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feat(topic): avoid `lists:reverse` when intersecting

This commit is contained in:
Andrew Mayorov 2024-05-29 13:00:29 +02:00 committed by Serge Tupchii
parent 24be189728
commit 7b8f466adf
1 changed files with 28 additions and 25 deletions
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53
apps/emqx/src/emqx_topic.erl
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@ -112,37 +112,40 @@ match(_, _) ->
TopicOrFilter :: emqx_types:topic().
intersection(Topic1, Topic2) when is_binary(Topic1), is_binary(Topic2) ->
case intersect_start(words(Topic1), words(Topic2)) of
[] -> false;
Intersection -> join(lists:reverse(Intersection))
false -> false;
Intersection -> join(Intersection)
end.
intersect_start([<<"$", _/bytes>> | _], [W | _]) when ?IS_WILDCARD(W) ->
[];
false;
intersect_start([W | _], [<<"$", _/bytes>> | _]) when ?IS_WILDCARD(W) ->
[];
false;
intersect_start(Words1, Words2) ->
intersection(Words1, Words2, []).
intersect(Words1, Words2).
intersection(Words1, ['#'], Acc) ->
lists:reverse(Words1, Acc);
intersection(['#'], Words2, Acc) ->
lists:reverse(Words2, Acc);
intersection([W1], ['+'], Acc) ->
[W1 | Acc];
intersection(['+'], [W2], Acc) ->
[W2 | Acc];
intersection([W1 | T1], [W2 | T2], Acc) when ?IS_WILDCARD(W1), ?IS_WILDCARD(W2) ->
intersection(T1, T2, [wildcard_intersection(W1, W2) | Acc]);
intersection([W | T1], [W | T2], Acc) ->
intersection(T1, T2, [W | Acc]);
intersection([W1 | T1], [W2 | T2], Acc) when ?IS_WILDCARD(W1) ->
intersection(T1, T2, [W2 | Acc]);
intersection([W1 | T1], [W2 | T2], Acc) when ?IS_WILDCARD(W2) ->
intersection(T1, T2, [W1 | Acc]);
intersection([], [], Acc) ->
Acc;
intersection(_, _, _) ->
[].
intersect(Words1, ['#']) ->
Words1;
intersect(['#'], Words2) ->
Words2;
intersect([W1], ['+']) ->
[W1];
intersect(['+'], [W2]) ->
[W2];
intersect([W1 | T1], [W2 | T2]) when ?IS_WILDCARD(W1), ?IS_WILDCARD(W2) ->
intersect_join(wildcard_intersection(W1, W2), intersect(T1, T2));
intersect([W | T1], [W | T2]) ->
intersect_join(W, intersect(T1, T2));
intersect([W1 | T1], [W2 | T2]) when ?IS_WILDCARD(W1) ->
intersect_join(W2, intersect(T1, T2));
intersect([W1 | T1], [W2 | T2]) when ?IS_WILDCARD(W2) ->
intersect_join(W1, intersect(T1, T2));
intersect([], []) ->
[];
intersect(_, _) ->
false.
intersect_join(_, false) -> false;
intersect_join(W, Words) -> [W | Words].
wildcard_intersection(W, W) -> W;
wildcard_intersection(_, _) -> '+'.