Initial community commit

Src/Plugins/Input/in_dshow/base/cache.h

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+//------------------------------------------------------------------------------
+// File: Cache.h
+//
+// Desc: DirectShow base classes - efines a non-MFC generic cache class.
+//
+// Copyright (c) 1992-2001 Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------------------------
+
+
+/* This class implements a simple cache. A cache object is instantiated
+   with the number of items it is to hold. An item is a pointer to an
+   object derived from CBaseObject (helps reduce memory leaks). The cache
+   can then have objects added to it and removed from it. The cache size
+   is fixed at construction time and may therefore run out or be flooded.
+   If it runs out it returns a NULL pointer, if it fills up it also returns
+   a NULL pointer instead of a pointer to the object just inserted */
+
+/* Making these classes inherit from CBaseObject does nothing for their
+   functionality but it allows us to check there are no memory leaks */
+
+/* WARNING Be very careful when using this class, what it lets you do is
+   store and retrieve objects so that you can minimise object creation
+   which in turns improves efficiency. However the object you store is
+   exactly the same as the object you get back which means that it short
+   circuits the constructor initialisation phase. This means any class
+   variables the object has (eg pointers) are highly likely to be invalid.
+   Therefore ensure you reinitialise the object before using it again */
+
+
+#ifndef __CACHE__
+#define __CACHE__
+
+
+class CCache : CBaseObject {
+
+    /* Make copy constructor and assignment operator inaccessible */
+
+    CCache(const CCache &refCache);
+    CCache &operator=(const CCache &refCache);
+
+private:
+
+    /* These are initialised in the constructor. The first variable points to
+       an array of pointers, each of which points to a CBaseObject derived
+       object. The m_iCacheSize is the static fixed size for the cache and the
+       m_iUsed defines the number of places filled with objects at any time.
+       We fill the array of pointers from the start (ie m_ppObjects[0] first)
+       and then only add and remove objects from the end position, so in this
+       respect the array of object pointers should be treated as a stack */
+
+    CBaseObject **m_ppObjects;
+    const INT m_iCacheSize;
+    INT m_iUsed;
+
+public:
+
+    CCache(__in_opt LPCTSTR pName,INT iItems);
+    virtual ~CCache();
+
+    /* Add an item to the cache */
+    CBaseObject *AddToCache(__in CBaseObject *pObject);
+
+    /* Remove an item from the cache */
+    CBaseObject *RemoveFromCache();
+
+    /* Delete all the objects held in the cache */
+    void RemoveAll(void);
+
+    /* Return the cache size which is set during construction */
+    INT GetCacheSize(void) const {return m_iCacheSize;};
+};
+
+#endif /* __CACHE__ */
+