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>

1 files changed, 29 insertions, 0 deletions

diff --git a/src/corelib/tools/qmap.qdoc b/src/corelib/tools/qmap.qdoc
index ace09e7391..3fec85e5b2 100644
--- a/src/corelib/tools/qmap.qdoc
+++ b/src/corelib/tools/qmap.qdoc
@@ -334,6 +334,21 @@
     \sa clear(), take()
 */
 
+/*! \fn template <class Key, class T> template <typename Predicate> size_type QMap<Key, T>::removeIf(Predicate pred)
+    \since 6.1
+
+    Removes all elements for which the predicate \a pred returns true
+    from the map.
+
+    The function supports predicates which take either an argument of
+    type \c{QMap<Key, T>::iterator}, or an argument of type
+    \c{std::pair<const Key &, T &>}.
+
+    Returns the number of elements removed, if any.
+
+    \sa clear(), take()
+*/
+
 /*! \fn template <class Key, class T> T QMap<Key, T>::take(const Key &key)
 
     Removes the item with the key \a key from the map and returns
@@ -1372,3 +1387,17 @@
 
     \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
 */
+
+/*! \fn template <typename Key, typename T, typename Predicate> qsizetype erase_if(QMap<Key, T> &map, Predicate pred)
+    \relates QMap
+    \since 6.1
+
+    Removes all elements for which the predicate \a pred returns true
+    from the map \a map.
+
+    The function supports predicates which take either an argument of
+    type \c{QMap<Key, T>::iterator}, or an argument of type
+    \c{std::pair<const Key &, T &>}.
+
+    Returns the number of elements removed, if any.
+*/