%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2006-2009. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(next_perm).
-export([next_perm/1, prev_perm/1, load/0, all_perm/1]).
load() ->
case whereis(next_perm) of
undefined ->
case erl_ddll:load_driver(".", "next_perm") of
ok -> ok;
{error, already_loaded} -> ok;
E -> exit(E)
end,
Port = open_port({spawn, "next_perm"}, []),
register(next_perm, Port);
_ ->
ok
end.
list_to_integer_binaries(L) ->
[<<I:32/integer-native>> || I <- L].
next_perm(L) ->
next_perm(L, 1).
prev_perm(L) ->
next_perm(L, 2).
next_perm(L, Nxt) ->
load(),
B = list_to_integer_binaries(L),
Port = whereis(next_perm),
port_command(Port, [Nxt, B]),
receive
[Port | Result] ->
Result
end.
all_perm(L) ->
New = prev_perm(L),
all_perm(New, L, [New]).
all_perm(L, L, Acc) ->
Acc;
all_perm(L, Orig, Acc) ->
New = prev_perm(L),
all_perm(New, Orig, [New | Acc]).
