Add erase operation to QArrayDataOps

Change-Id: I37d3ac465f5beddb5038e22e9cda32acb16c78fc
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qarraydataops.h

@@ -117,6 +117,16 @@ struct QPodArrayOps
         ::memcpy(where, b, (e - b) * sizeof(T));
         this->size += (e - b);
     }
+
+    void erase(T *b, T *e)
+    {
+        Q_ASSERT(b < e);
+        Q_ASSERT(b >= this->begin() && b < this->end());
+        Q_ASSERT(e > this->begin() && e < this->end());
+
+        ::memmove(b, e, (this->end() - e) * sizeof(T));
+        this->size -= (e - b);
+    }
 };
 
 template <class T>
@@ -250,6 +260,25 @@ struct QGenericArrayOps
             *writeIter = *e;
         }
     }
+
+    void erase(T *b, T *e)
+    {
+        Q_ASSERT(b < e);
+        Q_ASSERT(b >= this->begin() && b < this->end());
+        Q_ASSERT(e > this->begin() && e < this->end());
+
+        const T *const end = this->end();
+
+        do {
+            *b = *e;
+            ++b, ++e;
+        } while (e != end);
+
+        do {
+            (--e)->~T();
+            --this->size;
+        } while (e != b);
+    }
 };
 
 template <class T>
@@ -324,6 +353,40 @@ struct QMovableArrayOps
         displace.commit();
         this->size += (e - b);
     }
+
+    void erase(T *b, T *e)
+    {
+        Q_ASSERT(b < e);
+        Q_ASSERT(b >= this->begin() && b < this->end());
+        Q_ASSERT(e > this->begin() && e < this->end());
+
+        struct Mover
+        {
+            Mover(T *&start, const T *finish, int &sz)
+                : destination(start)
+                , source(start)
+                , n(finish - start)
+                , size(sz)
+            {
+            }
+
+            ~Mover()
+            {
+                ::memmove(destination, source, n * sizeof(T));
+                size -= (source - destination);
+            }
+
+            T *&destination;
+            const T *const source;
+            size_t n;
+            int &size;
+        } mover(e, this->end(), this->size);
+
+        do {
+            // Exceptions or not, dtor called once per instance
+            (--e)->~T();
+        } while (e != b);
+    }
 };
 
 template <class T, class = void>

tests/auto/corelib/tools/qarraydata/simplevector.h

@@ -302,6 +302,32 @@ public:
         d->insert(where, first, last);
     }
 
+    void erase(iterator first, iterator last)
+    {
+        if (first == last)
+            return;
+
+        const T *const begin = d->begin();
+        const T *const end = begin + d->size;
+
+        if (d.needsDetach()) {
+            SimpleVector detached(Data::allocate(
+                        d->detachCapacity(size() - (last - first)),
+                        d->detachFlags()));
+            if (first != begin)
+                detached.d->copyAppend(begin, first);
+            detached.d->copyAppend(last, end);
+            detached.swap(*this);
+
+            return;
+        }
+
+        if (last == end)
+            d->truncate(end - first);
+        else
+            d->erase(first, last);
+    }
+
     void swap(SimpleVector &other)
     {
         qSwap(d, other.d);

tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp

@@ -1222,6 +1222,59 @@ void tst_QArrayData::arrayOps2()
         QCOMPARE(vo[i].id, i + 5);
         QCOMPARE(int(vo[i].flags), int(CountedObject::DefaultConstructed));
     }
+
+    ////////////////////////////////////////////////////////////////////////////
+    vi.resize(10);
+    vs.resize(10);
+    vo.resize(10);
+
+    for (size_t i = 7; i < 10; ++i) {
+        vi[i] = i;
+        vs[i] = QString::number(i);
+
+        QCOMPARE(vo[i].id, i);
+        QCOMPARE(int(vo[i].flags), int(CountedObject::DefaultConstructed));
+    }
+
+    QCOMPARE(CountedObject::liveCount, size_t(10));
+
+    ////////////////////////////////////////////////////////////////////////////
+    // erase
+    vi.erase(vi.begin() + 2, vi.begin() + 5);
+    vs.erase(vs.begin() + 2, vs.begin() + 5);
+    vo.erase(vo.begin() + 2, vo.begin() + 5);
+
+    QCOMPARE(vi.size(), size_t(7));
+    QCOMPARE(vs.size(), size_t(7));
+    QCOMPARE(vo.size(), size_t(7));
+
+    QCOMPARE(CountedObject::liveCount, size_t(7));
+    for (size_t i = 0; i < 2; ++i) {
+        QCOMPARE(vi[i], 0);
+        QVERIFY(vs[i].isNull());
+
+        QCOMPARE(vo[i].id, i);
+        QCOMPARE(int(vo[i].flags), CountedObject::DefaultConstructed
+                | CountedObject::CopyConstructed);
+    }
+
+    for (size_t i = 2; i < 4; ++i) {
+        QCOMPARE(vi[i], 0);
+        QVERIFY(vs[i].isNull());
+
+        QCOMPARE(vo[i].id, i + 8);
+        QCOMPARE(int(vo[i].flags), int(CountedObject::DefaultConstructed)
+                | CountedObject::CopyAssigned);
+    }
+
+    for (size_t i = 4; i < 7; ++i) {
+        QCOMPARE(vi[i], int(i + 3));
+        QCOMPARE(vs[i], QString::number(i + 3));
+
+        QCOMPARE(vo[i].id, i + 3);
+        QCOMPARE(int(vo[i].flags), CountedObject::DefaultConstructed
+                | CountedObject::CopyAssigned);
+    }
 }
 
 Q_DECLARE_METATYPE(QArrayDataPointer<int>)