Refactoring LookupContext.h

Extracting class AlreadyConsideredClassContainer to separate file

Change-Id: If3bb89df5ce0bae87723ad4ecab7118337df0655
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/libs/cplusplus/AlreadyConsideredClassContainer.h

@@ -0,0 +1,45 @@
+#ifndef CPLUSPLUS_ALREADYCONSIDEREDCLASSCONTAINER_H
+#define CPLUSPLUS_ALREADYCONSIDEREDCLASSCONTAINER_H
+
+#include <QSet>
+
+namespace CPlusPlus {
+
+template<typename T>
+class AlreadyConsideredClassContainer
+{
+public:
+    AlreadyConsideredClassContainer() : _class(0) {}
+    void insert(const T *item)
+    {
+        if (_container.isEmpty())
+            _class = item;
+        _container.insert(item);
+    }
+    bool contains(const T *item)
+    {
+        if (_container.contains(item))
+            return true;
+
+        foreach (const T *existingItem, _container) {
+            if (existingItem->isEqualTo(item))
+                return true;
+        }
+
+        return false;
+    }
+
+    void clear(const T *item)
+    {
+        if (_class != item || _container.size() == 1)
+            _container.clear();
+    }
+
+private:
+    QSet<const T *> _container;
+    const T * _class;
+};
+
+} // namespace CPlusPlus
+
+#endif // CPLUSPLUS_ALREADYCONSIDEREDCLASSCONTAINER_H