Simplify the code for QList::emplace()

Unify it with the code in QArrayDataOps and only have one
emplace method there that handles it all.

Adjust autotests to API changes in QArrayDataOps and fix a
wrong test case (that just happened to pass by chance before).

Change-Id: Ia08cadebe2f74b82c31f856b1ff8a3d8dc400a3c
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 21 insertions, 33 deletions

diff --git a/src/corelib/tools/qarraydataops.h b/src/corelib/tools/qarraydataops.h
index 3548424b53..c2414f22f2 100644
--- a/src/corelib/tools/qarraydataops.h
+++ b/src/corelib/tools/qarraydataops.h
@@ -1345,22 +1345,28 @@ public:
     }
 
     template<typename... Args>
-    void emplace(T *where, Args &&... args)
+    void emplace(qsizetype i, Args &&... args)
     {
-        Q_ASSERT(!this->isShared());
-        Q_ASSERT(where >= this->begin() && where <= this->end());
-        Q_ASSERT(this->allocatedCapacity() - this->size >= 1);
-
-        const T *begin = this->begin();
-        const T *end = this->end();
-        // Qt5 QList in insert(1): try to move less data around
-        // Now:
-        const bool shouldInsertAtBegin =
-                (where - begin) < (end - where) || this->freeSpaceAtEnd() <= 0;
-        if (this->freeSpaceAtBegin() > 0 && shouldInsertAtBegin) {
-            Base::emplace(GrowsBackwardsTag{}, where, std::forward<Args>(args)...);
+        typename QArrayData::GrowthPosition pos = QArrayData::GrowsAtEnd;
+        if (this->size != 0 && i <= (this->size >> 1))
+            pos = QArrayData::GrowsAtBeginning;
+        if (this->needsDetach() ||
+            (pos == QArrayData::GrowsAtBeginning && !this->freeSpaceAtBegin()) ||
+            (pos == QArrayData::GrowsAtEnd && !this->freeSpaceAtEnd())) {
+            T tmp(std::forward<Args>(args)...);
+            this->reallocateAndGrow(pos, 1);
+
+            T *where = this->begin() + i;
+            if (pos == QArrayData::GrowsAtBeginning)
+                Base::emplace(GrowsBackwardsTag{}, where, std::move(tmp));
+            else
+                Base::emplace(GrowsForwardTag{}, where, std::move(tmp));
         } else {
-            Base::emplace(GrowsForwardTag{}, where, std::forward<Args>(args)...);
+            T *where = this->begin() + i;
+            if (pos == QArrayData::GrowsAtBeginning)
+                Base::emplace(GrowsBackwardsTag{}, where, std::forward<Args>(args)...);
+            else
+                Base::emplace(GrowsForwardTag{}, where, std::forward<Args>(args)...);
         }
     }
 
diff --git a/src/corelib/tools/qlist.h b/src/corelib/tools/qlist.h
index a5cb560dc0..9c95d49bae 100644
--- a/src/corelib/tools/qlist.h
+++ b/src/corelib/tools/qlist.h
@@ -743,25 +743,7 @@ typename QList<T>::iterator
 QList<T>::emplace(qsizetype i, Args&&... args)
 {
     Q_ASSERT_X(i >= 0 && i <= d->size, "QList<T>::insert", "index out of range");
-
-    if (d->needsDetach() || (d.size == d.constAllocatedCapacity())) {
-        typename QArrayData::GrowthPosition pos = QArrayData::GrowsAtEnd;
-        if (d.size != 0 && i <= (d.size >> 1))
-            pos = QArrayData::GrowsAtBeginning;
-
-        DataPointer detached(DataPointer::allocateGrow(d, 1, pos));
-        const_iterator where = constBegin() + i;
-
-        // protect against args being an element of the container
-        T tmp(std::forward<Args>(args)...);
-
-        detached->copyAppend(constBegin(), where);
-        detached->emplace(detached.end(), std::move(tmp));
-        detached->copyAppend(where, constEnd());
-        d.swap(detached);
-    } else {
-        d->emplace(d.begin() + i, std::forward<Args>(args)...);
-    }
+    d->emplace(i, std::forward<Args>(args)...);
     return d.begin() + i;
 }