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Diffstat (limited to 'lib/compiler/src/cerl_sets.erl')
| -rw-r--r-- | lib/compiler/src/cerl_sets.erl | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/lib/compiler/src/cerl_sets.erl b/lib/compiler/src/cerl_sets.erl new file mode 100644 index 0000000000..4df78dc432 --- /dev/null +++ b/lib/compiler/src/cerl_sets.erl @@ -0,0 +1,206 @@ +%% +%% %CopyrightBegin% +%% +%% Copyright Ericsson AB 2000-2015. All Rights Reserved. +%% +%% The contents of this file are subject to the Erlang Public License, +%% Version 1.1, (the "License"); you may not use this file except in +%% compliance with the License. You should have received a copy of the +%% Erlang Public License along with this software. If not, it can be +%% retrieved online at http://www.erlang.org/. +%% +%% Software distributed under the License is distributed on an "AS IS" +%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See +%% the License for the specific language governing rights and limitations +%% under the License. +%% +%% %CopyrightEnd% +%% + +-module(cerl_sets). + +%% Standard interface. +-export([new/0,is_set/1,size/1,to_list/1,from_list/1]). +-export([is_element/2,add_element/2,del_element/2]). +-export([union/2,union/1,intersection/2,intersection/1]). +-export([is_disjoint/2]). +-export([subtract/2,is_subset/2]). +-export([fold/3,filter/2]). + +-export_type([set/0, set/1]). + +%%------------------------------------------------------------------------------ + +-type set() :: set(_). +-opaque set(Element) :: #{Element => 'ok'}. + +%%------------------------------------------------------------------------------ + +%% new() -> Set +-spec new() -> set(). + +new() -> #{}. + +%% is_set(Set) -> boolean(). +%% Return 'true' if Set is a set of elements, else 'false'. +-spec is_set(Set) -> boolean() when + Set :: term(). + +is_set(S) when is_map(S) -> true; +is_set(_) -> false. + +%% size(Set) -> int(). +%% Return the number of elements in Set. +-spec size(Set) -> non_neg_integer() when + Set :: set(). + +size(S) -> maps:size(S). + +%% to_list(Set) -> [Elem]. +%% Return the elements in Set as a list. +-spec to_list(Set) -> List when + Set :: set(Element), + List :: [Element]. + +to_list(S) -> maps:keys(S). + +%% from_list([Elem]) -> Set. +%% Build a set from the elements in List. +-spec from_list(List) -> Set when + List :: [Element], + Set :: set(Element). +from_list(Ls) -> maps:from_list([{K,ok}||K<-Ls]). + +%% is_element(Element, Set) -> boolean(). +%% Return 'true' if Element is an element of Set, else 'false'. +-spec is_element(Element, Set) -> boolean() when + Set :: set(Element). + +is_element(E,S) -> + case S of + #{E := _} -> true; + _ -> false + end. + +%% add_element(Element, Set) -> Set. +%% Return Set with Element inserted in it. +-spec add_element(Element, Set1) -> Set2 when + Set1 :: set(Element), + Set2 :: set(Element). + +add_element(E,S) -> S#{E=>ok}. + +-spec del_element(Element, Set1) -> Set2 when + Set1 :: set(Element), + Set2 :: set(Element). + +%% del_element(Element, Set) -> Set. +%% Return Set but with Element removed. +del_element(E,S) -> maps:remove(E,S). + +%% union(Set1, Set2) -> Set +%% Return the union of Set1 and Set2. +-spec union(Set1, Set2) -> Set3 when + Set1 :: set(Element), + Set2 :: set(Element), + Set3 :: set(Element). + +union(S1,S2) -> maps:merge(S1,S2). + +%% union([Set]) -> Set +%% Return the union of the list of sets. +-spec union(SetList) -> Set when + SetList :: [set(Element)], + Set :: set(Element). + +union([S1,S2|Ss]) -> + union1(union(S1, S2), Ss); +union([S]) -> S; +union([]) -> new(). + +union1(S1, [S2|Ss]) -> + union1(union(S1, S2), Ss); +union1(S1, []) -> S1. + +%% intersection(Set1, Set2) -> Set. +%% Return the intersection of Set1 and Set2. +-spec intersection(Set1, Set2) -> Set3 when + Set1 :: set(Element), + Set2 :: set(Element), + Set3 :: set(Element). + +intersection(S1, S2) -> + filter(fun (E) -> is_element(E, S1) end, S2). + +%% intersection([Set]) -> Set. +%% Return the intersection of the list of sets. +-spec intersection(SetList) -> Set when + SetList :: [set(Element),...], + Set :: set(Element). + +intersection([S1,S2|Ss]) -> + intersection1(intersection(S1, S2), Ss); +intersection([S]) -> S. + +intersection1(S1, [S2|Ss]) -> + intersection1(intersection(S1, S2), Ss); +intersection1(S1, []) -> S1. + +%% is_disjoint(Set1, Set2) -> boolean(). +%% Check whether Set1 and Set2 are disjoint. +-spec is_disjoint(Set1, Set2) -> boolean() when + Set1 :: set(Element), + Set2 :: set(Element). + +is_disjoint(S1, S2) when map_size(S1) < map_size(S2) -> + fold(fun (_, false) -> false; + (E, true) -> not is_element(E, S2) + end, true, S1); +is_disjoint(S1, S2) -> + fold(fun (_, false) -> false; + (E, true) -> not is_element(E, S1) + end, true, S2). + +%% subtract(Set1, Set2) -> Set. +%% Return all and only the elements of Set1 which are not also in +%% Set2. +-spec subtract(Set1, Set2) -> Set3 when + Set1 :: set(Element), + Set2 :: set(Element), + Set3 :: set(Element). + +subtract(S1, S2) -> + filter(fun (E) -> not is_element(E, S2) end, S1). + +%% is_subset(Set1, Set2) -> boolean(). +%% Return 'true' when every element of Set1 is also a member of +%% Set2, else 'false'. +-spec is_subset(Set1, Set2) -> boolean() when + Set1 :: set(Element), + Set2 :: set(Element). + +is_subset(S1, S2) -> + fold(fun (E, Sub) -> Sub andalso is_element(E, S2) end, true, S1). + +%% fold(Fun, Accumulator, Set) -> Accumulator. +%% Fold function Fun over all elements in Set and return Accumulator. +-spec fold(Function, Acc0, Set) -> Acc1 when + Function :: fun((Element, AccIn) -> AccOut), + Set :: set(Element), + Acc0 :: Acc, + Acc1 :: Acc, + AccIn :: Acc, + AccOut :: Acc. + +fold(F, Init, D) -> + lists:foldl(fun(E,Acc) -> F(E,Acc) end,Init,maps:keys(D)). + +%% filter(Fun, Set) -> Set. +%% Filter Set with Fun. +-spec filter(Pred, Set1) -> Set2 when + Pred :: fun((Element) -> boolean()), + Set1 :: set(Element), + Set2 :: set(Element). + +filter(F, D) -> + maps:from_list(lists:filter(fun({K,_}) -> F(K) end, maps:to_list(D))). |