compiler: Add cerl_sets module

A sets implementation based on maps.

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))).