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  1. Qt
  2. QTBUG-106176

Q(Multi)Hash is missing equal_range()

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    • Icon: Suggestion Suggestion
    • Resolution: Unresolved
    • Icon: P3: Somewhat important P3: Somewhat important
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    • Core: Containers and Algorithms
    • None
    • 8
    • Foundation PM Prioritized

      Q(Multi)Hash, unlike QMap containers, and unlike std::unordered_map, lacks the equal_range() function. Currently, the only option to find the range of equal elements in a QMultiHash is to loop over the successors of the result of find(), which is not very nice.

      Acceptance criteria: The following test passes and has complexity linear in N = std::distance(b, e):

      QMultiHash<int, QString> h = {
    {0, "zero"},
    {1, "one"},
    {1, "uno"},
    {2, "two"},
};
auto r = h.equal_range(1);
static_assert(std::is_same_v<decltype(r.first), QMultiHash<int, QString>::iterator>);
static_assert(std::is_same_v<decltype(r.second), QMultiHash<int, QString>::iterator>);
QCOMPARE_NE(r.first, h.end());
QCOMPARE_NE(r.second, h.end());
QCOMPARE_NEW(r.first, r.second);
QCOMPARE_EQ(std::distance(r.first, r.second), 2);
QCOMPARE_EQ(r.first.key(), 1);
QCOMPARE_EQ(std::next(r.first).key(), 1);
h.erase(r.first, r.second); // QTBUG-106175
QMultiHash<int, QString> res = {{0, "zero"), {2, "two"}};
QCOMPARE_EQ(h, res);

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            cnn Qt Core & Network
            mmutz Marc Mutz
            Vladimir Minenko Vladimir Minenko
            Alex Blasche Alex Blasche
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              Created:
              Updated:

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