, out, in, out) is semidet.
:- mode fold2(in(pred(in, in, out, mdi, muo) is semidet),
    in, in, out, mdi, muo) is semidet.
:- mode fold2(in(pred(in, in, out, di, uo) is semidet),
    in, in, out, di, uo) is semidet.

:- pred fold3(
    pred(T1, T2, T2, T3, T3, T4, T4), set_ctree234(T1),
    T2, T2, T3, T3, T4, T4).
:- mode fold3(in(pred(in, in, out, in, out, in, out) is det), in,
    in, out, in, out, in, out) is det.
:- mode fold3(in(pred(in, in, out, in, out, mdi, muo) is det), in,
    in, out, in, out, mdi, muo) is det.
:- mode fold3(in(pred(in, in, out, in, out, di, uo) is det), in,
    in, out, in, out, di, uo) is det.
:- mode fold3(in(pred(in, in, out, in, out, in, out) is semidet), in,
    in, out, in, out, in, out) is semidet.
:- mode fold3(in(pred(in, in, out, in, out, mdi, muo) is semidet), in,
    in, out, in, out, mdi, muo) is semidet.
:- mode fold3(in(pred(in, in, out, in, out, di, uo) is semidet), in,
    in, out, in, out, di, uo) is semidet.

:- pred fold4(
    pred(T1, T2, T2, T3, T3, T4, T4, T5, T5), set_ctree234(T1),
    T2, T2, T3, T3, T4, T4, T5, T5).
:- mode fold4(
    in(pred(in, in, out, in, out, in, out, in, out) is det),
    in, in, out, in, out, in, out, in, out) is det.
:- mode fold4(
    in(pred(in, in, out, in, out, in, out, mdi, muo) is det),
    in, in, out, in, out, in, out, mdi, muo) is det.
:- mode fold4(
    in(pred(in, in, out, in, out, in, out, di, uo) is det),
    in, in, out, in, out, in, out, di, uo) is det.
:- mode fold4(
    in(pred(in, in, out, in, out, in, out, in, out) is semidet),
    in, in, out, in, out, in, out, in, out) is semidet.
:- mode fold4(
    in(pred(in, in, out, in, out, in, out, mdi, muo) is semidet),
    in, in, out, in, out, in, out, mdi, muo) is semidet.
:- mode fold4(
    in(pred(in, in, out, in, out, in, out, di, uo) is semidet),
    in, in, out, in, out, in, out, di, uo) is semidet.

:- pred fold5(
    pred(T1, T2, T2, T3, T3, T4, T4, T5, T5, T6, T6),
    set_ctree234(T1), T2, T2, T3, T3, T4, T4, T5, T5, T6, T6).
:- mode fold5(
    in(pred(in, in, out, in, out, in, out, in, out, in, out) is det),
    in, in, out, in, out, in, out, in, out, in, out) is det.
:- mode fold5(
    in(pred(in, in, out, in, out, in, out, in, out, mdi, muo) is det),
    in, in, out, in, out, in, out, in, out, mdi, muo) is det.
:- mode fold5(
    in(pred(in, in, out, in, out, in, out, in, out, di, uo) is det),
    in, in, out, in, out, in, out, in, out, di, uo) is det.
:- mode fold5(
    in(pred(in, in, out, in, out, in, out, in, out, in, out) is semidet),
    in, in, out, in, out, in, out, in, out, in, out) is semidet.
:- mode fold5(
    in(pred(in, in, out, in, out, in, out, in, out, mdi, muo) is semidet),
    in, in, out, in, out, in, out, in, out, mdi, muo) is semidet.
:- mode fold5(
    in(pred(in, in, out, in, out, in, out, in, out, di, uo) is semidet),
    in, in, out, in, out, in, out, in, out, di, uo) is semidet.

:- pred fold6(
    pred(T1, T2, T2, T3, T3, T4, T4, T5, T5, T6, T6, T7, T7),
    set_ctree234(T1), T2, T2, T3, T3, T4, T4, T5, T5, T6, T6, T7, T7).
:- mode fold6(
    in(pred(in, in, out, in, out, in, out, in, out, in, out, in, out) is det),
    in, in, out, in, out, in, out, in, out, in, out, in, out) is det.
:- mode fold6(
    in(pred(in, in, out, in, out, in, out, in, out, in, out, mdi, muo) is det),
    in, in, out, in, out, in, out, in, out, in, out, mdi, muo) is det.
:- mode fold6(
    in(pred(in, in, out, in, out, in, out, in, out, in, out, di, uo) is det),
    in, in, out, in, out, in, out, in, out, in, out, di, uo) is det.
:- mode fold6(
    in(pred(in, in, out, in, out, in, out, in, out, in, out, in, out)
        is semidet),
    in, in, out, in, out, in, out, in, out, in, out, in, out) is semidet.
:- mode fold6(
    in(pred(in, in, out, in, out, in, out, in, out, in, out, mdi, muo)
        is semidet),
    in, in, out, in, out, in, out, in, out, in, out, mdi, muo) is semidet.
:- mode fold6(
    in(pred(in, in, out, in, out, in, out, in, out, in, out, di, uo)
        is semidet),
    in, in, out, in, out, in, out, in, out, in, out, di, uo) is semidet.

%--------------------------------------------------%
%--------------------------------------------------%