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lightning-sunbird  0.9+nobinonly
nsPtrHashKey.h
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00003 /* ***** BEGIN LICENSE BLOCK *****
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00015  *
00016  * The Original Code is the Metrics extension.
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00022  * Contributor(s):
00023  *  Brian Ryner <bryner@brianryner.com>
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00038 
00039 // This class defines a templatized hash key type for holding raw pointers.
00040 // Use it like this:
00041 //   nsDataHashtable< nsPtrHashKey<SomeClass>, SomeValueType > mTable;
00042 //
00043 // This is identical to nsVoidPtrHashKey with void* replaced by T*.
00044 
00045 #ifndef nsPtrHashKey_h_
00046 #define nsPtrHashKey_h_
00047 
00048 #include "pldhash.h"
00049 #include "nscore.h"
00050 
00051 template<class T>
00052 class nsPtrHashKey : public PLDHashEntryHdr
00053 {
00054  public:
00055   typedef const T *KeyType;
00056   typedef const T *KeyTypePointer;
00057 
00058   nsPtrHashKey(const T *key) : mKey(key) {}
00059   nsPtrHashKey(const nsPtrHashKey<T> &toCopy) : mKey(toCopy.mKey) {}
00060   ~nsPtrHashKey() {}
00061 
00062   KeyType GetKey() const { return mKey; }
00063   KeyTypePointer GetKeyPointer() const { return mKey; }
00064 
00065   PRBool KeyEquals(KeyTypePointer key) const { return key == mKey; }
00066 
00067   static KeyTypePointer KeyToPointer(KeyType key) { return key; }
00068   static PLDHashNumber HashKey(KeyTypePointer key)
00069   {
00070     return NS_PTR_TO_INT32(key) >> 2;
00071   }
00072   enum { ALLOW_MEMMOVE = PR_TRUE };
00073 
00074  private:
00075   const T *mKey;
00076 };
00077 
00078 #endif  // nsPtrHashKey_h_