Add QIntrusiveList::contains() function

QIntrusiveList is nice, but it needs a contains() function.

Change-Id: I17adf63db080ffd39acac18cd8ecb23e48d76ed6
Reviewed-on: http://codereview.qt.nokia.com/2569
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Aaron Kennedy <aaron.kennedy@nokia.com>

src/declarative/qml/qintrusivelist.cpp

@@ -112,6 +112,12 @@ removed and inserted at the head of this list.
 Remove \a object from the list.  \a object must not be null.
 */
 
+/*!
+\fn bool QIntrusiveList::contains(N *object) const
+
+Returns true if the list contains \a object; otherwise returns false.
+*/
+
 /*!
 \fn N *QIntrusiveList::first() const
 

src/declarative/qml/qintrusivelist_p.h

@@ -68,6 +68,7 @@ public:
     inline bool isEmpty() const;
     inline void insert(N *n);
     inline void remove(N *n);
+    inline bool contains(N *) const;
 
     class iterator {
     public:
@@ -201,6 +202,18 @@ void QIntrusiveList<N, member>::remove(N *n)
     nnode->remove();
 }
 
+template<class N, QIntrusiveListNode N::*member>
+bool QIntrusiveList<N, member>::contains(N *n) const
+{
+    QIntrusiveListNode *nnode = __first;
+    while (nnode) {
+        if (nodeToN(nnode) == n)
+            return true;
+        nnode = nnode->_next;
+    }
+    return false;
+}
+
 template<class N, QIntrusiveListNode N::*member>
 N *QIntrusiveList<N, member>::first() const 
 {