Associative containers: add erase_if
Use a trick similar to the one we use for their ranged constructors: support predicates that either take a container's iterator, or that take a std::pair (for STL compatibility). [ChangeLog][QtCore][QMap] Added removeIf() and erase_if(). [ChangeLog][QtCore][QMultiMap] Added removeIf() and erase_if(). [ChangeLog][QtCore][QHash] Added removeIf() and erase_if(). [ChangeLog][QtCore][QMultiHash] Added removeIf() and erase_if(). Change-Id: Ie40aadf6217d7a4126a626c390d530812ebcf020 Reviewed-by: Andrei Golubev <andrei.golubev@qt.io> Reviewed-by: Lars Knoll <lars.knoll@qt.io> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Giuseppe D'Angelo
parent
9341f2e3d0
commit
e12e2b43b7
@ -215,6 +215,58 @@ qsizetype qset_erase_if(QSet<T> &set, Predicate &pred)
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return result;
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}
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// Prerequisite: F is invocable on ArgTypes
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template <typename R, typename F, typename ... ArgTypes>
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struct is_invoke_result_explicitly_convertible : std::is_constructible<R, std::invoke_result_t<F, ArgTypes...>>
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{};
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// is_invocable_r checks for implicit conversions, but we need to check
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// for explicit conversions in remove_if. So, roll our own trait.
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template <typename R, typename F, typename ... ArgTypes>
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constexpr bool is_invocable_explicit_r_v = std::conjunction_v<
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std::is_invocable<F, ArgTypes...>,
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is_invoke_result_explicitly_convertible<R, F, ArgTypes...>
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>;
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template <typename Container, typename Predicate>
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auto associative_erase_if(Container &c, Predicate &pred)
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{
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// we support predicates callable with either Container::iterator
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// or with std::pair<const Key &, Value &>
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using Iterator = typename Container::iterator;
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using Key = typename Container::key_type;
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using Value = typename Container::mapped_type;
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using KeyValuePair = std::pair<const Key &, Value &>;
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typename Container::size_type result = 0;
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auto it = c.begin();
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const auto e = c.end();
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while (it != e) {
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if constexpr (is_invocable_explicit_r_v<bool, Predicate &, Iterator &>) {
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if (pred(it)) {
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it = c.erase(it);
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++result;
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} else {
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++it;
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}
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} else if constexpr (is_invocable_explicit_r_v<bool, Predicate &, KeyValuePair &&>) {
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KeyValuePair p(it.key(), it.value());
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if (pred(std::move(p))) {
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it = c.erase(it);
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++result;
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} else {
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++it;
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}
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} else {
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static_assert(sizeof(Container) == 0, "Predicate has an incompatible signature");
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}
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}
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return result;
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}
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} // namespace QtPrivate
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QT_END_NAMESPACE
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@ -1521,6 +1521,21 @@ size_t qHash(long double key, size_t seed) noexcept
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\sa clear(), take()
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*/
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/*! \fn template <class Key, class T> template <typename Predicate> qsizetype QHash<Key, T>::removeIf(Predicate pred)
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\since 6.1
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Removes all elements for which the predicate \a pred returns true
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from the hash.
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The function supports predicates which take either an argument of
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type \c{QHash<Key, T>::iterator}, or an argument of type
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\c{std::pair<const Key &, T &>}.
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Returns the number of elements removed, if any.
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\sa clear(), take()
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*/
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/*! \fn template <class Key, class T> T QHash<Key, T>::take(const Key &key)
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Removes the item with the \a key from the hash and returns
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@ -2651,6 +2666,21 @@ size_t qHash(long double key, size_t seed) noexcept
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\sa remove()
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*/
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/*! \fn template <class Key, class T> template <typename Predicate> qsizetype QMultiHash<Key, T>::removeIf(Predicate pred)
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\since 6.1
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Removes all elements for which the predicate \a pred returns true
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from the multi hash.
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The function supports predicates which take either an argument of
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type \c{QMultiHash<Key, T>::iterator}, or an argument of type
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\c{std::pair<const Key &, T &>}.
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Returns the number of elements removed, if any.
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\sa clear(), take()
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*/
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/*! \fn template <class Key, class T> T QMultiHash<Key, T>::take(const Key &key)
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Removes the item with the \a key from the hash and returns
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@ -3338,4 +3368,32 @@ size_t qHash(long double key, size_t seed) noexcept
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Type \c T must be supported by qHash().
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*/
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/*! \fn template <typename Key, typename T, typename Predicate> qsizetype erase_if(QHash<Key, T> &hash, Predicate pred)
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\relates QHash
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\since 6.1
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Removes all elements for which the predicate \a pred returns true
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from the hash \a hash.
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The function supports predicates which take either an argument of
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type \c{QHash<Key, T>::iterator}, or an argument of type
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\c{std::pair<const Key &, T &>}.
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Returns the number of elements removed, if any.
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*/
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/*! \fn template <typename Key, typename T, typename Predicate> qsizetype erase_if(QMultiHash<Key, T> &hash, Predicate pred)
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\relates QMultiHash
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\since 6.1
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Removes all elements for which the predicate \a pred returns true
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from the multi hash \a hash.
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The function supports predicates which take either an argument of
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type \c{QMultiHash<Key, T>::iterator}, or an argument of type
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\c{std::pair<const Key &, T &>}.
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Returns the number of elements removed, if any.
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*/
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QT_END_NAMESPACE
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@ -872,6 +872,11 @@ public:
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d->erase(it);
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return true;
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}
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template <typename Predicate>
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qsizetype removeIf(Predicate pred)
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{
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return QtPrivate::associative_erase_if(*this, pred);
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}
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T take(const Key &key)
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{
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if (isEmpty()) // prevents detaching shared null
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@ -1354,6 +1359,11 @@ public:
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d->erase(it);
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return n;
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}
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template <typename Predicate>
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qsizetype removeIf(Predicate pred)
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{
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return QtPrivate::associative_erase_if(*this, pred);
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}
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T take(const Key &key)
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{
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if (isEmpty()) // prevents detaching shared null
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@ -1946,6 +1956,18 @@ inline size_t qHash(const QMultiHash<Key, T> &key, size_t seed = 0)
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return hash;
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}
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template <typename Key, typename T, typename Predicate>
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qsizetype erase_if(QHash<Key, T> &hash, Predicate pred)
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{
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return QtPrivate::associative_erase_if(hash, pred);
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}
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template <typename Key, typename T, typename Predicate>
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qsizetype erase_if(QMultiHash<Key, T> &hash, Predicate pred)
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{
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return QtPrivate::associative_erase_if(hash, pred);
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}
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QT_END_NAMESPACE
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#endif // QHASH_H
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@ -343,6 +343,12 @@ public:
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return result;
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}
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template <typename Predicate>
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size_type removeIf(Predicate pred)
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{
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return QtPrivate::associative_erase_if(*this, pred);
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}
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T take(const Key &key)
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{
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if (!d)
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@ -742,6 +748,12 @@ public:
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Q_DECLARE_ASSOCIATIVE_ITERATOR(Map)
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Q_DECLARE_MUTABLE_ASSOCIATIVE_ITERATOR(Map)
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template <typename Key, typename T, typename Predicate>
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qsizetype erase_if(QMap<Key, T> &map, Predicate pred)
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{
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return QtPrivate::associative_erase_if(map, pred);
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}
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//
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// QMultiMap
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//
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@ -938,6 +950,12 @@ public:
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return result;
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}
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template <typename Predicate>
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size_type removeIf(Predicate pred)
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{
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return QtPrivate::associative_erase_if(*this, pred);
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}
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T take(const Key &key)
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{
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if (!d)
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@ -1441,6 +1459,12 @@ QMultiMap<Key, T> operator+=(QMultiMap<Key, T> &lhs, const QMultiMap<Key, T> &rh
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return lhs.unite(rhs);
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}
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template <typename Key, typename T, typename Predicate>
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qsizetype erase_if(QMultiMap<Key, T> &map, Predicate pred)
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{
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return QtPrivate::associative_erase_if(map, pred);
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}
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QT_END_NAMESPACE
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#endif // QMAP_H
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@ -334,6 +334,21 @@
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\sa clear(), take()
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*/
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/*! \fn template <class Key, class T> template <typename Predicate> size_type QMap<Key, T>::removeIf(Predicate pred)
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\since 6.1
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Removes all elements for which the predicate \a pred returns true
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from the map.
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The function supports predicates which take either an argument of
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type \c{QMap<Key, T>::iterator}, or an argument of type
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\c{std::pair<const Key &, T &>}.
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Returns the number of elements removed, if any.
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\sa clear(), take()
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*/
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/*! \fn template <class Key, class T> T QMap<Key, T>::take(const Key &key)
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Removes the item with the key \a key from the map and returns
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@ -1372,3 +1387,17 @@
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\sa{Serializing Qt Data Types}{Format of the QDataStream operators}
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*/
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/*! \fn template <typename Key, typename T, typename Predicate> qsizetype erase_if(QMap<Key, T> &map, Predicate pred)
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\relates QMap
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\since 6.1
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Removes all elements for which the predicate \a pred returns true
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from the map \a map.
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The function supports predicates which take either an argument of
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type \c{QMap<Key, T>::iterator}, or an argument of type
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\c{std::pair<const Key &, T &>}.
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Returns the number of elements removed, if any.
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*/
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@ -352,6 +352,21 @@
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\sa clear(), take()
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*/
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/*! \fn template <class Key, class T> template <typename Predicate> size_type QMultiMap<Key, T>::removeIf(Predicate pred)
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\since 6.1
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Removes all elements for which the predicate \a pred returns true
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from the multi map.
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The function supports predicates which take either an argument of
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type \c{QMultiMap<Key, T>::iterator}, or an argument of type
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\c{std::pair<const Key &, T &>}.
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Returns the number of elements removed, if any.
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\sa clear(), take()
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*/
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/*! \fn template <class Key, class T> T QMultiMap<Key, T>::take(const Key &key)
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Removes the item with the key \a key from the multi map and returns
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@ -1508,3 +1523,17 @@
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\sa{Serializing Qt Data Types}{Format of the QDataStream operators}
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*/
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/*! \fn template <typename Key, typename T, typename Predicate> qsizetype erase_if(QMultiMap<Key, T> &map, Predicate pred)
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\relates QMultiMap
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\since 6.1
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Removes all elements for which the predicate \a pred returns true
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from the multi map \a map.
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The function supports predicates which take either an argument of
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type \c{QMultiMap<Key, T>::iterator}, or an argument of type
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\c{std::pair<const Key &, T &>}.
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Returns the number of elements removed, if any.
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*/
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@ -334,6 +334,9 @@ private:
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template <typename Container>
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void erase_if_impl() const;
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template <typename Container>
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void erase_if_associative_impl() const;
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private Q_SLOTS:
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void erase_QList() { erase_impl<QList<int>>(); }
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void erase_QVarLengthArray() { erase_impl<QVarLengthArray<int>>(); }
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@ -355,6 +358,10 @@ private Q_SLOTS:
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erase_if_impl<std::vector<int>>();
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#endif
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}
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void erase_if_QMap() { erase_if_associative_impl<QMap<int, int>>(); }
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void erase_if_QMultiMap() {erase_if_associative_impl<QMultiMap<int, int>>(); }
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void erase_if_QHash() { erase_if_associative_impl<QHash<int, int>>(); }
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void erase_if_QMultIHash() { erase_if_associative_impl<QMultiHash<int, int>>(); }
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};
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void tst_ContainerApiSymmetry::init()
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@ -647,6 +654,17 @@ Container make(int size)
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return c;
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}
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template <typename Container>
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Container makeAssociative(int size)
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{
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using K = typename Container::key_type;
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using V = typename Container::mapped_type;
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Container c;
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for (int i = 1; i <= size; ++i)
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c.insert(K(i), V(i));
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return c;
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}
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static QString s_string = QStringLiteral("\1\2\3\4\5\6\7");
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template <> QString make(int size) { return s_string.left(size); }
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@ -728,5 +746,54 @@ void tst_ContainerApiSymmetry::erase_if_impl() const
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QCOMPARE(c.size(), S(0));
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}
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template <typename Container>
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void tst_ContainerApiSymmetry::erase_if_associative_impl() const
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{
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using S = typename Container::size_type;
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using K = typename Container::key_type;
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using V = typename Container::mapped_type;
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using I = typename Container::iterator;
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using P = std::pair<const K &, V &>;
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auto c = makeAssociative<Container>(20);
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QCOMPARE(c.size(), S(20));
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auto result = erase_if(c, [](const P &p) { return Conv::toInt(p.first) % 2 == 0; });
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QCOMPARE(result, S(10));
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QCOMPARE(c.size(), S(10));
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result = erase_if(c, [](const P &p) { return Conv::toInt(p.first) % 3 == 0; });
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QCOMPARE(result, S(3));
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QCOMPARE(c.size(), S(7));
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result = erase_if(c, [](const P &p) { return Conv::toInt(p.first) % 42 == 0; });
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QCOMPARE(result, S(0));
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QCOMPARE(c.size(), S(7));
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result = erase_if(c, [](const P &p) { return Conv::toInt(p.first) % 2 == 1; });
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QCOMPARE(result, S(7));
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QCOMPARE(c.size(), S(0));
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// same, but with a predicate taking a Qt iterator
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c = makeAssociative<Container>(20);
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QCOMPARE(c.size(), S(20));
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result = erase_if(c, [](const I &it) { return Conv::toInt(it.key()) % 2 == 0; });
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QCOMPARE(result, S(10));
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QCOMPARE(c.size(), S(10));
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result = erase_if(c, [](const I &it) { return Conv::toInt(it.key()) % 3 == 0; });
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QCOMPARE(result, S(3));
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QCOMPARE(c.size(), S(7));
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result = erase_if(c, [](const I &it) { return Conv::toInt(it.key()) % 42 == 0; });
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QCOMPARE(result, S(0));
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QCOMPARE(c.size(), S(7));
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result = erase_if(c, [](const I &it) { return Conv::toInt(it.key()) % 2 == 1; });
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QCOMPARE(result, S(7));
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QCOMPARE(c.size(), S(0));
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}
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QTEST_APPLESS_MAIN(tst_ContainerApiSymmetry)
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#include "tst_containerapisymmetry.moc"
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