Non-associative containers: add range constructors

Something nice we'd like to detect for array-backed containers
is if the iterator passed is a Contiguous one; if the type is also
trivially copyable / Q_PRIMITIVE_TYPE, we could memcpy() the whole
range.

However, there's no trait in the Standard to detect contiguous
iterators (the best approximation would be detecting if the iterator
is actually a pointer). Also, it's probably not smart to do the work
now for QVector since QVector needs refactoring anyhow, and this work
will be lost.

QString and QByteArray are left in another commit.

[ChangeLog][QtCore][QVector] Added range constructor.

[ChangeLog][QtCore][QVarLengthArray] Added range constructor.

[ChangeLog][QtCore][QList] Added range constructor.

[ChangeLog][QtCore][QStringList] Added range constructor.

[ChangeLog][QtCore][QLinkedList] Added range constructor.

[ChangeLog][QtCore][QSet] Added range constructor.

Change-Id: I220edb796053c9c4d31a6dbdc7efc5fc0f6678f9
Reviewed-by: Milian Wolff <milian.wolff@kdab.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/src/corelib/tools/qset.h b/src/corelib/tools/qset.h
index aa915f7ed1..7ae715d247 100644
--- a/src/corelib/tools/qset.h
+++ b/src/corelib/tools/qset.h
@@ -41,6 +41,8 @@
 #define QSET_H
 
 #include <QtCore/qhash.h>
+#include <QtCore/qcontainertools_impl.h>
+
 #ifdef Q_COMPILER_INITIALIZER_LISTS
 #include <initializer_list>
 #endif
@@ -59,12 +61,16 @@ public:
     inline QSet() noexcept {}
 #ifdef Q_COMPILER_INITIALIZER_LISTS
     inline QSet(std::initializer_list<T> list)
+        : QSet(list.begin(), list.end()) {}
+#endif
+    template <typename InputIterator, QtPrivate::IfIsInputIterator<InputIterator> = true>
+    inline QSet(InputIterator first, InputIterator last)
     {
-        reserve(int(list.size()));
-        for (typename std::initializer_list<T>::const_iterator it = list.begin(); it != list.end(); ++it)
-            insert(*it);
+        QtPrivate::reserveIfForwardIterator(this, first, last);
+        for (; first != last; ++first)
+            insert(*first);
     }
-#endif
+
     // compiler-generated copy/move ctor/assignment operators are fine!
     // compiler-generated destructor is fine!