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#pragma once
namespace storm {
/**
* Location dependency declarations for objects in the GC.
*
* This object encapsulates an interface which enables users to query if an object has been
* moved by the GC since the last time it was accessed. This is useful when implementing hash
* maps for which the object's location is its key into the table. Moving the object alters this
* identity, and therefore destroys the hash map. Using a GcWatch to keep track of changes
* allows the map to detect these conditions and act accordingly.
*
* Note: Call runtime::createWatch() to create GcWatch objects.
*/
class GcWatch : NoCopy {
public:
// Add an address to be watched.
virtual void add(const void *addr) = 0;
// Remove an address from the watchlist.
virtual void remove(const void *addr) = 0;
// Clear all watched addresses.
virtual void clear() = 0;
// See if any object has moved. May return false positives.
virtual bool moved() = 0;
// See if the object has moved. May return false positives.
virtual bool moved(const void *addr) = 0;
// See if this object is tagged, i.e. making 'moved' always return true.
virtual bool tagged() = 0;
// Clone this GcWatch (and its current state).
virtual GcWatch *clone() const = 0;
};
}
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