Added const accessors to the IDC Values Cache

Event/EventContainers/EventContainers/IdentifiableValueCache.h

@@ -47,9 +47,15 @@ public:
    ///Retrieve the Value stored in that hash
    T retrieve(size_t i){   return m_vec.at(i).load(); }
 
+   /// As above, but no cache extension
+   T retrieve(size_t i) const {  return i < maxSize() ? static_cast<T>(m_vec[i]) : emptyValue() ; }
+
    ///Returns true if the value is set to anything but the emptyValue
    bool present(size_t i){  return m_vec.at(i).load() != emptyValue();   }
 
+   /// As above, but no cache extension
+   bool present(size_t i) const {  return  i < maxSize() and m_vec[i] != emptyValue() ? true : false; }
+
    ///Set the given hash to the value
    bool setOrDrop(size_t i, const T &value);
 

Event/EventContainers/EventContainers/IdentifiableValueContainer.h

@@ -21,6 +21,8 @@ class IdentifiableValueContainer : IdentifiableValueContainerBase{
 
 public:
 
+  typedef IdentifiableValueCache<T> Cache;
+
    //Prevent accidental copying
    IdentifiableValueContainer(const IdentifiableValueContainer<T>&) = delete;
 
@@ -69,9 +71,12 @@ public:
    ///Get read only access to the whole external cache. This could be useful for special situations
    const std::vector<std::atomic<T>>& wholeEventReadAccess() const { return m_cache->rawReadAccess(); }
 
+   /// Obtain const access to the cache
+   const Cache* cache() const { return m_cache; }
+
 private:
    std::vector<bool> m_mask;
-   IdentifiableValueCache<T> *m_cache;
+   Cache *m_cache;
    bool m_own;
 };